Model test device and method for simulating the influence of karst cave filling loss on a tunnel

Abstract

The application discloses a model test device and method for simulating the influence of karst cave filling flow loss on a tunnel, and has the structure that a tunnel contour is reserved on a front transparent plate of a transparent model test box to install a tunnel model; a water inlet pipe is arranged on the top of the model test box, and the pipe opening extends to the bottom; a sand discharge hole is arranged on the left side of the model test box; a plurality of rib plates are arranged outside the model test box; a lining model is arranged on the inner side of the tunnel model, a grouting ring is arranged on the outer side of the tunnel model, a karst cave model is arranged outside the grouting ring, and the karst cave model is filled with fillings; the model test device can quantitatively study the influence of large karst cave filling flow loss on a tunnel under the action of underground water, can simulate the whole process of karst cave filling flow loss, and can study the mechanical properties of the tunnel. The model test device is simple, easy to use and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of tunnel and underground engineering testing, and particularly relates to a model test device and method for simulating the impact of karst cave filling material loss on tunnels. Background Technology

[0002] Karst phenomena are widespread in my country, occurring in many regions, particularly prominent in the southwest. The presence of karst landforms poses significant inconvenience and threats to tunnel construction and operation. Under the influence of surface and groundwater, large karst caves frequently experience water inrushes, collapses, and other accidents. Furthermore, the karst infill material around tunnels may be lost due to groundwater flow, causing substantial damage and economic losses to tunnel construction and operation. The loss of karst infill material alters the stress field around the tunnel during construction, and the lost karst cavities are at risk of collapse. Under the influence of karst water, the tunnel lining structure also directly bears the water pressure and faces the risk of collapse of the karst cavities behind it. Therefore, research on the loss of infill material in large karst caves is of great significance.

[0003] Current research on the impact of material loss from general types of karst cave filling on tunnels is relatively common, but there are few quantitative studies on model tests of material loss from large-scale karst cave filling. This invention uses indoor model tests to simulate the impact of material loss from large-scale karst filling on tunnel lining under different water heads, as well as the impact of the degree of loss under the same water head. Summary of the Invention

[0004] In order to simulate the entire process of material loss from karst cave filling and to study the mechanical properties of tunnel lining, this invention provides a model test device and method for simulating the impact of material loss from karst cave filling on tunnels.

[0005] The present invention provides a model test device for simulating the impact of karst cave filling material loss on tunnels, specifically comprising: a transparent model test box with a tunnel outline reserved on the front transparent plate for installing the tunnel model; a water inlet pipe provided at the top of the model test box, with the inlet pipe extending to the bottom; a sand discharge hole provided on the left side of the model test box; and several ribs provided on the outside of the model test box.

[0006] A lining model is set inside the tunnel model, and a grouting ring is set on the outside of the tunnel model. The cavity model is set outside the grouting ring and filled with filling material.

[0007] Furthermore, the transparent model test chamber is 120cm long, 30cm wide, and 160cm high; the sand drainage hole has a diameter of 15cm.

[0008] Furthermore, a 10cm rock column was reserved near the sand-draining hole of the model test chamber.

[0009] Furthermore, the boundary of the grouting ring is shaped into a circle with fine wire mesh and padded with gauze, and the shoulder of the fine wire mesh extends 5cm into the soil above the tunnel arch.

[0010] Furthermore, the filling material consists of coarse sand and silt mixed with fine sand, and the surrounding rock of the tunnel model consists of dolomite and limestone.

[0011] Furthermore, strain gauges, displacement gauges, hydraulic pressure gauges, and earth pressure cells are installed at equal intervals along the longitudinal direction of the tunnel model.

[0012] Furthermore, the lining model uses gypsum plaster containing wire mesh as the lining material.

[0013] The present invention provides a model test method for simulating the impact of karst cave filling material loss on tunnels, comprising the following steps:

[0014] Step 1: Select similar materials for the surrounding rock, design orthogonal tests to configure similar materials for the surrounding rock, and use physical and mechanical tests to determine the specific gravity, strength, elastic modulus, cohesion, internal friction angle, permeability coefficient and porosity of the similar materials; configure similar materials for the lining, and use physical and mechanical tests to test the specific gravity, strength and elastic modulus of the materials.

[0015] Step 2: Load the surrounding rock similar material into the model test chamber to the designed elevation position of the cavity model.

[0016] Step 3: Arrange the strain gauges, displacement gauges, water pressure gauges and earth pressure cells on the lining model as required, and put in the water inlet pipe.

[0017] Step 4: Use fine wire mesh wrapped with gauze to simulate the cavity model and the boundary of the grouting ring. Place it in the predetermined position in the model test box. Then, fill the cavity model with sand in layers, fill the grouting ring with grouting-like material, and then fill the surrounding rock with surrounding rock-like material to the design height and compact it. Then let it stand for a period of time.

[0018] Step 5: Start simulated excavation and support. Select gypsum as the initial lining material. After setting the excavation advance, apply the initial lining material evenly to the excavation surface. Let it stand for a period of time and test the stress, displacement and earth pressure data. Then carry out the next excavation and support cycle. Repeat the above steps until the excavation and initial support of the tunnel are completed.

[0019] Step 6: Place the precast secondary lining and use a grouting device to inject the primary support material between the primary support and the secondary lining to ensure a tight fit between the primary support and the secondary lining. At the same time, monitor and record the changes in various data.

[0020] Step 7: Open the water inlet pipe and fill the tunnel with water to the preset head above the invert arch. After standing for a period of time, monitor various data and observe the stress condition of the tunnel lining to see if there are any cracks or damages. If so, record them.

[0021] Step 8: Open the sand drainage hole on the side of the model test chamber to allow the filling material to flow out from the sand drainage hole. At the same time, monitor and record the changes in various data to simulate the impact of the entire process of the loss of karst filling material under the same water head on the tunnel.

[0022] Step 9: Refill the soil in layers, repeating steps 7-8 to simulate the impact of fill material loss on the tunnel under different water head conditions.

[0023] The beneficial technical effects of this invention are as follows:

[0024] The model test device of this invention is simple, easy to use, and low in cost. It can simulate the entire process of material loss from karst caverns and study the mechanical properties of tunnels. It can quantitatively study the impact of the loss of filling material from large karst caves on tunnels under the influence of groundwater. Attached Figure Description

[0025] Figure 1 This is a front view of the model test chamber of the present invention;

[0026] Figure 2 This is a side view of the model test chamber of the present invention;

[0027] Figure 3 This is a schematic diagram of the cavity model and tunnel model of the present invention.

[0028] In the diagram: 1. Model test chamber; 2. Water inlet pipe; 3. Rib plate; 4. Tunnel model; 5. Cavity model; 6. Tunnel outline tunnel; 7. Sand discharge tunnel; 8. Grouting ring; 9. Tunnel lining; 10. Filling material. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0030] The present invention provides a model test device for simulating the impact of karst cave filling material loss on tunnels, such as... Figure 1 As shown, specifically: the transparent model test chamber 1 has a pre-reserved tunnel outline 6 on its front transparent plate for mounting the tunnel model 4; a water inlet pipe 2 is installed at the top of the model test chamber 1, with the inlet of the water inlet pipe 2 extending to the bottom. Figure 2 As shown, the sand discharge hole 7 is set on the left side of the model test box 1. Its height can be set according to the specific test conditions. The prefabricated hole is sealed with a sealing strip to prevent water from entering before the test. Several ribs 3 are provided on the outside of the model test box 1 to improve the constraint rigidity.

[0031] like Figure 3 As shown, a lining model 9 is set inside the tunnel model 4, and a grouting ring 8 is set outside the tunnel model 4. The cavity model 5 is set outside the grouting ring 8, and the cavity model 5 is filled with filling material 10.

[0032] Furthermore, the transparent model test chamber 1 is 120cm long, 30cm wide, and 160cm high; the sand drainage hole 7 has a diameter of 15cm.

[0033] Furthermore, a 10cm rock pillar was reserved near the sand cave 7 in the model test box to prevent the cave from collapsing after the filling material is lost.

[0034] Furthermore, the boundary of grouting ring 8 is shaped into a circle with fine wire mesh and padded with gauze to prevent collapse after the filling sand is lost. It does not bear a large load and mainly serves as a facing. The shoulder of the fine wire mesh extends 5cm into the soil above the tunnel arch to make it more stable and play its role.

[0035] Furthermore, the filling material 10 is composed of coarse sand and silt mixed with fine sand, and the surrounding rock of the tunnel model 4 is composed of dolomite and limestone.

[0036] Furthermore, strain gauges, displacement gauges, hydraulic pressure gauges, and earth pressure cells are installed at equal intervals along the longitudinal direction of the tunnel in tunnel model 4. Among them, the earth pressure gauge monitoring sections are set at 10cm, 15cm, and 20cm along the longitudinal direction.

[0037] Furthermore, gypsum plaster containing steel wire mesh was selected as the lining material for lining model 9.

[0038] The present invention provides a model test method for simulating the impact of karst cave filling material loss on tunnels, comprising the following steps:

[0039] Step 1: Select similar materials for the surrounding rock, design orthogonal tests to configure similar materials for the surrounding rock, and use physical and mechanical tests to determine the specific gravity, strength, elastic modulus, cohesion, internal friction angle, permeability coefficient and porosity of the similar materials; configure similar materials for the lining, and use physical and mechanical tests to test the specific gravity, strength and elastic modulus of the materials.

[0040] Step 2: Load the surrounding rock similar material into the model test chamber 1 to the designed elevation position of the cavity model 5.

[0041] Step 3: Arrange the strain gauges, displacement gauges, water pressure gauges and earth pressure cells on the lining model 9 as required, and put in the water inlet pipe 2.

[0042] Step 4: Use fine wire mesh wrapped with gauze to simulate the boundary between the cavity model 5 and the grouting ring 8, place it in the predetermined position in the model test box 1, then fill the cavity model 5 with sand in layers, fill the grouting ring 8 with grouting-like material, and then fill the surrounding rock-like material to the design height and compact it, and then let it stand for a period of time.

[0043] Step 5: Start simulated excavation and support. Select gypsum as the initial lining material. After setting the excavation advance, apply the initial lining material evenly to the excavation surface. Let it stand for a period of time and test the stress, displacement and earth pressure data. Then carry out the next excavation and support cycle. Repeat the above steps until the excavation and initial support of the tunnel are completed.

[0044] Step 6: Place the precast secondary lining and use a grouting device to inject the primary support material between the primary support and the secondary lining to ensure a tight fit between the primary support and the secondary lining. At the same time, monitor and record the changes in various data.

[0045] Step 7: Open the water inlet pipe 2 and inject water to the preset water head above the invert arch. After standing for a period of time, monitor various data and observe the stress condition of the tunnel lining 9 to see if there are any cracks or damages. If so, record them.

[0046] Step 8: Open the sand drainage hole 7 on the side of the model test chamber 1 to allow the filling material 10 to flow out from the sand drainage hole 7. At the same time, monitor and record the changes in various data to simulate the impact of the entire process of the loss of karst filling material under the same water head on the tunnel.

[0047] Step 9: Refill the soil in layers, repeating steps 7-8 to simulate the impact of fill material loss on the tunnel under different water head conditions.

Claims

1. A model test device for simulating the impact of karst cave filling material loss on tunnels, characterized in that, The transparent model test box (1) has a tunnel outline hole (6) reserved on the front transparent plate for installing the tunnel model (4); the model test box (1) has a water inlet pipe (2) at the top, and the water inlet pipe (2) extends to the bottom; the model test box (1) has a sand discharge hole (7) on the left side, and a 10cm rock column is reserved near the sand discharge hole (7); the model test box (1) has several ribs (3) on the outside. The tunnel model (4) is provided with a lining model (9) inside, and a grouting ring (8) is provided on the outside of the tunnel model (4). The cavity model (5) is provided outside the grouting ring (8), and the cavity model (5) is filled with filling material (10). The filling material (10) is composed of coarse sand and silt mixed with fine sand, and the surrounding rock of the tunnel model (4) is composed of dolomite and limestone; The tunnel model (4) is equipped with strain gauges, displacement gauges, water pressure gauges and earth pressure cells at equal intervals along the longitudinal direction of the tunnel.

2. The model test device for simulating the impact of karst cave filling material loss on tunnels according to claim 1, characterized in that, The transparent model test chamber (1) is 120cm long, 30cm wide and 160cm high; the sand drainage hole (7) is 15cm in diameter.

3. The model test device for simulating the impact of karst cave filling material loss on tunnels according to claim 1, characterized in that, The boundary of the grouting ring (8) is shaped into a circle with fine wire mesh and padded with gauze. The shoulder of the fine wire mesh extends 5cm into the soil above the tunnel arch.

4. The model test device for simulating the impact of karst cave filling material loss on tunnels according to claim 1, characterized in that, The lining model (9) uses gypsum with steel wire mesh as the lining material.

5. A model test method for simulating the impact of karst cave filling material loss on tunnels, characterized in that, The method using the model test apparatus for simulating the impact of karst cave filling material loss on tunnels as described in claim 1 includes the following steps: Step 1: Select similar materials for the surrounding rock, design orthogonal experiments to configure similar materials for the surrounding rock, and use physical and mechanical tests to determine the specific weight, strength, elastic modulus, cohesion, internal friction angle, permeability coefficient, and porosity of the similar materials; configure similar materials for the lining, and use physical and mechanical tests to test the specific weight, strength, and elastic modulus of the materials. Step 2: Load the surrounding rock similar material into the model test box (1) to the designed elevation position of the cavity model (5); Step 3: Arrange the strain gauges, displacement gauges, water pressure gauges and earth pressure cells on the lining model (9) as required, and put in the water inlet pipe (2); Step 4: Use fine wire mesh wrapped with gauze to simulate the boundary of the cavity model (5) and the grouting ring (8), place it in the predetermined position in the model test box (1), then fill sand in layers in the cavity model (5), fill grouting similar material in the grouting ring (8), then fill surrounding rock similar material to the design height and compact it, and then let it stand for a period of time; Step 5: Start simulated excavation and support. Select gypsum as the initial lining material. After setting the excavation advance, apply the initial lining material evenly to the excavation surface. Let it stand for a period of time and test the stress, displacement and earth pressure data. Then carry out the next excavation and support cycle. Repeat the above steps until the excavation and initial support of the tunnel are completed. Step 6: Place the precast secondary lining and use a grouting device to inject the primary support material between the primary support and the secondary lining to ensure a tight fit between the primary support and the secondary lining. At the same time, monitor and record the changes in various data. Step 7: Open the water inlet pipe (2), inject water to the preset water head above the invert arch, let it stand for a period of time, monitor various data, observe the stress of the tunnel lining and whether there are cracks or damage, if so, record it; Step 8: Open the sand discharge hole (7) on the side of the model test box (1) to allow the filling material (10) to flow out from the sand discharge hole (7). At the same time, monitor and record the changes in various data to simulate the impact of the entire process of the loss of karst filling material under the same water head on the tunnel. Step 9: Refill the soil in layers, repeating steps 7-8 to simulate the impact of fill material loss on the tunnel under different water head conditions.

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