CN109682624B - Deep tunnel whole ring test method - Google Patents
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Abstract
The invention provides a deep tunnel whole ring test method, which comprises the following steps: firstly, calculating the stress characteristic according to the surrounding rock pressure to be borne and the self weight of a lining segment ring under the theoretical embedding depth of an experimental lining segment ring, and selecting a loading scheme; preparing a longitudinal loading counter-force frame, an outer radial loading counter-force frame and an inner radial loading counter-force frame: preparing an experimental lining pipe sheet ring; thirdly, based on the measuring points selected in the first step, oil cylinders are arranged on the longitudinal loading counter-force frame, the outer radial loading counter-force frame and the inner radial loading counter-force frame corresponding to the measuring points; according to the loading scheme, the outer side oil cylinder and the inner side oil cylinder are divided into a plurality of load groups, and the oil cylinder of each load group is driven by a group of jacking hydraulic devices; and fourthly, driving one or more of the longitudinal oil cylinder, the outer side oil cylinder and the inner side oil cylinder according to the loading scheme, and carrying out graded loading on the experimental lining segment ring. The method has high precision and can effectively inhibit fine adjustment of the PID controller.
Description
Technical Field
The invention relates to a tunnel lining segment, in particular to a deep tunnel whole ring test method.
Background
After the subway tunnel is built and operated, along with the continuous accumulation of operation time, due to the inherent quality defect of the subway lining, the defects of cracking and shedding of the lining, concrete carbonization, water leakage and the like are easily caused. The subway tunnel lining structure cracking is the most common disease condition, and is also a direct cause of various diseases such as leakage, slurry pumping, block falling and the like in the tunnel.
The formation reasons of the tunnel lining cracks are various and very complex, so the formation reasons, the development and the overall damage condition of the tunnel lining cracks are researched, and the common test method is a field in-situ test or an indoor model test. The former has more authenticity and reliability, but the experiment is influenced by external factors such as topography and geology, etc., and the experiment controllability is poor, and the experiment difficulty is far greater than the latter. The model has the advantages of small test difficulty, strong operability, small influence from the outside, and wide application range, and is also the most applied means in the experiment for exploring the tunnel disease mechanism.
The existing loading test bed for tunnel model tests is mainly divided into two types, one type is that acting force is applied to soil bodies around a tunnel, the interaction of a tunnel structure and surrounding rocks is considered by the loading test bed, but the size of the tunnel model is obviously limited by considering the boundary effect of the model, the loading test bed can only complete the loading test of a small scale, the formation and the development of tunnel lining diseases are not easy to observe, and the structural stress is relatively not clear enough; the other one is that a direct loading mode is adopted to simulate the stress condition of the tunnel surrounding rock soil body, the acting force is directly applied to the tunnel model, the constraint of the tunnel boundary effect is avoided, the loading test with a large scale can be completed, the application range is wider, and the method is favorable for observing the whole gradual damage and instability process from the microscopic damage of the material to the macroscopic local damage of the structure and then to the overall instability of the structure in the loading process of the tunnel lining diseases.
For example, chinese patent application No. 201810386841.9 discloses a tunnel three-dimensional model loading test bed and a test method for tunnel disease observation, and the structure thereof is: the device comprises a counterforce frame foundation internally penetrated with a tunnel model, a wheel-rail device for placing and moving the tunnel model, a loading system for simulating load and a measuring system; the reaction frame foundation comprises a bottom plate, a door-shaped frame arranged on the bottom plate and a cambered surface reaction frame arranged in the door-shaped frame; the wheel rail device comprises a track above a bottom plate, a translation vehicle capable of relatively sliding along the track and a model base arranged on the translation vehicle, wherein the bottom of the model base is connected with the translation vehicle through a base spring; the loading system comprises a loading device arranged on the inner side of the cambered reaction frame, a cambered loading plate supported on the outer side wall of the top of the tunnel model, and a loading spring connected with the loading device and the cambered loading plate; the measuring system comprises a pressure sensor and a displacement meter, wherein the pressure sensor is arranged on the cambered surface loading plate and the model base, and the displacement meter is arranged on the inner side wall of the tunnel model. The loading device comprises jacks and hydraulic pump sets for outputting pressure to the jacks, the jacks are 2 groups and are arranged corresponding to the positions of the portal frame, the number of the jacks in each group is 7, and the jacks are uniformly arranged on the outer sides of the side wall and the top wall of the tunnel model at intervals along the circumferential direction of the tunnel model.
The hydraulic system of the loading device is poor in control precision, the difference value between the set pressure and the actual pressure is large, and when the whole annular duct piece is loaded, if the annular closing force of the whole duct piece is not zero, the whole ring can move. In the test, force loading with different grades and different directions is carried out, and the total force must be zero. The pressure of each group of oil cylinders is required to be accurately controlled, and the pressure error is extremely small. The loading device is difficult to meet the requirement of high-precision testing.
The invention is provided for overcoming the defects in the prior art.
Disclosure of Invention
The invention aims to provide a deep tunnel whole ring test method aiming at the structural defects of the prior art, the deep tunnel whole ring test method is provided with a longitudinal loading counter-force mechanism, an outer side radial loading counter-force mechanism and an inner side radial loading counter-force mechanism, the system pressure and the rodless cavity pressure of an oil cylinder are used as feedback, the oil cylinder loading load is controlled by a PID closed-loop control energy accumulator and a proportional overflow valve, and the precision is higher.
In order to achieve the above purpose, the deep tunnel whole ring test method provided in the embodiments of the present invention is implemented by the following technical solutions:
a deep tunnel whole ring test method is used for carrying out loading tests on lining pipe rings installed on a movable support and is characterized by comprising the following steps:
calculating a stress characteristic according to the surrounding rock pressure to be borne and the self weight of a lining segment ring under the theoretical embedding depth of an experimental lining segment ring, and selecting a loading scheme based on the stress characteristic, wherein the loading scheme comprises measuring points to be loaded and loading loads of the measuring points;
preparing a longitudinal loading counter-force frame, an outer radial loading counter-force frame and an inner radial loading counter-force frame: preparing an experimental lining pipe sheet ring; assembling and positioning the experiment lining pipe sheet ring, the longitudinal loading counter-force frame, the outer radial loading counter-force frame and the inner radial loading counter-force frame;
thirdly, based on the measuring points selected in the first step, a longitudinal oil cylinder is arranged on the longitudinal loading counterforce frame corresponding to each measuring point, an outer oil cylinder is arranged on the outer radial loading counterforce frame corresponding to each measuring point, and an inner oil cylinder is arranged on the inner radial loading counterforce frame corresponding to each measuring point; according to the loading scheme selected in the step one, the oil cylinders on the outer side and the oil cylinders on the inner side are divided into a plurality of load groups, the oil cylinders of each load group are driven by a group of jacking hydraulic devices, and the oil cylinders in any group of load groups are loaded with the same load;
driving one or more of a longitudinal oil cylinder, an outer side oil cylinder and an inner side oil cylinder according to the loading scheme determined in the step one, and carrying out graded loading on the experimental lining segment ring:
A. the PID controller controls the jacking hydraulic device to drive the oil cylinder to extend out, closed-loop control is carried out on the system pressure before the pressure information of the rodless cavity of the oil cylinder received by the PID controller forms a stable value, the system pressure information is used as feedback, and the loaded load is controlled according to the feedback data;
B. after the pressure information of the rodless cavity of the oil cylinder received by the PID controller forms a stable value, adopting pressure closed-loop control of the rodless cavity of the oil cylinder, taking the pressure information of the rodless cavity of the oil cylinder as feedback, and controlling the loading load according to the feedback data;
C. maintaining the pressure according to the set time after reaching the set pressure level, and measuring experimental data; then, continuously adopting oil cylinder rodless cavity pressure closed-loop control to control the oil cylinder to further extend out to enter the next pressure level;
D. repeating step C until the loading scheme is completed;
in the loading process, the loading load of the oil cylinder in each load group increases progressively along with the theoretical embedding depth of the corresponding segment ring.
Step B, C, D further includes the steps of:
a. and (3) calculating and judging whether the overshoot of the system is higher than a set overshoot threshold value according to the pressure information of the rodless cavity and an internal target value calculated by the PID controller: if the value is higher than the overshoot threshold value, performing the step F; if not, performing step G;
b. the overshoot compensation controller cuts off the data connection between the PID controller and the D/A conversion module, inputs the overshoot suppression correction information to the D/A conversion module until the system overshoot is lower than the overshoot threshold value, and restores the data connection between the PID controller and the D/A conversion module;
c. and performing PID calculation and control according to the internal target value calculated by the PID.
The loading scheme comprises an outer-side oil cylinder loading scheme and an inner-side oil cylinder loading scheme; in the outboard-only cylinder loading scheme and the inboard-only cylinder loading scheme, step B, C, D further includes the steps of:
when the rodless cavity pressure is detected to exceed a set threshold value, one or more groups with the highest loading load in the load groups are selected based on the rodless cavity pressure of each load group, and the PID controller controls the oil cylinders of the selected load groups to periodically and reciprocally stretch at the frequency of 0.5-2 Hz; in the reciprocating expansion process, the highest value of the loading data output by the PID controller is an internal target value, and the lowest value is (internal target value-pressure error).
The jacking hydraulic device comprises a pump driven by a motor, a proportional overflow valve with an amplifier, an energy accumulator and an electromagnetic directional valve; an oil inlet of the pump is connected to an oil tank, and an oil outlet of the pump is connected with a first pressure sensor, a first oil port of the proportional overflow valve and a first oil port of the electromagnetic directional valve through a one-way valve; a second oil port of the proportional overflow valve is connected with an energy accumulator; a second oil port of the electromagnetic directional valve is connected with a shunting module, is connected with a second pressure sensor after shunting, and is connected to a rodless cavity of each oil cylinder of a group of load groups in the outer radial loading counterforce frame or the inner radial loading counterforce frame; the rod cavities of the load group oil cylinders are connected back to the corresponding flow dividing modules and are connected with the third oil port of the electromagnetic directional valve after confluence; and a fourth oil port of the electromagnetic directional valve is connected with an oil return tank through an oil return pipeline.
The outside cylinder and the inside cylinder are divided into 9 load groups.
Compared with the prior art, the invention has the beneficial effects that:
1. the system pressure and the rodless cavity pressure of the oil cylinder are used as feedback, and the oil cylinder loading load is controlled through a PID closed-loop control energy accumulator and a proportional overflow valve, so that full-automatic control is realized. In the whole experiment, the oil cylinder extends out from the original state, the oil cylinder does not contact a pipe piece, the pressure of a rodless cavity of the oil cylinder does not form a stable value, the pressure of the system is controlled in a closed loop mode, and the pressure of an oil pump system is used as feedback. So that the cylinders are in contactThe pressure error is smaller when the pipe piece. When the oil cylinder contacts the pipe piece, the pressure of the rodless cavity of the oil cylinder forms a stable value, the pressure of the rodless cavity of the oil cylinder is controlled in a closed loop mode, the pressure of the rodless cavity of the oil cylinder is used as feedback, and the precision error is smaller than 0.1Kg/cm2。
2. According to the experimental requirement specification, when a pressure grade is increased to another pressure grade in a test, if the PID constants are not matched when meeting the pressure point of the energy accumulator, the pressure is slightly overshot, and then the overshoot compensation controller automatically gives out the overshoot suppression correction information until the overshoot amount of the PID controller is lower than the overshoot threshold value, and the data connection between the PID controller and the D/A conversion module is recovered.
3. Because the accumulator is easy to oscillate repeatedly after absorbing pressure, the one-way throttle valve is added on the connection pipe section of the accumulator, so that hydraulic oil can smoothly enter the accumulator when the accumulator absorbs pressure impact, and the hydraulic oil in the accumulator is controlled by throttle damping when flowing back, thereby eliminating oscillation.
Drawings
The above features and advantages of the present invention will become more apparent and readily appreciated from the following description of the exemplary embodiments thereof taken in conjunction with the accompanying drawings.
FIG. 1 is a structural diagram of an outer radial loading counter-force mechanism and an inner radial loading counter-force mechanism of a deep tunnel full ring test according to an embodiment of the invention;
FIG. 2 is a hydraulic schematic diagram I of the deep tunnel full ring test method according to the embodiment of the invention;
FIG. 3 is a hydraulic schematic diagram II of the deep tunnel full ring test method according to the embodiment of the invention;
FIG. 4 is a schematic diagram of a deep tunnel full ring testing method according to an embodiment of the present invention;
FIG. 5 is a diagram of the arrangement of measuring points of a hydraulic oil cylinder and a segment outer arc surface in a deep tunnel full ring test according to the embodiment of the invention;
FIG. 6 is a schematic cross-sectional view A-A of FIG. 1;
FIG. 7 is a schematic cross-sectional view B-B of FIG. 1.
Detailed Description
The invention is described in further detail below with reference to the attached drawing figures to facilitate understanding by those skilled in the art:
referring to fig. 1 to 7, the invention provides a deep tunnel whole ring test method, which is used for carrying out loading tests on lining pipe ring 2 installed on a movable support 1, and the deep tunnel whole ring test method mainly uses the following equipment:
outer radial loading counterforce mechanism 3
The outer radial loading counterforce mechanism 3 comprises an outer frame 31 surrounding the periphery of the lining pipe piece ring 2, and the outer frame 31 is provided with outer oil cylinders 32 corresponding to each measuring point on the periphery of the lining pipe piece ring 2 respectively and used for applying radial load to the lining pipe piece ring 2.
As shown in fig. 6-7, the outer frame 31 is provided with an axial loading jack reaction beam 33, and the outer cylinder 32 is fixed on the axial loading jack reaction beam 33; disposed within the lining tube segment ring 2 is a support steel plate 34 supported on the inside face of the segment 22. The axial loading jack reaction beam 33 and the supporting steel plate 34 are connected through a connecting pull rod 35. In addition, a pad beam 36 is arranged between the jacking end of the outer side oil cylinder 32 and the outer side surface of the pipe piece 21.
Referring to fig. 5, the distributed graph of the measuring points on the outer peripheral surface of the lining pipe segment ring 2 and the oil cylinder 32 on the outer side can be seen, and the measuring points on the outer peripheral surface of the lining pipe segment ring 2 mainly comprise joint opening angle (opening amount) measuring points, annular gap radial dislocation measuring points, concrete strain measuring points and lining pipe segment ring radial displacement measuring points. And the outer side oil cylinders 32 correspond to each measuring point one by one and supply 96 oil cylinders.
In order to simulate the influence of the self weight of the structure on the whole stress process of the structure and fully simulate the stress state of the lining structure in the actual soil body; based on the theoretical burying depth of the segment 22 corresponding to the outer side oil cylinder 32 in different geological environments, which should bear the surrounding rock pressure and the self weight of the lining pipe segment ring 2, the outer side oil cylinder 32 is divided into 9 load groups, which are marked as P1, P2, P3, P4, P5, P6, P7, P8 and P9. Wherein:
load groups P1 and P9 each consist of 4 outboard cylinders 32.
The load groups P3, P5 and P7 are respectively composed of 8 outer side oil cylinders 32.
The load groups P2, P4, P6 and P8 are respectively composed of 16 outer side oil cylinders 32.
Inner radial loading counterforce mechanism 4
The inner radial loading reaction mechanism 4 comprises an inner frame 41 arranged in the lining pipe ring 2, and a plurality of inner oil cylinders 42 are arranged on the inner frame 41. The inner frame 41 is also connected with the lining segment ring 2 through a supporting steel plate, an axial loading jack reaction beam and a connecting pull rod, and the specific structural description and the drawing are omitted since the structure is similar to that of the outer radial loading reaction mechanism 3.
Considering that the measuring points on the outer peripheral surface and the measuring points on the inner peripheral surface of the lining pipe sheet ring 2 correspond to each other one by one, the number and the arrangement positions of the inner side oil cylinders 42 are the same as those of the outer side oil cylinders 32, and the arrangement diagram of the measuring points of the inner side oil cylinders 42 is omitted.
The influence of the self weight of the structure on the whole stress process of the structure is simulated, and the stress state of the lining structure in the actual soil body is fully simulated; based on the theoretical embedding depth of the segment 22 corresponding to the inner side oil cylinder 42 in different geological environments, which should bear the surrounding rock pressure and the self weight of the lining pipe segment ring 2, the inner side oil cylinder 42 is also divided into 9 load groups, which are marked as F1, F2, F3, F4, F5, F6, F7, F8 and F9. Wherein:
load groups F1 and F9 each consist of 4 outboard cylinders 32.
The load groups F3, F5 and F7 are respectively composed of 8 outer side oil cylinders 32.
The load groups F2, F4, F6 and F8 are respectively composed of 16 outer side oil cylinders 32.
Longitudinal loading counterforce mechanism
The longitudinal loading counterforce mechanism 5 comprises an upper side frame 51 which is supported on the ground and arranged above the lining segment ring 2, wherein the upper side frame 51 is provided with upper side oil cylinders 52 corresponding to each measuring point on the upper end surface of the lining segment ring respectively and used for applying load along the longitudinal direction of the lining segment ring to the lining segment ring, and the number of the upper side oil cylinders 52 is 24.
Actuating mechanism
The actuator 6 includes an outer sub-actuator 61, an inner sub-actuator and a longitudinal sub-actuator 61.
Wherein:
referring to fig. 2, the outer sub-actuator 62 includes an oil tank 621 and 9 sets of lift-up hydraulic devices corresponding to the load sets of the outer radial load reaction mechanism 3 one by one. Each set of jacking hydraulic devices comprises an oil tank 621, an electromagnetic directional valve 622, a pump 623, a proportional overflow valve 625 and an accumulator 624.
The pump 623 may be a vane pump and may be driven by an ac motor of 11 kw. An oil inlet of the pump 623 is connected to the oil tank 621, and an oil outlet of the pump 623 is connected to a first oil port of the proportional relief valve 625, a first oil port of the electromagnetic directional valve 622 and a first pressure sensor 627 through a check valve 626. First pressure sensor 627 is used to detect the system pressure.
An amplifier is arranged on the proportional relief valve 625 and used for changing the pressure of the hydraulic oil entering the system. And a second oil port of proportional relief valve 625 is connected with accumulator 624. Since accumulator 624 is prone to repeated oscillation after absorbing pressure, a one-way throttle valve is added to the connected pipe section of accumulator 624, namely, between the second port of proportional relief valve 625 and accumulator 524. So that the hydraulic oil can smoothly enter the accumulator 624 when the accumulator 624 absorbs pressure impact, and the hydraulic oil in the accumulator is controlled by throttling damping to eliminate oscillation when the hydraulic oil flows back.
The second oil port of the electromagnetic directional valve 622 is connected with a flow dividing module 628, is connected with a second pressure sensor 628 after being divided, and is connected to each outer cylinder 32 rodless cavity of a group of load groups in the outer radial loading counterforce mechanism 3. The second pressure sensor 628 is used to detect the pressure in the rodless chamber of the outside cylinder 32.
The rod cavity of the outer cylinder 32 of each load group of the outer radial loading reaction mechanism 3 is connected with a flow dividing module 628, and after confluence, the flow dividing module 628 is connected with the third oil port of the electromagnetic directional valve 622. The fourth port of the electromagnetic directional valve 622 is connected to the oil return tank 621 through a cooler and a filter and an oil return line.
In this embodiment, the shunting module 628 has different structures corresponding to different load groups. The shunting modules 628 of the load groups P1, P9 perform the shunting with a first shunting block. The shunting modules 628 of the load groups P3, P5 and P7 are structured as second shunting blocks connected in parallel with 2 first shunting blocks and are arranged in a left-right manner. The load groups P2, P4, P6 and P8 are respectively connected with 4 first shunt blocks by using second shunt blocks. The first shunting block is provided with 2 oil inlets and 8 oil outlets; the second flow dividing block is 2 oil inlets and 8 oil outlets.
The inner side sub-actuating mechanism and the outer side sub-actuating mechanism have the same structure, the electromagnetic directional valves of each group of jacking hydraulic devices are connected with the rod-free cavities of the inner side oil cylinders of one group of load groups of the inner side radial loading counterforce mechanism after being divided by the dividing module, and the third pressure sensors are used for detecting the pressure of the rod-free cavities of the inner side oil cylinders 42. And a rod cavity of the oil cylinder at the inner side of the load group is connected with a third oil port of the electromagnetic directional valve through a corresponding flow dividing module in a converging manner. The hydraulic schematic of the inner sub-actuator is omitted here.
As shown in fig. 3, the structure of the longitudinal sub-actuator 61 is substantially the same as that of the outer sub-actuator 62, and the outer sub-actuator 61 includes an oil tank 611, an electromagnetic directional valve 612, a pump 613, a proportional relief valve 615, and an accumulator 614.
The pump 613 may be a vane pump and may be driven by an ac motor of 11 kw. An oil inlet of the pump 613 is connected to an oil tank 611, and an oil outlet thereof is connected to a first oil port of the proportional relief valve 615, a first oil port of the electromagnetic directional valve 612, and a first pressure sensor 617 through a check valve 616. The first pressure sensor 617 is used to detect the system pressure. An amplifier is arranged on the proportional overflow valve 615 and is used for changing the pressure of hydraulic oil entering the system. The second port of the proportional overflow valve 615 is connected to an accumulator 614. Since the accumulator 614 is prone to repeated oscillation after absorbing pressure, a check throttle valve is added to the connection pipe section of the accumulator 614, namely, the check throttle valve is arranged between the second oil port of the proportional overflow valve 615 and the accumulator 524. Therefore, when the accumulator 614 absorbs pressure impact, the hydraulic oil can smoothly enter the accumulator 614, and when the hydraulic oil in the accumulator flows back, the hydraulic oil is controlled by throttling damping to eliminate oscillation.
The second oil port of the electromagnetic directional valve 612 is connected to a flow dividing module 618, and the flow dividing module 618 has 2 oil inlets and 48 oil outlets. After being branched, the third pressure sensor 618 is connected to the rodless chambers of the 24 upper side cylinders 52. The second pressure sensor 618 is for detecting the pressure in the rodless chamber of the upper side cylinder 52.
The rod chambers of the 24 upper side oil cylinders 52 are connected with a flow dividing module 618, and after confluence, the rod chambers are connected with a third oil port of the electromagnetic directional valve 612 through the flow dividing module 618. The fourth port of the electromagnetic directional valve 612 is connected to the return tank 611 through a cooler and filter and a return line.
The first pressure sensor, the second pressure sensor, the third pressure sensor and the fourth pressure sensor constitute a detection unit of the device.
Control unit
The control unit receives the data information transmitted by the detection unit. The control unit is provided with an experimental loading scheme, and the loading scheme is set based on experimental design requirements and the situation that the pipe pieces corresponding to the outer side oil cylinder and the inner side oil cylinder bear the surrounding rock pressure and the self weight of the ring of the lining pipe piece under the theoretical embedding depth.
And the control unit designs control instructions for the outer side oil cylinder and the inner side oil cylinder by adopting a PID closed-loop control mode according to the loading load information, the rodless cavity pressure information and the system pressure information. The executing mechanism 6 is connected with each of the outer side oil cylinder and the inner side oil cylinder in a control mode, receives control instruction information transmitted by the control unit, and controls the outer side oil cylinder and the inner side oil cylinder to load through a proportional overflow valve with an amplifier.
Referring to fig. 4, the control unit at least includes an a/D conversion module for receiving the signal information transmitted by the detection unit and converting the analog signal into a digital signal, and a PID controller, the a/D conversion module is connected to an input end of the PID controller, an output end of the PID controller is connected to the D/a conversion module, and the D/a conversion module is connected to input ends of motors and proportional relief valves of the outer side sub-actuator and the inner side sub-actuator.
In combination with the above description of each device used in the method of this embodiment, the deep tunnel whole ring test method provided in this embodiment mainly includes the following steps:
calculating the stress characteristic according to the surrounding rock pressure to be borne under the theoretical embedding depth of the experimental lining pipe piece ring and the self weight of the lining pipe piece ring, and selecting a loading scheme based on the stress characteristic, wherein the loading scheme comprises measuring points to be loaded and loading loads of the measuring points;
secondly, according to the structure described above, preparing a longitudinal loading counterforce frame, an outer radial loading counterforce frame and an inner radial loading counterforce frame:
preparing an experimental lining pipe sheet ring: prefabricating a cambered surface loading plate, an experimental lining segment ring base and a movable support in a factory according to the size and the profile curvature of the experimental lining segment ring; then pouring an experimental lining pipe sheet ring; correspondingly placing the experimental lining segment ring on the movable support;
then positioning an experiment lining pipe ring, and assembling and positioning the experiment lining pipe ring, the longitudinal loading counter-force frame, the outer radial loading counter-force frame and the inner radial loading counter-force frame;
thirdly, based on the measuring points selected in the first step, a longitudinal oil cylinder is arranged on the longitudinal loading counterforce frame corresponding to each measuring point, an outer oil cylinder is arranged on the outer radial loading counterforce frame corresponding to each measuring point, and an inner oil cylinder is arranged on the inner radial loading counterforce frame corresponding to each measuring point;
driving one or more of a longitudinal oil cylinder, an outer side oil cylinder and an inner side oil cylinder according to the loading scheme determined in the step one, and carrying out graded loading on the experimental lining segment ring:
A. the PID controller controls the jacking hydraulic device to drive the oil cylinder to extend out, closed-loop control is carried out on the system pressure before the pressure information of the rodless cavity of the oil cylinder received by the PID controller forms a stable value, the system pressure information is used as feedback, and the PID controller outputs the set pressure of the proportional overflow valve to control the loading load according to the feedback data;
B. after the pressure information of the rodless cavity of the oil cylinder received by the PID controller forms a stable value, adopting pressure closed-loop control of the rodless cavity of the oil cylinder, taking the pressure information of the rodless cavity of the oil cylinder as feedback, and controlling the loading load by the PID controller outputting the set pressure of the proportional relief valve according to the feedback data;
C. maintaining the pressure according to the set time after reaching the set pressure level, and measuring experimental data; then, continuously adopting oil cylinder rodless cavity pressure closed-loop control to control the oil cylinder to further extend out to enter the next pressure level;
D. repeating step C until the loading scheme is completed;
in the loading process, the loading load of the oil cylinder in each load group increases progressively along with the theoretical embedding depth of the corresponding segment ring.
In addition, in order to avoid overshoot of the PID controller, especially when the pressure level rises from one pressure level to another pressure level during the test, the PID constants may not match when the pressure point of the accumulator is encountered, so as to cause a slight overshoot of the pressure, step B, C, D further includes the following steps:
a. and (3) calculating and judging whether the overshoot of the system is higher than a set overshoot threshold value according to the pressure information of the rodless cavity and an internal target value calculated by the PID controller: if the value is higher than the overshoot threshold value, the step b is carried out; if not, performing step c;
b. the overshoot compensation controller cuts off the data connection between the PID controller and the D/A conversion module, inputs the overshoot suppression correction information to the D/A conversion module until the system overshoot is lower than the overshoot threshold value, and restores the data connection between the PID controller and the D/A conversion module;
c. and performing PID calculation and control according to the internal target value calculated by the PID.
The overshoot compensation controller is connected with the detection unit and is connected with the D/A conversion module and the PID controller through a switch relay.
In the loading scheme, the scheme comprises a scheme of loading the outer side oil cylinder and a scheme of loading the inner side oil cylinder at the same time, and the resultant force of the stress of the experimental lining segment ring is zero; and simultaneously, the test device also comprises an outer side oil cylinder loading scheme and an inner side oil cylinder loading scheme, and is used for simulating and testing the condition of single-side stress of the experimental lining segment ring.
In the outboard only cylinder loading scheme and the inboard only cylinder loading scheme, step B, C, D further includes the steps of:
when the pressure of the rodless cavity monitored by the detection unit exceeds a set threshold value, based on the pressure of the rodless cavity of each load group, the PID controller selects one or more groups with the highest load in the load groups, and then the PID controller controls the oil cylinders of the selected load groups to periodically and repeatedly stretch and retract at the frequency of 0.5-2 Hz. In the reciprocating expansion process, the PID controller outputs loading load data, the wave crest value of the loading load data is an internal target value, and the wave trough value is equal to the internal target value-pressure error.
The reason for setting this step is: in view of the fact that the loading pressure of different load groups is increased along with the increase of the embedding depth of the corresponding pipe piece, the circumferential stress of the experimental lining pipe piece ring is not uniform in the loading process, and the deformation of the circumferential surface of the experimental lining pipe piece ring is also unequal along with the height of the loading load. When the loading load is higher (more than 200 Kg/cm)2) And the experimental lining segment ring is damaged due to different segment deformation quantities, so that the experiment fails. Therefore, within the allowable range of experimental error, the load group with higher loading load is controlled to perform periodic reciprocating expansion with extremely small amplitude, so that the damage of the experimental lining pipe sheet ring can be effectively avoided.
Compared with the prior art, the deep tunnel whole ring test device has the beneficial effects that:
1. the system pressure and the rodless cavity pressure of the oil cylinder are used as feedback, and the oil cylinder loading load is controlled through a PID closed-loop control energy accumulator and a proportional overflow valve, so that full-automatic control is realized. In the whole experiment, the oil cylinder extends out from the original state, the oil cylinder does not contact a pipe piece, the pressure of a rodless cavity of the oil cylinder does not form a stable value, the pressure of the system is controlled in a closed loop mode, and the pressure of an oil pump system is used as feedback. Therefore, the pressure error is smaller when the oil cylinder contacts the pipe piece. When the oil cylinder contacts the pipe piece, the pressure of the rodless cavity of the oil cylinder forms a stable value, the pressure of the rodless cavity of the oil cylinder is controlled in a closed loop mode, the pressure of the rodless cavity of the oil cylinder is used as feedback, and the precision error is smaller than 0.1Kg/cm2。
2. According to the experimental requirement specification, when a pressure grade is increased to another pressure grade in a test, if the PID constants are not matched when meeting the pressure point of the energy accumulator, the pressure is slightly overshot, and then the overshoot compensation controller automatically gives out the overshoot suppression correction information until the overshoot amount of the PID controller is lower than the overshoot threshold value, and the data connection between the PID controller and the D/A conversion module is recovered.
3. Because the accumulator is easy to oscillate repeatedly after absorbing pressure, the one-way throttle valve is added on the connection pipe section of the accumulator, so that hydraulic oil can smoothly enter the accumulator when the accumulator absorbs pressure impact, and the hydraulic oil in the accumulator is controlled by throttle damping when flowing back, thereby eliminating oscillation.
Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that the above embodiments are only one of the preferred embodiments of the present invention, and not all embodiments can be enumerated herein for the sake of brevity, and any embodiment that can embody the claims of the present invention is within the protection scope of the present invention.
Claims (4)
1. A deep tunnel whole ring test method is used for carrying out loading tests on lining pipe rings installed on a movable support and is characterized by comprising the following steps:
calculating a stress characteristic according to the surrounding rock pressure to be borne and the self weight of a lining segment ring under the theoretical embedding depth of an experimental lining segment ring, and selecting a loading scheme based on the stress characteristic, wherein the loading scheme comprises measuring points to be loaded and loading loads of the measuring points;
preparing a longitudinal loading counter-force frame, an outer radial loading counter-force frame and an inner radial loading counter-force frame: preparing an experimental lining pipe sheet ring; assembling and positioning the experiment lining pipe sheet ring, the longitudinal loading counter-force frame, the outer radial loading counter-force frame and the inner radial loading counter-force frame;
thirdly, based on the measuring points selected in the first step, a longitudinal oil cylinder is arranged on the longitudinal loading counterforce frame corresponding to each measuring point, an outer oil cylinder is arranged on the outer radial loading counterforce frame corresponding to each measuring point, and an inner oil cylinder is arranged on the inner radial loading counterforce frame corresponding to each measuring point; according to the loading scheme selected in the step one, the oil cylinders on the outer side and the oil cylinders on the inner side are divided into a plurality of load groups, the oil cylinders of each load group are driven by a group of jacking hydraulic devices, and the oil cylinders in any group of load groups are loaded with the same load;
driving one or more of a longitudinal oil cylinder, an outer side oil cylinder and an inner side oil cylinder according to the loading scheme determined in the step one, and carrying out graded loading on the experimental lining segment ring:
A. the PID controller controls the jacking hydraulic device to drive the oil cylinder to extend out, closed-loop control is carried out on the system pressure before the pressure information of the rodless cavity of the oil cylinder received by the PID controller forms a stable value, the system pressure information is used as feedback, and the loaded load is controlled according to the feedback data;
B. after the pressure information of the rodless cavity of the oil cylinder received by the PID controller forms a stable value, adopting pressure closed-loop control of the rodless cavity of the oil cylinder, taking the pressure information of the rodless cavity of the oil cylinder as feedback, and controlling the loading load according to the feedback data;
C. maintaining the pressure according to the set time after reaching the set pressure level, and measuring experimental data; then, continuously adopting oil cylinder rodless cavity pressure closed-loop control to control the oil cylinder to further extend out to enter the next pressure level;
D. repeating step C until the loading scheme is completed;
in the loading process, the loading load of the oil cylinder in each load group increases progressively along with the theoretical embedding depth of the corresponding segment ring.
2. The deep tunnel full ring test method of claim 1, wherein: the step B, C, D further includes the following steps:
a. and (3) calculating and judging whether the overshoot of the system is higher than a set overshoot threshold value according to the pressure information of the rodless cavity and an internal target value calculated by the PID controller: if the value is higher than the overshoot threshold value, the step b is carried out; if not, performing step c;
b. the overshoot compensation controller cuts off the data connection between the PID controller and the D/A conversion module, inputs the overshoot suppression correction information to the D/A conversion module until the system overshoot is lower than the overshoot threshold value, and restores the data connection between the PID controller and the D/A conversion module;
c. and performing PID calculation and control according to the internal target value calculated by the PID.
3. The deep tunnel full ring test method of claim 2, wherein the loading scheme comprises an outboard-only cylinder loading scheme and an inboard-only cylinder loading scheme; in the outboard-only cylinder loading scheme and the inboard-only cylinder loading scheme, step B, C, D further includes the steps of:
when the rodless cavity pressure is detected to exceed a set threshold value, one or more groups with the highest loading load in the load groups are selected based on the rodless cavity pressure of each load group, and the PID controller controls the oil cylinders of the selected load groups to periodically and reciprocally stretch at the frequency of 0.5-2 Hz; in the reciprocating expansion process, the change amplitude of the loading load data output by the PID controller is as follows: the peak value is the internal target value, and the trough value is the internal target value-pressure error.
4. The deep tunnel full ring test method of claim 3, wherein: the jacking hydraulic device comprises a pump driven by a motor, a proportional overflow valve with an amplifier, an energy accumulator and an electromagnetic directional valve; an oil inlet of the pump is connected to an oil tank, and an oil outlet of the pump is connected with a first pressure sensor, a first oil port of the proportional overflow valve and a first oil port of the electromagnetic directional valve through a one-way valve; a second oil port of the proportional overflow valve is connected with an energy accumulator; a second oil port of the electromagnetic directional valve is connected with a shunting module, is connected with a second pressure sensor after shunting, and is connected to a rodless cavity of each oil cylinder of a group of load groups in the outer radial loading counterforce frame or the inner radial loading counterforce frame; the rod cavities of the load group oil cylinders are connected back to the corresponding flow dividing modules and are connected with the third oil port of the electromagnetic directional valve after confluence; and a fourth oil port of the electromagnetic directional valve is connected with an oil return tank through an oil return pipeline.
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| CN112381283A (en) * | 2020-11-10 | 2021-02-19 | 中铁（天津）隧道工程勘察设计有限公司 | Tunnel disease treatment method |
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