Testing device for simulating mechanical response of adjacent laminated wall induced by foundation pit excavation

Abstract

The invention discloses a test device for simulating the mechanical response of an adjacent laminated wall induced by foundation pit excavation, and the device comprises a model box which is divided into a pressurization region, a water storage region and a soil-rock composite stratum region; the bottoms of the pressurization area and the water storage area are communicated with a first overflowing channel, and second overflowing channels are arranged between the water storage area and the soil-rock composite stratum area at intervals in the height direction; the water level fluctuation control unit comprises a movable device which can lift in a reciprocating manner and is connected to the inner wall of the pressurizing area in a sealing and sliding manner; the rock stratum section simulation system comprises a plurality of rock simulation units arranged at the bottom of a soil-rock composite stratum area and an external control terminal. The rock simulation unit is constructed as a lifting structure so as to adjust the top height under the control of an external control terminal; the flexible elastic interlayer covers the top surface of the rock simulation unit, and the periphery of the flexible elastic interlayer is hermetically connected; the soft elastic interlayer is filled with soil for the model; and the composite wall simulation unit and the foundation pit simulation unit are buried in the soil for the model. The device further comprises a monitoring system used for collecting test data.

Description

Technical Field

[0001] The present invention relates to the technical field of building underground engineering, and particularly relates to a test device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation. Background Technique

[0002] With the rapid advancement of the urbanization process, urban land resources have become increasingly scarce. Developing urban underground space has become an important way to solve traffic congestion, the shortage of infrastructure land, and optimize the urban land structure. Since urban underground space is usually located in the central area of the city, there are a large number of existing buildings (structures) such as high-rise buildings, underground municipal pipelines, urban utility tunnels, urban roads, and elevated roads around it. Therefore, there are relatively high requirements for the structural stability and waterproof performance of underground space. However, in some areas, especially in the coastal and river-adjacent areas of our country, the strata undulate complexly, the foundation bearing strength is low, the groundwater is widely distributed, and there are frequent fluctuations affected by tides and runoff, making the construction of underground space face great challenges. In some projects, the diaphragm wall is combined with the side wall of the underground main structure as a permanent structure to form a composite wall. The composite wall has the advantages of good anti-seepage performance, large structural stiffness, and small deformation, which not only enhances the stability of the underground space structure but also improves the flexibility of underground space organization, effectively alleviating the above-mentioned engineering problems.

[0003] In urban construction projects, especially in the urban central area with a large density of underground and above-ground buildings, the load released during the foundation pit excavation construction is extremely likely to cause disturbances to adjacent buildings (structures) including the underground composite wall, bringing certain structural safety hazards. Therefore, it is necessary to provide a test simulation device that can accurately simulate the mechanical response of the underground composite wall induced by the excavation construction of the adjacent foundation pit under the action of multiple factors such as groundwater level fluctuations and complex strata, providing scientific hardware support for the mechanical research of relevant underground space structures. Summary of the Invention

[0004] The main technical problem to be solved by the present invention is to provide a test simulation device to provide hardware support for accurately simulating the mechanical response of the underground composite wall induced by the excavation construction of the adjacent foundation pit under the action of multiple factors such as groundwater level fluctuations and complex strata.

[0005] To solve the above technical problems, the present invention provides a test device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation, including a model box, a water level fluctuation control unit, a rock stratum section simulation system, a flexible elastic interlayer, model soil, a composite wall simulation unit, and a foundation pit simulation unit;

[0006] At least a pressurized area, a water storage area and a soil-rock composite stratum area are delimited in the model box; the pressurized area and the water storage area are delimited by a first partition board, and the first partition board is provided with a first flow-through channel at the bottom or near the bottom; the water storage area and the soil-rock composite stratum area are delimited by a second partition board, and a plurality of second flow-through channels are arranged at intervals along the height direction on the second partition board;

[0007] The water level fluctuation control unit is arranged in the pressurized area and includes a movable device that moves up and down along the height direction; the movable device is hermetically and slidably connected to the inner wall of the pressurized area;

[0008] The rock section simulation system includes a plurality of rock simulation units arranged at the bottom of the soil-rock composite stratum area and an external control terminal arranged outside the model box; the rock simulation unit is configured as a structure that moves up and down along the height direction; the rock simulation unit is connected to the external control terminal to adjust the top height under the control of the external control terminal;

[0009] The flexible elastic interlayer covers the top surface of the rock simulation unit and is hermetically connected to the inner wall of the soil-rock composite stratum area; the connection position of the flexible elastic interlayer on the second partition board is not higher than the lowest second flow-through channel;

[0010] The soil for the model is filled above the flexible elastic interlayer; the laminated wall simulation unit and the foundation pit simulation unit are buried in the soil for the model; the foundation pit simulation unit includes at least two relatively arranged first diaphragm walls and internal supports; the laminated wall simulation unit includes an underground main structure and at least two second diaphragm walls; the second diaphragm walls are relatively connected to the outer sides of the side walls of the underground main structure;

[0011] A monitoring system is further included for collecting test data.

[0012] In a preferred embodiment, the water level fluctuation control unit further includes a controller and a first connecting rod; the controller is connected to the movable device below through the first connecting rod; the first connecting rod expands and contracts vertically under the drive of the controller to drive the movable device to move up and down.

[0013] In a preferred embodiment, an interaction panel is arranged on the controller for setting parameters of the movable device.

[0014] In a preferred embodiment, a plurality of the rock simulation units are closely laid on the bottom of the soil-rock composite stratum area to form a rock module matrix on the top surface.

[0015] In a preferred embodiment, the rock simulation unit includes a rock module and a height controller; the height controller is configured with a motor and a second connecting rod, and the second connecting rod telescopically moves along the height direction through spiral commutation cooperation with the motor; the rock module is arranged at the top of the second connecting rod; the height controller is connected to the external control terminal.

[0016] In a preferred embodiment, the model box includes a bottom plate, and the bottom plate is made of steel plate; a magnetic base is arranged at the bottom of the rock simulation unit to adsorb on the bottom plate.

[0017] In a preferred embodiment, the top of the water storage area is sealed.

[0018] In a preferred embodiment, the foundation pit simulation unit and the composite wall simulation unit extend along the width direction of the model box.

[0019] In a preferred embodiment, the second flow-through channel is configured as a water passing hole.

[0020] In a preferred embodiment, the second partition plate is provided with a wire mesh at least in the plane area of the second flow-through channel.

[0021] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0022] The device provided by the present invention uses a mechanical water level fluctuation control unit to accurately control the rising and falling amplitude and frequency of the water level in the water storage area. It can not only stably reproduce periodic water level changes such as tidal ebb and flow, but also adjust the fluctuation parameters according to experimental requirements, solving the problems of lag and insufficient accuracy in the traditional water injection and drainage methods. In terms of the simulation of the rock formation section, a modular rock module matrix is adopted, and each rock module is independently adjusted in height through an external control terminal, which can not only quickly construct an uneven rock formation section, but also dynamically adjust the rock formation shape during the test to realize the rapid switching of different geological profiles. Further, both the water level and the rock formation simulation systems of the device adopt digital control, and the operator can accurately control the test conditions through a parameterized interface, making the device have high test operability. In summary, the device can accurately and controllably simulate the influence of complex geological environments on underground structures, providing a flexible and reliable hardware basis for optimizing engineering designs. Description of the Drawings

[0023] Figure 1 It is a vertical sectional view of the test device for simulating the mechanical response of an adjacent composite wall induced by the excavation of a foundation pit in an embodiment of the present invention;

[0024] Figure 2 It is a three-dimensional schematic view of the model box in an embodiment of the present invention;

[0025] Figure 3 A three-dimensional schematic diagram of the second partition in the embodiment of the present invention;

[0026] Figure 4 A three-dimensional schematic diagram of the water level fluctuation control unit in the embodiment of the present invention;

[0027] Figure 5 A top view schematic diagram of the rock module matrix in the embodiment of the present invention;

[0028] Figure 6 A schematic diagram of the rock stratum cross-section simulation system in the embodiment of the present invention (one rock simulation unit is taken);

[0029] Figure 7 A three-dimensional schematic diagram of the underground main structure in the embodiment of the present invention.

[0030] The markings in the figure are: 1 - model box, 101 - pressurized area, 102 - water storage area, 103 - soil-rock composite stratum area, 11 - bottom plate, 12 - side plate, 13 - first partition, 131 - first flow-through channel, 14 - second partition, 141 - water passage hole, 2 - water level fluctuation control unit, 21 - controller, 211 - interaction panel, 22 - first connecting rod, 23 - actuator, 3 - rock stratum cross-section simulation system, 31 - rock simulation unit, 311 - rock module, 312 - height controller, 3121 - second connecting rod, 3122 - magnetic base, 32 - external control terminal, 33 - data line, 4 - high-elastic diaphragm, 5 - model soil, 6 - foundation pit simulation unit, 61 - first diaphragm wall, 62 - internal support member, 7 - composite wall simulation unit, 71 - underground main structure, 711 - floor slab, 712 - support column, 713 - side wall, 72 - second diaphragm wall. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "top / bottom end", 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 construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, terms such as "installation", "provided with", "sheathed / connected", "connection", etc. should be understood in a broad sense. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0034] As Figures 1 to 7 As shown, an experimental device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to an embodiment of the present invention includes a model box 1, a water level fluctuation control unit 2, a rock stratum section simulation system 3, a high-elastic diaphragm 4, model soil 5, a composite wall simulation unit 7, and a foundation pit simulation unit 6. The device studies the influence of underground water level fluctuations and rock stratum undulations on the mechanical properties of the underground composite wall structure during the foundation pit excavation process by simulating different geological conditions and construction conditions.

[0035] As Figure 2As shown, the model box 1 includes a bottom plate 11 and side plates 12 spliced orthogonally, and partitions vertically arranged inside the box. The bottom plate 11 is made of steel plate material to ensure structural stability and meet the bearing requirements; the side plates 12 and partitions are made of high-strength plexiglass material to facilitate visual observation of the internal soil and structure during the test. According to the functional division, the inside of the model box 1 is divided into a water storage area 102, a pressurized area 101, and a soil-rock composite stratum area 103 by several partitions arranged at intervals and parallel to each other along the length direction. In this embodiment, to improve the simulation accuracy, a group of water storage areas 102 and pressurized areas 101 are mirror-symmetrically arranged on both sides of the soil-rock composite stratum area 103 to achieve multi-directional uniform water supply. In this embodiment, the top of the water storage area 102 is sealed. The top of the pressurized area 101 is of an open design to facilitate the installation of the water level fluctuation control system. The soil-rock composite stratum area 103 is the core test area, and the top is completely open for the installation of various components, the filling of the model soil 5, and the simulated excavation of the foundation pit. Specifically, the partition includes a first partition 13 and a second partition 14. The first partition 13 is used to divide the pressurized area 101 and the water storage area 102, and the second partition 14 divides the water storage area 102 and the soil-rock composite stratum area 103. The first partition 13 is configured with a first flow-through channel 131 at the bottom or near the bottom to communicate the pressurized area 101 and the water storage area 102. Specifically, the bottom of the first partition 13 is higher than the bottom plate 11 of the model box 1 to jointly form the first flow-through channel 131 with the bottom plate 11. A number of second flow-through channels are arranged at intervals along the height direction on the second partition 14 to allow the water in the water storage area 102 to penetrate into the soil-rock composite stratum area 103. As Figure 3 shown, in this embodiment, the second flow-through channel is configured as a water passing hole 141. Preferably, the second partition 14 is provided with a screen at least in the plane area of the water passing hole 141 to effectively prevent the soil particles behind from entering the water storage area 102 and causing blockage.

[0036] Before the test starts, water should be injected into the pressurized area 101. Preferably, the amount of water injected is equal to the volume of the water storage area 102, so that when the water level in the pressurized area 101 is lowered to the lowest point, the water storage area 102 is exactly at the full water level. It should be understood that this measurement does not consider the penetration of water at the water passing hole 141. Subsequently, the water level fluctuation control unit 2 is installed in the pressurized area 101. As Figure 1 、 Figure 4As shown in the figure, the water level fluctuation control unit 2 includes a controller 21, a first connecting rod 22 and an actuator 23. The controller 21 is connected to the lower actuator 23 through the first connecting rod 22. The first connecting rod 22 expands and contracts vertically under the drive of the controller 21 to drive the actuator 23 to move up and down. The first connecting rod 22 is one, two or more arranged in parallel. Necessarily, the side of the actuator 23 is slidably and sealingly connected to the inner wall of the pressurized area 101 to meet the airtightness requirements. In this way, when the actuator 23 reciprocates up and down in the height direction under the drive of the controller 21, the water pressure in the pressurized area 101 changes accordingly, pushing the water level in the water storage area 102 to fluctuate periodically. When the water level in the water storage area 102 rises to the height of the water passing hole 141 on the second partition 14, the water body seeps into the soil-rock composite stratum area 103; when the actuator 23 rises and causes the water level in the water storage area 102 to drop, the water body in the soil-rock composite stratum area 103 flows back to the water storage area 102, truly simulating the fluctuation of the groundwater level in the coastal and riverside areas caused by the influence of tides. Preferably, in this embodiment, an interaction panel 211 is provided on the controller 21 to facilitate the precise adjustment of the movement frequency and displacement of the actuator 23 by setting parameters.

[0037] As Figure 1 , Figure 6 shown in the figure, the rock stratum section simulation system 3 includes a number of rock simulation units 31 and an external control terminal 32 arranged outside the model box 1. Similar to the water level fluctuation control unit 2, the rock simulation unit 31 is configured as a structure that moves up and down in the height direction. Specifically, the rock simulation unit 31 includes a rock module 311 and a height controller 312. The height controller 312 is internally provided with a motor and a second connecting rod 3121. The second connecting rod 3121 expands and contracts in the height direction through spiral commutation with the motor. The bottom of the rock module 311 is threadedly connected to the top of the height controller 312, that is, the top of the second connecting rod 3121, and the height is adjusted as the second connecting rod 3121 expands and contracts. Each height controller 312 is connected to the external control terminal 32 through a data line 33 to adjust the height of the rock module 311 under the instruction of the external control terminal 32. In this embodiment, a magnetic base 3122 is configured at the bottom of each height controller 312, which can be quickly adsorbed on the steel bottom plate 11 of the model box 1 to form a stable connection. As Figure 5As shown, a plurality of rock simulation units 31 are closely laid on the bottom plate 11 within the soil-rock composite formation area, forming an independently controllable matrix of rock modules 311 on the top surface. The specific material of the rock module 311 depends on the test requirements. After the rock formation cross-section simulation system 3 is installed, the test personnel input the preset rock formation undulation parameters at the external control terminal 32, and control each group of height controllers 312 to independently adjust their respective top heights, so that the matrix of rock modules 311 presents a three-dimensional shape conforming to the actual geological profile. This design breaks through the limitations of traditional fixed rock formation models and can flexibly simulate complex rock formation structures with different dips and offsets.

[0038] As Figure 1 shown, after the arrangement of the rock formation cross-section simulation system 3 is completed, a flexible elastic isolation layer needs to be covered on its top. In this embodiment, the flexible elastic isolation layer uses a high-elastic diaphragm 4. The edge of the high-elastic diaphragm 4 is closely bonded to the side plate 12 and the second partition 14 of the model box 1, and the bottom completely wraps the undulating surface of the rock module 311 to form a continuous sealing layer. The connection position of the high-elastic diaphragm 4 on the second partition 14 is not higher than the lowest water passing hole 141, which neither blocks the water penetration path nor allows water to enter the rock formation cross-section simulation system 3 and cause damage. The high extensibility of the high-elastic diaphragm 4 enables it to adapt to rock modules 311 of different heights and maintain the conformity and continuity of the water isolation interface.

[0039] During the soil filling stage of the test, according to the layer thickness and compaction degree requirements determined by the test plan, the model soil 5 is filled in layers above the diaphragm. During the soil filling process, the foundation pit simulation unit 6 and the composite wall simulation unit 7 need to be buried synchronously. As Figure 1 shown, the foundation pit simulation unit 6 is arranged within the soil-rock composite formation area 103 and includes at least two first underground diaphragm walls and a number of internal support members 62. The several first underground diaphragm walls are vertically and relatively buried in the model soil 5. Preferably, the underground diaphragm wall extends along the width direction of the model box 1. Preferably, the underground continuous wall is made of acrylic board, concrete thin board or cement thin board. The internal support members 62 are made of organic glass tubes, wooden strips, etc., and are vertically supported between the two first underground diaphragm walls to simulate the lateral support system during the foundation pit excavation. The composite wall simulation unit 7 includes an underground main structure 71 and a second underground diaphragm wall 72. As Figure 7As shown, the underground main structure 71 includes a floor slab 711, support columns 712 and side walls 713 that are orthogonally connected. For technicians in this technical field, the simulation structure of underground buildings is a conventional test component, which will not be described in detail in this article. Preferably, the side wall 713 of the underground main structure 71 extends along the width direction of the model box 1. The second continuous wall is relatively attached to the outside of the side wall 713. In actual engineering, structural measures are adopted between the underground continuous wall and the side wall 713 of the underground main structure 71 to connect them as a composite wall. Therefore, in this device, the second underground continuous wall 72 and the side wall 713 are bonded as a whole by strong glue to simulate the composite wall.

[0040] During the formal test, the model soil 5 in the foundation pit simulation unit 6 is removed layer by layer according to the predetermined excavation sequence. After each level of excavation depth is completed, the internal support components at the corresponding position are installed in time until the designed pit bottom elevation is reached. During the whole process, the monitoring system pre-buried on the surface of the composite wall simulation unit 7, the surface of the foundation pit simulation unit 6 and the model soil 5 continuously collects test data. The monitoring system includes: an earth pressure box and a water pressure box, which are respectively used to measure the earth pressure and water pressure on both sides of the composite wall; a strain gauge, which is used to measure the strain on both sides of the composite wall simulation unit 7; a displacement meter, which is used to measure the soil settlement and the horizontal displacement and settlement of the composite wall simulation unit 7; a liquid level meter, which is used to measure the water level in the soil. These real-time data provide a reliable basis for analyzing the mechanical response of the composite wall under the combined action of water level fluctuations and rock strata ups and downs.

[0041] In summary, the device provided by the embodiment of the present invention can simulate the influence of complex geological environment on underground structure with high precision and controllability, and provides a flexible and reliable hardware foundation for optimizing engineering design. For the simulation of groundwater level fluctuation, the device adopts a mechanical water level fluctuation control unit 2 to accurately control the amplitude and frequency of water level rise and fall in the water storage area 102, which can not only stably reproduce periodic water level changes such as tidal fluctuations, but also adjust the fluctuation parameters according to experimental requirements, solving the problems of lag and insufficient precision in the traditional injection and drainage method. In terms of rock section simulation, a modular rock module 311 matrix is adopted, and each rock module 311 is independently height-adjusted through an external control terminal 32, which can not only quickly construct an undulating rock section, but also dynamically adjust the rock morphology during the test, and realize the rapid switching of different geological profiles. Furthermore, the water level and rock simulation systems of the device are both digitally controlled, and the operator can accurately control the test conditions through the parameterized interface, so that the device has a high test operability.

[0042] The above description is only a preferred specific implementation mode of the present invention, and does not limit the patent scope of the present invention. Any technical equivalent changes made using the contents of the present invention specification shall fall within the protection scope of the present invention.

Claims

1. An experimental device for simulating the mechanical response of adjacent composite walls induced by foundation pit excavation, characterized in that: It includes a model box, a water level fluctuation control unit, a rock stratum section simulation system, a flexible elastic interlayer, model soil, a laminated wall simulation unit, and a foundation pit simulation unit; At least a pressurized area, a water storage area, and a soil-rock composite stratum area are demarcated inside the model box; the pressurized area and the water storage area are demarcated by a first partition board, and the first partition board is provided with a first flow passage at the bottom or near the bottom; the water storage area and the soil-rock composite stratum area are demarcated by a second partition board, and a plurality of second flow passages are arranged at intervals along the height direction on the second partition board; The water level fluctuation control unit is arranged in the pressurized area and includes an actuator that moves up and down along the height direction; the actuator is hermetically and slidably connected to the inner wall of the pressurized area; The rock stratum section simulation system includes a plurality of rock simulation units arranged at the bottom of the soil-rock composite stratum area and an external control terminal arranged outside the model box; the rock simulation unit is configured as a structure that moves up and down along the height direction; the rock simulation unit is connected to the external control terminal to adjust the top height under the control of the external control terminal; The flexible elastic interlayer covers the top surface of the rock simulation unit and is hermetically connected to the inner wall of the soil-rock composite stratum area; the connection position of the flexible elastic interlayer on the second partition board is not higher than the lowest second flow passage; The model soil is filled above the flexible elastic interlayer; the laminated wall simulation unit and the foundation pit simulation unit are buried in the model soil; the foundation pit simulation unit includes at least two relatively arranged first diaphragm walls and internal bracing members; the laminated wall simulation unit includes an underground main structure and at least two second diaphragm walls; the second diaphragm walls are relatively connected to the outer sides of the side walls of the underground main structure; It further includes a monitoring system for collecting test data.

2. The test device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to claim 1, wherein: The water level fluctuation control unit further includes a controller and a first connecting rod; the controller is connected to the actuator below through the first connecting rod; the first connecting rod expands and contracts vertically under the drive of the controller to drive the actuator to move up and down.

3. An experimental device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to claim 2, characterized in that: An interaction panel is arranged on the controller for setting parameters of the actuator.

4. An experimental device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to claim 1, characterized in that: A plurality of the rock simulation units are closely laid at the bottom of the soil-rock composite stratum area to form a rock module matrix on the top surface.

5. An experimental device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to claim 1, characterized in that: The rock simulation unit includes a rock module and a height controller; the height controller is configured with a motor and a second connecting rod, and the second connecting rod expands and contracts along the height direction through spiral commutation cooperation with the motor; the rock module is arranged at the top of the second connecting rod; the height controller is connected to the external control terminal.

6. The test device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to claim 1, characterized in that: The model box includes a bottom plate made of steel plate; a magnetic base is arranged at the bottom of the rock simulation unit to adsorb on the bottom plate.

7. An experimental device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to claim 1, characterized in that: The top of the water storage area is sealed.

8. An experimental device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to claim 1, characterized in that: The foundation pit simulation unit and the laminated wall simulation unit extend along the width direction of the model box.

9. The test device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to claim 1, characterized in that: The second flow passage is configured as a water passing hole.

10. An experimental device for simulating the mechanical response of an adjacent composite wall induced by foundation pit excavation according to claim 1, characterized in that: The second partition board is provided with a screen at least in the plane area of the second flow passage.

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