Model test device and test method for simulating excavation process of water-rich parallel tunnel

Abstract

The invention discloses a model test device and test method for simulating a water-rich parallel tunnel excavation process. The model test device comprises a seepage model system, an underground water system, a rainfall simulation system and a data monitoring system, the seepage model system comprises a box body, a transparent area positioned on the surface of the box body, and a water-permeable bottom plate and two water-permeable side plates which are positioned in the box body; the transparent area is provided with two parallel tunnel holes and a breast board; the underground water system is used for supplying water to the seepage cavity; the rainfall simulation system is used for simulating a rainfall environment at the top of the box body; the data monitoring system comprises a CCD camera, a displacement sensor and a pressure sensor; the displacement sensor is used for monitoring the surface displacement of the filler in the box body; and the pressure sensor is used for monitoring the internal pressure of the filler in the box body. The problems that in the prior art, water-rich parallel tunnel water level changes and the alternating excavation whole-process construction process are difficult to reproduce, and research data are difficult to provide for erosion characteristics and failure modes of parallel tunnel surrounding rocks in a water-rich stratum can be solved.

Description

Technical Field

[0001] The invention relates to the field of underground engineering tests, and in particular to a model test device and a test method for simulating a water-rich parallel tunnel excavation process. Background Art

[0002] As the scale of tunnel construction becomes larger and larger, the construction environment of tunnel construction becomes more and more complex. Whether it is tunnel construction in urban areas or in mountainous areas, in order to meet the requirements of design and use functions, the tunnel construction often adopts a double-cavity parallel layout. When parallel tunnels are excavated, the two caverns have a significant impact on each other, and the surrounding rock stress changes more complex. Once the surrounding rock is damaged during the parallel tunnel excavation process, it is very easy to cause serious accidents such as collapse of the arch tops of the tunnels on both sides.

[0003] Parallel tunnels are inevitably affected by groundwater during construction. Water gushing and sand bursting in tunnels are common in the construction of parallel tunnel projects due to groundwater intrusion into the tunnel. Water-rich strata refer to geological structures with high water content and strong permeability in underground rock or soil, which usually show significant groundwater storage characteristics and engineering impacts. At the same time, under water-rich conditions, stratum water is easily affected by surface water, rainfall or recharge from adjacent aquifers, and groundwater levels change significantly, which may form confined water or phreatic layers.

[0004] When parallel tunnels are constructed in water-rich strata, due to poor stratum precipitation, surface or stratum runoff water recharge, rainfall infiltration and other reasons, a large amount of groundwater can easily flow into the parallel tunnels, causing partial or overall collapse of the tunnel surrounding rock, water gushing and sand bursting at the heading face and other accidents. These accidents usually have short warning times and are difficult to control, posing severe challenges to the safe construction of parallel tunnels.

[0005] The deformation and failure problem of parallel tunnels in water-rich strata is a complex three-dimensional problem related to groundwater changes, surrounding rock properties, excavation process and tunnel structural characteristics. The current research results on the stability of parallel tunnels in water-rich conditions mainly come from field observations, theoretical analysis and numerical simulation. Among them, field observations have high implementation costs and observation difficulties. The theoretical analysis method can only provide analytical solutions for some water-rich parallel tunnel projects with simple shapes and simplified boundary conditions, and the analytical results still need to be verified by measured data and model tests. The material parameter values ​​assigned in the numerical simulation process often cannot fully reflect the real mechanical behavior of the surrounding rock of the parallel tunnel in the water-rich strata, and the simulation results also need to be verified by measured data.

[0006] In the research technology of tunnel construction, the technical idea of ​​using model tests has also emerged. Model tests can more realistically reflect the changes in the stress field and displacement field of the surrounding rock of tunnel construction under the premise of satisfying the similarity theory. However, when studying the excavation erosion and destruction process of parallel tunnels in water-rich strata, the existing model test devices and methods cannot fully consider the entire construction process, cannot evaluate the construction impact of parallel tunnels on each other, and cannot effectively evaluate the impact of groundwater level changes and surface runoff on the erosion evolution characteristics of the surrounding rock of parallel tunnels. As a result, the accuracy and breadth of model tests are insufficient, the test efficiency is low, and the test results lack persuasiveness, which is not conducive to the study of the erosion characteristics and failure mode of the surrounding rock of parallel tunnels in water-rich strata under the coupling of convection forces. Summary of the invention

[0007] The present invention provides a model test device and a test method for simulating the excavation process of water-rich parallel tunnels, so as to solve the problems that the prior art is difficult to reproduce the water level changes of water-rich parallel tunnels and the whole process of alternating excavation construction, and is difficult to provide research data for the erosion characteristics and failure modes of the surrounding rocks of parallel tunnels in water-rich strata.

[0008] The present invention is achieved through the following technical solutions: A model test device for simulating the excavation process of a water-rich parallel tunnel, comprising a seepage model system, a groundwater system, a rainfall simulation system and a data monitoring system; The seepage model system comprises a box, a transparent area located on the surface of the box, a permeable bottom plate and two permeable side plates located inside the box, a liquid collecting cavity is provided below the permeable bottom plate, and a seepage cavity is formed between the permeable side plates and the inner wall of the box; the liquid collecting cavity is connected to a drainage device; two parallel tunnel openings are provided on the transparent area, and a retaining plate matching the parallel tunnel openings is also provided, and the retaining plate is detachably connected to the transparent area and / or the box; The groundwater system is used to supply water to the seepage cavity; The rainfall simulation system is used to simulate a rainfall environment on the top of the box; The data monitoring system includes a CCD camera, a displacement sensor and a pressure sensor; the shooting direction of the CCD camera is facing the transparent area; the displacement sensor is used to monitor the surface displacement of the filling in the box; and the pressure sensor is used to monitor the internal pressure of the filling in the box.

[0009] During the research process, the inventor team of this case found that the tunnel construction model test in the existing technology generally only considered the impact of formation water seepage on the tunnel construction process and tunnel safety, and most of them could only simulate the process of tunnel destruction due to the gradual seepage of formation water; in water-rich strata, the impact of formation water on tunnels is not only reflected in the form of gradual seepage. The tunnel construction process in water-rich strata has obvious water level changes, and this water level change will bring more complex and severe working conditions. It is difficult for the existing technology to carry out experimental simulations; and for parallel tunnels in water-rich strata, different excavation schemes (such as simultaneous excavation, alternating excavation, or completing one tunnel before excavating another tunnel) may induce different water level changes, which in turn leads to different complex working conditions. It is also difficult for the existing technology to effectively simulate it and provide effective support for actual engineering construction. In short, it is difficult for the existing technology to reproduce the water level changes and the full process of alternating excavation of water-rich parallel tunnels, and it is difficult to provide effective support for the erosion characteristics and failure mode of the surrounding rock of parallel tunnels in water-rich strata.

[0010] Based on this, the present invention first proposes a model test device for simulating the excavation process of a water-rich parallel tunnel, which includes four parts: a seepage model system, a groundwater system, a rainfall simulation system, and a data monitoring system. The seepage model system includes a box, a permeable bottom plate is located at a low position inside the box, and the area below the permeable bottom plate is a liquid collecting chamber. The water level in the model can be adjusted by a drainage device, thereby more accurately simulating the rise and fall of the groundwater level. The area above the permeable bottom plate and between the two permeable side plates is the test area of ​​the device, which is used to fill the surrounding rock and soil materials to simulate the lithology of the formation. The transparent area is located on the observation surface of the box, which is convenient for the test personnel to observe the changes inside the box with the naked eye, and also convenient for the CCD camera in the data monitoring system to capture image information of the test process. Two parallel tunnel openings are reserved on the transparent area. The size, shape and distance between the parallel tunnel openings can be adaptively opened according to the test conditions, and no specific restrictions are made here. Before the test proceeds to the tunnel excavation operation, the parallel tunnel openings are temporarily shielded by retaining plates to avoid overflow of surrounding rock and soil materials filled inside the box and water seepage. The retaining plates can be connected to the box or directly connected to the transparent area. No matter which method is used to temporarily connect the retaining plates, it is necessary to ensure that the parallel tunnel openings have good sealing performance.

[0011] The present application supplies water to the seepage cavity through the groundwater system to simulate the water-rich stratum environment around the parallel tunnel. The water in the seepage cavity can enter the test area through the permeable side plate to simulate the water-rich characteristics of high water content and strong permeability. The present application also has a rainfall simulation system for simulating the rainfall environment on the top of the box, and then the surface runoff can be formed by simulating rainfall, so as to obtain the impact data of surface runoff on the erosion evolution characteristics of the surrounding rock of the parallel tunnel.

[0012] In addition to the CCD camera, the data monitoring system of the present application also includes a displacement sensor and a pressure sensor; the displacement sensor is used to monitor the surface displacement of the filling material in the box, that is, the top displacement of the surrounding rock soil material filled in the test area, so as to obtain the settlement and collapse of the surrounding rock during the excavation of parallel tunnels separately or simultaneously and after the tunnel is formed; the pressure sensor is located inside the surrounding rock soil material and is used to monitor the stress and strain conditions.

[0013] It can be seen that the model test device of the present application can more fully simulate the construction of parallel tunnels in water-rich strata, and fully considers the whole process factors of parallel tunnel construction in water-rich strata, including precipitation operations, alternating excavation processes, groundwater recovery processes and surface runoff processes. It can fully reflect the seepage erosion characteristics and damage modes of surrounding rocks during the excavation of water-rich parallel tunnels, and better restore and simulate the erosion and damage characteristics of surrounding rocks of water-rich parallel tunnels under the combined action of groundwater level changes and excavation unloading, effectively overcoming the shortcomings of the prior art that only considers the simulation of excavation conditions and ignores the simulation of groundwater changes during the test, thereby making the test process more in line with the actual situation and the test results more reliable. In addition, the present application can be used to simulate the construction impact between parallel tunnels, evaluate the safety of parallel tunnels under different excavation schemes, and provide effective support for actual engineering construction.

[0014] Furthermore, it also includes a first partition detachably connected between the two permeable side plates, and a second partition detachably connected in the seepage cavity; the first partition divides the area between the two permeable side plates into two filling parts, and the second partition divides the seepage cavity into two sub-seepage parts; the two filling parts correspond to the two sub-seepage parts one by one; The transparent areas are arranged on the front and rear surfaces of the box body, and the two transparent areas correspond to the two filling parts one by one.

[0015] In this solution, the test area inside the box is divided into two parts, namely two filling parts, by a first partition; and each seepage cavity is divided into two sub-seepage parts by a second partition; thereby, the present application has two complete test spaces, and two working condition simulations can be completed through one test. In specific tests, a single working condition single simulation or dual working condition simultaneous simulation can be carried out according to the test design and engineering construction plan. Compared with the prior art, the influence of secondary filling on the test results during dual working condition simulation is reduced; at the same time, the present solution can also realize the separate control of groundwater changes and excavation processes in each working condition during dual working condition simulation, further improving the efficiency of the model test and the utilization rate of the test equipment, and reducing the cost of the dual working condition test by at least half compared with the prior art.

[0016] It should be noted that in the present solution, the first partition and the second partition are both made of water-impermeable plates, and their respective detachable connection methods are not specifically limited here, but both must meet good sealing requirements.

[0017] Furthermore, the groundwater system includes a first water tank, a water pump and a water inlet pipe connected in sequence, the water inlet pipe is connected to the seepage cavity, and a water inlet valve and a water inlet flow meter are arranged on the water inlet pipe; it also includes a liquid level monitoring device for monitoring the liquid level height in the seepage cavity.

[0018] Water is pumped from the first water tank into the water inlet pipe through a water pump, so that the water flows into the seepage cavity through the water inlet pipe, and the liquid level height in the seepage cavity is determined by a liquid level monitoring device, so as to accurately simulate the groundwater level height and realize accurate simulation of precipitation construction operations and groundwater level recovery processes. The use of water inlet valves and water inlet flowmeters enables this solution to achieve accurate simulation and control of groundwater levels and water injection volumes. Compared with the test methods that are mostly qualitative simulations in the prior art, the control accuracy of test parameters is significantly improved, which is conducive to improving the accuracy of test results.

[0019] Furthermore, the rainfall simulation system includes a sprinkler pipe located above the box body, a second water tank for supplying water to the sprinkler pipe, and a water level control component for driving the second water tank to rise and fall.

[0020] Since this application needs to simulate the surface runoff environment caused by rainfall, a height control component is set to adjust the water head height to obtain rainfall environment simulation results of different degrees, which is more conducive to flexible and accurate simulation of the surface runoff environment caused by rainfall.

[0021] Furthermore, the second water tank is installed on the storage platform, and the water level control component is used to drive the storage platform to rise and fall; the spray pipe and the second water tank are connected by a hose, and a spray pipe valve and a spray pipe flow meter are provided on the spray pipe or the hose; and it also includes a plurality of spray pipe brackets for supporting the spray pipe, and the spray pipe brackets are distributed on the outside of the box.

[0022] In this solution, the height of the spray pipe is kept constant relative to the box body and supported by a number of spray pipe brackets. Therefore, the spray pipe and the second water tank are connected by a hose so that there will be no interference when adjusting the lifting of the storage platform. When the spray pipe valve is closed, the water in the second water tank cannot enter the spray pipe; the spray pipe flow meter is used to monitor the amount of water entering the spray pipe, which is conducive to accurately controlling the precipitation and more accurately simulating the surface runoff.

[0023] Furthermore, the water level control assembly includes a base plate, a threaded column rotatably connected to the base plate, a fixed bracket fixedly connected to the base plate, a chain meshed with the threaded column, and a rotating device for driving the chain to rotate; the fixed bracket movably passes through the storage table, and the threaded column rotates through the storage table via threads or gears; a plurality of longitudinally distributed positioning holes are arranged on the surface of the fixed bracket, and the bottom of the storage table has through holes matching the positioning holes, and also includes a positioning rod matching the positioning hole and the through hole; and also includes a height scale value arranged on the surface of the fixed bracket.

[0024] In this solution, the chain is driven to rotate by a rotating device, and the forward or reverse rotation of the chain drives the threaded column to rotate forward or reverse, thereby driving the storage table to perform lifting and lowering movements. When the storage table is adjusted to the required height, the through hole is aligned with the nearest positioning hole, and then the positioning rod is passed through to achieve temporary fixation. The height scale value on the surface of the fixed bracket allows the user to quickly confirm the height of the storage table, which is beneficial for accurately controlling the water head height. The water level height control component in this solution can realize manual adjustment through a simple structure, avoiding the need for equipment required for air source, hydraulic source or electric power adjustment, which is beneficial for reducing the production and use costs of this application.

[0025] Furthermore, the data monitoring system also includes connecting brackets installed at opposite ends of the top of the box, a slider connected to the connecting bracket along a transverse sliding motion, and a first fixing knob for fixing the slider on the connecting bracket; the sliders on the connecting brackets at opposite ends correspond to each other one by one, and a connecting rod is connected between the two corresponding sliders, and a plurality of displacement sensors are installed on the connecting rod.

[0026] In this solution, connecting brackets are provided at both opposite ends of the top of the box, and corresponding sliders are provided on the connecting brackets at both ends, so that a connecting rod across the top of the box can be provided between the two corresponding sliders, and a large number of displacement sensors are installed on the connecting rod, so as to obtain the top displacement of the surrounding rock and soil materials more fully and completely. At the same time, there are more than one connecting rods, so that the top displacement corresponding to different tunnel depths can be monitored during the parallel tunnel excavation process, so as to collect more sufficient displacement data. In this solution, after the slider is moved into place on the corresponding connecting bracket, it can be temporarily fixed by the first fixing knob.

[0027] Furthermore, the connecting rod is slidably connected to a plurality of displacement meter fixing devices, and two rigid gaskets parallel to each other are arranged on the surface of the displacement meter fixing device, and also includes a horizontal screw rod which passes through one of the rigid gaskets through a thread; and also includes a second fixing knob for fixing the displacement meter fixing device on the connecting rod.

[0028] In this solution, each displacement meter fixture is used to install a displacement sensor; specifically, the displacement sensor is set between two rigid gaskets, and the horizontal screw is tightened to firmly abut the displacement sensor between the two rigid gaskets. After the displacement meter fixture is slid on the connecting rod and adjusted into place, it is temporarily fixed by the second fixing knob.

[0029] Based on the model test device in the present application, the present application also provides a model test method for simulating the excavation process of a water-rich parallel tunnel, comprising the following steps: S1. Based on the test plan, the parallel tunnel opening is opened on the transparent area, and a retaining plate is connected at the parallel tunnel opening; S2, filling the seepage cavity with gravel; filling the surrounding rock and soil material layer by layer into the area inside the box and between the two permeable side plates until the surrounding rock and soil material is at the same height as the top of the box, and pre-buried a number of the pressure sensors in the surrounding rock and soil material according to the test plan during the filling process; installing a CCD camera and a displacement sensor, so that the shooting direction of the CCD camera faces the transparent area, and the monitoring end of the displacement sensor faces downward and is indirectly in contact with the top of the surrounding rock and soil material through a metal gasket; S3, injecting water into the seepage cavity through the groundwater system to simulate the initial groundwater level; S4, starting the data monitoring system to collect monitoring data in real time; S5, precipitation construction simulation: open the drainage device until the water level inside the box drops below the tunnel arch bottom position set in the test plan, and then close the drainage device; S6. Parallel tunnel excavation process simulation: dismantling the retaining plate and performing parallel tunnel excavation from the parallel tunnel opening according to the test plan; S7, simulation of groundwater recovery conditions: injecting water into the seepage cavity again through the groundwater system to simulate the groundwater level recovery process until the water level in the seepage cavity is highly stabilized to the recovery water level designed in the test scheme; S8. Surface runoff simulation: The rainfall simulation system is used to simulate rainfall on the top of the box, forming surface runoff on the surface of the surrounding rock and soil material until the surrounding rock around the parallel tunnel is completely eroded and destroyed by the water flow.

[0030] Furthermore, when it is necessary to simulate dual working conditions simultaneously, before filling gravel into the seepage cavity in step S2, a first partition is connected between the two permeable side plates and a second partition is connected in the seepage cavity, so that the first partition divides the area between the two permeable side plates into two filling parts, and the second partition divides the seepage cavity into two sub-seepage parts, so that the two filling parts correspond one to one with the two sub-seepage parts.

[0031] Furthermore, when it is necessary to conduct comparative simulations of different excavation schemes, when parallel tunnel excavation operations are performed in step S6, comparative tests are conducted on the two filling parts using different excavation schemes.

[0032] Compared with the prior art, the present invention has at least the following advantages and beneficial effects: 1. The present invention provides a model test device and test method for simulating the excavation process of water-rich parallel tunnels, which fully considers the whole process factors of parallel tunnel construction in water-rich strata, including dewatering operations, alternating excavation processes, groundwater recovery processes and surface runoff processes, and can comprehensively reflect the seepage erosion characteristics and damage modes of surrounding rocks in the excavation process of water-rich parallel tunnels, better restore and simulate the erosion and damage characteristics of surrounding rocks of water-rich parallel tunnels under the combined effects of groundwater level changes and excavation unloading, and effectively overcomes the deficiency of the prior art that only excavation conditions are considered during the test while groundwater change simulation is ignored, thereby making the test process more in line with the actual situation and the test results more reliable.

[0033] 2. The model test device and test method of the present invention for simulating the excavation process of water-rich parallel tunnels can be used to simulate the construction impact between parallel tunnels, evaluate the safety of parallel tunnels under different excavation schemes, and provide effective support for actual engineering construction.

[0034] 3. The present invention provides a model test device and test method for simulating the excavation process of a water-rich parallel tunnel. In a specific test, a single simulation of a single working condition or a simultaneous simulation of two working conditions can be performed according to the test design and the engineering construction plan. Compared with the prior art, the influence of secondary filling on the test results during the dual working condition simulation is reduced.

[0035] 4. The present invention provides a model test device and test method for simulating the excavation process of a water-rich parallel tunnel, which can realize the separate control of groundwater changes and excavation processes in each working condition during dual-condition simulation, further improving the efficiency of the model test and the utilization rate of the test device, and reducing the cost of the dual-condition test by at least half compared with the prior art.

[0036] 5. The model test device and test method of the present invention for simulating the excavation process of a water-rich parallel tunnel can realize accurate simulation and control of groundwater level, stratum water injection volume, and runoff volume. Compared with the test methods of the prior art which are mostly qualitative simulation, the control accuracy of the test parameters is significantly improved, which is beneficial to improving the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings: Figure 1 It is a structural schematic diagram of a specific embodiment of the present invention; Figure 2 It is a structural schematic diagram of a box body in a specific embodiment of the present invention; Figure 3 It is a schematic diagram of the structure of the water-permeable side plate in a specific embodiment of the present invention; Figure 4 It is a schematic structural diagram of a water-permeable bottom plate in a specific embodiment of the present invention; Figure 5 It is a structural schematic diagram of a slider in a specific embodiment of the present invention; Figure 6 It is a structural schematic diagram of a displacement meter fixing device in a specific embodiment of the present invention; Figure 7 It is a structural schematic diagram of a rainfall simulation system in a specific embodiment of the present invention; Figure 8 It is a side view of a water level control assembly in a specific embodiment of the present invention.

[0038] Marks and corresponding parts names in the attached drawings: 1-box, 2-transparent area, 3-parallel tunnel opening, 4-permeable side plate, 5-permeable bottom plate, 6-partition slot, 7-first partition, 8-second partition, 9-connecting bracket, 10-slider, 11-first fixing knob, 12-connecting rod, 13-displacement meter fixing device, 14-rigid gasket, 15-horizontal screw, 16-second fixing knob, 17-liquid level monitoring device, 18-drainage device, 19-bottom plate, 20-rotating device bracket , 21-rotating device, 22-chain, 23-threaded column, 24-fixed bracket, 25-storage table, 26-positioning rod, 27-second water tank, 28-spray pipe bracket, 29-spray pipe, 30-spray pipe valve, 31-spray pipe flow meter, 32-first water tank, 33-water pump, 34-water inlet pipe, 35-water inlet valve, 36-water inlet flow meter, 37-CCD camera, 38-static strain acquisition system, 39-computer. DETAILED DESCRIPTION

[0039] In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the examples and the accompanying drawings. The schematic embodiments of the present invention and the description thereof are only used to explain the present invention and are not intended to limit the present invention. In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application.

[0040] Example 1

[0041] like Figures 1 to 4 A model test device for simulating the excavation process of a water-rich parallel tunnel is shown, comprising a seepage model system, a groundwater system, a rainfall simulation system and a data monitoring system; The seepage model system includes a box body 1, a transparent area 2 located on the surface of the box body 1, a permeable bottom plate 5 and two permeable side plates 4 located inside the box body 1, a liquid collecting chamber is provided below the permeable bottom plate 5, and a seepage chamber is formed between the permeable side plates 4 and the inner wall of the box body 1; the liquid collecting chamber is connected to a drainage device 18; two parallel tunnel openings 3 are arranged on the transparent area 2, and also include a retaining plate matching the parallel tunnel openings 3, and the retaining plate is detachably connected to the transparent area 2 and / or the box body 1.

[0042] In this embodiment, the box body 1 is 1600mm long, 1300mm high, and 600mm wide. The surface of the box body 1 is made of high-strength steel plate, and the transparent area 2 is a tempered glass plate. The transparent area 2 and the surface of the box body 1 are sealed by waterproof sealant. A water-permeable bottom plate 5 is welded at the lower end of the box body 1. Water-permeable side plates 4 are welded above the water-permeable bottom plate 5 and on both sides of the box body 1, so that the left and right sides of the box body are separated into a seepage cavity with a width of 200mm and a height of 1300mm. In this embodiment, the height of the seepage cavity is 100mm. There are a number of water-permeable holes evenly distributed on the surface of the water-permeable side plate 4 and the water-permeable bottom plate 5; the drainage device 18 is a drainage valve.

[0043] The groundwater system is used to supply water to the seepage cavity; The rainfall simulation system is used to simulate a rainfall environment on the top of the box 1 .

[0044] This embodiment also includes a first partition plate 7 detachably connected between the two permeable side plates 4, and a second partition plate 8 detachably connected in the seepage cavity; the first partition plate 7 divides the area between the two permeable side plates 4 into two filling parts, and the second partition plate 8 divides the seepage cavity into two sub-seepage parts; the two filling parts correspond one-to-one to the two sub-seepage parts; the front and rear surfaces of the box body 1 are both provided with the transparent areas 2, and the two transparent areas 2 correspond one-to-one to the two filling parts respectively.

[0045] In this embodiment, Figure 3 and Figure 4As shown, a partition slot 6 is provided in the middle of the permeable side plate 4 and the permeable bottom plate 5, for temporarily installing the corresponding first partition 7 or second partition 8. In a specific test, the first partition 7 or the second partition 8 can be taken out, and a parallel tunnel excavation process model of a single working condition can be carried out; the first partition 7 or the second partition 8 can also be sealed and installed (such as applying waterproof glue around), and then excavation is carried out from the front and back sides of the box respectively, and a parallel tunnel excavation test of multiple working conditions is carried out at the same time.

[0046] The groundwater system includes a first water tank 32, a water pump 33 and a water inlet pipe 34 connected in sequence, the water inlet pipe 34 is connected to the seepage cavity, and a water inlet valve 35 and a water inlet flow meter 36 are arranged on the water inlet pipe 34; and also includes a liquid level monitoring device 17 for monitoring the liquid level in the seepage cavity. The liquid level monitoring device 17 in this embodiment is a liquid level pipe connected to the seepage cavity.

[0047] In this embodiment, tap water is stored in the first water tank 32 for supplying water to the interior of the box, thereby simulating the underground water-rich environment of the tunnel rock and soil. The water inlet end of the water pump 33 is connected to the first water tank 32, and the water outlet end is connected to the water inlet pipe 34. The water inlet pipe 34 is divided into two branches, which are respectively connected to the front and rear spaces of the seepage cavity. Each branch is equipped with an inlet valve 35 and an inlet flow meter 36. The water pump 33 can pump the extracted tap water into the seepage cavities on both sides through the inlet pipe 34. Since the seepage cavities are provided on both sides of the box 1 in this embodiment, a groundwater system is provided on each side of the box 1.

[0048] The data monitoring system includes a CCD camera 37, a displacement sensor and a pressure sensor; the shooting direction of the CCD camera 37 is facing the transparent area 2; the displacement sensor is used to monitor the surface displacement of the filling in the box body 1; the pressure sensor is used to monitor the internal pressure of the filling in the box body 1.

[0049] In this embodiment, the data monitoring system also includes connecting brackets 9 installed at opposite ends of the top of the box body 1, a slider 10 connected to the connecting bracket 9 along a transverse sliding motion, and a first fixing knob 11 for fixing the slider 10 on the connecting bracket 9; the sliders 10 on the connecting brackets 9 at opposite ends correspond to each other one by one, and a connecting rod 12 is connected between the two corresponding sliders 10, and a plurality of displacement sensors are installed on the connecting rod 12.

[0050] The connecting bracket 9 in this embodiment is a stainless steel bracket, which is fixedly installed on the upper part of the box body 1. A single connecting bracket 9 consists of two vertical rods and a smooth round cross bar; the slider 10 is made of aluminum alloy, which can slide freely along the smooth round cross bar of the connecting bracket 9. The slider 10 can be fixed by the first fixing knob 11. A threaded hole is reserved on the upper part of the slider 10 for connecting the connecting rod 12.

[0051] The connecting rod 12 is an aluminum alloy round rod, on which a plurality of displacement meter fixing devices 13 are slidably connected. Two mutually parallel rigid gaskets 14 are arranged on the surface of the displacement meter fixing device 13, and it also includes a horizontal screw rod 15 that penetrates one of the rigid gaskets 14 through a thread; it also includes a second fixing knob 16 for fixing the displacement meter fixing device 13 on the connecting rod 12.

[0052] The rigid gasket 14 in this embodiment is made of metal material; the displacement sensor in this embodiment can be a displacement meter in the prior art. When in use, the displacement meter is placed between the two rigid gaskets 14, and the horizontal screw 15 is tightened to fix the displacement meter to prevent the displacement meter from loosening and causing incorrect monitoring data. The displacement meter fixing device 13 is installed on the connecting rod 12 through a circular hole on one side, and the displacement meter fixing device 13 is fixed to the connecting rod 12 by rotating the second fixing knob 16.

[0053] The data monitoring system in this embodiment also includes a static strain acquisition system 38 and a computer 39; the static strain acquisition system 38 is used to collect monitoring data of displacement sensors, pressure sensors, etc. during the test. The computer 39 is used to control the CCD camera 37 and the static strain acquisition system 38 to run and display and / or store monitoring data in real time.

[0054] This embodiment can realize the simulation of the whole process factors of parallel tunnel construction in water-rich strata, including dewatering operations, alternating excavation processes, groundwater recovery and surface runoff processes. It can better restore the construction environment of water-rich parallel tunnels under the combined effects of groundwater level changes and excavation unloading, and can realize multi-condition water-rich parallel tunnel excavation simulation through a set of devices.

[0055] Example 2

[0056] A model test device simulating the excavation process of water-rich parallel tunnels, based on Example 1, as Figures 1 to 8 As shown, the rainfall simulation system includes a spray pipe 29 located above the box body 1, a second water tank 27 for supplying water to the spray pipe 29, and a water level control component for driving the second water tank 27 to rise and fall.

[0057] The second water tank 27 is installed on the storage platform 25, and the water level control component is used to drive the storage platform 25 to rise and fall; the spray pipe 29 and the second water tank 27 are connected by a hose, and a spray pipe valve 30 and a spray pipe flow meter 31 are set on the spray pipe 29 or the hose; it also includes a plurality of spray pipe brackets 28 for supporting the spray pipe 29, and the spray pipe brackets 28 are distributed on the outside of the box body 1.

[0058] The water level control assembly includes a base plate 19, a threaded column 23 rotatably connected to the base plate 19, a fixed bracket 24 fixedly connected to the base plate 19, a chain 22 meshed with the threaded column 23, and a rotating device 21 for driving the chain 22 to rotate; the fixed bracket 24 moves through the storage platform 25, and the threaded column 23 rotates through the storage platform 25 via threads or gears; a plurality of longitudinally distributed positioning holes are arranged on the surface of the fixed bracket 24, and the bottom of the storage platform 25 has a through hole matching the positioning hole, and also includes a positioning rod 26 matching the positioning hole and the through hole; and also includes a height scale value arranged on the surface of the fixed bracket 24.

[0059] In this embodiment, a rotating device bracket 20 is bolted to the base plate 19, and a rotating device 21 is installed on the rotating device bracket 20; the upper end of the rotating device 21 is a hand-turned round handle, and a sprocket is installed at the lower end; one end of the chain 22 is meshed on the sprocket, and the other end is connected to the gear on the threaded column 23, and the chain 22 can be driven to rotate by the hand-turned round handle. The lower end of the threaded column 23 is connected to the base plate 19 through a bearing, and the upper end is connected to the fixed bracket 24 through a bearing; when the chain 22 rotates, the threaded column 23 can be driven to rotate. At the same time, the threaded column 23 passes through the hole in the storage platform 25 and cooperates with the storage platform 25 through a thread. When the threaded column 23 rotates clockwise or counterclockwise, the storage platform 25 can be raised or lowered.

[0060] The fixing bracket 24 in this embodiment is in an inverted L-shape, and the lower part is connected to the bottom plate 19 by bolts.

[0061] In this embodiment, a through long slot is formed in the middle of the storage platform 25 along the thickness direction, and the fixing bracket 24 movably passes through the through long slot.

[0062] In this embodiment, four spray pipe brackets 28 are respectively placed around the box body 1, and the height is slightly higher than the top surface of the box body 1. The spray pipe 29 is installed on the spray pipe bracket 28, one end of the spray pipe 29 is connected to the bottom of the second water tank 27 through a hose, and a spray pipe valve 30 and a spray pipe flow meter 31 are connected to the inlet end of the spray pipe 29. The spray pipe 29 extends to the top of the box body 1 and has a number of evenly distributed spray holes. Because the first partition 7 divides the inside of the box body 1 into two parts, two sets of independently controllable spray pipes 29 are set in this embodiment.

[0063] Example 3

[0064] A model test method for simulating the excavation process of water-rich parallel tunnels is based on Figures 1 to 8 The experimental device shown is implemented, and the specific steps include: S1. Based on the test plan, the parallel tunnel opening 3 is opened on the transparent area 2, and a retaining plate is connected at the parallel tunnel opening 3.

[0065] This embodiment relies on the actual engineering background and test purpose to determine the data such as the burial depth, cross-sectional dimensions, relative position relationship, excavation conditions, groundwater level and surface runoff of the test parallel tunnels, so as to determine the opening parameters of the two parallel tunnel openings 3 on the transparent area 2 according to the test plan; then the corresponding openings are made and equipped with matching retaining plates.

[0066] S2. Decide whether to install the first partition 7 and the second partition 8 according to the excavation conditions: for a single-condition excavation plan, the first partition 7 and the second partition 8 may not be installed; for a dual-condition excavation plan, install the first partition 7 and the second partition 8, so as to divide the box body and the seepage cavity into two independent spaces along the width direction, and each space can be subjected to a separate excavation condition simulation. After the first partition 7 and the second partition 8 are installed in place, sealant is applied on all sides for waterproofing.

[0067] According to the test plan, sealant is applied around the transparent area 2 for waterproofing, and the retaining plate is fixed with waterproof glue at the parallel tunnel opening 3.

[0068] Afterwards, the seepage cavity is filled with gravel; the surrounding rock and soil material is filled layer by layer into the area inside the box 1 and between the two permeable side plates 4 until the surrounding rock and soil material is at the same height as the top of the box 1. During the filling process, a number of the pressure sensors or stress sensors are pre-buried in the surrounding rock and soil material according to the test plan; The CCD camera 37 is installed so that the shooting direction of the CCD camera 37 faces the transparent area 2 .

[0069] Install the displacement sensor so that the monitoring end of the displacement sensor faces downward and is in indirect contact with the top of the surrounding rock and soil material through a metal gasket; specifically: Two sliders 10 are respectively installed on the connecting brackets 9 on both sides, and two connecting rods 12 are horizontally installed on the sliders 10 on both sides. The sliders 10 are moved so that the two connecting rods 12 are respectively located in the middle position above the surrounding rock and soil materials in the front and rear spaces of the box body. Nine displacement meter fixtures 13 are installed on each of the connecting rods 12. The displacement meter is placed between two rigid gaskets 14 on each displacement meter fixture 13. At the same time, the horizontal screw 15 is tightened to fix the displacement meter so that the measuring end of the displacement meter faces downward. After the displacement meter is installed, a thin metal gasket needs to be placed at the position where the lower end (i.e., the measuring end) of each displacement meter contacts the surrounding rock and soil material to prevent the lower end of the displacement meter from being inserted into the surrounding rock and soil material and affecting the displacement monitoring accuracy.

[0070] S3, injecting water into the seepage cavity through the groundwater system to simulate the initial groundwater level; specifically: The water pumps 33 and water inlet valves 35 of the two groundwater systems are turned on. The water pumps 33 extract the water in the first water tank 32 and inject water into the front and rear spaces of the seepage cavity through the water inlet pipe 34. The water volume injected into the front and rear spaces of the seepage cavity is recorded by the water inlet flowmeter 36. The water level change of the corresponding liquid level monitoring device 17 is observed. When the water level in the front and rear seepage cavities reaches the design water level height corresponding to the respective working conditions for the first time, the corresponding water inlet valves 35 and water pumps 33 are closed in turn and left to stand. During the standing process, the water in the seepage cavity will penetrate into the surrounding rock and soil material through the permeable side plate 4. When the water level in the seepage cavity drops, the corresponding water pumps 33 and water inlet valves 35 need to be opened and closed repeatedly until the water level in each seepage cavity is stabilized to the design water level of the working condition, and the water injection is stopped to complete the simulation of the initial groundwater level of each working condition. During the entire water injection stage mentioned above, if leakage occurs around the retaining plate at the parallel tunnel opening 3 on the transparent area 2, waterproof glue needs to be applied in time.

[0071] S4, start the data monitoring system to collect monitoring data in real time; specifically: The displacement sensor and the pressure sensor are connected to the static strain acquisition system 38 and the computer 39 , and the initial data is acquired and displayed by the computer 39 , and the CCD camera 37 is turned on.

[0072] S5, precipitation construction simulation: open the drainage device 18 until the water level inside the box 1 drops below the tunnel arch bottom position set in the test plan, and then close the drainage device 18; specifically: The drainage device 18 is turned on, and the water in the surrounding rock soil material flows out through the liquid collecting cavity and the drainage device 18, simulating the surrounding rock dewatering process before tunnel excavation. The displacement and pressure change process is recorded by the computer 39, and the overall deformation of the surrounding rock is recorded by the CCD camera 37. During the dewatering process, the water level change is observed by the liquid level monitoring device 17 to determine the water level drop in the two seepage cavities. When the water level drops below the tunnel arch bottom position, the drainage device 18 is closed to complete the pre-construction dewatering construction operation simulation.

[0073] S6, parallel tunnel excavation process simulation: the retaining plate at the parallel tunnel opening 3 is removed, and the parallel tunnel excavation simulation is performed by manual excavation according to the designed excavation plan. The excavation plan can be simultaneous excavation, alternating excavation, or completing one tunnel before excavating another tunnel, etc. During the parallel tunnel excavation process, the displacement and pressure changes are recorded in real time by the computer 39, and the overall deformation of the surrounding rock is recorded by the CCD camera 37.

[0074] S7. Simulation of groundwater recovery conditions; specifically: After the excavation of the parallel tunnel is completed, water is injected into the seepage cavity again to simulate the process of groundwater level recovery after construction; the water pumps 33 and water inlet valves 35 of the two groundwater systems are turned on to inject water into the seepage cavity. During the water injection process, the water volume injected into the front and rear parts of the seepage cavity is recorded by the water inlet flowmeter 36 respectively, and the water level change is observed by the liquid level monitoring device 17 until the water level height stabilizes to the working condition design water level, and then the water pump 33 and the water inlet valve 35 are turned off to stop the water injection; during the process of groundwater recovery, the displacement meter and pressure gauge data changes are recorded by the computer 39, and the deformation and damage of the rock around the parallel tunnel hole is recorded by the CCD camera 37.

[0075] S8. Surface runoff simulation; specific: Remove the two positioning rods 26 on the water level control assembly, manually rotate the rotating device 21 to drive the storage platform 25 to rise and fall along the fixed bracket 24, read the height scale value on the fixed bracket 24, and when the second water tank 27 rises to the predetermined water head height, pass the positioning rod 26 through the corresponding positioning hole and through hole to temporarily position the storage platform 25 on the fixed bracket 24, fill the second water tank 27 with water, open the spray pipe valve 30, and spray water to the upper part of the soil in the box through the spray pipe 29 to simulate the surface runoff generated by rainfall. At the same time, the rainfall is recorded through the spray pipe flowmeter 31, and the displacement and pressure changes are recorded through the computer 39 during the surface runoff stage. The deformation and damage of the rock around the parallel tunnel hole are recorded through the CCD camera 37; after the surrounding rock of the parallel tunnel is completely destroyed by water erosion, the spray pipe valve 30 is closed and the data monitoring system is turned off.

[0076] It can be seen that the test method of this embodiment includes dewatering operations, excavation, groundwater recovery process and surface runoff process, which can comprehensively reflect the seepage erosion characteristics and failure modes of the surrounding rock during the excavation of water-rich parallel tunnels, and better restore and simulate the erosion and failure characteristics of the surrounding rock of water-rich parallel tunnels under the combined action of groundwater level changes and excavation unloading, making the test process more in line with the actual situation and the test results more reliable.

[0077] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0078] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, the term "connected" used in this article can be directly connected or indirectly connected via other components without special explanation.

Claims

1. A model test device for simulating the excavation process of a water-rich parallel tunnel, characterized in that: Including seepage model system, groundwater system, rainfall simulation system and data monitoring system; The seepage model system comprises a box (1), a transparent area (2) located on the surface of the box (1), a permeable bottom plate (5) located inside the box (1), and two permeable side plates (4), wherein a liquid collecting chamber is provided below the permeable bottom plate (5), and a seepage chamber is formed between the permeable side plates (4) and the inner wall of the box (1); the liquid collecting chamber is connected to a drainage device (18); two parallel tunnel openings (3) are provided on the transparent area (2), and a retaining plate matching the parallel tunnel openings (3) is also included, and the retaining plate is detachably connected to the transparent area (2) and / or the box (1); The groundwater system is used to supply water to the seepage cavity; The rainfall simulation system is used to simulate a rainfall environment on the top of the box (1); The data monitoring system comprises a CCD camera (37), a displacement sensor and a pressure sensor; the shooting direction of the CCD camera (37) is facing the transparent area (2); the displacement sensor is used to monitor the surface displacement of the filling material in the box body (1); and the pressure sensor is used to monitor the internal pressure of the filling material in the box body (1).

2. A model test device for simulating the excavation process of a water-rich parallel tunnel according to claim 1, characterized in that: It also comprises a first partition plate (7) detachably connected between the two water-permeable side plates (4), and a second partition plate (8) detachably connected in the seepage cavity; the first partition plate (7) divides the area between the two water-permeable side plates (4) into two filling parts, and the second partition plate (8) divides the seepage cavity into two sub-seepage parts; the two filling parts correspond to the two sub-seepage parts in a one-to-one manner; The transparent areas (2) are provided on the front and rear surfaces of the box body (1), and the two transparent areas (2) correspond to the two filling parts respectively.

3. A model test device for simulating the excavation process of water-rich parallel tunnels according to claim 1, characterized in that: The groundwater system comprises a first water tank (32), a water pump (33) and a water inlet pipe (34) which are connected in sequence, the water inlet pipe (34) being connected to the seepage cavity, and a water inlet valve (35) and a water inlet flow meter (36) being provided on the water inlet pipe (34); and also comprises a liquid level monitoring device (17) for monitoring the liquid level in the seepage cavity.

4. A model test device for simulating the excavation process of water-rich parallel tunnels according to claim 1, characterized in that: The rainfall simulation system comprises a spray pipe (29) located above the box body (1), a second water tank (27) for supplying water to the spray pipe (29), and a water level control component for driving the second water tank (27) to rise and fall.

5. A model test device for simulating the excavation process of water-rich parallel tunnels according to claim 4, characterized in that: The second water tank (27) is installed on the storage platform (25), and the water level control assembly is used to drive the storage platform (25) to rise and fall; the spray pipe (29) and the second water tank (27) are connected via a hose, and a spray pipe valve (30) and a spray pipe flow meter (31) are provided on the spray pipe (29) or the hose; and the system further comprises a plurality of spray pipe brackets (28) for supporting the spray pipe (29), and the spray pipe brackets (28) are distributed on the outside of the box body (1).

6. A model test device for simulating the excavation process of water-rich parallel tunnels according to claim 5, characterized in that: The water level control assembly comprises a base plate (19), a threaded column (23) rotatably connected to the base plate (19), a fixed bracket (24) fixedly connected to the base plate (19), a chain (22) meshed with the threaded column (23), and a rotating device (21) for driving the chain (22) to rotate; the fixed bracket (24) movably passes through the storage platform (25), and the threaded column (23) rotates through the storage platform (25) via threads or gears; a plurality of longitudinally distributed positioning holes are arranged on the surface of the fixed bracket (24), and the bottom of the storage platform (25) has through holes matching the positioning holes, and also comprises positioning rods (26) matching both the positioning holes and the through holes; and also comprises height scale values ​​arranged on the surface of the fixed bracket (24).

7. A model test device for simulating the excavation process of water-rich parallel tunnels according to claim 1, characterized in that: The data monitoring system further comprises connecting brackets (9) mounted at opposite ends of the top of the box body (1), a slider (10) connected to the connecting bracket (9) in a lateral sliding manner, and a first fixing knob (11) for fixing the slider (10) to the connecting bracket (9); the sliders (10) on the connecting brackets (9) at opposite ends correspond to each other, a connecting rod (12) is connected between the two corresponding sliders (10), and a plurality of displacement sensors are mounted on the connecting rod (12).

8. A model test device for simulating the excavation process of water-rich parallel tunnels according to claim 7, characterized in that: The connecting rod (12) is slidably connected to a plurality of displacement meter fixing devices (13), and the surface of the displacement meter fixing device (13) is provided with two mutually parallel rigid gaskets (14), and also includes a horizontal screw rod (15) that penetrates one of the rigid gaskets (14) through a thread; and also includes a second fixing knob (16) for fixing the displacement meter fixing device (13) on the connecting rod (12).

9. A test method based on a model test device for simulating the excavation process of a water-rich parallel tunnel according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Based on the test plan, the parallel tunnel opening (3) is opened on the transparent area (2), and a retaining plate is connected at the parallel tunnel opening (3); S2, filling the seepage cavity with crushed stone; filling the surrounding rock and soil material layer by layer into the area inside the box (1) and between the two permeable side plates (4) until the surrounding rock and soil material is at the same height as the top of the box (1), and during the filling process, pre-embed a number of the pressure sensors in the surrounding rock and soil material according to the test plan; installing a CCD camera (37) and a displacement sensor, so that the shooting direction of the CCD camera (37) faces the transparent area (2), and the monitoring end of the displacement sensor faces downward and is in indirect contact with the top of the surrounding rock and soil material through a metal gasket; S3, injecting water into the seepage cavity through the groundwater system to simulate the initial groundwater level; S4, starting the data monitoring system to collect monitoring data in real time; S5, dewatering construction simulation: opening the drainage device (18) until the water level inside the box (1) drops below the tunnel arch bottom position set in the test plan, and closing the drainage device (18); S6. Parallel tunnel excavation process simulation: dismantling the retaining plate and performing parallel tunnel excavation from the parallel tunnel opening according to the test plan; S7, simulation of groundwater recovery conditions: injecting water into the seepage cavity again through the groundwater system to simulate the groundwater level recovery process until the water level in the seepage cavity is highly stabilized to the recovery water level designed in the test scheme; S8, surface runoff simulation: The rainfall simulation system is used to simulate rainfall on the top of the box (1), so that surface runoff is formed on the surface of the surrounding rock and soil material until the surrounding rock around the parallel tunnel is completely eroded and destroyed by the water flow.

10. The test method according to claim 9, characterized in that: Before filling the seepage cavity with gravel in step S2, a first partition plate (7) is connected between the two permeable side plates (4), and a second partition plate (8) is connected in the seepage cavity, so that the first partition plate (7) divides the area between the two permeable side plates (4) into two filling parts, and the second partition plate (8) divides the seepage cavity into two sub-seepage parts, so that the two filling parts correspond to the two sub-seepage parts one by one; when parallel tunnel excavation is carried out in step S6, a comparative test is carried out on the two filling parts using different excavation schemes.

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