CN106247965A - Tunnel surrounding monitoring method based on multifunctional intellectual anchor pole - Google Patents

Abstract

The invention discloses a tunnel surrounding rock monitoring method based on a multifunctional intelligent bolt. According to the analysis data such as the geological condition of the location of the tunnel, the design of the support structure, the surrounding environment and the vulnerability, the section to be monitored is selected for monitoring. Monitoring; the bolts arranged in different positions of the tunnel are gathered to the fiber grating demodulator through the armored optical cable drawn out to form a monitoring sensor network; the fiber grating demodulator connected to each bolt is connected to the control computer, and through the monitoring System software to build a surrounding rock monitoring system. The principle of the surrounding rock monitoring method of the present invention is simple and reliable. It can not only test the axial force of the bolt and its distribution along the longitudinal direction, thereby obtaining the surrounding rock pressure of the tunnel, but also calculate the deformation of the surrounding rock of the excavation face or a certain amount. Deformation of surrounding rock in a section. The invention can be used for the construction monitoring during the excavation of the new Austrian method tunnel, and can also be used for the deformation and stability monitoring of the tunnel during the operation period in the future.

Description

Surrounding Rock Monitoring Method of Tunnel Based on Multifunctional Intelligent Bolt

technical field

The invention relates to a bolt-based structural deformation monitoring method for tunnel, foundation pit and slope engineering, in particular to a monitoring method for surrounding rock based on a long-gauge fiber grating-based multifunctional intelligent bolt.

Background technique

The new Austrian tunnel construction method (hereinafter referred to as the new Austrian method) was proposed by the Austrian scholar L.V.RABCEWICZ (L.V.RABCEWICZ) in the 1950s. It is based on tunnel engineering experience and the theory of rock mechanics, and is carried out on the basis of practice. A new theory and new concept of tunnel engineering developed. The new Austrian method combines anchor rods and shotcrete as a construction method of the main support means. After many practical and theoretical studies in some countries, it obtained the patent right and officially named it in the 1960s. After that, this method has been developed very rapidly in many underground projects in Western Europe, Northern Europe, the United States and Japan, and has become one of the new technology symbols of modern tunnel engineering. The New Austrian Law was introduced to our country in the 1960s, and developed rapidly in the late 1970s and early 1980s. So far, it can be said that the new Austrian method is inseparable from all key and difficult underground projects, and it has almost become a basic method for building tunnels in weak and broken surrounding rocks.

The core of NATM tunnel excavation is timely support and diligent measurement, real-time or regular monitoring of the force, bearing capacity, and possible damage of the anchor rod in the surrounding rock in the support system, so as to It is very important to judge the support and stability of surrounding rock, and it has become an important topic in related fields. However, the test of anchor bolts cannot provide useful help to the displacement of surrounding rock, especially the convergence monitoring during the tunnel excavation construction stage. For the deformation convergence monitoring of the surrounding rock, the tests based on the steel ruler convergence gauge, the level test, and the total station test are commonly used at home and abroad. These methods have always been common methods for tunnel section convergence, but in practical applications there are still shortcomings such as the need for manual measurement, large random errors, difficult operation due to harsh environments, and incapable of real-time monitoring.

The fiber grating technology developed in recent years, due to its high precision, the strain measurement can reach 1με, and it can be waterproof and corrosion-resistant after packaging, and its long-term performance is relatively good. It can not only sense, but also be used for data transmission, which is conducive to networking And real-time monitoring, has been widely used in structural health monitoring. Southeast University has also developed the production and testing technology of long-gauge fiber gratings, which can measure the average strain within a certain gauge length, avoiding the distortion caused by local stress concentration caused by the structure or the installation of sensors. In addition, through Continuous strain can also measure its macroscopic displacement. This provides us with a new way of thinking about tunnel monitoring.

As for the impact of tunnel excavation on the surrounding rock formations, it can be seen that the relatively obvious deformation and displacement of the rock formations are mainly in the rock formations near the excavation section. As the distance increases, the impact of displacement decreases rapidly. In some places, the displacement of surrounding rock due to excavation is very small compared with the nearby surrounding rock, not only the absolute displacement but also the rate of change of the convergence rate, so it accounts for a very small part of the overall displacement. Therefore, in the excavation of tunnels in non-weak rock strata, we can approximately consider that the rock stratum far away from the excavation face is stable, which is approximately the fixed end. In the present invention, the anchor rod and the stable rock stratum are anchored and integrated with the rock stratum, so its far end can be approximately regarded as being fixed on the immovable rock stratum, that is, it is approximately a fixed end. Measure and obtain the distributed strain along the entire length of the bolt, so as to obtain the total deformation of the bolt, that is, the deformation and convergence of the surrounding rock of the excavation face and its rate.

The present invention proposes a new method for monitoring the excavation section of the new Austrian method tunnel. By arranging intelligent bolts in the surrounding rock perpendicular to its arch section, not only the stress, strain and damage of the bolts at different depths in the rock formation can be tested At the same time, the deformation and convergence of the section can be obtained, so as to realize the monitoring during the construction stage of the new Austrian method. At the same time, after entering the tunnel operation period, it can also continue to collect data and implement continuous monitoring.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a tunnel surrounding rock monitoring method based on multifunctional intelligent bolts.

The technical solution adopted in the present invention is: a multi-functional intelligent bolt, including multi-grating sensor with long gauge length without fusion, fiber grating multi-point temperature compensation auxiliary sensor, epoxy resin or planting glue, armored optical cable and soft plastic sleeve Tube;

The non-welded long-gauge-length multi-grating sensor and the fiber-optic grating multi-point temperature compensation auxiliary sensor are installed in the small groove opened along the longitudinal direction of the anchor rod, and are encapsulated by epoxy resin or embedding glue;

The fusion-free long-gauge multi-grating sensor includes a plurality of long-gauge fiber grating sensing units serially connected in series, and the long-gauge fiber grating sensing unit includes a sleeve, an optical fiber packaged in the sleeve, and an optical fiber written on the optical fiber. The grating, the two ends of the optical fiber are respectively fixed on the anchor section of the sleeve;

The fiber grating multi-point temperature compensation auxiliary sensor includes a sleeve, an optical fiber encapsulated in the sleeve, and a grating written on the optical fiber. One end of the optical fiber is fixed at the anchoring section of the sleeve, the other end is free, and both ends of the sleeve are closed;

The non-welded long-gauge-length multi-grating sensor and the fiber-optic grating multi-point temperature compensation auxiliary sensor are respectively connected with armored optical cables and led out from the bolt, and the armored optical cables are passed through soft plastic sleeves.

A tunnel surrounding rock monitoring method based on a multifunctional intelligent anchor comprises the following steps:

(1) According to the analysis data such as the geological condition of the tunnel location, the design of the support structure, the surrounding environment and the vulnerability, select the section to be monitored for monitoring; in each section, the top (about 90-degree direction) can be selected Five typical parts, namely, two waists (about 45 degrees and 135 degrees directions) and two bottoms (about 0 degrees and 180 degrees directions) are monitored.

(2) The anchor rods arranged in different positions of the tunnel are collected to the fiber grating demodulator through the armored optical cable drawn out to form a monitoring sensor network. Generally speaking, the gratings in the same anchor rod (including the gratings contained in the non-fused long-scale multi-grating sensor and the temperature compensation auxiliary sensor) will be sent to the same channel, and each channel of the fiber grating demodulator can generally be based on Its ability to connect the number of gratings, use a coupler to connect multiple anchor rods at the same time, but there cannot be gratings with the same wavelength or very close wavelengths in each channel. The number of smart anchor rods and gratings connected to each channel of the fiber grating demodulator is mainly determined by considering the wavelength range of the fiber grating demodulator, the required wavelength spacing between the gratings, and the optical loss caused by the connection.

(3) The fiber grating demodulator connected to each bolt is connected to the control computer, and the surrounding rock monitoring system is constructed through the monitoring system software. The bolts are used for sensing and perception of the state of the surrounding rock, the fiber grating demodulator is used for data collection, and the monitoring software system realizes the functions of data analysis, evaluation of the state of the surrounding rock and early warning.

(4) The long-gauge-length wavelength readings of the long-gauge-length multi-grating sensors in each bolt should be accurately temperature-compensated at the corresponding positions by the corresponding multi-point temperature compensation sensor, and then converted into the average value within the gauge length. Strain value, to obtain the strain distribution along the longitudinal direction of the bolt;

(5) Surrounding rock monitoring First, according to the strain distribution at different depths of the anchor, the stress distribution along the anchor can be obtained according to the stress-strain relationship of the anchor, and then the pressure characteristics of the surrounding rock at different depths can be obtained; at the same time, based on the anchor The strain distribution of the rod can obtain the deformation in each gauge length, obtain the distribution of the deformation in different depth sections along the longitudinal direction of the bolt, and further obtain the total deformation of the surrounding rock excavation surface. Here On the basis, the convergence rate of the surrounding rock is obtained through the change of the deformation on the time axis, and the stability of the deformation of the surrounding rock is judged. The damage of the anchor can be judged according to whether the maximum value of the distributed stress/strain of the anchor reaches the yield point. In this way, the pressure characteristics of the surrounding rock at different depths, the deformation and convergence of the surrounding rock, and the damage of the anchor rod can be obtained.

(6) This surrounding rock monitoring method adopts continuous and uninterrupted real-time monitoring, or adopts continuous monitoring with a certain time interval to obtain the real-time continuous change characteristics and convergence rate of surrounding rock pressure and deformation. Periodic testing methods during the period and operation period.

As a preference, if continuous monitoring with a certain time interval is adopted, the following method shall be followed:

Construction period monitoring:

Monitoring content: tunnel surrounding rock pressure, surrounding rock deformation, surrounding rock deformation convergence rate

Monitoring time: start within 24 hours after blasting, and measure the distance between the section and the excavation surface according to the monitoring;

(0～1)B: 1～2 times/day; (1～2)B: 1 time/day; (2～5)B: 2 times/day; >5B:

1 time/week; (Note: B is the tunnel excavation width)

Operation period monitoring:

Monitoring content: tunnel surrounding rock pressure, surrounding rock deformation

Monitoring time: 1 time/week or as required.

Beneficial effects of the present invention:

(1) The principle of the intelligent bolt used in the present invention is simple and reliable, and the testing method is novel and ingenious. The present invention mainly utilizes the fiber grating sensor installed on the intelligent anchor to measure its average strain within the gauge length, and according to the strain distribution of the intelligent anchor along the length direction, a certain gauge range or even the full length of the anchor can be obtained. Elongation (compression) amount;

(2) The long gauge fiber grating sensor of the present invention is made up of a plurality of long gauge fiber grating sensing units connected in series, and can measure the strain and the axial force situation of the bolt of different depths, therefore can monitor to the different depths and positions Internal force condition of surrounding rock;

(3) Surrounding rock deformation and convergence monitoring method of the present invention is ingenious, and principle is simple, anchors the vertical section of longer anchor bolt to far away rock stratum that can be approximated as immovable, then the near-end anchor bolt deformation amount is the section surface The total amount of deformation of the surrounding rock, so the monitoring of the deformation and convergence of the surrounding rock can be achieved through the monitoring of the bolt strain;

(4) The surrounding rock monitoring of the present invention can be automatically collected and analyzed by program control by leading the lead wire of the armored optical cable to the fiber grating acquisition instrument arranged in a safe position;

(5) The manufacturing process of the intelligent bolt used in the present invention is simple, the cost is comparatively low, and the layout is convenient. The layout of intelligent anchors in the tunnel can be used not only for monitoring, but also as a stress member for reinforcement and support, which has broad application prospects and good economic benefits;

(6) Since the long-gauge fiber grating sensor in the smart bolt used in the present invention is encapsulated with composite materials and epoxy resin, it has excellent performances such as water resistance, rust resistance, and corrosion resistance, and is not afraid of electromagnetic shielding and interference, and is integrated with the bolt After chemical encapsulation, it is more suitable for environmental erosion, with good durability and wide applicability;

(7) The test accuracy of the present invention is high, and its strain test accuracy can reach 1με, or even smaller;

(8) The present invention can simultaneously monitor anchors at multiple positions such as the top surface, two waists, and bottoms of both sides of the section, and can also implant smart anchors at multiple positions according to specific monitoring requirements to realize the monitoring of an area. Overall monitoring.

(9) The monitoring method of the present invention is not only suitable for the construction monitoring of the tunnel, but also suitable for the monitoring of the operation period of the tunnel. The means of monitoring can be uninterrupted real-time monitoring, or continuous monitoring with a certain time interval.

Description of drawings

Fig. 1 is the structure schematic diagram of multifunctional intelligent bolt of the present invention;

Fig. 2 is a longitudinal sectional view of Fig. 1;

Fig. 3 is a transverse sectional view of Fig. 1;

Fig. 4 is a schematic diagram of the structure of the non-welded long-gauge-length multi-grating sensor of the present invention;

Fig. 5 is a schematic diagram of the structure of the fiber grating multi-point temperature compensation auxiliary sensor of the present invention;

6 and 7 are schematic diagrams of the installation and layout of the multifunctional intelligent anchor rod of the present invention;

Fig. 8 is a schematic diagram of the tunnel surrounding rock monitoring system of the present invention;

Fig. 9 is a schematic diagram of displacement calculation based on long gauge strain distribution;

Figure 10 is a schematic diagram of the time history curve of the tunnel surrounding rock displacement with time;

Figure 11 is a schematic diagram of the convergence rate of the surrounding rock.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1-5, a multi-functional intelligent bolt based on long-gauge fiber gratings, including non-fused long-gauge multi-grating sensors 1, fiber grating multi-point temperature compensation auxiliary sensors 2, epoxy resin or planting bars Glue 3, armored optical cable 4 and soft plastic casing 5;

The non-welding long gauge length multi-grating sensor 1 and the fiber grating multi-point temperature compensation auxiliary sensor 2 are installed in the small groove opened in the longitudinal direction of the anchor rod 6, and are encapsulated by epoxy resin or embedding glue 3;

The non-fusion long gauge multi-grating sensor 1 includes a plurality of long gauge fiber grating sensing units connected in series in sequence, and the long gauge fiber grating sensing unit includes a sleeve, an optical fiber packaged in the sleeve, and an optical fiber written on the optical fiber. The grating on the top, and the two ends of the optical fiber are respectively fixed on the anchoring section of the sleeve;

The fiber grating multi-point temperature compensation auxiliary sensor 2 includes a sleeve, an optical fiber packaged in the sleeve, and a grating written on the optical fiber. One end of the optical fiber is fixed at the anchoring section of the sleeve, the other end is free, and both ends of the sleeve are closed;

The non-welding long gauge length multi-grating sensor 1 and the optical fiber grating multi-point temperature compensation auxiliary sensor 2 are respectively connected with the armored optical cable 4 and drawn out from the anchor rod 6, and the armored optical cable 4 is passed through the soft plastic sleeve 5 middle.

The manufacturing method of the above-mentioned multifunctional intelligent anchor comprises the following steps:

(1) Manufacture non-welded long gauge multi-grating sensor

(a1) Design and write multiple gratings with a certain spacing and different wavelengths on a single-mode optical fiber according to actual engineering requirements;

(a2) Select a thin smooth sleeve with an inner diameter slightly thicker than the optical fiber, design the anchor point position of each grating according to the engineering test requirements, and cut a number of gaps on the sleeve according to the anchor position, and penetrate the grating with Single-mode optical fiber with multiple gratings, adjust the position of the grating and the notch of the sleeve;

(a3) Apply a certain prestress to both ends of the optical fiber through the pulling device, and at the same time inject consolidation glue into the gap of the sleeve to form an anchor, and release the pulling device after consolidation, thereby encapsulating multiple continuous long-gauge optical fibers Long gauge multi-grating sensor with grating sensing unit and no fusion points;

(a4) For each long-gauge fiber grating sensing unit, the two ends of the optical fiber in the sleeve are respectively fixed with the sleeve by cement, and the rest of the optical fiber has no contact with the inner wall of the sleeve or has a slight contact, but the friction is negligibly small;

(a5) Further wrap the composite material outside the sleeve and infiltrate epoxy resin, and carry out the integrated packaging and reinforcement of the non-welded long-gauge-length multi-grating sensor itself;

(2) Make multi-point temperature compensation auxiliary sensor

(b1) Design and write multiple gratings with a certain spacing and different wavelengths on a single-mode optical fiber according to actual engineering requirements; the position design of these gratings can correspond to multiple gratings in the multi-grating sensor without fusion splicing , or design the position of the temperature-compensated grating according to the idea of temperature interpolation along the length of the bolt; the wavelengths of these gratings cannot be the same in the temperature-compensated sensor, and cannot be the same as those in the long-gauge-length multi-grating sensor without fusion have the same wavelength;

(b2) Choose a thin smooth sleeve with an inner diameter slightly thicker than the optical fiber, and seal it with glue on the first layer of the sleeve, cut one end of the engraved multi-grating pigtails short, and then insert it into the sleeve, so that The position of the grating is near a certain designed position, and the pigtail on the side of the short-cut fiber is shrunk inside the casing and has a certain distance from the tail of the casing, so that the pigtail will not touch the tail of the casing. Encapsulation glue is the principle, and then inject a little curing glue at both ends of the casing to seal it to form a temperature compensation sensor with multiple gratings.

(b3) For the optical fiber pigtail with multiple gratings packaged in the sleeve, one end is completely free in the sleeve, and the other end is fixed with the sleeve and used as a lead-out wire, and the optical fiber can slide freely in the sleeve;

(b4) Further wrapping the composite material outside the casing and infiltrating epoxy resin, and performing integrated packaging and reinforcement of the temperature compensation auxiliary sensor itself;

(3) Making multifunctional smart anchor rods

(c1) Select a solid anchor rod and open a small slot along the longitudinal direction; prepare two armored optical cables of moderate length, and put them through a soft plastic sleeve with moderate diameter and hardness. The tube is slightly longer, and the two ends are exposed;

(c2) Fix the non-welded long gauge multi-grating sensor and temperature compensation auxiliary sensor in the small groove opened by the anchor rod, and connect them with armored optical cables respectively, and lead them out from the anchor rod; The welding joints of the multi-grating sensor and the temperature compensation auxiliary sensor are respectively welded with the armored optical cable in the small groove of the anchor rod, and the armored optical cable is kept in the small groove with a length that can play an anchoring role, so that the outer optical cable after packaging The force of the sensor will not cause the internal sensor to be stressed;

(c3) Inject epoxy resin or planting glue into the small groove of the anchor rod to fill it up, and package the non-welded long-gauge-length multi-grating sensor and multi-point temperature compensation auxiliary sensor with the anchor rod to form the final multi-functional intelligent Anchor.

As shown in Figures 6 and 7, the installation and layout method of the long-gauge fiber grating intelligent anchor rod of the present invention includes the following steps:

(d1) According to the specific situation of the specific tunnel project, select the specific section position for monitoring; generally speaking, you can choose the critical and dangerous section for monitoring. For each section, you can choose the top (about 90 degree direction), two The five parts of the waist (about 45 degrees and 135 degrees) and the two bottoms (about 0 degrees and 180 degrees) are deployed for monitoring;

(d2) Drill holes in the depth direction on the rock mass or other medium where the bolts need to be arranged, and the hole diameter is slightly larger than the bolts; at the same time, install and fix the optical cable junction box not far from the monitoring section;

(d3) Insert one end of the packaged smart anchor rod without the lead-out optical cable into the drilled anchor hole to a certain depth, and lead the lead-out cable roundly and naturally along the surrounding rock or steel mesh or steel frame to the pre-installed In the fixed wire box, make necessary fixation and protection on the way to complete the placement of the smart anchor;

(d4) Inject quick-setting cement mortar into the channel of the anchor rod, wherein the grouting quality control and the setting of the cover plate can refer to the installation manual of the ordinary anchor rod; the layout and installation of the intelligent anchor rod will be completed after the cement mortar is solidified;

(d5) After the two lead-out optical cables connected with non-fused long-gauge-length multi-grating sensors and temperature-compensated auxiliary sensors are drawn out from the intelligent anchor rod, after passing through the junction box, use a fiber optic coupler to couple the two, and the coupling connection part is placed in the junction box. In the junction box, the coupled output optical cable is led out from the junction box, along the inner wall of the tunnel structure, leading to the installed fiber grating demodulator, and necessary fixing and protection are done on the way;

(d6) After the smart anchor rod and other anchor rods and rigid skeleton are installed in place, spray concrete to spray the anchor immediately to complete the lining construction at the section position.

The multi-functional intelligent bolt based on long-gauge optical fiber gratings can also be drilled in the depth direction on rock mass or other media, and the quick-setting anchoring drug roll can be loaded into the tunnel, and then inserted into the bolt to break through the quick-setting anchoring. The medicine volume realizes the consolidation installation. For a softer viscous medium like a mud layer, a hole with a diameter slightly smaller than the anchor rod can be drilled, the anchor rod can be directly inserted, and the end can be jacked in by hammering or other methods.

As shown in Figure 8, a tunnel surrounding rock monitoring method based on a multifunctional intelligent bolt includes the following steps:

(1) According to the geological conditions, structural design and vulnerability analysis of the tunnel location, select the section to be monitored for monitoring; in each section, you can choose the top (about 90-degree direction), the two waists (about 45-degree and 135-degree directions) and two bottoms (about 0-degree and 180-degree directions) for monitoring.

(2) The bolts 6 arranged in different positions of the tunnel are collected to the fiber grating demodulator 7 through the armored optical cable 4 drawn out to form a monitoring sensor network. Generally speaking, the gratings in the same bolt 6 (including the gratings contained in the non-fused long-scale multi-grating sensor and the temperature compensation auxiliary sensor) will be sent to the same channel, and each channel of the fiber grating demodulator 7 is generally According to the ability to connect the number of gratings, a coupler can be used to connect multiple anchor rods at the same time, but there cannot be gratings with the same wavelength or very close wavelengths in each channel. The number of anchor rods and gratings connected to each channel of the fiber grating demodulator 7 is mainly determined by considering the wavelength range of the fiber grating demodulator 7, the required wavelength spacing between gratings, and the optical loss caused by the connection.

(3) The fiber grating demodulator 7 connected to each bolt 6 is connected to the control computer 8, and a surrounding rock monitoring system is built through the monitoring system software. The bolts 6 are used for sensing the surrounding rock state, the fiber grating demodulator 7 is used for data collection, and the monitoring software system realizes the functions of data analysis, surrounding rock state evaluation and early warning.

(4) The long-gauge-length wavelength readings of the long-gauge-length multi-grating sensors in each bolt 6 within their respective gauge lengths should be accurately temperature-compensated at the corresponding positions by the corresponding multi-point temperature compensation sensors, and then converted into Average strain value, to obtain the strain distribution along the longitudinal direction of the bolt;

(5) Surrounding rock monitoring First, according to the strain distribution at different depths of the anchor, the stress distribution along the anchor can be obtained according to the stress-strain relationship of the anchor, and then the pressure characteristics of the surrounding rock at different depths can be obtained; at the same time, based on the anchor The strain distribution of the rod can obtain the deformation in each gauge length, obtain the distribution of the deformation in different depth sections along the longitudinal direction of the bolt, and further obtain the total deformation of the surrounding rock excavation surface. Here On the basis, the convergence rate of the surrounding rock is obtained through the change of the deformation on the time axis, and the stability of the deformation of the surrounding rock is judged. The damage of the anchor can be judged according to whether the maximum value of the distributed stress/strain of the anchor reaches the yield point. In this way, the stress characteristics of the surrounding rock at different depths, the deformation and convergence of the surrounding rock, and the damage of the anchor rod can be obtained.

(6) This surrounding rock monitoring method adopts continuous and uninterrupted real-time monitoring, or adopts continuous monitoring with a certain time interval to obtain the real-time continuous change characteristics and convergence rate of surrounding rock pressure and deformation. Periodic testing methods during the period and operation period.

If continuous monitoring with a certain time interval is adopted, proceed as follows:

Construction period monitoring:

Monitoring content: tunnel surrounding rock pressure, surrounding rock deformation, surrounding rock deformation convergence rate

Monitoring time: start within 24 hours after blasting, and measure the distance between the section and the excavation surface according to the monitoring;

(0～1)B: 1～2 times/day; (1～2)B: 1 time/day; (2～5)B: 2 times/day; >5B:

1 time/week; (Note: B is the tunnel excavation width)

Operation period monitoring:

Monitoring content: tunnel surrounding rock pressure, surrounding rock deformation

Monitoring time: 1 time/week or as required.

The working principle of the convergence monitoring of the surrounding rock section based on the intelligent bolt of the present invention is as follows:

Regarding the impact of tunnel excavation on the surrounding rock formations, it can be seen that the relatively obvious deformation and displacement of the rock formations are mainly in the rock formations near the excavation section. With the increase of the distance, the deformation effect decreases rapidly. In some places, the deformation of surrounding rock due to excavation is very small compared with the nearby surrounding rock, not only the absolute displacement, but also the rate of change of the convergence rate, so it accounts for a very small proportion of the overall displacement. Therefore, when excavating tunnels in non-weak rock formations, we can approximately consider the rock formations that are a little farther away from the excavation face to be stable rock formations. In the present invention, the bolt is extended and arranged to a slightly far rock formation, and after anchoring, it is integrated with the rock formation, so its far end can be approximately considered as fixed on a stable rock formation, that is, it is approximately a fixed end. The measurement of the multi-grating sensor obtains the strain distribution along the longitudinal direction of the bolt, and obtains the force of the bolt at different depths, and at the same time obtains the total deformation of the smart bolt relative to the fixed end, so as to obtain the excavation surface circumference. Deformation and convergence of rock and its rate.

The calculation of the deformation of the surrounding rock can be carried out as follows: first calculate the strain value within the gauge length of each long-gauge-sensing unit after temperature compensation, and then multiply it by its gauge length to obtain the deformation of the long-gauge-sensing unit amount, and then accumulate the amount of deformation on the entire anchor rod. As shown in Figure 9, by measuring the average strains ε1, ε2 and ε3 between the gauge lengths L1, L2 and L3, the strain at both ends of the bolt can be calculated according to the formula Δ=ε1·L1+ε2·L2+ε3·L3 The total displacement Δ.

After the surrounding rock is excavated by blasting, it will gradually deform toward the excavation section, so the measured deformation will gradually increase, but as the surrounding rock gradually stabilizes, the displacement Δ will gradually tend to a constant value, as shown in Figure 10 It is a schematic diagram of the time-history curve of the tunnel surrounding rock displacement changing with time.

At the same time, the deformation convergence rate of the surrounding rock, that is, the change rate of the deformation, is an important index reflecting the support of the surrounding rock. When the surrounding rock is excavated by blasting, deformation occurs due to the sudden imbalance of internal stress, and its deformation rate is the fastest at the beginning of blasting excavation. Later, with the redistribution of internal forces, the surrounding rock tends to be stable, and the deformation rate gradually decreases and eventually tends to At 0, the process can be shown in Figure 11. The calculation of displacement change rate can be calculated according to the following formula:

Rate of change of deformation Δ = (Δ(t _i )-Δ(t _i-1 ))/(t _i -t _i-1 )

Where: Δ(t _i ) is the deformation amount at t _i , and Δ(t _i-1 ) is the deformation amount at t _i-1 .

It should be pointed out that those skilled in the art can make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components that are not specified in this embodiment can be realized by existing technologies.

Claims (2)

1. tunnel surrounding monitoring method based on multifunctional intellectual anchor pole, it is characterised in that: described multifunctional intellectual anchor pole includes The many grating sensors of the long gauge length of weldless, fiber grating multi-point temp compensate aiding sensors, epoxy resin or anchoring adhesive, armouring Optical cable and flexible plastic sleeve；

The many grating sensors of the long gauge length of described weldless and fiber grating multi-point temp compensate aiding sensors and are arranged on anchor pole edge In the sulculus longitudinally opened, and encapsulated by epoxy resin or anchoring adhesive；

The many grating sensors of the long gauge length of described weldless include multiple long gauge length optical fibre grating sensing unit being sequentially connected in series, described Long gauge length optical fibre grating sensing unit includes sleeve pipe, the optical fiber being encapsulated in sleeve pipe and the grating being scribed on optical fiber, optical fiber Two ends are separately fixed at the anchoring section of sleeve pipe；

Described fiber grating multi-point temp compensates aiding sensors and includes sleeve pipe, the optical fiber being encapsulated in sleeve pipe and be scribed at optical fiber On grating, one end of optical fiber is fixed on the anchoring section of sleeve pipe, the other end freely, sleeve pipe closed at both ends；

The many grating sensors of the long gauge length of described weldless and fiber grating multi-point temp compensate aiding sensors respectively with armouring light Cable connects, and draws in anchor pole, and described armored optical cable is through among flexible plastic sleeve；

Described monitoring method comprises the following steps:

(1) according to these analysiss of data of geological state, support structure design, surrounding and vulnerability of present position, tunnel, The selected section needing monitoring is monitored；At each section, top, two waists and these 5 typical parts of two ends are selected to supervise Survey；

(2) it is laid in the anchor pole of tunnel diverse location, by the armored optical cable drawn, is pooled to fiber Bragg grating (FBG) demodulator, formed Monitoring sensing network；Grating in same anchor pole will be delivered to same passage, each passage root of fiber Bragg grating (FBG) demodulator Connect the ability of grating quantity according to it, be simultaneously connected with many anchor poles with bonder, but wavelength can not be had in each passage identical or Grating closely；The each passage of fiber Bragg grating (FBG) demodulator connects the quantity of anchor pole and grating by the ripple of fiber Bragg grating (FBG) demodulator Wavelength spacing, the several aspect of light loss of connection generation required between long scope, grating account for determining；

(3) fiber Bragg grating (FBG) demodulator connecting each anchor pole is connected with controlling computer, and by monitoring system software, builds country rock prison Examining system；Each anchor pole is used for data acquisition for the sensory-perceptible of state of surrounding rock, fiber Bragg grating (FBG) demodulator, and monitoring software system is then Realize the analysis of data, the assessment of state of surrounding rock and warning function；

(4) the long gauge length wavelength readings in respective gauge length of the many grating sensors of long gauge length in each anchor pole should be many by correspondence Point temperature compensation sensor carries out the accurate temperature compensation of relevant position, the mean strain value being then converted in gauge length, obtains Stress distribution along anchor pole longitudinal direction orientation；

(5) stress distribution of the first different depth position according to anchor pole of wall rock's level, according to the stress-strain relation of anchor pole, obtains Along the stress distribution of anchor pole, then obtain the pressure from surrounding rock feature of different depth；Meanwhile, stress distribution based on anchor pole can be obtained Deflection in each gauge length, obtains the distribution situation of deflection along anchor pole longitudinal direction different depth section, and further Obtain the total deformation of country rock excavation face, on this basis, by deflection change on a timeline, obtain the convergence of country rock Speed, it is judged that surrouding rock deformation stable case；Whether the damage of anchor pole then reaches in the wrong according to the distributed stress/strain maximum of anchor pole Clothes point judges；The most i.e. obtain country rock at pressure from surrounding rock feature, surrouding rock deformation and the convergence situation of different depth and anchor The degree of impairment of bar；

(6) this Monitoring Method For Surrounding Rock uses and monitors the most in real time, or employing has the persistence of intervals to supervise Surveying, it is possible to obtain pressure from surrounding rock, the real-time continuous variation characteristic of deformation and rate of convergence, this method can be as tunnel in construction Phase and the method for operation phase periodic detection.

Tunnel surrounding monitoring method based on multifunctional intellectual anchor pole the most according to claim 1, it is characterised in that: as adopted Monitor by the persistence having intervals, then carry out according to following method:

Monitoring during construction:

Contents for Monitoring: Tunnel Surrounding Rock Pressure, surrouding rock deformation, surrouding rock deformation rate of convergence；

The monitoring time: proceed by 24 hours after explosion, by monitoring measurement section away from excavation face distance；

(0～1) B:1～2 times/day；(1～2) B:1 times/day；(2～5) B:2 times/day；> 5B:

1 time/week；Note: B is tunnel excavation width；

The operation phase monitors:

Contents for Monitoring: Tunnel Surrounding Rock Pressure, surrouding rock deformation；

The monitoring time: 1 time/week or on request monitoring frequency.