Tunnel lining and surrounding rock mechanical characteristics test model device and test method

Abstract

The present invention relates to the technical field of tunnel construction, and in particular to a tunnel lining and surrounding rock mechanical characteristics test model device, comprising a tunnel model, a test bench, a loading system and a measuring system, wherein the tunnel model is simulated and constructed according to the actual tunnel size in a scaled ratio and using similar materials, and the tunnel model is arranged in the test bench, the loading system is also arranged in the test bench to load the tunnel model, and the measuring system measures the force and deformation of the tunnel model, wherein the tunnel model comprises the tunnel lining and surrounding rock. The tunnel lining and surrounding rock mechanical characteristics test model device of the present invention can be used by a large number of scientific researchers to study the harmful mechanism of the cavity behind the lining, and the test results can provide reference and reference for actual engineering.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a model device and a method for testing mechanical characteristics of tunnel lining and surrounding rock. Background Art

[0002] The cavity on the back of the tunnel lining is a common quality defect. Due to the particularity of tunnel engineering and the complexity of the engineering geological and hydrogeological conditions, the hazard mechanism of the cavity on the back of the tunnel lining is unclear, and the interaction between the surrounding rock and the support is also unclear. At present, there are deficiencies in the research using only theoretical analysis and numerical calculation techniques.

[0003] A large number of engineering practices have proved that the geomechanical model test method is an effective method that can objectively reflect the relationship between the surrounding rock and the tunnel lining structure, and the test results are more intuitive.

[0004] Therefore, it is urgently necessary to provide a tunnel lining and surrounding rock mechanical characteristics test model device and experimental method with good simulation performance and intuitive results, which can enable engineering and technical personnel to grasp the mechanical characteristics, deformation trends and stability characteristics of the tunnel lining and surrounding rock, thereby guiding engineering and technical personnel to make accurate judgments. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In order to solve the above problems in the prior art, the present invention provides a tunnel lining and surrounding rock mechanical characteristics testing model device and testing method with good simulation performance and intuitive results.

[0007] (II) Technical solution

[0008] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0009] A model device for testing the stress characteristics of tunnel lining and surrounding rock.

[0010] It includes a tunnel model, a bench, a loading system and a measuring system. The tunnel model is simulated and constructed according to the actual tunnel size in a scaled ratio and using similar materials. The tunnel model is set in the bench, the loading system is also set in the bench to load the tunnel model, and the measuring system measures the force and deformation of the tunnel model.

[0011] Wherein, the tunnel model includes tunnel lining and surrounding rock.

[0012] Preferably, the stand comprises: a reaction force support plate 1, two left and right side plates 2, a load-bearing plate 3, a bottom plate 4, six front and rear side plates 5, and two front and rear side plate reinforcements 6;

[0013] The reaction support plate 1 and the bottom plate 4 are arranged horizontally and parallel to the ground;

[0014] The two left and right side plates 2 are respectively vertically arranged at the two ends of the reaction support plate 1 and the bottom plate 4, connected by bolts, and the bearing plate 3 is directly placed on the simulated surrounding rock;

[0015] The two front and rear side plate reinforcement members 6 respectively connect the three front side plates and the three rear side plates into a whole with bolts, and are vertically bolted to the reaction support plate 1 and the bottom plate 4;

[0016] The tunnel lining model 7 is arranged at the center of a space surrounded by a bearing plate 3, two left and right side plates 2, six front and rear side plates 5, and a bottom plate 4, and is filled with simulated surrounding rock.

[0017] Preferably, the loading system comprises a jack 8 , and the jack 8 is arranged between the reaction support plate 1 and the bearing plate 3 .

[0018] Preferably, the measuring system comprises: a pressure gauge 9, a strain gauge 10 and an earth pressure cell 11;

[0019] The pressure gauge 9 is arranged at a corresponding position between the jack 8 and the bearing plate 3;

[0020] The strain gauge 10 is pasted on the corresponding position of the tunnel model, and the earth pressure cell 11 is buried in the corresponding position of the tunnel model.

[0021] Preferably, the reaction support plate 1 and the two left and right side plates 2 are all made of No. 32 processed channel steel;

[0022] The bearing plate 3 is a 8 mm thick steel plate;

[0023] Among the six front and rear side panels 5, the four front and rear panels near the left and right sides are made of 8mm thick steel plates, and the two front and rear middle panels are made of 8mm thick transparent organic glass.

[0024] Preferably, a 10 mm thick steel support is provided on the two left and right side panels 2, and the steel support forms a triangle with the ground;

[0025] A 10 mm thick steel support is provided in the six front and rear side panels 5 , and the steel support forms a triangle with the ground.

[0026] Preferably, the tunnel model 7 is made of barite and quartz sand as aggregates, vaseline as a binder, and the ratio of barite:quartz sand:vaseline is 10:8:1. The model material for simulating cast-in-place reinforced concrete is iron wire with a diameter of 4 mm and gypsum with a water-to-gypsum ratio of 1:1.05, and is simulated by the method of equivalent bending stiffness of the prototype and the model.

[0027] Preferably, the measurement system further comprises: a lining strain measurement system, a surrounding rock pressure measurement system and a surrounding rock displacement measurement system;

[0028] The lining strain measurement is achieved by sticking strain gauges on the inner and outer surfaces of the lining. The strain gauges are resistance strain gauges.

[0029] The surrounding rock pressure measurement is achieved by burying a micro pressure cell with a diameter of 16 mm;

[0030] The lining strain and surrounding rock pressure are collected by steel string data collector;

[0031] The surrounding rock displacement measurement system is realized by measuring the displacement of deformed fibers embedded in simulated surrounding rock materials.

[0032] Preferably, the geometric similarity ratio C between the tunnel model and the tunnel prototype is l =1:60, take the bulk density similarity ratio C γ =1:1, Poisson's ratio similarity ratio C μ =1:1, similarity ratio of internal friction angle Cohesion similarity ratio C c =1:60, elastic modulus similarity ratio C E =1:1.

[0033] The technical solution also provides a method for testing the stress characteristics of tunnel lining and surrounding rock, comprising the following steps:

[0034] Step S1: Assemble the bench, and tightly connect the bottom plate 4, two left and right side plates 2, six front and rear side plates 5 and two front and rear side plate reinforcements through bolts; after the bench is assembled, a tunnel surrounding rock model with a maximum net size of 3000 mm in length, 320 mm in width and 1500 mm in height can be formed;

[0035] Step S2: According to the tunnel lining cross-section design drawing and the size similarity ratio, the lining model size is determined, the template is customized, and the lining model is made on site using iron wire with a diameter of 4 mm and gypsum with a water-to-cement ratio of 1:1.05;

[0036] Step S3: After the lining model is manufactured, the resistance strain gauges 10 are symmetrically arranged on the inner and outer sides of the lining model, and the corresponding circuits are connected;

[0037] Step S4: preparing simulated surrounding rock material according to the ratio of barite: quartz sand: vaseline = 10:8:1;

[0038] Step S5: filling simulated surrounding rock materials in layers to the bottom surface of the lining model installation position; then installing the lining model in place, and continuing to fill the simulated surrounding rock materials on the back of the side walls on both sides of the lining model to the vault plane; finally, continue to fill the simulated surrounding rock materials to the bottom surface of the bearing plate 3;

[0039] During the entire filling process, horizontal and vertical deformation fibers 12 are buried according to the position of the surrounding rock deformation to be measured. The deformation fibers should be buried close to the organic glass side plate for easy observation.

[0040] Bury the earth pressure box 11 according to the location where the surrounding rock pressure is to be measured;

[0041] All connections should be convenient and not affect loading; during the filling process, reserve the cavity area on the back of the lining model according to actual needs and actual construction conditions.

[0042] Step S6: installing the bearing plate 3 and the reaction force support plate 1;

[0043] Step S7: Install the jack 8 and the pressure gauge 9, and connect the soil pressure box 11 and the resistance strain gauge test line to the data acquisition instrument;

[0044] Step S8: Load in stages according to the actual situation and read the data until the lining model is destroyed;

[0045] Step S9: Obtain the lining internal force, surrounding rock pressure, and surrounding rock displacement through calculation and observation, then draw a graph, analyze the data, observe the failure mode of the lining model, and study the law.

[0046] (III) Beneficial effects

[0047] The beneficial effects of the present invention are as follows: the tunnel lining and surrounding rock stress characteristics test model device of the present invention can simulate the stress environment of the tunnel under real conditions, and the measurement system monitors the stress and deformation of the tunnel lining and surrounding rock model. It provides a material basis for scientific researchers to study the harmful mechanism of the voids behind the lining, and the test results can provide reference and reference for actual engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a front view of the model device for testing the stress characteristics of the tunnel lining and surrounding rock of the present invention;

[0049] Figure 2 It is a side view of the model device for testing the stress characteristics of the tunnel lining and surrounding rock of the present invention;

[0050] Figure 3 It is a top view of the model device for testing the stress characteristics of the tunnel lining and surrounding rock of the present invention;

[0051] Figure 4This is a reference layout diagram of the earth pressure cell, strain gauge, and deformable fiber of the present invention.

[0052] [Description of Reference Numerals]

[0053] 1: reaction support plate; 2: left and right side plates; 3: bearing plate; 4: bottom plate; 5: front and rear side plates; 6: front and rear side plate reinforcements; 7: tunnel model; 8: jack; 9: pressure gauge; 10: strain gauge; 11: soil pressure box; 12: deformation fiber. DETAILED DESCRIPTION

[0054] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below in conjunction with the accompanying drawings through specific implementation methods. The present invention provides a model device for testing the mechanical characteristics of tunnel lining and surrounding rock, including a tunnel model, a test bench, a loading system and a measurement system. The tunnel model is arranged in the test bench, and the loading system is also arranged in the test bench to load the tunnel model so that the tunnel model bears the load, simulating the real stress environment of the tunnel and the surrounding rock. The measurement system measures the stress and deformation of the tunnel model; wherein the tunnel model includes the tunnel lining and the surrounding rock.

[0055] Specifically, the platform includes a reaction support plate 1, left and right side plates 2, a bearing plate 3, a bottom plate 4, front and rear side plates 5, and front and rear side plate reinforcements 6. The reaction support plate 1 and the bottom plate 4 are arranged parallel to the ground and are tightly fixed to the two left and right side plates 2 and the two front and rear side plate reinforcements 6 by bolts. The two left and right side plates 2 and the two front and rear side plate reinforcements 6 are perpendicular to the ground. The six front and rear side plates 5 are tightly fixed to the left and right side plates 2 and the front and rear side plate reinforcements 6 by bolts, and are perpendicular to the ground. The bearing plate 3 is directly placed on the simulated surrounding rock. The tunnel model 7 is arranged at the center of the space surrounded by the bearing plate 3, the two left and right side plates 2, the six front and rear side plates 5, and the bottom plate 4, and is filled with simulated surrounding rock.

[0056] Furthermore, the loading system includes a jack 8 , which is disposed between the reaction support plate 1 and the bearing plate 3 , and the tunnel model is loaded through the jack 8 .

[0057] Furthermore, the measuring system includes a pressure gauge 9 , which is arranged at a position corresponding to the jack 9 and the bearing plate 3 to measure the load applied by the jack 8 .

[0058] Optionally, the reaction support plate 1 and the left and right side plates 2 are made of 32#A processed channel steel and 10# steel plate, the load-bearing plate 3 is an 8mm steel plate, and among the six front and rear side plates, the middle side plate is made of 8mm thick transparent plexiglass, and the remaining four are made of 8mm thick steel plates and 10mm thick steel plates.

[0059] Preferably, 10 mm thick steel supports are respectively provided on the two left and right side panels and the four steel front and rear side panels, and the steel supports are triangular with the ground to facilitate storage, assembly and reinforcement.

[0060] Furthermore, the tunnel model adopts a plane strain model, the cross-sectional shape is a scaled shape of the actual tunnel cross-sectional shape, the model material uses barite and quartz sand as aggregates, and vaseline as a binder, barite: quartz sand: vaseline = 10:8:1, and the model material for simulating molded reinforced concrete uses iron wire with a diameter of 4mm and gypsum with a water-to-cement ratio of 1:1.05, which is simulated by the equivalent bending stiffness method of the prototype and the model. The tunnel model is simulated by the method of prefabrication and on-site installation.

[0061] Furthermore, the measurement system also includes a lining strain measurement system, a surrounding rock pressure measurement system, and a surrounding rock displacement measurement system;

[0062] The lining strain measurement is achieved by sticking strain gauges on the inner and outer surfaces of the lining. The strain gauges are resistance strain gauges.

[0063] The surrounding rock pressure measurement is achieved by burying a micro pressure cell with a diameter of 16 mm;

[0064] The lining strain and surrounding rock pressure are collected by steel string data collector;

[0065] The surrounding rock displacement measurement system is realized by measuring the displacement of deformed fibers buried in simulated surrounding rock materials. Specifically, Figure 4 As shown, at the position where the surrounding rock deformation is to be observed, a deformation fiber 12 with striking colors is set close to the front and rear middle side plates (the front and rear middle side plates are made of 8mm thick transparent organic glass). The deformation fiber 12 can be set horizontally and vertically. The deformation of the deformation fiber can be observed at any time during the experiment. An earth pressure box 11 is set at the position where the surrounding rock pressure is to be measured, and an earth pressure box 11 in the vertical direction is set above the tunnel model. The positions of all test components are adjustable.

[0066] Furthermore, when filling the simulated surrounding rock material and installing the tunnel lining model, the distribution range and size of the cavities on the back of the tunnel lining can be set, and plastic sheets bent into the shape of the cavities can be used for reservation.

[0067] Furthermore, the geometric similarity ratio C between the tunnel model and the tunnel engineering prototype is l =1:60. Generally speaking, it is difficult to achieve complete similarity between the prototype material and the model material within the elastic range. According to experience, the bulk density similarity ratio C is taken. γ =1:1, Poisson's ratio similarity ratio C μ =1:1, similarity ratio of internal friction angle Cohesion similarity ratio Cc =1:60, elastic modulus similarity ratio C E =1:1, the tunnel model material simulates the prototype lining material through the equivalent bending stiffness EI.

[0068] Furthermore, after the assembly of the bench, a tunnel model space with a maximum net size of 3000mm in length, 320mm in width and 1500mm in height can be formed. The bench structure material can withstand a pressure greater than 0.3MPa and the deformation under the load limit does not exceed 0.3mm. The machining accuracy of the bench is not less than 0.5‰. At the same time, the bench and the corresponding construction steps can complete a plane strain similarity model test with a boundary length of 3m and a height of 1.5m.

[0069] Furthermore, the loading system includes a hydraulic jack, a pressure gauge, a reaction support plate and a load-bearing plate. A jack is arranged between the reaction support plate made of 32# A channel steel and the 8mm load-bearing plate. A pressure gauge is arranged at the jack. During loading, graded loading is achieved through the hydraulic jack and the pressure sensor.

[0070] Through the on-site radar nondestructive testing of the tunnel, it was found that there were a large number of cavities of different sizes behind the lining near the tunnel vault and spandrel, but there were generally no cavities at the side walls and other locations. Therefore, the model test was mainly aimed at studying the influence of cavities of different ranges near the vault and spandrel on the safety of the lining structure. Therefore, according to the above-mentioned device, a test method is now provided, comprising the following steps:

[0071] Step S1: Assemble the bench, and tightly connect the bottom plate 4, two left and right side plates 2, six front and rear side plates 5 and two front and rear side plate reinforcements through bolts. After the bench is assembled, a tunnel surrounding rock model space with a maximum net size of 3000 mm in length, 320 mm in width and 1500 mm in height can be formed;

[0072] Step S2: According to the tunnel lining cross-section design drawing and the size similarity ratio, the lining model size is determined, the template is customized, and the lining model is made on site using iron wire with a diameter of 4 mm and gypsum with a water-to-cement ratio of 1:1.05;

[0073] Step S3: After the lining model is manufactured, the resistance strain gauges are symmetrically arranged on the inner and outer sides of the lining model, and the corresponding circuits are connected;

[0074] Step S4: preparing simulated surrounding rock material according to the ratio of barite: quartz sand: vaseline = 10:8:1;

[0075] Step S5: fill the simulated surrounding rock material in layers to the bottom surface of the lining model installation position; then install the lining model in place, and continue to fill the simulated surrounding rock material on the back of the side walls on both sides of the lining model to the vault plane; finally continue to fill the simulated surrounding rock material to the bottom surface of the bearing plate 3; during the entire filling process, bury the horizontal and vertical deformation fibers 10 according to the surrounding rock deformation position to be measured, and the deformation fibers should be buried close to the organic glass side panels for easy observation; bury the earth pressure box 11 according to the surrounding rock pressure position to be measured; all wiring should be convenient and not affect loading; during the filling process, reserve the cavity range on the back of the lining model according to scientific research needs and actual construction conditions.

[0076] Step S6: installing the bearing plate 3 and the reaction force support plate 1;

[0077] Step S7: Install the jack 9 and the pressure gauge 10, and connect the soil pressure box 11 and the resistance strain gauge test line to the data acquisition instrument;

[0078] Step S8: Load in stages according to the actual situation and read the data until the lining model is destroyed;

[0079] Step S9: Obtain the lining internal force, surrounding rock pressure, and surrounding rock displacement through calculation and observation, then draw a graph, analyze the data, observe the failure mode of the lining model, and study the law.

[0080] It should be understood that the above description of the specific embodiments of the present invention is only for illustrating the technical route and features of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, but the present invention is not limited to the above specific implementation methods. Any changes or modifications made within the scope of the claims of the present invention should be included in the protection scope of the present invention.

Claims

1. A model device for testing the stress characteristics of tunnel lining and surrounding rock, characterized in that: It includes a tunnel model, a bench, a loading system and a measuring system. The tunnel model is simulated and constructed according to the actual tunnel size in a scaled ratio and using similar materials. The tunnel model is set in the bench, the loading system is also set in the bench to load the tunnel model, and the measuring system measures the force and deformation of the tunnel model. Wherein, the tunnel model includes tunnel lining and surrounding rock; The stand comprises: a reaction force support plate (1), two left and right side plates (2), a bearing plate (3), a bottom plate (4), six front and rear side plates (5), and two front and rear side plate reinforcement members (6); The reaction force support plate (1) and the bottom plate (4) are arranged horizontally and parallel to the ground; The two left and right side plates (2) are respectively vertically arranged at the two ends of the reaction support plate (1) and the bottom plate (4), and are connected by bolts. The bearing plate (3) is directly placed on the simulated surrounding rock. Two front and rear side panel reinforcement members (6) respectively connect the three front side panels and the three rear side panels into a whole by bolts, and are vertically bolted to the reaction support plate (1) and the bottom plate (4); The tunnel model is arranged at the center of a space surrounded by a bearing plate (3), two left and right side plates (2), six front and rear side plates (5), and a bottom plate (4), and is surrounded by simulated surrounding rock; The loading system comprises a jack (8), wherein the jack (8) is arranged between the reaction force support plate (1) and the bearing plate (3); The measuring system comprises: a pressure gauge (9), a strain gauge (10) and an earth pressure box (11); The pressure gauge (9) is arranged at a corresponding position between the jack (8) and the bearing plate (3); The strain gauge (10) is adhered to a corresponding position of the tunnel model, and the earth pressure box (11) is buried at a corresponding position in the tunnel model. The tunnel model material uses barite and quartz sand as aggregates, vaseline as a binder, and the barite:quartz sand:vaseline=10:8:

1. The model material for simulating cast-in-place reinforced concrete uses iron wire with a diameter of 4 mm and gypsum with a water-to-gypsum ratio of 1:1.05, and is simulated by the method of equivalent bending stiffness of the prototype and the model.

2. The tunnel lining and surrounding rock stress characteristics testing model device according to claim 1 is characterized in that: The reaction force support plate (1) and the two left and right side plates (2) are all made of No. 32 processed channel steel; The bearing plate (3) is a steel plate with a thickness of 8 mm; Of the six front and rear side panels (5), the four on the front and rear sides are made of 8 mm thick steel plates, and the two in the middle of the front and rear are made of 8 mm thick transparent organic glass.

3. The tunnel lining and surrounding rock stress characteristics testing model device according to claim 2 is characterized in that: A 10 mm thick steel support is provided on the two left and right side plates (2), and the steel support forms a triangle with the ground; 10 mm thick steel supports are provided in the six front and rear side panels (5), and the steel supports are triangular with the ground.

4. The tunnel lining and surrounding rock stress characteristics testing model device according to claim 1 is characterized in that: The measurement system also includes: a lining strain measurement system, a surrounding rock pressure measurement system and a surrounding rock displacement measurement system; The lining strain measurement is achieved by sticking strain gauges on the inner and outer surfaces of the lining. The strain gauges are resistance strain gauges. The surrounding rock pressure measurement is achieved by burying a micro pressure cell with a diameter of 16 mm; The lining strain and surrounding rock pressure are collected by steel string data collector; The surrounding rock displacement measurement system is realized by measuring the displacement of deformed fibers embedded in simulated surrounding rock materials.

5. The tunnel lining and surrounding rock stress characteristics testing model device according to claim 1 is characterized in that: The geometric similarity ratio C between the tunnel model and the tunnel prototype l , take the bulk density similarity ratio , Poisson's ratio similarity ratio , similarity ratio of internal friction angle , cohesion similarity ratio C c , elastic modulus similarity ratio C E .

6. A method for testing the stress characteristics of tunnel lining and surrounding rock, characterized in that: The following steps are involved: Step S1: assembling the bench, and tightly connecting the bottom plate (4), the two left and right side plates (2), the six front and rear side plates (5) and the two front and rear side plate reinforcements by bolts; after the bench is assembled, a tunnel surrounding rock model with a maximum net size of 3000 mm in length, 320 mm in width and 1500 mm in height can be formed; Step S2: According to the tunnel lining cross-section design drawing and the size similarity ratio, the lining model size is determined, the template is customized, and the lining model is made on site using iron wire with a diameter of 4 mm and gypsum with a water-to-cement ratio of 1:1.05; Step S3: After the lining model is manufactured, the resistance strain gauges are symmetrically arranged on the inner and outer sides of the lining model, and the corresponding circuits are connected; Step S4: preparing simulated surrounding rock material according to the ratio of barite: quartz sand: vaseline = 10:8:1; Step S5: filling simulated surrounding rock materials in layers to the bottom surface of the lining model installation position; then installing the lining model in place, and continuing to fill the simulated surrounding rock materials on the back of the side walls on both sides of the lining model to the vault plane; finally, continue to fill the simulated surrounding rock materials to the bottom surface of the bearing plate (3); During the entire filling process, horizontal and vertical deformation fibers (12) are buried according to the locations where the surrounding rock deformation is to be measured. The deformation fibers should be buried close to the organic glass side panels for easy observation. Burying an earth pressure cell (11) according to the location where the surrounding rock pressure is to be measured; All connections should be convenient and not affect loading; during the filling process, reserve the cavity range on the back of the lining model according to actual needs and actual construction conditions; Step S6: installing the bearing plate (3) and the reaction force support plate (1); Step S7: Install the jack (8) and the pressure gauge (9), and connect the soil pressure box (11) and the resistance strain gauge test line to the data acquisition instrument; Step S8: Load in stages according to the actual situation and read the data until the lining model is destroyed; Step S9: Obtain the lining internal force, surrounding rock pressure, and surrounding rock displacement through calculation and observation, then draw a graph, analyze the data, observe the failure mode of the lining model, and study the law.

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