CN115507808B - Test device and method for simulating stress-deformation characteristics of existing tunnels under adjacent tunnel construction conditions - Google Patents
Test device and method for simulating stress-deformation characteristics of existing tunnels under adjacent tunnel construction conditions Download PDFInfo
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- CN115507808B CN115507808B CN202211115355.6A CN202211115355A CN115507808B CN 115507808 B CN115507808 B CN 115507808B CN 202211115355 A CN202211115355 A CN 202211115355A CN 115507808 B CN115507808 B CN 115507808B
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
- G01B21/32—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring the deformation in a solid
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
- G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
- G01N2001/366—Moulds; Demoulding
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- General Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
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Abstract
The device comprises a model box, an existing tunnel model, a newly built tunnel model, test sand and a monitoring system, wherein the existing tunnel model and the newly built tunnel model are arranged in an orthogonal mode; the existing tunnel model comprises a plurality of tunnel pipe rings which are printed in a 3D mode and spliced into a whole, wherein each tunnel pipe ring is formed by splicing 1 capping pipe piece, 2 adjacent pipe pieces and 3 standard pipe pieces through bolts; the newly built tunnel model is made of an aluminum alloy pipe, and the pipe wall of the aluminum alloy pipe is wrapped with a plurality of liquid bags; the monitoring system comprises a ground surface deformation monitoring system and an existing tunnel model stress deformation monitoring system. The invention is convenient to assemble and disassemble, can simulate various construction working conditions close to the tunnel and well reflect the stressed deformation characteristic of the actual tunnel, can well reflect stratum loss caused by construction by a liquid discharge method, does not need to adopt dragging or jacking equipment to finish the installation of the tunnel, improves the feasibility of the test and reduces the cost of the test.
Description
Technical Field
The invention relates to the field of tunnel engineering, in particular to a test device and a test method for simulating stress deformation characteristics of an existing tunnel under the construction condition of an adjacent tunnel.
Background
With the rapid development of urban underground space, more and more underground building structures are close to the existing building structures for construction, the existing shield tunnel is early in planning and design and shallow in burial depth, the ground is mostly an urban building, and no redundant space is suitable for upper crossing of a newly-built tunnel. In addition to further development of underground space, more and more newly built tunnels adopt a construction scheme of lower crossing. The construction of a newly built tunnel can cause the surrounding soil body to generate complex change processes such as extrusion, shearing, twisting, relaxation and the like, so that the stress field and the displacement field of the stratum are changed. These effects can directly act on the adjacent existing tunnel to induce the existing tunnel to displace, deform and twist, thereby causing the seam to open and the lining segment to be damaged, and causing the potential safety hazard of the existing tunnel structure.
The model test is a relatively visual and reliable means for researching geotechnical engineering problems. At present, two main methods are adopted for simulating the influence of a model test on the construction of a newly-built tunnel: direct and indirect processes. The direct method simulates the jacking process of the shield tunnel in a jacking or dragging mode, for example, a model simulation test device for the existing tunnel to pass through under the tunnel is developed in the publication of application number 202110796587.1, and the tunnel passing-through process is simulated in a steel wire rope traction mode, but the direct method has higher requirements on the model device, requires an additional power device and a deviation correcting device, and is extremely easy to cause larger errors if the operation is improper. For the indirect method, the influence of the tunnel construction process, such as a movable door method, a flexible tunneling method, a liquid discharge method and the like, is indirectly reflected by simulating soil deformation and stratum loss, but the related invention related to the indirect method is less introduced. In addition, the above techniques focus much on simulating the construction process of a newly built tunnel, but do not focus on accurate simulation of existing tunnel stress and deformation response.
The traditional model test research for analyzing the stress deformation characteristics of the shield tunnel is to simplify the tunnel into a whole, and the tunnel model is built by adopting an organic glass tube, a PE tube or a whole pouring mode. Although the similar method can reflect the structural characteristics of the shield tunnel to a certain extent, because the model test often needs to meet the relation of the similarity ratio, the detailed structure of the tunnel is changed into a micro structure with millimeter as a unit, and the test precision is difficult to ensure by adopting the traditional methods such as irrigation and the like.
As an emerging rapid prototyping technology, 3D printing technology has achieved a certain effort in the manufacture of shield tunnel models in recent years. The publication with the application number 202111450599.5 provides a shield tunnel model device and a method, and introduces a method for manufacturing an integral shield tunnel model by adopting a 3D printing technology in more detail, but iron wires are adopted to simulate bending screws between actual tunnel segments in the publication, and the method is adopted to simulate the connection behavior between the segments and the pipe rings, so that the connection strength between the segments cannot be accurately controlled.
From the background, a test device and a test method capable of accurately simulating the stress deformation characteristics of the existing shield tunnel under the construction condition of the adjacent tunnel are still lacking. A large number of researches show that stratum loss is a main reason for stratum settlement and deformation of the existing shield tunnel caused by tunnel construction. Therefore, the influence of the construction of the adjacent tunnel is simplified by simulating stratum loss, the stress deformation characteristics of the existing tunnel are reflected by manufacturing the shield tunnel through the 3D printing tube sheet, and a more feasible and accurate test design thought can be provided for the simulation of the stress deformation characteristics of the existing shield tunnel under the condition of the construction of the adjacent tunnel.
Disclosure of Invention
The invention aims to solve the technical problems that the conventional shield tunnel stress deformation characteristic test has the defects, and provides the test device and the test method for simulating the stress deformation characteristic of the existing tunnel under the construction condition of the adjacent tunnel, the model box is convenient to assemble and disassemble, can simulate various construction working conditions of the adjacent tunnel and well reflect the stress deformation characteristic of the actual tunnel, the drainage method can well reflect stratum loss caused by construction, and the tunnel is installed without adopting dragging or jacking equipment, so that the test feasibility is improved and the test cost is reduced.
The invention adopts the technical scheme for solving the technical problems that:
The test device for simulating the stress deformation characteristics of the existing tunnel under the construction condition of the adjacent tunnel comprises a model box, an existing tunnel model, a newly-built tunnel model, test sand and a monitoring system, wherein the test sand is arranged in the model box, the existing tunnel model and the newly-built tunnel model are arranged in the test sand, the existing tunnel model and the newly-built tunnel model are orthogonally arranged, and the axis of the newly-built tunnel model is positioned below an intermediate ring of the existing tunnel model (the newly-built tunnel model penetrates through the existing tunnel model);
The existing tunnel model comprises a plurality of tunnel pipe rings which are printed in a 3D mode and spliced into a whole, and each tunnel pipe ring is formed by splicing 1 capping pipe piece, 2 adjacent pipe pieces and 3 standard pipe pieces through bolts;
The novel tunnel model is made of an aluminum alloy pipe, a plurality of sections of aluminum pipe grooves are engraved on the outer surface of the aluminum alloy pipe along the circumferential direction, a plurality of liquid bags are wrapped on the pipe wall of the aluminum alloy pipe, each liquid bag is fixed in the aluminum pipe groove on the outer surface of the aluminum alloy pipe through a hoop, a liquid outlet is formed in each liquid bag and is respectively connected with one pipe, one end of each pipe penetrates through an aluminum pipe opening of the pipe wall of the aluminum alloy pipe, the other end of each pipe is led out to the outside of the aluminum alloy pipe from an inner cavity (inside the novel tunnel model) of the aluminum alloy pipe, and a valve is arranged at a position close to the tail end of the pipe led out to the outside (the flow of liquid is controlled through opening and closing of the valve); the tail ends of all the guide pipes are connected with a general guide pipe, and the tail ends of the general guide pipes are provided with rubber joints;
The monitoring system comprises a ground surface deformation monitoring system and an existing tunnel model stress deformation monitoring system and is used for monitoring and analyzing longitudinal displacement of an existing tunnel model, tunnel surface soil pressure, tunnel transverse convergence, tunnel transverse strain, ground surface subsidence and deep soil displacement.
According to the scheme, the model box comprises a bottom plate and all around organic glass plates, wherein the bottom plate and the all around organic glass plates are spliced by angle steel, the bottom plate is made of solid wood, and bottom plate grooves are carved on the bottom plate; the organic glass plate is divided into an upper plate, a middle plate and a lower plate according to the position of each surface, the lower plate is inserted into a groove of the bottom plate and fixed on the bottom plate through angle steel and reinforcing bolts, and then the middle plate and the upper plate are sequentially installed and reinforced in the transverse direction and the vertical direction through angle steel; the angle steel is provided with an angle steel bolt hole; the lower plates of the two organic glass plates at the front and rear of the model box are respectively provided with a sand discharge opening, the two sand discharge openings are provided with a corresponding baffle plate, the sand discharge openings are kept closed by the baffle plate in the sand filling process, and the baffle plate is opened to rapidly discharge sand through the sand discharge openings during sand discharging; the middle plate center positions of the two organic glass plates on the left side and the right side of the model box are provided with existing tunnel mounting holes for mounting existing tunnel models, and the lower plates of the organic glass plates on the front and the rear of the model box are provided with new tunnel mounting holes for mounting new tunnel models; shallow grooves are engraved in the existing tunnel mounting holes and the newly-built tunnel mounting holes, and rubber rings are arranged in the grooves; and slide bar mounting holes are formed in the upper plates of the front and rear organic glass plates of the model box and the upper plates of the organic glass plates on the left side and the right side.
According to the scheme, the longitudinal seam positions of the capping segment, the adjoining segment and the standard segment are smooth, and the circumferential seam positions of the segments are provided with concave-convex mortises; the longitudinal seams of the capping pipe piece, the adjacent pipe piece and the standard pipe piece are provided with 3 pipe piece bolt rough holes or pipe piece bolt fine holes, and the circumferential seams of the tunnel pipe rings spliced into a whole are provided with 16 pipe piece bolt rough holes or pipe piece bolt fine holes; the tunnel pipe ring is connected with pipe piece bolt holes of adjacent spliced pipe pieces through pipe piece bolt rough holes by bolts; the duct piece bolt rough hole is formed in one side of a nut at the position where the duct piece is installed and connected; adjacent duct pieces of each ring of tunnel pipe ring are connected through small-scale reduction bolts, and adjacent tunnel pipe rings are connected through concave-convex mortises and oblique bolts at the positions of duct piece circular seams.
According to the scheme, the earth surface deformation monitoring system comprises a first sliding rod, a second sliding rod and an earth surface displacement meter, wherein the first sliding rod and the second sliding rod are respectively positioned at the upper parts of the axes of the existing tunnel model and the newly-built tunnel model, the first sliding rod and the second sliding rod are fixed in a sliding rod mounting hole of an upper plate of an organic glass plate through connectors, and the earth surface displacement meter is arranged on the first sliding rod and the second sliding rod; a number of wood shims are arranged at the surface along the tunnel axis position, with the surface displacement meter probe resting on the wood shims (the deformation of the surface is reflected by the displacement of the wood shims).
According to the scheme, the existing tunnel stress deformation monitoring system comprises a tunnel displacement meter, a strain gauge, a miniature soil pressure meter, a third sliding rod and a universal clamp, wherein the universal clamp is fixed on the outer wall of a model box through a connector, and the universal clamp clamps the third sliding rod and ensures that the third sliding rod is not contacted with the inner wall of an existing tunnel model; the tunnel displacement meter is arranged on a third sliding rod (respectively monitoring tunnel deformation at the positions of the vault, the arch bottom and the arch waist of the existing tunnel model); the strain gauge and the miniature soil pressure are respectively stuck to the outer surface of the existing tunnel model (used for monitoring the deformation among rings of the existing tunnel model and the soil pressure distribution condition of the surface of the tunnel); the sensing elements are all connected to a signal acquisition instrument.
The invention also provides a manufacturing and installing method of the test device for simulating the stress deformation characteristics of the existing tunnel under the construction condition of the adjacent tunnel, which comprises the following steps:
step 1, manufacturing an existing tunnel model:
① Determining a model similarity ratio: (based on the similar three theorem, the similar positive theorem, the pi theorem and the similar inverse theorem), and determining the geometric similarity ratio of the prototype tunnel and the existing tunnel model by combining the 3D printing technical requirement, the measurement precision and the scale of the test platform;
② Selecting a duct piece: designing the existing tunnel model duct piece according to the structural characteristics of the prototype tunnel duct piece, and selecting a proper 3D printing material;
③ Bolt selection: the bent bolts of the prototype tunnel are changed into inclined bolts which are easier to process and install, so that the pretightening force of each group of bolts is ensured to be equal; the whole structure is positioned in the bolt hole after the installation of the bolt is completed, and the whole structure is not exposed (the installation of a subsequent sensing element is not influenced);
④ Drawing model tunnel duct piece files on a computer according to the duct piece and bolt selection, wherein each tunnel duct ring 22 consists of 1 capping duct piece, 2 adjacent duct pieces and 3 standard duct pieces; the model tunnel segment file is led into a 3D printer, and all tunnel tube rings are spliced into a whole through inclined bolts and nuts at the connecting segment to finish the manufacture of the existing tunnel model 13;
step 2, manufacturing a newly built tunnel model:
① Manufacturing an aluminum alloy pipe: the main body structure of the newly-built tunnel model is an aluminum alloy pipe, an aluminum pipe groove is engraved on the outer wall of the aluminum alloy pipe, and an aluminum pipe opening is preset on the pipe wall of the aluminum alloy pipe;
② Installing a liquid sac: the rubber film is adopted to manufacture an annular liquid bag, the inner diameter of the liquid bag is slightly smaller than the outer diameter of the aluminum alloy pipe, and the width of the liquid bag is slightly larger than the width of the aluminum alloy pipe; sleeving the liquid bag on the wall of the aluminum alloy pipe, aligning the liquid bag liquid outlet with the opening of the aluminum pipe, and fixing the liquid bag at the groove of the aluminum pipe on the outer surface of the aluminum alloy pipe by adopting a hoop; each liquid outlet is connected with a guide pipe and then connected with the main guide pipe;
step 3, manufacturing a model box:
① And (3) manufacturing a bottom plate: firstly, cutting a groined bottom plate groove on a bottom plate, forming a square by the inner periphery of the groined shape, and punching a plurality of holes along the inner side of the square edge to facilitate the installation of later-stage angle steel;
② Manufacturing an organic glass plate: manufacturing 12 organic glass plates, wherein the organic glass plates respectively comprise 4 upper plates, 4 middle plates and 4 lower plates, holes are punched in the bottoms of the inner side and the outer side of the 4 lower plates, and a small number of holes are formed in the other organic glass plates along the two vertical edges so as to facilitate angle steel installation; cutting existing tunnel mounting holes in the center of the middle plates on the left side and the right side in advance, cutting newly-built tunnel mounting holes and sand discharge openings in advance for the lower plates on the front and the rear sides, grooving the holes after the mounting holes are cut, mounting rubber rings in the holes, and arranging slide bar mounting holes on the upper plates on the front and the rear sides and the upper plates on the left side and the right side of the model box 1;
③ Installing angle steel: the angle steel is L-shaped, and each side surface of the model box is provided with 3 horizontal angle steels and 4 vertical angle steels, and 16 angle steels are arranged in total; the front and rear angle steels are respectively arranged at the joint of the bottom plate and the lower plate of the organic glass plate and the joint of the adjacent organic glass plates, and the left and right angle steels are respectively arranged at the joint of the bottom plate and the lower plate of the organic glass plate and the lap joint of the front and rear angle steels;
④ Assembling a model box: inserting the lower plate of the organic glass plate into the grooves of the four-side bottom plate, and connecting and fixing the bottom plate, the organic glass plate and the angle steel through bolts; installing vertical angle steel; after the vertical angle steel is installed, installing organic glass plates layer by layer, and further reinforcing the joint of the upper organic glass plate and the lower organic glass plate by adopting horizontal angle steel; setting and fixing baffles at two sand discharge ports;
Step 4, preparing test sand, and arranging an existing tunnel model and a newly-built tunnel model: filling sand samples by adopting a sand rain method, and stopping filling when the filling height of the sand samples slightly exceeds the installation hole position of the newly built tunnel model; jacking the newly-built tunnel model from a newly-built tunnel model mounting hole on one side until reaching another newly-built tunnel model mounting hole, and fixing the exposed part of the newly-built tunnel model through a universal clamp on the outer wall of the model box; injecting water into each liquid sac one by one; after water injection is completed, closing each valve to complete the installation of the newly built tunnel model; continuing filling sand, stopping filling when the filling height of the sand sample slightly exceeds the installation hole position of the existing tunnel model, and starting the installation of the existing tunnel model, wherein the installation mode of the existing tunnel model is the same as that of the newly-built tunnel model; continuing to fill sand until the sand sample is buried in the existing tunnel model and is higher than the existing tunnel model by a section of height, and ending the sand filling;
step 5, installing a monitoring system:
① Installation of a surface deformation monitoring system: firstly, determining the position of a tunnel axis on the ground surface, and arranging a plurality of veneer sheets along two axes respectively; determining the positions of sliding rods according to the positions of the thin wood pieces, and installing a first sliding rod and a second sliding rod through a sliding rod installation hole in the upper part of the model box; the first slide bar and the second slide bar are connected with a plurality of earth surface displacement meters, and earth surface displacement meter probes are propped against the veneer;
② The existing tunnel stress deformation monitoring system is installed: the installation of the strain gauge and the miniature soil pressure gauge is completed before the existing tunnel model is embedded; the miniature earth pressure gauge is stuck on the surface of the existing tunnel model by adopting glass cement; the strain gauge is stuck on the outer surface of the existing tunnel model (703 rubber is used for sealing and protecting the strain gauge after the strain gauge is stuck); the position of the tunnel displacement meter on the third slide bar is determined and fixed in advance, and then the third slide bar passes through the interior of the existing tunnel model; after the tunnel displacement meter is installed in place, installing a universal clamp on the external angle steel of the existing tunnel model, and fixing the position of the third sliding rod;
③ After the sensor element is installed, various sensor cables are connected to a signal acquisition instrument, the signal acquisition instrument is connected to a computer, and whether the acquisition instrument can receive related signals is checked; after 24 hours of sand sample settling, all sensing element signals were zeroed and ready to begin the test.
According to the scheme, the geometrical similarity ratio of the original tunnel to the existing tunnel model in the step 1 is 35:1; the prototype tunnel duct piece material is C50 concrete, the duct piece material of the existing tunnel model is photosensitive resin, and the similarity ratio of the duct piece elastic modulus is 15:1.
According to the scheme, the water injection test in the step 2 is changed into injecting CaCl 2 solution into the liquid bag (compared with distilled water, the colloid state of the mud-water mixture at the outer side of the actual shield tunnel can be better simulated).
According to the scheme, the miniature soil pressure gauge in the step 5 adopts a resistance strain gauge type soil pressure box, the model is HC-350 (the thickness is 5mm, the diameter is 15mm, the measuring range is 50kPa, and the resistance is 350 omega), and the miniature soil pressure gauge is arranged in a full bridge mode; the strain gauge adopts a BX120-3AA miniature resistor type strain gauge (the resistance value is 120 omega, and the length multiplied by the width of the strain grid is 3mm multiplied by 2 mm); the surface displacement meter adopts a YWC type displacement meter (the measurement precision is 0.01mm and the measuring range is 20 mm), and the acquisition instrument is a TST3826 static and dynamic strain test system (60 channels).
The invention also provides a test method for simulating the stress deformation characteristic of the existing tunnel under the construction condition of the adjacent tunnel, which comprises the following steps:
S1, testing longitudinal bending rigidity of a tunnel: the longitudinal bending stiffness characteristics of the existing tunnel model are tested before the formal test; the method comprises the steps of intensively loading a middle ring of a tunnel pipe ring in a mode similar to the neutral point loading of a simply supported beam, obtaining a vertical displacement distribution rule of the whole tunnel along the axial direction through a tunnel displacement meter arranged along the longitudinal direction, and ensuring that the whole tunnel displacement distribution curve is continuous and the bending stiffness is in a reasonable range through adjusting the position of a duct piece and the torque of a bolt;
s2, water injection pre-test: connecting a general conduit with an injector, determining the change of the outer diameter of the liquid sac caused by different water injection amounts through a water injection pre-experiment, and further determining the relation between the water injection amount and the stratum loss rate;
S3, performing construction simulation of a newly built tunnel model; sequentially discharging liquid from one end according to groups, weighing the discharged liquid in real time through a high-precision electronic scale, and calculating the volume of discharged water; after each group of liquid discharge is finished, standing for 20 minutes, and starting the next group of liquid discharge until each group of liquid bags are finished liquid discharge; then ending the test, and storing the collected data of each sensing element; and opening a sand discharge port at the lower side of the organic glass plate, removing sand samples, taking out the existing tunnel model and the newly-built tunnel model, and disassembling the model box layer by layer.
Compared with the prior art, the invention has the following beneficial effects:
1. The model box structure is formed by splicing the organic glass plates, the angle steel and the reinforcing bolts, the organic glass plates are convenient to replace and process, the model box is convenient to assemble and disassemble, the model box can be used for simulating the model box which is affected by the downward penetration of a tunnel and can also provide a new thought for simulating the construction working conditions of other tunnels, such as upper stacking, foundation pit adjacent construction, upward penetration, oblique penetration, parallel penetration and the like, and meanwhile, the test cost can be greatly saved;
2. the existing tunnel model is manufactured by adopting a 3D printing technology, the stress deformation characteristic of an actual tunnel can be well reflected, the flow of model similarity selection, duct piece and bolt type selection and integral bending stiffness calibration of the tunnel is described in detail, and the method has good reference significance for manufacturing the tunnel model by adopting the 3D printing technology subsequently; the segment stress mechanism of the existing tunnel model is consistent with that of an actual tunnel segment, manual assembly is simple, and the displacement meter is convenient to install in the tunnel;
3. when the influence rule of the stress deformation of the existing shield tunnel by the adjacent tunnel construction is researched, the stratum loss caused by the new tunnel construction can be well simulated by adopting a self-made liquid bag and a liquid discharge method, and on the other hand, the tunnel is not required to be installed by adopting dragging or jacking equipment, so that the feasibility of a test is greatly improved and the test cost is reduced; in the process of advancing the new tunnel excavation face, monitoring and analyzing longitudinal displacement, tunnel surface soil pressure, tunnel transverse convergence, tunnel transverse strain, earth surface subsidence and deep soil displacement of the existing tunnel, summarizing stress deformation rules of the existing shield tunnel under the working condition of the adjacent tunnel, and qualitatively analyzing the stress deformation rules;
4. the invention adopts the sand rain method to prepare the sand sample, can better overcome the defects of low repeatability and large disturbance of the traditional sand sample filling method, and ensures the accuracy of the stress deformation characteristic of the fine structure of the 3D printing tunnel.
Drawings
FIG. 1 is an exploded view of a mold box of the present invention;
FIG. 2 is an overall schematic diagram of a model test apparatus of the present invention;
FIG. 3 is a schematic diagram of an installation of the surface deformation monitoring system of the present invention;
FIG. 4 is a front view of a tunnel ring of an existing tunnel model of the present invention;
FIG. 5 is a three-dimensional schematic view of a tunnel ring of an existing tunnel model of the present invention;
FIG. 6 is a three-dimensional schematic view of a capping segment of an existing tunnel model of the present invention;
FIG. 7 is a three-dimensional schematic view of adjacent segments of an existing tunnel model of the present invention;
FIG. 8 is a three-dimensional schematic view of a standard segment of an existing tunnel model of the present invention;
FIG. 9 is a schematic view of a tongue and groove between adjacent rings of a segment of an existing tunnel model according to the present invention;
FIG. 10 is a schematic view of the installation of bolts between adjacent segments at the circumferential seam of a tube of an existing tunnel model;
FIG. 11 is a schematic diagram of the installation of bolts between adjacent segments at longitudinal seams of segments of an existing tunnel model according to the present invention;
FIG. 12 is a schematic diagram of the overall structure of an existing tunnel model according to the present invention;
FIG. 13 is a schematic illustration of calibration of longitudinal bending stiffness of an existing tunnel model according to the present invention;
FIG. 14 is a schematic diagram of a tunnel displacement meter arrangement of an existing tunnel model stress deformation monitoring system of the present invention;
FIG. 15 is a schematic view of a strain gage and miniature earth pressure gauge arrangement of an existing tunnel model stress deformation monitoring system of the present invention;
FIG. 16 is a schematic view of a newly constructed tunnel model in accordance with the present invention;
FIG. 17 is a cross-sectional view of FIG. 16;
FIG. 18 is an enlarged partial schematic view of FIG. 17;
In the figure: 1-model box, 2-angle steel, 3-existing tunnel installation hole, 4-slide bar installation hole, 5-organic glass plate, 6-bottom plate, 7-sand discharge port, 8-new tunnel installation hole, 9-O-shaped rubber ring, 10-bottom plate groove, 11-angle steel bolt hole, 12-new tunnel model, 13-existing tunnel model, 14-general conduit, 15-universal clamp, 16-first slide bar, 17-veneer, 18-surface displacement meter, 19-capping segment, 20-adjacent segment, 21-standard segment, 22-tunnel pipe ring, 23-concave-convex tongue groove, 24-segment bolt rough hole, 25-inclined bolt, 26-gasket groove, 27-inlaid slot, 28-pipe ring slot, 29-segment longitudinal slot, 30-aluminum pipe groove, 31-liquid bag, 32-hoop, 33-liquid discharge port, 34-conduit, 35-valve, 36-rubber joint, 37-strain gauge, 38-micro soil pressure meter, 39-aluminum pipe opening, 40-support, 41-loading device, 42-connecting position, 43-second segment, 43-slide bar and 46-slide bar bolt hole.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the following description of the embodiments of the present invention will be given with reference to the accompanying drawings.
As shown in fig. 1-2, the invention utilizes 3D printing technology, sand rain method and other technologies to manufacture a whole set of device capable of truly simulating stress deformation response of the existing shield tunnel under various adjacent tunnel construction conditions, in particular to a test device for simulating stress deformation characteristics of the existing tunnel under the adjacent tunnel construction conditions, which comprises a model box 1, an existing tunnel model 13, a new tunnel model 12, test sand and a monitoring system, wherein the test sand is arranged in the model box 1, the existing tunnel model 13 and the new tunnel model 12 are arranged in the test sand, the existing tunnel model 13 is arranged orthogonal to the new tunnel model 12, and the axis of the new tunnel model 12 is positioned below the middle ring of the existing tunnel model 13 (the new tunnel model 12 penetrates through the existing tunnel model 13).
As shown in fig. 1, the mold box 1 is formed by splicing a plastic glass plate 5, a bottom plate 6 and angle steel 2, the size of the mold box 1 is 1.1×1.1×1.8m (length×width×height), the bottom plate 6 is solid wood, the size is 1.5×1.5×0.04m (length×width×thickness), and a bottom plate groove 10 with a depth of about 2cm is carved on the bottom plate 6; the dimensions of the organic glass plates 5 are the same and are 1.1x0.6x0.01 m (length x width x thickness), the organic glass plates 5 are divided into an upper plate, a middle plate and a lower plate according to the positions of each surface, the lower plates are inserted into the grooves 10 of the bottom plate and fixed on the bottom plate 6 through angle steel 2 and reinforcing bolts, then the middle plate and the upper plate are sequentially installed, and the organic glass plates are reinforced in the transverse direction and the vertical direction through the angle steel 2; angle steel 2 is 4cm wide and 5mm thick, angle steel bolt holes 11 are formed in the angle steel 2, and the length of the angle steel 2 is controlled by self cutting; the lower plates of the two organic glass plates 5 at the front and rear of the model box 1 are respectively provided with a sand discharge opening 7 with the length of 30cm and the height of 10cm from the bottom 10cm, the two sand discharge openings 7 are respectively provided with a corresponding baffle, the sand discharge opening 7 is kept closed by the baffle in the sand loading process, and the baffle is opened to rapidly discharge sand through the sand discharge opening 7 during sand unloading; the center positions of the middle plates of the two organic glass plates 5 on the left side and the right side of the model box 1 are provided with existing tunnel mounting holes 3 with the diameter of 18cm for mounting an existing tunnel model 13, and the lower plates of the two organic glass plates 5 on the front and the rear of the model box 1 are also provided with new tunnel mounting holes 8 with the diameter of 18cm at the position 30cm away from the bottom plate for mounting a new tunnel model 12; shallow grooves are engraved in the existing tunnel mounting holes 3 and the newly-built tunnel mounting holes 8, and O-shaped rubber rings 9,O and rubber rings 9 are arranged in the grooves and are used for protecting tunnel structures when the existing tunnel models 13 and the newly-built tunnel models 12 are placed on one hand and preventing sand leakage in the test process on the other hand; it should be noted that the above-mentioned arrangement of the positions is only for convenience of explaining the structure of the present invention, and in actual operation, the opening positions can be arranged in a manner of wearing down, wearing up, parallel and staggered crossing, etc. in combination with the condition of the engineering to be simulated; the upper plates of the front and rear organic glass plates 5 of the model box 1 and the upper plates of the organic glass plates 5 on the left side and the right side are provided with circular slide bar mounting holes 4.
As shown in fig. 4-12, the existing tunnel model 13 includes a plurality of tunnel pipe rings 22 integrally formed by 3D printing and splicing, and each tunnel pipe ring 22 is formed by splicing 1 capping pipe piece 19, 2 adjacent pipe pieces 20 and 3 standard pipe pieces 21 by bolts; the positions of the duct piece longitudinal seams 29 of the capping duct piece 19, the adjacent duct piece 20 and the standard duct piece 21 are smooth, and the positions of the duct piece circular seams 28 are provided with concave-convex mortises 23 for simulating the connection characteristics among the duct rings of the actual shield tunnel; the longitudinal seams of the capping segment 19, the adjacent segment 20 and the standard segment 21 are provided with 3 segment bolt rough holes 24 or segment bolt fine holes 46, and the circumferential seams of the tunnel pipe ring 22 spliced into a whole are provided with 16 segment bolt rough holes 24 or segment bolt fine holes 46; the duct piece bolt rough hole 24 is formed on one side of a nut 42 at the position where the duct piece is installed; adjacent duct pieces of each ring of tunnel pipe rings 22 are connected through small-scale bolts 25, and adjacent tunnel pipe rings 22 are connected through concave-convex mortises 23 and inclined bolts 25 at the positions of duct piece annular gaps 28.
As shown in fig. 16-18, the newly built tunnel model 12 is made of an aluminum alloy pipe, a plurality of aluminum pipe grooves 30 are engraved on the outer surface of the aluminum alloy pipe along the circumferential direction, a plurality of liquid bags 31 are wrapped on the wall of the aluminum alloy pipe, two sides of each liquid bag 31 are fixed on the outer surface of the aluminum alloy pipe through hoops 32 in the aluminum pipe grooves 30, and liquid is discharged from different liquid bags 31 group by group to simulate stratum loss (liquid discharge method) in the process of pushing up the shield tunnel; the liquid bags 31 are provided with liquid discharge ports 33, the liquid discharge ports 33 are respectively connected with one guide pipe 34, one end of each guide pipe 34 passes through an aluminum pipe opening 39 on the wall of the aluminum alloy pipe, the other end of each guide pipe 34 is led out of the aluminum alloy pipe from an inner cavity of the aluminum alloy pipe (the inside of the newly built tunnel model 12), and the guide pipe 34 led out to the outside is provided with a valve 35 (the flow of liquid is controlled by opening and closing the valve 35) at a position close to the tail end of the guide pipe 34; the ends of all the pipes 34 are connected with the general pipe 14, the end of the general pipe 14 is provided with a rubber joint 36, the pipes 34 are connected by penetrating a syringe into the rubber joint 36 when discharging liquid, the discharge of liquid in each group of liquid bags 31 is controlled by opening and closing a valve 35 on each pipe 34, and the discharge amount of the liquid is calculated by scales on the syringe.
The monitoring system comprises a ground surface deformation monitoring system and an existing tunnel model stress deformation monitoring system, and is used for monitoring and analyzing the longitudinal displacement of the existing tunnel model 13, the tunnel surface soil pressure, the tunnel transverse convergence, the tunnel transverse strain, the ground surface subsidence and the deep soil displacement. As shown in fig. 3, the earth surface deformation monitoring system comprises a first slide bar 16, a second slide bar 43 and an earth surface displacement meter 18, wherein the first slide bar 16 and the second slide bar 43 are respectively positioned at the upper parts of the axes of the existing tunnel model 13 and the newly-built tunnel model 12, the first slide bar 16 and the second slide bar 43 are fixed in a slide bar mounting hole 4 of the upper plate of the organic glass plate 5 through joints, and the earth surface displacement meter 18 is arranged on the first slide bar 16 and the second slide bar 43; in order to monitor the deformation characteristics of the earth's surface, a plurality of wood pieces 17 are arranged at the earth's surface along the tunnel axis position, and an earth's surface displacement meter 18 probe is placed on the wood pieces 17, and the deformation of the earth's surface is reflected by the displacement of the wood pieces 17. As shown in fig. 14-15, the existing tunnel stress deformation monitoring system comprises a tunnel displacement meter 45, a strain gauge 37, a miniature soil pressure meter 38, a third sliding rod 44 and a universal clamp 15, wherein the universal clamp 15 is fixed on the outer wall of the model box 1 through a connector, and the universal clamp 15 clamps the third sliding rod 44 and ensures that the third sliding rod 44 is not contacted with the inner wall of the existing tunnel model 13; the tunnel displacement meter 45 is arranged on the third slide bar 44 and is used for monitoring tunnel deformation at the vault, the arch bottom and the arch waist positions of the existing tunnel model 13 respectively; the strain gauge 37 and the miniature soil pressure gauge 38 are respectively stuck to the outer surface of the existing tunnel model 13 and are used for monitoring the deformation between rings of the existing tunnel model 13 and the soil pressure distribution condition of the tunnel surface; the sensing elements are connected to a signal acquisition instrument through sensor wires, and the signal acquisition instrument is connected with a computer.
The invention relates to a manufacturing and installing method of a test device for simulating the stress deformation characteristic of an existing tunnel under the construction condition of an adjacent tunnel, which comprises the following steps:
step 1, manufacturing an existing tunnel model 13:
① Determining a model similarity ratio: based on the similar three theorem (similar positive theorem, pi theorem and similar inverse theorem), combining the 3D printing technical requirement, the measurement precision and the scale of a test platform, determining that the geometric similarity ratio of the prototype tunnel to the existing tunnel model 13 is 35:1; based on the similarity ratio, the similarity relation between the duct piece and the bolt is further determined, the elastic modulus ratio of the duct piece prototype to the model is determined to be 15:1 by combining the performance of the current 3D printing material, and the similarity of the duct piece gravity is not strictly required because the influence of the duct piece dead weight on the bending resistance is considered to be small;
② Selecting a duct piece: the existing tunnel model duct piece is designed according to the structural characteristics of the original tunnel duct piece, and mainly comprises duct piece size, duct piece type (such as a top sealing block, a standard block and a connecting block), a hole opening position, a mortise structure and the like, wherein in the test, the longitudinal seam position of the duct piece is smooth, and the circumferential seam position is provided with a concave-convex mortise 23; after the duct piece size is determined, duct piece materials are further determined, when 3D printing test materials are selected, the factors such as strength, surface quality, elasticity, printing precision and cost of a printing finished product are mainly considered, 3-4 materials to be selected are then determined, standard components are manufactured according to relevant standards, stretching and compression tests are carried out, and proper 3D printing materials are selected by comparing various materials with stress-strain curve characteristics of a prototype duct piece; only photosensitive resin EvoLVe 128) and the ratio of the compressive and tensile elastic modulus to the C50 concrete elastic modulus are 14.8 and 13.5, respectively, closest to the given elastic modulus similarity constant 15. In addition, photosensitive resin [ ]EvoLVe 128) has similar stress deformation characteristics as C50 concrete, and the finished product manufactured by adopting the material through 3D printing has the advantages of smooth surface, high manufacturing precision, easy molding and the like. Therefore, the photosensitive resin is finally selectedEvoLVe 128, 128) is a segment 3D printing material;
③ Bolt selection: the prototype tunnel was bolted using M30 bend bolts. Because the small-scale model adopted in the test has the advantages that after the diameters of the bolt and the bolt hole are reduced, the processing and mounting difficulties of the bent bolt are high, and the actual operation difficulty is increased. Therefore, when a test model is manufactured, the bent bolt of the prototype tunnel is changed into an inclined bolt 25 which is easier to process and install, and the fixed torque electric screwdriver is adopted for installing the bolts, so that the pretightening force of each group of bolts can be ensured to be equal; the whole structure is positioned in the bolt hole after the installation of the bolt is completed, and the installation of the subsequent sensing element is not affected;
④ According to the pipe sheet and bolt selection, drawing a model tunnel pipe sheet file on a computer, wherein each tunnel pipe ring 22 consists of 1 capping pipe sheet 19, 2 adjacent pipe sheets 20 and 3 standard pipe sheets 21, and in the embodiment, the inner diameter of the tunnel pipe ring 22 is 157mm, the outer diameter of the tunnel pipe ring is 177mm, and the width of the tunnel pipe ring 22 along the longitudinal ring is 34.3mm and the thickness of the tunnel pipe ring is 10mm; the radian of the short side of the capping segment 19 is 12 degrees, the radian of the long side is 20 degrees, the radian of the short side of the adjacent segment 20 is 68.75 degrees, the radian of the long side is 72.75 degrees, and the radian of the standard segment 21 is 67.5 degrees; the duct piece longitudinal joint 29 is provided with 3 duct piece bolt rough holes 24 or duct piece bolt fine holes 46, the spacing is uniformly arranged and is 8.575mm, and the directions of the holes are staggered; the duct piece bolt rough hole 24 is one side of a nut 42 at the installation connection duct piece; the duct piece circumferential seam 28 is provided with 16 duct piece bolt rough holes 24 or duct piece bolt fine holes 46 uniformly distributed, and the radian interval between every two duct piece bolt rough holes 24 or duct piece bolt fine holes 46 is 22.5 degrees; because the inclined bolts 25 which are easier to install and process are adopted, the duct piece bolt fine holes 46 are provided with the diameter of 0.86mm and the length of 10mm, and the duct piece bolt rough holes 24 are provided with the diameter of 2mm, so that the nuts 42 at the connecting duct pieces can be conveniently installed. In the duct piece longitudinal seam 29, the position of the duct piece longitudinal seam 29 is smooth, a sealing gasket groove 26 with the length of 1mm and the width of 0.5mm is arranged at a position 1mm inward from the outer surface of the duct piece, and a caulking groove 27 with the length of 1mm and the width of 0.25mm is arranged at the outer surface of the duct piece outward; in the circular seam 28 of the duct piece, a sealing gasket groove 26 with the length of 1mm and the width of 0.5mm is arranged at a position 1mm inward from the outer surface of the duct piece, a caulking groove 27 with the length of 1mm and the width of 0.25mm is arranged at the outer surface of the duct piece outward, a concave-convex tenon 23 is arranged at the circular seam position, the convex and concave dimensions of the concave-convex tenon 23 are 2mm, the convex width is 8mm, and two ends of the concave-convex tenon 23 are inverted by a right angle of 1 mm; after drawing a model tunnel duct piece on a computer, importing a model tunnel duct piece file into a 3D printer, and printing 32 capping duct pieces 19, 64 adjacent duct pieces 20 and 96 standard duct pieces 21 for finishing a 32-ring mortised joint assembly tunnel model; preparing enough inclined bolts 25 with the diameter of 0.86mm and the length of 10mm and nuts 42 at the connecting duct pieces; when the bolts 25 are assembled, the adjacent rings are staggered by an angle of 45 degrees, and the fixed torque electric screwdriver is adopted for mounting the bolts, so that the pretightening force of each group of bolts can be ensured to be equal; the whole structure is positioned in the hole after the installation of the inclined bolt 25 is completed, the whole structure is not exposed, the installation of a subsequent sensing original is not affected, all duct pieces and duct rings are connected and assembled, and the manufacture of the existing tunnel model 13 is completed.
Step 2, manufacturing a newly built tunnel model 12:
Because the rigidity of the tunnel segment is relatively larger than that of the soil body, the jacking process of the shield tunnel hardly affects the tunnel structure. Therefore, the device and the method mainly focus on the simulation of stratum loss caused by shield tunnel construction, but do not focus on the stress deformation characteristics of the structure of the existing tunnel. The simulation of the construction process of the newly-built tunnel mainly comprises the following steps:
① Manufacturing an aluminum alloy pipe: the main structure of the new tunnel model 12 is an aluminum alloy pipe, the size of the aluminum alloy pipe is equal to the size proportion of the new tunnel, the outer diameter of the aluminum alloy pipe is 177mm, the wall thickness is 30mm, the length is 1.2m, the outer wall of the aluminum alloy pipe is uniformly engraved with aluminum pipe grooves 30 with the width of 5 rings being 1cm and the depth being 1cm, the pipe wall of the aluminum alloy pipe is preset with aluminum pipe holes 39, and the diameter of the aluminum pipe holes 39 is 1cm;
② Installation of the liquid bag 31: 6 annular liquid bags 31 are manufactured by adopting rubber films, the inner diameter of each liquid bag 31 is slightly smaller than the outer diameter of the aluminum alloy pipe, and the width of each liquid bag 31 is slightly larger than the width of the aluminum alloy pipe; sleeving the liquid bag 31 on the wall of an aluminum alloy pipe, arranging a liquid outlet 33 with proper length on the liquid bag 31, aligning the liquid outlet 33 of the liquid bag 31 with an aluminum pipe opening 39, and fixing the liquid bag 31 at an aluminum pipe groove 30 on the outer surface of the aluminum alloy pipe by adopting a hoop 32; each liquid outlet 33 is connected with a conduit 34 and then connected with the main conduit 14;
Step 3, manufacturing a model box 1:
① Manufacturing a bottom plate 6: firstly, preparing a 1.5x1.5x0.05m (length x width x height) uniform wooden base plate 6, cutting a groined base plate groove 10 with the width of about 1cm and the depth of about 2cm on the base plate 6, enclosing the groined inside to form a square with the diameter of 1.1m, and punching a plurality of holes with the diameter of 10mm along the inner side of the square edge so as to facilitate the installation of later-stage angle steel 2;
② Production of the organic glass plate 5: manufacturing a total of 12 organic glass plates 5 with the length x width x height of 1.1x0.6x0.01m, punching 10mm diameter holes at the bottoms of the inner side and the outer side of the lower plate of the 4 organic glass plates 5, and punching a small number of 10mm diameter holes at the two edges of the rest organic glass plates 5 along the vertical direction so as to facilitate the installation of the angle steel 2; for the middle plate of the left and right side organic glass plates 5, the existing tunnel mounting holes 3 with the diameter of 180mm are cut in advance at the center position, for the position of 30cm of the lower plate of the front and rear organic glass plates 5, newly built tunnel mounting holes 8 with the diameter of 180mm are cut in advance, one sand discharge opening 7 with the length of 30cm and the height of 10cm is arranged at the position 10cm away from the bottom, after the hole cutting is finished, grooves are cut in the holes, O-shaped rubber rings 9 are arranged, and circular slide bar mounting holes 4 with the diameter of 39mm are arranged at the positions of 1.7m of the heights of the upper plates of the front and rear organic glass plates 5 and the upper plates of the left and right organic glass plates 5 of the model box 1;
③ Mounting of angle steel 2: the cross section is long, wide and thick=1200 mm, 40mm and 5mm, and is L-shaped; 3 horizontal angle steels 2 are mounted on each side face of the model box 1, 4 vertical angle steels 2 are mounted on the model box 1, and 16 angle steels 2 are mounted on the model box 1; the front upper angle steel 2 and the rear upper angle steel 2 are respectively arranged at the joint of the bottom plate 6 and the lower plate of the organic glass plate 5 and the joint of the adjacent organic glass plate 5, and the left upper angle steel 2 and the right upper angle steel 2 are respectively arranged at the joint of the bottom plate 6 and the lower plate of the organic glass plate 5 and the lap joint of the front angle steel 2 and the rear angle steel 2;
④ Assembling the model box 1: inserting the lower plate of the organic glass plate 5 into the grooves 10 of the four-side bottom plate, and connecting and fixing the bottom plate 6, the organic glass plate 5 and the angle steel 2 through M10 bolts; installing a vertical angle steel 2; installing organic glass plates 5 layer by layer, and further reinforcing the joint of the upper organic glass plate 5 and the lower organic glass plate by adopting a horizontal angle steel 2; setting and fixing baffles at the two sand discharge openings 7;
Step 4, preparing test sand, arranging an existing tunnel model 13 and a newly built tunnel model 12:
Considering that the 3D printing tunnel model structure is finer, in order to reduce adverse effects caused by a sand filling mode, a sand rain method is adopted for filling sand samples; coating vaseline on the organic glass plate 5 of the test box to reduce the influence of boundary friction force; stopping filling when the filling height of the sand sample slightly exceeds the 8 hole sites of the newly built tunnel model mounting hole; ensuring the fixed position of the liquid sac 31 on the newly built tunnel model 12, and ensuring that each conduit 34 is connected normally and has no liquid leakage phenomenon; jacking the newly-built tunnel model 12 from a newly-built tunnel model mounting hole 8 on one side until reaching the other newly-built tunnel model mounting hole 8, and fixing the exposed part of the newly-built tunnel model 12 through a universal clamp 15 on the outer wall of the model box 1; injecting water into each liquid sac 31 one by one or CaCl 2 solution according to 120% of the water injection amount determined by a pre-experiment so as to avoid that part of liquid in the guide pipe 34 or the liquid sac 31 is not poured out; after water injection is completed, each valve 35 is closed, and the installation of the newly built tunnel model 12 is completed; continuing filling sand, stopping filling when the filling height of the sand sample slightly exceeds the hole position of the installation hole 3 of the existing tunnel model, and starting the installation of the existing tunnel model 13, wherein the installation mode of the existing tunnel model 13 is the same as that of the newly-built tunnel model 12; ensuring that the surface strain gauge 37 and the miniature soil pressure gauge 38 of the existing tunnel model 13 are not damaged, and then continuing to fill sand until the filling height of a sand sample is about 1.5m, and ending the sand filling;
step 5, installing a monitoring system:
① Installation of a surface deformation monitoring system: firstly, determining the position of a tunnel axis on the ground surface, and arranging a plurality of wood sheets 17 along two axes respectively; determining the positions of the first slide bar 16 and the second slide bar 43 according to the positions of the veneer 17, processing two steel pipes with the length of 1.5m, the wall thickness of 5mm and the outer diameter of 40mm as the first slide bar 16 and the second slide bar 43, and installing the first slide bar 16 and the second slide bar 43 by sliding a bar installation hole 4 at the upper part of the model box 1; 13 earth surface displacement meters 18 are connected to the first slide bar 16 and the second slide bar 43, the probes of the earth surface displacement meters 18 are propped against the veneer 17, and the deformation condition of the earth surface is reflected through the displacement of the veneer 17; the earth surface displacement meter 18 adopts a YWC type displacement meter, the measurement precision is 0.01mm, the measuring range is 20mm, the acquisition instrument is a TST3826 static and dynamic strain test system, and the measurement precision is 60 channels;
② The existing tunnel stress deformation monitoring system is installed: the installation of the existing tunnel stress deformation system comprises the installation of the strain gauge 37, the miniature soil pressure gauge 38 and the tunnel displacement gauge 45, wherein the installation of the strain gauge 37 and the miniature soil pressure gauge 38 is completed before the existing tunnel model 13 is embedded; the miniature soil pressure gauge 38 adopts a resistance strain gauge type soil pressure box, the model HC-350, the thickness is 5mm, the diameter is 15mm, the measuring range is 50kPa, the resistance is 350 omega, the miniature soil pressure gauge is arranged in a full bridge mode, the miniature soil pressure gauge is stuck on the surface of the existing tunnel model 13 by adopting glass cement, the measuring points are 14 in the longitudinal direction, the number of the arches at the two sides of the middle ring is 1 respectively, and 16 in total, and the miniature soil pressure gauge is used for monitoring the deformation rule of the soil pressure in the longitudinal direction; the strain gauge 37 adopts a BX120-3AA miniature resistor type strain gauge 37, the resistance value is 120Ω, the strain grating is 3mm multiplied by 2mm (length multiplied by width), the monitoring content of the strain gauge 37 comprises middle annular strain and annular seam strain, and the annular strain measuring points are uniformly distributed at the inner side and the outer side of the middle ring, and 16 strain measuring points are distributed; the number of the ring seam measuring points is 32, the number of the strain measuring points is 48, and after the strain gauge 37 is stuck, 703 rubber is used for sealing and protecting the ring seam measuring points; the model of the tunnel displacement meter 45 is the same as that of the ground surface displacement meter 18, and 7 displacement monitoring points (7 tunnel displacement meters 45) are longitudinally arranged by arranging a third sliding rod 44 inside the existing tunnel model 13; a steel pipe with the length of 1.5m, the wall thickness of 5mm and the outer diameter of 40mm is processed as a third slide bar 44, the position of a tunnel displacement meter 45 on the third slide bar 44 is determined and fixed in advance, and then the third slide bar 44 passes through the interior of the existing tunnel model 13; the third slide bar 44 is prevented from colliding with the tunnel segment in the process of passing through the tunnel, and the probe of the displacement meter is provided with a ball; after the tunnel displacement meter 45 is installed in place, installing a plurality of universal clamps 15 on the external angle steel 2 of the existing tunnel model 13, and fixing the position of the third sliding rod 44;
③ After the sensor element is installed, various sensor cables are connected to a signal acquisition instrument, the signal acquisition instrument is connected to a computer, and whether the signal acquisition instrument can receive related signals is checked; after 24 hours of sand sample settling, all sensing element signals were zeroed and ready to begin the test.
The invention discloses a test method for simulating the stress deformation characteristics of an existing tunnel under the construction condition of an adjacent tunnel, which comprises the following steps:
S1, testing longitudinal bending rigidity of a tunnel: because the shield tunnel model formed by splicing the 3D printing segments is finer, in order to ensure that the stress deformation response of the tunnel model accords with the actual rule, the longitudinal bending stiffness characteristic of the existing tunnel model 13 is tested before the formal test; as shown in fig. 13, a loading device 41 is arranged in the middle of the tunnel pipe ring 22, supports 40 are arranged at two ends of the tunnel pipe ring, the middle ring of the tunnel pipe ring 22 assembly group is subjected to concentrated loading, a vertical displacement distribution rule of the whole tunnel along the axial direction is obtained through a tunnel displacement meter arranged longitudinally, and the whole continuity of the tunnel displacement distribution curve and the bending rigidity in a reasonable range are ensured through adjusting the position of a segment and the torque of a bolt;
S2, water injection pre-test: connecting the general conduit 14 with an injector, determining the change of the outer diameter of the liquid sac 31 caused by different water injection amounts through a water injection pre-experiment, and further determining the relation between the water injection amount and the stratum loss rate; the relation between the water injection amount and the stratum loss rate is measured by a pre-test and is shown in table 1. In the test of the embodiment of the present invention, in order to more clearly observe the deformation relationship of the soil layer-tunnel, a stratum loss rate of 9% was set in the test, i.e., 450ml of total drainage water was provided per sac 31.
TABLE 1 Water injection and corresponding formation loss Rate
S3, performing construction simulation of a newly built tunnel model 12; sequentially discharging liquid from one end according to groups, weighing the discharged liquid in real time through a high-precision electronic scale, and calculating the volume of discharged water; after each group of liquid discharge is finished, standing for 20 minutes, and starting the next group of liquid discharge until each group of liquid bags 31 are finished liquid discharge; then ending the test, and storing the collected data of each sensing element; and opening a sand discharge port 7 at the lower side of the organic glass plate 5, removing sand samples, taking out the existing tunnel model 13 and the newly built tunnel model 12, and disassembling the model box 1 layer by layer.
The foregoing embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the present invention and to implement the same, not to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.
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| CN102434166A (en) * | 2011-11-24 | 2012-05-02 | 上海交通大学 | Device and method for testing influence of tunnel excavation on existing close-distance parallel tunnel |
| CN115306397A (en) * | 2022-07-01 | 2022-11-08 | 武汉市市政建设集团有限公司 | Unloading balance construction method for newly-built rectangular pipe-jacking upward-penetrating existing subway tunnel |
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| JP3605791B2 (en) * | 1999-06-16 | 2004-12-22 | 五洋建設株式会社 | Shield connection method to existing tunnel |
| JP2001115772A (en) * | 1999-10-21 | 2001-04-24 | Kajima Corp | Joining method of existing tunnel and new tunnel |
| JP2004294261A (en) * | 2003-03-27 | 2004-10-21 | Central Giken:Kk | Method for diagnosing healthiness of existing tunnel |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102434166A (en) * | 2011-11-24 | 2012-05-02 | 上海交通大学 | Device and method for testing influence of tunnel excavation on existing close-distance parallel tunnel |
| CN115306397A (en) * | 2022-07-01 | 2022-11-08 | 武汉市市政建设集团有限公司 | Unloading balance construction method for newly-built rectangular pipe-jacking upward-penetrating existing subway tunnel |
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