A linear water-containing zone frost heave model for tunnels in cold regions and its preparation and test methods

Abstract

The present invention relates to the field of tunnel engineering model test, specifically, a cold-region tunnel linear water-containing zone frost heave model and its preparation and test method. It includes a frost heave surrounding rock system, an environmental control system and a frost heave force data acquisition system; the frost heave surrounding rock system includes simulated surrounding rock, secondary lining and frost heave surrounding rock linear fracture zone, the secondary lining runs through the simulated surrounding rock distribution, the frost heave surrounding rock linear fracture zone is a strip hole set on the simulated surrounding rock and can be injected with water, and the frost heave surrounding rock linear fracture zone includes a surrounding rock linear water-containing zone distributed inside the simulated surrounding rock and a lining back water-containing zone distributed between the simulated surrounding rock and the secondary lining; the present invention can objectively reflect the influence of different water storage structures of the surrounding rock on the frost heave force of the tunnel, and simulate the influence and distribution law of different linear water-containing zone lengths, positions, widths, etc. on the frost heave force of the tunnel under different burial depths and temperature environments through model tests, providing guidance for the prevention and control of frost heave disasters in cold-region tunnels.

Description

Technical Field

[0001] The invention relates to the field of tunnel engineering model tests, in particular to a linear water-containing zone frost heave model of a cold region tunnel and a preparation and test method thereof. Background Art

[0002] my country is one of the three countries with the largest permafrost distribution area in the world. Building tunnels in permafrost and water-rich areas is prone to generate large frost heaving forces and thus cause frost damage problems, such as concrete falling off, lining cracking, water leakage, ice hanging, spalling, etc. These frost damage phenomena have a serious impact on tunnel structure and operational safety. Therefore, it is imperative to study the laws of frost heaving damage to tunnel surrounding rocks.

[0003] Many scholars at home and abroad have conducted field tests and model test studies on the deformation of tunnels in cold regions and the frost heave of surrounding rocks, and found that local water storage at the defective positions of tunnel surrounding rocks is the main cause of frost heave damage to surrounding rocks. In actual projects, surrounding rock defects mostly exist in the form of caves, holes, cracks, etc.; in tunnel construction, large-scale cavities are generally not generated behind the support lining, but it is possible that small cavities or flat cracks are generated behind the lining due to the lack of density between the supporting arch frame or anchor concrete and the surrounding rock. When these areas are filled with groundwater and frozen, they often cause frost heave on the lining and surrounding rock, and additional frost heave force will be generated between the surrounding rock and the lining. The indoor test models of frost heave force of tunnels in cold regions in the prior art have not comprehensively considered the influence of water storage in various parts of the surrounding rock on the frost heave force of the tunnel, resulting in the test data that cannot objectively and truly reflect the influence of different water storage structures of the surrounding rock on the frost heave force of the tunnel. Summary of the invention

[0004] The present invention aims to provide a linear water-containing zone frost heave model for cold-region tunnels and its preparation and testing methods, objectively reflecting the influence of different water storage structures of surrounding rocks on the frost heave force of tunnels, and simulating the influence and distribution law of different linear water-containing zone lengths, positions, widths, etc. on the frost heave force of tunnels under different burial depths and temperature environments through model tests, so as to provide guidance for the prevention and control of frost heave disasters in cold-region tunnels.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a linear water-bearing zone frost heave model of cold-region tunnels, including a frost heave surrounding rock system, an environmental control system and a frost heave force data acquisition system;

[0006] The frost heaving surrounding rock system includes simulated surrounding rock, secondary lining and linear fracture zone of frost heaving surrounding rock. The secondary lining runs through the simulated surrounding rock. The linear fracture zone of frost heaving surrounding rock is a strip hole set on the simulated surrounding rock and can be injected with water. The linear fracture zone of frost heaving surrounding rock includes the linear water-bearing zone of surrounding rock distributed inside the simulated surrounding rock and the water-bearing zone behind the lining distributed between the simulated surrounding rock and the secondary lining.

[0007] The environmental control system includes a refrigeration device and a biaxial reaction frame device; the refrigeration device includes a hollow sandwich plate arranged around the periphery of the simulated surrounding rock, a plurality of ribs distributed in a crisscross pattern are arranged in the inner cavity of the hollow sandwich plate, the plurality of ribs divide the inner cavity of the hollow sandwich plate into a plurality of chambers, through holes for the circulation of refrigeration liquid in adjacent chambers are provided on the ribs, an input valve for the entry of refrigeration liquid and an output valve for the discharge of refrigeration liquid are also provided on the hollow sandwich plate; the reaction frame device includes a frame structure sleeved on the periphery of the hollow sandwich plate, a plurality of jacks for applying loads to the simulated surrounding rock through the hollow sandwich plate are arranged at intervals on the frame structure;

[0008] The frost heave force data acquisition system includes a plurality of sensor groups which are respectively arranged between the simulated surrounding rock and the secondary lining and located at the arch crown, arch foot, side wall and invert arch of the secondary lining. Any sensor group includes a pressure sensor and a temperature sensor, and all the pressure sensors and temperature sensors are connected to a computer.

[0009] Preferably, the simulated surrounding rock is in the shape of a cube, and the secondary lining is distributed horizontally through the center of the simulated surrounding rock.

[0010] Preferably, the number of the hollow sandwich panels is four, and the four hollow sandwich panels are respectively arranged on four side walls of the simulated surrounding rock corresponding to the circumference of the secondary lining.

[0011] Preferably, the hollow sandwich panel comprises two base plates which are spaced apart and arranged in parallel, and the outer edges of the two base plates are connected by a strip-shaped sealing plate.

[0012] Preferably, in the same hollow sandwich panel, an insulation layer is provided on the outer side of the sealing plate and a base plate away from the simulated surrounding rock; the material of the insulation layer is polyurethane, and the thickness of the insulation layer is not less than 3 cm.

[0013] Preferably, the frame structure includes a rectangular frame and two horizontal load plates and two vertical load plates fixed on the rectangular frame, and the cylinder ends of the plurality of jacks are respectively vertically fixed on the corresponding horizontal load plates or vertical load plates.

[0014] Preferably, the secondary lining is made of welded steel plates, and a threading hole is provided in the middle of the secondary lining for the foot wire of the sensor group to pass through.

[0015] A method for preparing a linear water-containing zone frost heave model of a cold region tunnel comprises the following steps:

[0016] 1) Make secondary lining, refrigeration device and double-axis reaction frame device;

[0017] 2) Assemble the secondary lining, refrigeration device and biaxial reaction frame device in sequence and place them upright on a rigid horizontal plate;

[0018] 3) Wrap the blasting fuse and the steel wire together to form a long strip of water-bearing belt generating parts. Part of the water-bearing belt generating parts are wound around the outer periphery of the secondary lining in the shape of the water-bearing belt behind the lining, and the remaining part of the water-bearing belt generating parts are fixed on the rigid horizontal plate in the shape of the linear water-bearing belt of the surrounding rock;

[0019] 4) Fill and compact simulated surrounding rock between the secondary lining and the refrigeration device. After half of the filling is completed, set up sensor groups on the outer periphery of the secondary lining and at the corresponding positions of the arch crown, arch foot, side wall and invert arch of the secondary lining, and then continue to fill simulated surrounding rock;

[0020] 5) After the simulated surrounding rock filling is completed, rotate 90° to make the secondary lining horizontal;

[0021] 6) After igniting the blasting fuse and pulling out the steel wire and flushing the gunpowder residue, a linear water-bearing zone of the surrounding rock is formed inside the simulated surrounding rock, and a water-bearing zone behind the lining is formed between the simulated surrounding rock and the secondary lining.

[0022] A test method for a linear water-containing zone frost heave model of a cold region tunnel comprises the following steps:

[0023] 1) Start the refrigeration device, and introduce liquid ammonia at normal pressure and low temperature into the hollow sandwich plate through the input valve. Adjust the input and output of liquid ammonia to keep the temperature of the simulated surrounding rock below 0℃ for 15 minutes;

[0024] 2) According to the actual situation of the simulated tunnel surrounding rock, vertical and horizontal loads are applied to the simulated surrounding rock through jacks, water is injected into the linear fracture zone of the frost heave surrounding rock, and the water outlet is blocked on the outside of the surrounding rock;

[0025] 3) According to the actual situation of the simulated surrounding rock, adjust the input and output of liquid ammonia, lower or increase the temperature of the simulated surrounding rock, monitor and record the changes in the earth pressure gauge readings, and provide a basis for frost heave force analysis.

[0026] Beneficial Effects

[0027] The linear water-containing zone frost heave model and test method of the cold region tunnel of the present invention simulates the influence and distribution law of different linear water-containing zone lengths, positions, widths, etc. on the tunnel frost heave force under different burial depths and temperature environments, and provides guidance for the prevention and control of frost heave disasters in cold region tunnels. Considering the plane strain stress state of the tunnel surrounding rock, a biaxial reaction frame loading system simulating the tunnel burial depth conditions is designed; a low-temperature refrigeration device is constructed using a hollow sandwich plate, and the low-temperature environment of the tunnel surrounding rock is simulated by regulating the liquid ammonia flow.

[0028] The method for preparing the linear water-containing zone frost heave model of a cold zone tunnel of the present invention utilizes the characteristic of volume reduction after the blasting fuse is burned in the linear water-containing zone structure inside the surrounding rock and behind the lining to realize the prefabrication of arbitrary linear water-containing cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the longitudinal section structure of the linear water-containing zone frost heave model of a cold region tunnel of the present invention;

[0030] Figure 2 for Figure 1 AA section view in the figure;

[0031] Figure 3 It is a structural schematic diagram of the frost heave surrounding rock system part in the present invention;

[0032] Figure 4 It is a structural schematic diagram of the dual-axis reaction frame device part of the present invention;

[0033] Figure 5 A schematic diagram of the distribution of the sensor group in the frost heave force data acquisition system of the present invention;

[0034] Markings in the figure: 1. Simulated surrounding rock, 2. Water-bearing zone behind lining, 3. Secondary lining, 4. Linear water-bearing zone of surrounding rock, 5. Biaxial reaction frame device, 501. Jack, 502. Frame structure, 502-1. Vertical load plate, 502-2. Rectangular frame, 502-3. Horizontal load plate, 6. Refrigeration device, 601. Sealing plate, 602. Base plate, 603. Insulation layer, 604. Rib plate, 605. Through hole, 606. Output valve, 607. Input valve, 7. Temperature sensor, 8. Pressure sensor. DETAILED DESCRIPTION

[0035] like Figure 1 As shown, a linear water-bearing zone frost heave model of a cold region tunnel of the present invention mainly includes a frost heave surrounding rock system, an environmental control system and a frost heave force data acquisition system.

[0036] like Figure 3 As shown, the frost heaving surrounding rock system includes a simulated surrounding rock 1, a secondary lining 3, and a linear fracture zone of the frost heaving surrounding rock. The simulated surrounding rock 1 is a cubic structure, and the secondary lining 3 is composed of steel plates assembled and welded, and is horizontally distributed through the center of the simulated surrounding rock 1, simulating the surrounding rock and lining structure in a real tunnel. The linear fracture zone of the frost heaving surrounding rock is a strip hole set on the simulated surrounding rock 1 and can be injected with water. Both ends of the strip hole are open and can be closed by blind heads to facilitate water injection into the interior, and cooperate with the environmental control system to truly simulate the influence of the water-bearing zone structure on the frost heaving force of the tunnel. The linear fracture zone of the frost heaving surrounding rock in the present invention includes a linear water-bearing zone 4 of the surrounding rock distributed inside the simulated surrounding rock 1 and a water-bearing zone 2 behind the lining distributed between the simulated surrounding rock 1 and the secondary lining 3. Through the influence and distribution law of different linear water-bearing zone lengths, positions, widths, etc. on the frost heaving force of the tunnel, the real situation is objectively reflected, and accurate guidance is provided for the prevention and control of frost heaving disasters in cold-region tunnels.

[0037] The environmental control system includes a refrigeration device 6 and a dual-axis reaction frame device 5 .

[0038] Combination Figure 1 and Figure 2 As shown, the refrigeration device 6 includes four hollow sandwich panels respectively arranged above, below, left and right of the simulated surrounding rock 1. On the one hand, the hollow sandwich panels are used to generate low temperatures to simulate the ambient temperature of the tunnel; on the other hand, they are also used as carriers for the biaxial reaction frame device 5 to apply horizontal and vertical loads toward the simulated surrounding rock 1. Any hollow sandwich panel includes a base plate 602 made of two steel plates corresponding to the shape and size of the side wall of the simulated surrounding rock 1 and distributed in parallel and at intervals. The outer edges of the two base plates 602 are sealed and welded by a sealing plate 601 made of a long strip and made of steel plate. An input valve 607 and an output valve 606 are provided on the sealing plate 601 for the refrigeration liquid to enter and exit the inner cavity of the hollow sandwich panel. In order to realize the load carrier function of the hollow sandwich panel, a plurality of ribs 604 distributed in a criss-cross pattern are provided in the inner cavity of the hollow sandwich panel. The inner cavity of the hollow sandwich plate is divided into a plurality of chambers by a plurality of ribs 604 , and through holes 605 are also provided through the ribs 604 for cooling liquid to flow in adjacent chambers, so as to uniformly control the temperature of the simulated surrounding rock 1 .

[0039] In this embodiment, on the same hollow sandwich plate, an insulation layer 603 is provided on the outside of the sealing plate 601 and a base plate 602 away from the simulated surrounding rock 1 to reduce heat loss during the test. The insulation layer 603 is made of polyurethane, and the thickness of the insulation layer 603 is not less than 3 cm.

[0040] Combination Figure 1 class Figure 4 As shown, the reaction frame device includes a frame structure 502 sleeved on the outer periphery of the hollow sandwich plate, and a plurality of jacks 501 for applying load to the simulated surrounding rock 1 through the hollow sandwich plate are arranged at intervals on the frame structure 502. The frame structure 502 includes a rectangular frame 502-2 formed by welding four angle steels, and two horizontal load plates 502-3 and two vertical load plates 502-1 fixed on the rectangular frame 502-2. Four jacks 501 are arranged on any horizontal load plate 502-3 or vertical load plate 502-1. The cylinder ends of the jacks 501 are respectively vertically fixed on the corresponding horizontal load plates 502-3 or vertical load plates 502-1; the pressure heads of the jacks 501 act on the hollow sandwich plates at corresponding positions.

[0041] like Figure 5As shown, the frost heave force data acquisition system includes a plurality of sensor groups respectively arranged between the simulated surrounding rock 1 and the secondary lining 3 and located at the vault, arch foot, side wall and invert of the secondary lining 3. Any sensor group includes a pressure sensor 8 and a temperature sensor 7. All pressure sensors 8 and temperature sensors 7 are connected to a computer, and the pressure and temperature information measured by the sensor group is recorded by the computer. A threading hole is provided in the middle of the secondary lining 3 for the foot wire of the sensor group to pass through and connect to the computer.

[0042] The method for preparing the linear water-containing zone frost heave model of the cold region tunnel comprises the following steps:

[0043] 1) Manufacturing the secondary lining 3, four hollow sandwich panels in the refrigeration device 6 and the biaxial reaction frame device 5;

[0044] 2) The secondary lining 3, the refrigeration device 6 and the biaxial reaction frame device 5 are assembled in sequence and placed vertically on a rigid horizontal plate, so that a filling space simulating the surrounding rock 1 is formed between the four hollow sandwich plates and the secondary lining 3;

[0045] 3) Select a civilian blasting fuse and a steel wire of equal length, twist the blasting fuse and the steel wire into a twist shape to form a long strip of water-bearing belt forming parts, and wrap part of the water-bearing belt forming parts around the outer periphery of the secondary lining 3 in the shape of the water-bearing belt 2 behind the lining, and fix the remaining part of the water-bearing belt forming parts on the rigid horizontal plate in the shape of the linear water-bearing belt 4 of the surrounding rock;

[0046] 4) Fill and compact the simulated surrounding rock 1 between the secondary lining 3 and the refrigeration device 6. After half of the filling, set the sensor group on the outer periphery of the secondary lining 3 and at the arch top, arch foot, side wall and invert position of the secondary lining 3, and then continue to fill the simulated surrounding rock 1;

[0047] 5) After the simulated surrounding rock 1 is filled, rotate it 90° to make the secondary lining 3 horizontal;

[0048] 6) Ignite the blasting fuse and pull out the steel wire, and use high-pressure water to wash the gunpowder residue, so as to form a surrounding rock linear water-bearing zone 4 inside the simulated surrounding rock 1, and form a lining back water-bearing zone 2 between the simulated surrounding rock 1 and the secondary lining 3, thereby completing the production of the model of the present invention.

[0049] The test method of the linear water-containing zone frost heave model of the cold region tunnel comprises the following steps:

[0050] 1) Installation and debugging of the frost heave force data acquisition system. After the model is completed, the foot wires of the pressure sensor 8 and the temperature sensor 7 are connected to the reader and the control computer, the installation survival rate of the test components is checked, and the working stability of the test system is preliminarily debugged;

[0051] 2) Refrigeration system debugging: the refrigeration device 6 is connected to the atmospheric low-temperature liquid ammonia storage tank through the input valve 607 and the output valve 606. The freezing of the surrounding rock 1 is simulated by the flow of liquid ammonia in the low-temperature refrigeration device 6. The freezing temperature is obtained by the temperature sensor 7 between the secondary lining 3 and the surrounding rock.

[0052] 3) Start the refrigeration device 6, and introduce liquid ammonia at normal pressure and low temperature into the hollow sandwich plate through the input valve 607, and adjust the input and output of liquid ammonia to keep the temperature of the simulated surrounding rock 1 below 0°C for 15 minutes;

[0053] 4) According to the actual situation of the surrounding rock of the simulated tunnel, vertical and horizontal loads are applied to the simulated surrounding rock 1 through the jack 501, water is injected into the linear fracture zone of the frost-heaving surrounding rock, and the water outlet is blocked on the outside of the surrounding rock;

[0054] 5) According to the actual situation of the simulated surrounding rock 1, adjust the input and output of liquid ammonia, reduce or increase the temperature of the simulated surrounding rock 1, monitor and record the changes in the earth pressure gauge readings, and provide a basis for frost heave force analysis.

Claims

1. A linear water-containing zone frost heave model for cold region tunnels, characterized by: Including frost heave surrounding rock system, environmental control system and frost heave force data acquisition system; The frost heaving surrounding rock system comprises a simulated surrounding rock (1), a secondary lining (3) and a linear fracture zone of the frost heaving surrounding rock, wherein the secondary lining (3) is distributed throughout the simulated surrounding rock (1), the linear fracture zone of the frost heaving surrounding rock is a strip-shaped hole arranged on the simulated surrounding rock (1) and capable of injecting water, and the linear fracture zone of the frost heaving surrounding rock comprises a linear water-bearing zone (4) of the surrounding rock distributed inside the simulated surrounding rock (1) and a water-bearing zone (2) behind the lining distributed between the simulated surrounding rock (1) and the secondary lining (3); The environmental control system comprises a refrigeration device (6) and a biaxial reaction frame device (5); the refrigeration device (6) comprises a hollow sandwich plate arranged around the outer periphery of the simulated surrounding rock (1); a plurality of ribs (604) arranged in a crisscross pattern are arranged in the inner cavity of the hollow sandwich plate; the plurality of ribs (604) divide the inner cavity of the hollow sandwich plate into a plurality of chambers; through holes (605) are provided on the ribs (604) for cooling liquid to flow in adjacent chambers; an input valve (607) for cooling liquid to enter and an output valve (606) for cooling liquid to discharge are also provided on the hollow sandwich plate; the reaction frame device comprises a frame structure (502) sleeved around the outer periphery of the hollow sandwich plate; a plurality of jacks (501) for applying loads to the simulated surrounding rock (1) through the hollow sandwich plate are arranged at intervals on the frame structure (502); The frost heave force data acquisition system comprises a plurality of sensor groups respectively arranged between the simulated surrounding rock (1) and the secondary lining (3) and located at the arch top, arch foot, side wall and invert arch of the secondary lining (3), any one of the sensor groups comprises a pressure sensor (8) and a temperature sensor (7), and all the pressure sensors (8) and temperature sensors (7) are connected to a computer; The method for preparing the linear water-containing zone frost heave model of a cold region tunnel comprises the following steps: 1) manufacturing a secondary lining (3), a refrigeration device (6) and a dual-axis reaction frame device (5); 2) assembling the secondary lining (3), the refrigeration device (6) and the dual-axis reaction frame device (5) in sequence and placing them upright on a rigid horizontal plate; 3) The blasting fuse and the steel wire are wound together to form a long strip of water-bearing belt forming parts, part of the water-bearing belt forming parts are arranged around the outer periphery of the secondary lining (3) in the shape of the water-bearing belt (2) behind the lining, and the remaining part of the water-bearing belt forming parts are fixed on the rigid horizontal plate in the shape of the linear water-bearing belt (4) of the surrounding rock; 4) Fill the simulated surrounding rock (1) between the secondary lining (3) and the refrigeration device (6) and compact it. After half of the filling is completed, a sensor group is fixedly installed on the outer periphery of the secondary lining (3) and at the arch top, arch foot, side wall and invert position of the secondary lining (3), and then continue to fill the simulated surrounding rock (1); 5) After the simulated surrounding rock (1) is filled, it is rotated 90° to make the secondary lining (3) horizontal; 6) After igniting the blasting fuse and pulling out the steel wire and flushing the gunpowder residue, a surrounding rock linear water-bearing zone (4) is formed inside the simulated surrounding rock (1), and a lining back water-bearing zone (2) is formed between the simulated surrounding rock (1) and the secondary lining (3).

2. A linear water-containing zone frost heave model for cold region tunnels according to claim 1, characterized in that: The simulated surrounding rock (1) is in the shape of a cube, and the secondary lining (3) is distributed horizontally through the center of the simulated surrounding rock (1).

3. A linear water-containing zone frost heave model for cold region tunnels according to claim 2, characterized in that: The number of the hollow sandwich panels is four, and the four hollow sandwich panels are respectively arranged on four side walls of the simulated surrounding rock (1) corresponding to the circumference of the secondary lining (3).

4. A linear water-containing zone frost heave model for cold region tunnels according to claim 3, characterized in that: The hollow sandwich panel comprises two base plates (602) which are spaced apart and arranged in parallel, and the outer edges of the two base plates (602) are connected via a strip-shaped sealing plate (601).

5. A linear water-containing zone frost heave model for cold region tunnels according to claim 4, characterized in that: In the same hollow sandwich panel, a thermal insulation layer (603) is provided on the outside of the sealing plate (601) and a base plate (602) away from the simulated surrounding rock (1); the material of the thermal insulation layer (603) is polyurethane, and the thickness of the thermal insulation layer (603) is not less than 3 cm.

6. The linear water-containing zone frost heave model of cold region tunnel according to claim 2, characterized in that: The frame structure (502) comprises a rectangular frame (502-2) and two horizontal load plates (502-3) and two vertical load plates (502-1) fixed on the rectangular frame (502-2), and the cylinder ends of the plurality of jacks (501) are respectively vertically fixed on the corresponding horizontal load plates (502-3) or vertical load plates (502-1).

7. The linear water-containing zone frost heave model of cold region tunnel according to claim 2, characterized in that: The secondary lining (3) is made of welded steel plates, and a threading hole for the foot wire of the sensor group to pass through is provided in the middle of the secondary lining (3).

8. A test method for the linear water-containing zone frost heave model of a cold region tunnel as claimed in claim 1, characterized in that: The following steps are involved: 1) Start the refrigeration device (6), and introduce liquid ammonia at normal pressure and low temperature into the hollow sandwich plate through the input valve (607), and adjust the input and output of the liquid ammonia to keep the temperature of the simulated surrounding rock (1) below 0°C for 15 minutes; 2) According to the actual situation of the simulated tunnel surrounding rock, vertical and horizontal loads are applied to the simulated surrounding rock (1) through a jack (501), water is injected into the linear fracture zone of the frost heave surrounding rock, and the water outlet is blocked on the outside of the surrounding rock; 3) According to the actual conditions of the simulated surrounding rock (1), adjust the input and output of liquid ammonia, reduce or increase the temperature of the simulated surrounding rock (1), monitor and record the changes in the earth pressure gauge readings, and provide a basis for frost heave force analysis.

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