CN112067477A - Boundary loading device for tunnel underground structure vibrating table geomechanical model test - Google Patents
Boundary loading device for tunnel underground structure vibrating table geomechanical model test Download PDFInfo
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- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
- G01N3/36—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces generated by pneumatic or hydraulic means
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Abstract
The invention discloses a boundary loading device for a tunnel underground structure vibrating table geomechanics model test, and belongs to the technical field of underground structure model tests. The invention comprises a model box, a stratum system, a deformation measuring system, a soil pressure monitoring system and an air bag loading system, wherein the air bag loading system is divided into a vertical air bag loading system and a lateral air bag loading system, and belongs to the core of the invention. The device can simulate the ground stress load of the vertical pressure and the lateral pressure of the periphery of the tunnel under the deep burying condition, and can accurately and uniformly apply the ground stress load of the vertical pressure and the lateral pressure according to the actual geological condition, so that a reliable loading mode is provided for the test.
Description
Technical Field
The invention belongs to the technical field of underground structure model tests, and provides technical support for loading of the ground stress of peripheral strata in the geomechanical model test of underground structure vibration tables such as tunnels.
Background
As is well known, the infrastructure construction mainly based on traffic is one of the important factors for determining the economic development level of a region. With the continuous improvement of the economic level of China, the demand of people on the development of transportation is increased like a blowout well, but China is a multi-mountain country, mountains, plateaus and hills occupy about 67% of the land area, and the development of transportation is greatly hindered by complex and various terrains. In order to improve the traffic speed and the driving comfort of infrastructures such as expressways and railways, the construction of tunnels is imperative. In the design, construction and operation process of the tunnel, a plurality of scientific problems still exist and need to be further discussed and solved, and the geomechanical model test is an important means for solving complex scientific problems including the seismic problem. In a geomechanical model test, a tunnel and peripheral rock-soil bodies are correspondingly scaled down and placed in a model box, and a ground stress is applied to the boundary of the model box to replace the mechanical condition of the tunnel in an original rock semi-infinite space, which is an important premise and step for carrying out test design. With the development of test technology and material science, the application technology of ground stress has more and more approached the real situation of geomechanics. The research and development of the problems can be more helpful for scientifically researching the mechanical principle of the tunnel, thereby providing more scientific and reasonable guidance for actual tunnel engineering and other underground engineering and making more contribution to the development of infrastructure in China.
The loading system of the existing tunnel geomechanical model experiment is mainly divided into a rigid hydraulic loading system and a flexible air bag loading system. The hydraulic loading system mainly loads the model boundary through a jack and a loading plate so as to achieve the purpose of applying the ground stress, for example, Liliping and the like adopt a large-scale combined three-dimensional uniform gradient loading test system which is independently researched and developed, and the reaction rule of the ground stress which continuously changes along with the burial depth is researched; the method is characterized in that high ground stress true three-dimensional loading model test systems are adopted to simulate the ground stress state of deep roadways by Chenxu light and the like, and the model rock mass is pressurized by 50t of jacks at the royal mean time to simulate the initial stress condition in the rock mass. In a vibration table model test of an underground structure including a tunnel project and the like, a model test box needs to be placed on a vibration table. If the rigid loading mode is adopted, a jack and a loading beam need to be arranged for jacking, the self weight of the test device is large, and the influence of the device on the self-vibration frequency of the model box and the rock-soil mass in the box is difficult to eliminate in a vibration table. In this case, the flexible loading has particular advantages: the frame which does not need a loading beam and a fixed beam is loaded by adopting an air bag; the self-weight of the air bag is light, and the influence on the self-vibration frequency of the model box is small; the air bag is flexible, and the generated stress boundary is more in line with the actual geomechanical principle. The airbag in the model test device for simulating the tunnel excavation process developed by Zhaxu et al only meets the simulation of vertical pressure loading, and fails to consider the loading of tunnel lateral pressure. The boundary loading device for the tunnel geomechanical vibration table model test, which is researched by the invention, can accurately and uniformly apply the ground stress load of vertical pressure and lateral pressure, and provides a reliable loading mode for the test.
Disclosure of Invention
The method utilizes a boundary loading device of a tunnel underground structure vibration table geomechanical model test to simulate the ground stress of the tunnel and the periphery of rock-soil bodies thereof in the vibration table test so as to simulate the mechanical state of a geological prototype of the underground structure in practical engineering, and the method mainly solves the following technical problems:
(1) precise control of vertical and lateral loading. The device not only can realize the loading of the vertical ground stress such as overburden pressure, but also is provided with the airbag device loaded on the side surface in consideration of the common horizontal structural stress in an underground structure, particularly a deep-buried structure, so as to realize the loading condition of the peripheral ground stress in the tunnel simulation process; and the vertically and laterally loaded air bags are very light, and the influence on the whole model in the loading process is small.
(2) And realizing lateral ground stress under different burial depth conditions. The model test chamber is designed as a plane strain test device, and the front vertical surface of the model test chamber is 2000mm in width, 1500mm in height and 500mm in thickness (as shown in figure 5). 1 loading air bags are arranged at the top of the model box; the two sides of the loading air bags are respectively provided with 6 loading air bags which are arranged in a building block mode in a lateral overlapping mode, the air bag pressure of 0.01-0.4MPa can be provided under the control of a precise pressure reducing valve, and the loading of lateral stress of the boundary soil body at different heights from the upper part to the lower part in the vertical direction is realized.
(3) Stability and reliability of the airbag. The loading air bag adopts a double-layer design, the inner bag adopts carbon fibers, the carbon fibers have the characteristics of strong tensile capacity of carbon materials and soft processability of fibers, and the air bag made of carbon fibers has the characteristics of high strength, high modulus, low density, small linear expansion coefficient and the like; the outer bag is made of TPU flexible material, and the TPU flexible material has the characteristics of high mechanical strength, good processing performance and the like.
(4) The influence on the natural vibration frequency of the model box is small. The biggest advantage of this patent is exactly that vertical loading gasbag and side direction loading gasbag mass density are little, and it is little to the natural frequency of vibration frequency influence of model box when keeping the loading in the vibration process, has improved analogue test's accuracy nature to a great extent.
(5) The installation process of the device is simple and easy to operate. Model tests of underground structures require model boxes and are often provided with loading devices, so that simulation experiment devices with large volumes are usually needed to realize the model tests, and the model devices are complex to manufacture, install and operate. The device adopts a simple model box frame and an air bag loading system, realizes simple assembly of the simulation device, and is easy to load and operate.
(6) And (4) accurately observing formation deformation. The front vertical face of the model box is provided with an acrylic transparent plate with the thickness of 20mm, the front vertical face is provided with a non-contact strain displacement measurement and analysis system and a tunnel structure strain measurement system for continuous monitoring, formation deformation in the tunnel simulation process is measured and analyzed, the deformation of the surrounding rock of the model tunnel and the whole-course real-time measurement of the surface of the tunnel structure can be recorded in real time, and the model box has the characteristics of convenience in operation, high data acquisition precision and the like.
The utility model provides a boundary loading device of tunnel underground structure shaking table geomechanical model test which characterized in that: the device comprises a model box, a stratum system, a deformation measuring system, a soil pressure monitoring system and an air bag loading system;
the deformation measuring system comprises a non-contact strain displacement measuring and analyzing system and a tunnel structure strain measuring system; the non-contact strain displacement measurement and analysis system comprises a high-resolution digital industrial camera, an image acquisition card and a computer, wherein the high-resolution digital industrial camera is connected with the computer through the image acquisition card; the high-resolution digital industrial camera shoots speckle characteristics of front and rear model observation surfaces of a deformation model box and a stratum system through a sub-pixel technology, and then carries out operation to obtain deformation information; the tunnel structure strain measurement system realizes measurement by arranging strain gauges on the surface of a tunnel structure. The vertical loading air bags are placed at the tops of the model box and the stratum system, vertical air vent pipe openings are reserved in the middle positions, the lateral loading air bags are placed on the lateral sides of the model box and the model box of the stratum system, and each lateral loading air bag is separated by a steel plate which is fixedly welded so as to eliminate mutual influence. And reserving a lateral air vent pipe port at the middle position of each lateral loading air bag close to the outside, filling model materials into model boxes of a model box and a stratum system in a layered mode, tamping, and implanting a soil pressure monitoring system at the position of each layer of experimental design. The method comprises the steps of starting an air bag loading system after a deformation measuring system is in place to operate, recording stratum deformation information in the whole model tunnel range in a model observation surface and on the surface of a tunnel structure by using a non-contact type strain displacement measuring and analyzing system and a tunnel structure strain measuring system in the whole process in the loading process, and obtaining pressure data between an air bag and a soil body by using a soil pressure monitoring system so as to monitor the actual operation condition of the air bag pressure.
The soil pressure monitoring system comprises a strain shaft type soil pressure sensor, a strain beam type soil pressure sensor, a wireless transmission system and a real-time monitoring system; the soil pressure sensor respectively monitors the soil pressure in the rock-soil body, the contact surface of the rock-soil body and the tunnel structure and the contact surface of the air bag and the rock-soil body according to the test design position;
further, the air bag loading system comprises a vertical loading air bag (9) and twelve side loading air bags (10).
Furthermore, the two sides of the model box frame of the model box and the stratum system are reinforced by adopting triangular rigid supports, channel steel and angle steel, and the lateral deformation of the model box frame under the maximum designed vertical load of 0.2MPa is not more than 0.02mm measured by a dial indicator after the support and reinforcement, so that the plane strain condition of the experimental requirement is completely met.
Further, air bags are arranged on two sides of the interior of the model box, filled with model materials and placed in the model structure, the air bags are arranged on the top of the model box, and a top cover of the model box is placed.
Furthermore, the deformation measurement system adopts a non-contact type strain displacement measurement analysis system and a tunnel structure strain measurement system, so that the deformation of the surrounding rock of the model tunnel and the whole course of the surface of the tunnel structure are measured in real time in the loading process, and effective strain displacement information is obtained.
Further, the air compressor adopts a piston type air compressor and provides the maximum pressure of 0.8 MPa; the range of the pressure regulating valve of the precision pressure reducing valve is 0.01-0.4MPa, the maximum measuring range of the barometer is 0.4MPa, and the precision is 0.02 MPa. The air bag loading system can provide stable pressure for the air bag; and the simulation loading of vertical ground stress and lateral ground stress under different burial depths can be realized, so that the reliable boundary loading of the model tunnel test is realized.
The model box and the stratum system, the model box frame, the model box cover plate and the model box side baffle plate are connected through the bolt to form a test model box, model materials are filled into the model box in a layering mode and tamped, and a layer of white lime is paved on the surface of each layer of model materials to serve as a mark layer so as to distinguish the buried depth of a soil body and facilitate stratum deformation measurement. The two sides of the model box frame are reinforced by adopting triangular rigid supports, channel steel and angle steel, and the lateral deformation of the model box frame under the maximum design vertical load of 0.2MPa is not more than 0.02mm measured by a dial indicator after the model box frame is supported and reinforced;
filling the model materials into the model box layer by layer and tamping, and controlling the tamped density by the mass and the volume of each layer of soil body during tamping to ensure that the density of each layer of soil body meets the test requirements.
The deformation measurement system adopts a non-contact strain displacement measurement and analysis system and a tunnel structure strain measurement system, can record the displacement of any point in the range of a tunnel model and the displacement of any point on the surface of a tunnel structure in real time in the whole process, and is simple and convenient to operate and high in precision.
The soil pressure monitoring system comprises a strain shaft type soil pressure sensor, a strain beam type soil pressure sensor, a wireless transmission system and a real-time detection system; the soil pressure sensor respectively monitors the soil pressure in the rock-soil body, the contact surface of the rock-soil body and the tunnel structure and the contact surface of the air bag and the rock-soil body according to the test design position;
the air bag loading system can provide vertical ground stress simulation load and lateral ground stress simulation load, and has the advantages of stable loading pressure, uniform loading, controllable loading pressure and the like. The loading size of horizontal and vertical ground stress under different burial depth conditions can be realized. Wherein:
in order to ensure the durability and the safety of the air bag in the using process, a double-layer design scheme is adopted, wherein an inner bag liner is made of a carbon fiber material, and an outer bag is made of a TPU flexible material;
a fixed flange is designed at the air inlet of each of the 1 vertical air bag and the 12 lateral air bags to be connected with a stainless steel interface, the stainless steel interface is connected with a precision pressure reducing valve, an air filter and an air compressor through a ventilation rubber tube, and the stainless steel interface and the ventilation rubber tube are hooped by a hose clamp to avoid the error of air leakage in the ventilation process;
the range of the pressure regulating valve of the precision pressure reducing valve is 0.01-0.4MPa, the maximum measuring range of the barometer is 0.4MPa, and the precision is 0.02 MPa.
Drawings
FIG. 1: the front view of a boundary loading device for a tunnel underground structure vibrating table geomechanical model test;
FIG. 2: a back view of a boundary loading device for a tunnel underground structure vibrating table geomechanical model test;
FIG. 3: a left view of a boundary loading device for a tunnel underground structure vibrating table geomechanical model test;
FIG. 4: a top view of a boundary loading device for a tunnel underground structure vibrating table geomechanical model test;
FIG. 5: a sectional view of a boundary loading device for a tunnel underground structure vibrating table geomechanical model test;
FIG. 6: a three-dimensional stereogram (front) of a boundary loading device for a tunnel underground structure vibrating table geomechanics model test;
FIG. 7: a three-dimensional stereo view (back) of a boundary loading device for a tunnel underground structure vibrating table geomechanics model test;
in the figure: 1. model box frame, 2 model box cover plate, 3 acrylic plate (model observation surface), 4 triangular rigid support, 5 channel steel support, 6 angle steel support, 7 hoisting hole, 8 disassembly boundary line, 9 vertical loading air bag, 10 lateral loading air bag, 11 vertical ventilation pipeline port, 12 lateral ventilation pipeline port, 13 steel plate partition, 14 tunnel hole, 15 model material
Detailed Description
The following description of the embodiments of the present invention is provided with reference to the accompanying drawings:
as shown in fig. 1-5, the boundary loading device is a core structure adopted by the invention, namely a boundary loading device for a tunnel underground structure vibrating table geomechanics model test, and comprises a model box, a stratum system, a deformation measurement system, a soil pressure monitoring system and an air bag loading system. The model box and stratum system comprises a model box frame (1), a model box cover plate (2), a tunnel hole (14), a model material (15), a vertical air duct port (11), a lateral air duct port (12), a hoisting hole (7), a triangular rigid support (4), a channel steel support (5), an angle steel support (6) and an acrylic plate (3), wherein the center of a front panel of the model box frame (1) is rectangular, and a hole is formed in the center of the acrylic plate (3); the model box frame (1) is connected with the acrylic plate (3) through a bolt to form a test model box; the air bag loading system comprises a vertical loading air bag (9) and twelve lateral loading air bags (10), and the air hose is connected with a precision reducing valve, an air compressor, an air filter and an air pressure gauge. In the air bag loading system, a steel plate partition (13) between an upper air bag and a lower air bag is considered by a pressurizing air bag, the friction effect of the model box wall on the pressurizing air bag and the maximum design pressure are designed in a double-layer mode, an inner bag is made of carbon fiber materials, an outer bag is made of TPU flexible materials, and the strength and the durability of the pressurizing air bag meet the requirements of tests. The deformation measurement system comprises a non-contact strain displacement measurement and analysis system and a tunnel structure strain measurement system; the non-contact strain displacement measurement and analysis system comprises a high-resolution digital industrial camera, an image acquisition card and a computer, wherein the high-resolution digital industrial camera is connected with the computer through the image acquisition card; the high-resolution digital industrial camera shoots speckle characteristics of front and rear model observation surfaces of a deformation model box and a stratum system through a sub-pixel technology, and then carries out operation to obtain deformation information; the tunnel structure strain measurement system realizes measurement by arranging strain gauges on the surface of a tunnel structure. The vertical loading air bags are placed at the top of the model box, a vertical air duct port is reserved in the middle of the vertical loading air bags, twelve lateral loading air bags are placed in the lateral direction of the model box, six air bags are respectively placed on the left side and the right side of the model box in a building block type vertical stacking mode, and each small air bag is separated by a steel plate which is fixedly welded so as to eliminate mutual influence. A lateral air duct port is reserved in the middle position, close to the outside, of each small air bag, then model materials are filled into a model box in six layers and tamped, each layer of sandy soil corresponds to the left small air bag and the right small air bag, and a soil pressure monitoring system is implanted at a test design position in the process. The system for loading the air bag is started after the deformation measuring system is in place to operate, the non-contact type strain displacement measuring and analyzing system and the tunnel structure strain measuring system are used for recording stratum deformation information in the whole model tunnel range in the observation surface of the model and on the surface of the tunnel structure in the whole process in the loading process, and the soil pressure monitoring system is used for obtaining pressure data between the air bag and the soil body so as to monitor the actual operation condition of the air bag pressure.
FIG. 6 is a three-dimensional perspective view (front) of a boundary loading device for a tunnel underground structure vibrating table geomechanical model test;
FIG. 7 is a three-dimensional perspective view (back side) of a boundary loading device for a tunnel underground structure vibrating table geomechanical model test;
the specific operation process is as follows:
firstly, assembling a model box.
Firstly, the acrylic plate is connected with a model box frame through bolts to form a test model box, and then the baffle on the back of the model box is detached so as to facilitate the filling of the model material.
And secondly, filling of the uniform model material and placing of the soil pressure monitoring system.
In order to reduce the friction between the inner wall of the model box and the model material and the friction between the model material and the lateral air bags, the inner wall of the model box is pasted with a surface self-adhesive wallpaper, then the model material is added, the model material is tamped layer by layer when being filled in the model box, a layer of white lime is scattered between every two layers of stratum materials to be used as a mark layer, the tamping height of each layer is controlled to be 200mm, and the tamping height of each layer corresponds to the height of the lateral air bags on the left side and the right side; and arranging a soil pressure monitoring system according to the design position of the measuring point in the tamping process, and finishing filling the model material.
And thirdly, mounting a vertical loading air bag and a lateral loading air bag.
Firstly, a vertical loading air bag and twelve lateral loading air bags are placed at the lateral position and the top position of a model box, after the air bags are installed and checked to have air leakage, a model box cover plate and a model box lateral baffle are installed at the top and the side of the model box through bolts, the air bags are connected with an air hose through an air duct port, the air hose is connected with an air filter and a precision pressure reducing valve, and then the installation of an air bag loading system is finished.
And fourthly, installing a non-contact type strain displacement measurement and analysis system and a tunnel structure strain measurement system.
After the preparation of the steps is finished, a high-resolution digital industrial camera is placed at a certain distance right in front of an observation surface of the model box, the lens of the camera is aligned to the whole plane of the model box, the camera is connected with a computer through a wire, and the displacement of any point in the range of the tunnel model and the displacement of any point on the surface of the tunnel structure are recorded through software of professional image analysis.
And fifthly, loading the boundary ground stress of the tunnel and the rock-soil body and acquiring data.
And simultaneously operating a non-contact strain displacement measurement and analysis system, a tunnel structure strain measurement system and a soil pressure monitoring system, then loading the vertical air bag and the lateral air bags to enable the internal pressure of the air bags to reach a test preset value and a pressure stable point, after the soil pressure monitoring system finishes data acquisition, adjusting to a preset pressure value of the next air bag according to the requirement of test simulation burial depth change, and at the moment, after the pressure is stable, acquiring data by using the soil pressure monitoring system again. In the whole process, the displacement of any point in the whole tunnel model range and the displacement of any point on the surface of the tunnel structure are recorded in real time and in the whole process by using the non-contact strain displacement measurement and analysis system and the tunnel structure strain measurement system.
And sixthly, processing data.
Analyzing and fitting the collected data, converting the data into an intuitive chart, and finally summarizing an experimental result by combining the chart data.
Claims (9)
1. The utility model provides a boundary loading device of tunnel underground structure shaking table geomechanical model test which characterized in that: the device comprises a model box, a stratum system, a deformation measuring system, a soil pressure monitoring system and an air bag loading system;
the deformation measuring system comprises a non-contact strain displacement measuring and analyzing system and a tunnel structure strain measuring system; the non-contact strain displacement measurement and analysis system comprises a high-resolution digital industrial camera, an image acquisition card and a computer, wherein the high-resolution digital industrial camera is connected with the computer through the image acquisition card; the high-resolution digital industrial camera shoots speckle characteristics of front and rear model observation surfaces of a deformation model box and a stratum system through a sub-pixel technology, and then carries out operation to obtain deformation information; the tunnel structure strain measurement system realizes measurement by arranging strain gauges on the surface of a tunnel structure; placing a vertical loading air bag at the top of a model box and a stratum system, reserving a vertical air vent pipeline port in the middle, placing lateral loading air bags on the lateral sides of the model box and the model box of the stratum system, and separating each lateral loading air bag by a steel plate which is fixedly welded; reserving a lateral air vent pipe port at the middle position of each lateral loading air bag close to the outside, filling model materials into model boxes of a model box and a stratum system in a layered mode, tamping, and implanting a soil pressure monitoring system at the position of each layer of experimental design; the method comprises the steps of starting an air bag loading system after a deformation measuring system is in place to operate, recording stratum deformation information in the whole model tunnel range in a model observation surface and on the surface of a tunnel structure by using a non-contact type strain displacement measuring and analyzing system and a tunnel structure strain measuring system in the whole process in the loading process, and obtaining pressure data between an air bag and a soil body by using a soil pressure monitoring system so as to monitor the actual operation condition of the air bag pressure.
2. The boundary loading device for the tunnel underground structure vibrating table geomechanical model test according to claim 1, characterized in that: the soil pressure monitoring system comprises a strain shaft type soil pressure sensor, a strain beam type soil pressure sensor, a wireless transmission system and a real-time monitoring system; the soil pressure sensor monitors the soil pressure inside the rock-soil body, the contact surface of the rock-soil body and the tunnel structure and the contact surface pressure of the air bag and the rock-soil body respectively according to the experimental design position.
3. The boundary loading device for the tunnel underground structure vibrating table geomechanical model test according to claim 1, characterized in that: the two sides of a model box frame of the model box and the stratum system are both reinforced by adopting triangular rigid supports, channel steel and angle steel, and the lateral deformation of the model box frame under the maximum design vertical load of 0.2MPa is not more than 0.02mm measured by a dial indicator after the support and reinforcement, so that the plane strain condition of the experimental requirement is completely met.
4. The boundary loading device for the tunnel underground structure vibrating table geomechanical model test according to claim 1, characterized in that: the deformation measurement system adopts a non-contact type strain displacement measurement analysis system and a tunnel structure strain measurement system, so that the deformation of the surrounding rock of the model tunnel and the whole course of the surface of the tunnel structure are measured in real time in the loading process, and strain displacement information is obtained.
5. The boundary loading device for the tunnel underground structure vibrating table geomechanical model test according to claim 1, characterized in that: in the model case and stratum system, the model case frame passes through bolted connection with model case apron and model case side baffle and forms experimental model case, and the model case is tamped in the model material layering, and every layer of model material surface tiling one deck white lime is as the marker layer, and model case frame both sides all adopt triangle-shaped rigid support and channel-section steel and angle steel to consolidate, and the lateral deformation of the model case frame under maximum design vertical load 0.2MPa is not more than 0.02mm through percentage table measurement after supporting the reinforcement.
6. The boundary loading device for the tunnel underground structure vibrating table geomechanical model test according to claim 1, characterized in that: filling the model materials into the model box layer by layer and tamping, and controlling the tamped density by the mass and the volume of each layer of soil body during tamping to ensure that the density of each layer of soil body meets the test requirements.
7. The boundary loading device for the tunnel underground structure vibrating table geomechanical model test according to claim 1, characterized in that: the deformation measurement system adopts a non-contact strain displacement measurement and analysis system and a tunnel structure strain measurement system, and can record the displacement of any point in the range of a tunnel model and the displacement of any point on the surface of a tunnel structure in real time and in the whole process.
8. The boundary loading device for the tunnel underground structure vibrating table geomechanical model test according to claim 1, characterized in that: the soil pressure monitoring system comprises a strain shaft type soil pressure sensor, a strain beam type soil pressure sensor, a wireless transmission system and a real-time detection system; the soil pressure sensor monitors the soil pressure inside the rock-soil body, the contact surface of the rock-soil body and the tunnel structure and the contact surface pressure of the air bag and the rock-soil body respectively according to the experimental design position.
9. The boundary loading device for the tunnel underground structure vibrating table geomechanical model test according to claim 1, characterized in that: the air bag loading system provides vertical ground stress simulation load and lateral ground stress simulation load, and can realize the loading of horizontal and vertical ground stress under different burial depth conditions.
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| CN115824813A (en) * | 2023-02-23 | 2023-03-21 | 叙镇铁路有限责任公司 | Test device and method for testing surrounding rock plastic zone range caused by tunnel excavation |
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