System and method for simulating stress and deformation of tunnel segments under frost heaving action of connecting passages

Abstract

The application discloses a tunnel segment stress and deformation simulation test system under the action of a liaison channel frost heaving, which comprises a thermostat, a tunnel segment, a water bag loading rubber cylinder and a freezing pipe; a rectangular opening is formed in the side surface of the thermostat, and the tunnel segment is clamped in the rectangular opening; a steel drum is installed in the thermostat, and the opening of the steel drum faces the rectangular opening; the water bag loading rubber cylinder is tightly attached to the inner wall of the steel drum; one end of the freezing pipe faces the opening of the steel drum, and the other end of the freezing pipe penetrates through the bottom wall of the steel drum and is in fluid communication with a refrigerant pipeline; the water bag loading rubber cylinder, the freezing pipe and the space between the freezing pipe are all filled with soil; the freezing pipe is distributed radially along the bottom wall of the steel drum, so that the soil around the freezing pipe is frozen to form a ring-shaped frozen curtain with the same shape as that in construction. The application is used for studying the interaction between the frozen soil and the tunnel segment and the deformation law of the tunnel segment under the action of frost heaving, and provides theoretical and experimental support for preventing large-diameter tunnel segments from being cracked due to artificial frost heaving.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel segment stress deformation simulation. Specifically, it is a tunnel segment stress and deformation simulation test system under the action of artificial frozen soil frost heaving of a connecting passage. BACKGROUND

[0002] Artificial ground freezing method is one of the main methods for constructing connecting passages, end shafts or handling accidents in water-containing soft ground in various cities in China. Among them, the most important application scenario of the freezing method is the construction of tunnel connecting passages. The connecting passage is a passage constructed between double-line tunnels for the purpose of connection, drainage, emergency evacuation, etc., and is an important part of tunnel engineering.

[0003] When the connecting passage is constructed by the freezing method, the freezing pipe is drilled into the ground from the side of the tunnel segment, and low-temperature brine is circulated in the pipe to form an annular frozen soil curtain (frozen wall), and the connecting passage is excavated and constructed under the protection of the frozen wall. As known from the properties of frozen soil, during the freezing process, the water in the soil around the frozen wall migrates to the freezing front under the action of the temperature gradient, and after phase change with the in-situ pore water, the volume increases, fills the internal pore volume of the frozen soil, and pushes the soil particles to move, thereby generating frost heaving deformation. When the frost heaving deformation is constrained by the segment or is not allowed to deform, the frozen soil will generate a pushing force on the constraint, i.e. the frost heaving force

see Figure 1 and Figure 2

[0004] The axial frost heaving pressure on the large-diameter shield tunnel segment is asymmetric, and significant stress concentration will occur at the intersection of the frozen soil and the structure (the horn), resulting in asymmetric deformation and local extrusion of the frost heaving, which may cause the tunnel segment to be misaligned and the horizontal convergence deformation to increase. If there are cracks in the segment, freezing may cause the cracks to further develop, and slight negligence may cause major economic losses and adverse social impact. In 2003, the frost heaving of a connecting passage of Shanghai Metro caused the fragmentation of 18 nearby tunnel segments, with a single crack up to 2m long, causing significant economic losses and delays in the construction period. In order to ensure the safe construction of large-diameter tunnel connecting passages, theoretical research on the interaction between frozen soil and large-diameter segment structure is imperative. Therefore, it is necessary to develop a frozen soil and segment model test system to facilitate the study of the interaction between frozen soil and segments and the deformation law of the segments under the action of frost heaving, and to provide theoretical support for preventing large-diameter segments from being fragmented due to the action of frost heaving. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to provide a tunnel segment stress and deformation simulation test system under the action of frost heaving of a connecting passage, which can be used to study the interaction between artificial frozen soil and segments and the deformation law of the segments under the action of frost heaving, and to provide theoretical support for preventing large-diameter segments from being fragmented due to the action of frost heaving of artificial frozen soil.

[0006] To solve the above technical problems, the present application provides the following technical solutions:

[0007] The tunnel segment stress and deformation simulation test system under the frost heaving action of the connecting passage comprises a thermostat, a tunnel segment, a water bag loading rubber cylinder, a steel barrel and a freezing pipe; one side of the thermostat is provided with a rectangular opening, the tunnel segment is clamped in the rectangular opening and connected with the box body of the thermostat; the steel barrel is installed in the thermostat, and the opening of the steel barrel faces the rectangular opening; the water bag loading rubber cylinder is located in the steel barrel and closely adheres to the inner wall of the steel barrel; one end of the freezing pipe faces the opening of the steel barrel and abuts against the tunnel segment, and the other end penetrates through the bottom wall of the steel barrel and is in fluid communication with a refrigerant pipeline; in the steel barrel, the space between the water bag loading rubber cylinder and the freezing pipe and the space between the freezing pipes are filled with soil; the freezing pipes are distributed radially along the bottom wall of the steel barrel, so that the soil around the freezing pipes is frozen to form an annular freezing curtain with the same shape as that in construction; a stress and deformation monitoring mechanism, such as a stress, strain and displacement monitoring device and a data automatic acquisition device, is installed on the tunnel segment.

[0008] The above-mentioned tunnel segment stress and deformation simulation test system under the frost heaving action of the connecting passage is provided with a water supplementing filter element in the soil, one end of the water supplementing filter element is adjacent to the tunnel segment, the other end penetrates through the bottom wall of the steel barrel and is in fluid communication with the fluid outlet end of a filter element water supplementing pipe; the fluid inlet end of the filter element water supplementing pipe extends out of the thermostat; a first one-way valve is installed on the water supplementing filter element adjacent to the fluid outlet end of the filter element water supplementing pipe.

[0009] The above-mentioned tunnel segment stress and deformation simulation test system under the frost heaving action of the connecting passage, the water supplementing filter element comprises a stainless steel pipe and thermal insulation cotton; the thermal insulation cotton is filled in the stainless steel pipe; water permeable holes are formed in the pipe wall of the stainless steel pipe.

[0010] The above-mentioned tunnel segment stress and deformation simulation test system under the frost heaving action of the connecting passage, the fluid inlet end of the refrigerant pipeline extends out of the thermostat.

[0011] The above-mentioned tunnel segment stress and deformation simulation test system under the frost heaving action of the connecting passage, the refrigerant in the refrigerant pipeline is low-temperature anhydrous ethanol with a temperature of-18 to-30 DEG C; compared with other refrigerants, anhydrous ethanol is not easy to become viscous at low temperature, and has a lower freezing point and a lower price.

[0012] The water bag loading rubber cylinder is in fluid communication with the fluid outlet end of the water bag water supplement pipe, and the fluid inlet end of the water bag water supplement pipe extends out of the thermostat.

[0013] The tunnel segment under the action of the communication passage frost heaving is simulated by the tunnel segment stress and deformation simulation test system.

[0014] The stress and deformation monitoring mechanism comprises a strain gauge and a dial gauge.

[0015] The tunnel segment is clamped in the rectangular opening through a segment buckle.

[0016] The tunnel segment under the action of the communication passage frost heaving is simulated by the tunnel segment stress and deformation simulation test system.

[0017] The technical scheme of the present application has the following beneficial technical effects:

[0018] The tunnel segment stress and deformation simulation test system can be used to carry out laboratory tests on the interaction between frozen soil and segments, and can realize the research on the interaction between frozen soil and segments and master the deformation law of segments under the action of frost heaving, thereby providing theoretical and experimental support for preventing large-diameter segments from being cracked due to artificial frost heaving. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Structure diagram of the position relationship between the communication passage and the tunnel segment;

[0020] Figure 2A schematic diagram of the force exerted by frost heave on tunnel segments in the connecting passageway;

[0021] Figure 3 A schematic diagram (front view) of the tunnel segment stress and deformation simulation test system under frost heave in the connecting passage in Embodiment 1 of the present invention;

[0022] Figure 4 A schematic diagram (side view) of the structure of the simulation test system for the stress and deformation of tunnel segments under frost heave in the connecting passage in Embodiment 1 of the present invention;

[0023] Figure 5 A schematic diagram (top view) of the simulation test system for the stress and deformation of tunnel segments under frost heave in the connecting passage in Embodiment 1 of the present invention.

[0024] The attached diagram is labeled as follows: 0-Constant temperature chamber; 1-Water-filled rubber cylinder; 2-Frozen soil curtain; 3-Filter element water supply pipe; 4-Refrigerator pipeline; 5-Water-filled pipe; 6-Water supply filter element; 7-First check valve; 8-Second check valve; 9-Tie rod; 10-Rubber pad; 11-Tie steel plate; 12-Tunnel segment; 13-Segment clip; 14-Fixing bolt; 15-Steel barrel; 16-Freezing pipe; 17-Connecting passage; 18-Soil; 19-Tie rod nut; 20-Frost heave; 21-Up line tunnel; 22-Down line tunnel; 23-Water-rich test soil layer. Detailed Implementation

[0025] like Figures 3-5 As shown, the simulation test system for the stress and deformation of tunnel segments under frost heave in this embodiment includes a constant temperature chamber 0, tunnel segments 12, a water-filled rubber cylinder 1, a steel bucket 15, and a freezing pipe 16. A rectangular opening is provided on one side of the constant temperature chamber 0 (in this embodiment, the constant temperature chamber 0 is a cube), and the tunnel segment 12 is secured in the rectangular opening by segment clips 13. The tunnel segment 12 is composed of a tie plate 11 and a semi-cylindrical segment model (because in actual working conditions, the tunnel segment is a symmetrical cylinder composed of two semi-cylindrical sections, and its structural mechanics is also symmetrical, with sliding supports hinged on both sides of the structure, therefore...). The tunnel segment in this embodiment is half of the structure in actual working conditions; the straight end face of the semi-cylindrical segment model is fixed on the tie plate 11, and the tie plate 11 and the semi-cylindrical segment model form a semi-cylinder; the semi-cylindrical segment model is composed of two or more segments; a rubber pad 10 is provided at the fixed connection between the semi-cylindrical segment model and the tie plate 11; one end of the tie rod 9 is threadedly connected to the tie plate 11 through the tie rod nut 19; the other end of the tie rod 9 is threadedly connected to the side wall of the constant temperature box 0 through the fixing bolt 14, so that the tunnel segment 12 can be tightly tied to the constant temperature box 0.

[0026] The steel barrel 15 is located in the thermostat 0, and the opening of the steel barrel 15 faces the rectangular opening; the water bag loading rubber cylinder 1 is located in the steel barrel 15, and the water bag loading rubber cylinder 1 is tightly attached to the inner wall of the steel barrel 15, so that the steel barrel can limit the outward expansion during the water bag loading process, and the pressure is fully applied to the soil in the water bag; the water bag loading rubber cylinder 1 is in fluid communication with the fluid outlet end of the water bag water supplement pipe 5, and the fluid inlet end of the water bag water supplement pipe 5 extends out of the thermostat 0; by controlling the water pressure, the water bag pressure of the water bag loading rubber cylinder 1 is adjusted, and then the soil pressure is adjusted to simulate the formation pressure at different depths; a second one-way valve 8 is installed on the water bag water supplement pipe 5 adjacent to the water bag loading rubber cylinder 1; one end of the freezing pipe 16 faces the opening of the steel barrel 15 and is tightly attached to the tunnel segment 12, and the other end penetrates the bottom wall of the steel barrel 15 and is in fluid communication with the refrigerant pipeline 4, the fluid inlet end of the refrigerant pipeline 4 extends out of the thermostat 0, and the refrigerant in the refrigerant pipeline 4 is low-temperature anhydrous alcohol at-28℃; in the steel barrel 15: the space between the water bag loading rubber cylinder 1 and the freezing pipe 16, and the space between the freezing pipes 16 are filled with soil 18; the freezing pipes 16 are distributed circumferentially along the bottom wall of the steel barrel 15, so that the surrounding soil of the freezing pipes 16 is frozen to form a frozen curtain 2; the middle part of the semi-cylindrical segment model is tightly attached to the frozen curtain 2; the thickness of the frozen wall of the frozen curtain 2 is converted according to the similarity criterion to simulate the thickness of the frozen wall in the actual project; a stress deformation monitoring mechanism is installed on the tunnel segment 12. The stress deformation monitoring mechanism includes a strain gauge and a dial indicator; the strain gauge is installed on the upper part of the tunnel segment 12, and the dial indicator is installed inside the tunnel segment 12.

[0027] A water supplement filter core 6 is installed inside the soil 18, one end of the water supplement filter core 6 is adjacent to the tunnel segment 12, and the other end penetrates the bottom wall of the steel barrel 15 and is in fluid communication with the fluid outlet end of the filter core water supplement pipe 3; the fluid inlet end of the filter core water supplement pipe 3 extends out of the thermostat 0 and is connected to a marie bottle to provide pressureless water supplement; the water supplement filter core 6 can provide water supplement for the freezing of the frozen wall of the frozen curtain 2 to simulate the water level of the underground water level on the water supplement effect in the freezing process; a first one-way valve 7 is installed on the water supplement filter core 6 adjacent to the fluid outlet end of the filter core water supplement pipe 3; the water supplement filter core 6 includes a stainless steel pipe and thermal insulation cotton; the thermal insulation cotton is filled in the stainless steel pipe; water permeable holes are formed in the pipe wall of the stainless steel pipe, so that the water adsorbed in the thermal insulation cotton enters the soil through the water permeable holes, achieving the effect of automatic water supplement.

[0028] The tunnel segment 12 is a segment model, which can be converted according to the real segment diameter and thickness, different rectangular openings are selected, and the segment buckle 13 of different sizes is replaced, so as to simulate tunnel segments of different diameters, and then the model test of segments of different diameters can be completed;

[0029] The process of the simulation test by using the tunnel segment stress and deformation simulation test system under the freeze-thaw action of the connecting passage of the embodiment is as follows:

[0030] Before the experiment, the soil body is compacted, the steel barrel 15 is installed in the thermostat 0, and other components are installed according to the tunnel segment stress and deformation simulation test system under the freeze-thaw action of the connecting passage in the embodiment 1, the model of the tunnel segment 12 is tightly connected with the soil body and the tie steel plate, and finally the strain gauges are pasted on the upper part of the segment to monitor the stress, and the dial gauges are installed in the segment to monitor the frost heaving deformation. The low-temperature anhydrous alcohol of-28℃ is introduced into the freezing pipe through the refrigerant pipeline 4 to start freezing. After freezing, the volume of the frozen soil increases, causing the stress and deformation of the tunnel segment 12, and the data of the strain gauges and the dial gauges appear. According to the thin-walled cylinder theory, the stress of the segment is solved. Through the test device, the size of the frost heaving force acting on the segment can be simulated, and then the deformation and stress law of the segment can be mastered.

[0031] Obviously, the above embodiments are only examples for clearly illustrating, and are not limited to the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. All the embodiments do not need to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the patent application claims.

Claims

1. A simulation test system for stress and deformation of a tunnel segment under the frost heaving effect of a connection passage, characterized in that, The utility model provides a kind of tunnel pipe piece stress deformation monitoring device, including thermostat (0), tunnel pipe piece (12), water bag loading rubber cylinder (1), steel drum (15) and freezing pipe (16);One side of the thermostat (0) is provided with rectangular opening, the tunnel pipe piece (12) is clamped in the rectangular opening, and is connected with the cabinet of the thermostat (0);The steel drum (15) is installed in the thermostat (0), and the opening of the steel drum (15) is towards the rectangular opening;The water bag loading rubber cylinder (1) is located in the steel drum (15), and the water bag loading rubber cylinder (1) is closely attached to the inner wall of the steel drum (15);One end of the freezing pipe (16) is towards the opening of the steel drum (15) and is tightly closed with the tunnel pipe piece (12), the other end is out of the bottom wall of the steel drum (15) and is fluidly communicated with refrigerant pipeline (4);In the steel drum (15):the space between the water bag loading rubber cylinder (1) and the freezing pipe (16), and the space between the freezing pipe (16) are filled with soil (18);The freezing pipe (16) is distributed along the bottom wall of the steel drum (15) circumferentially, so that the surrounding soil of the freezing pipe (16) is frozen to form frozen curtain (2);The tunnel pipe piece (12) is provided with stress deformation monitoring mechanism; The tunnel pipe piece (12) is composed of tie steel plate (11) and semicylindrical pipe piece model;The straight end surface of the semicylindrical pipe piece model is fixed on the tie steel plate (11), and the tie steel plate (11) and the semicylindrical pipe piece model enclose a semicylinder;The semicylindrical pipe piece model is composed of two or more than two pipe pieces;The middle part of the semicylindrical pipe piece model is tightly closed with the frozen curtain (2);The semicylindrical pipe piece model is provided with rubber pad (10) at the fixed connection with the tie steel plate (11);One end of pull rod (9) is threadedly connected with the tie steel plate (11) through pull rod nut (19);The other end of the pull rod (9) is threadedly connected with the side wall of the thermostat (0) through fixing bolt (14); The stress deformation monitoring mechanism includes strain gauge and dial indicator;The strain gauge is installed on the upper part of the tunnel pipe piece (12), and the dial indicator is installed inside the tunnel pipe piece (12).

2. The system according to claim 1, wherein The soil (18) is internally provided with water supplementing filter element (6), one end of the water supplementing filter element (6) is adjacent to the tunnel pipe piece (12), and the other end is out of the bottom wall of the steel drum (15) and is fluidly communicated with the fluid outlet end of filter element water supplementing pipe (3);The fluid inlet end of the filter element water supplementing pipe (3) is out of the thermostat (0);The first one-way valve (7) is installed on the water supplementing filter element (6) adjacent to the fluid outlet end of the filter element water supplementing pipe (3).

3. The system according to claim 2, wherein, The water supplementing filter element (6) includes stainless steel pipe and thermal insulation cotton;The thermal insulation cotton is filled in the stainless steel pipe;Water-permeable holes are formed in the pipe wall of the stainless steel pipe.

4. The system according to claim 1, wherein, The fluid inlet end of the refrigerant pipeline (4) is out of the thermostat (0).

5. The system according to claim 1, wherein The refrigerant in the refrigerant pipeline (4) is low-temperature anhydrous ethanol of-18 to-30 DEG C.

6. The system according to claim 1, wherein The water bag loading rubber cylinder (1) is in fluid communication with the fluid outlet end of the water bag water supplement pipe (5), and the fluid inlet end of the water bag water supplement pipe (5) extends out of the thermostat (0); a second one-way valve (8) is installed on the water bag water supplement pipe (5) adjacent to the water bag loading rubber cylinder (1).

7. The system according to claim 1, wherein, The tunnel segment (12) is clamped in the rectangular opening through a segment buckle (13).

8. A method for simulating stress and deformation of a tunnel segment under the effect of frost heaving of a connection passage, characterized in that, The simulation test is performed by using the simulation test system for stress and deformation simulation of tunnel segment under the frost heaving action of the communication passage according to any one of claims 1-7.

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