Fabricated supporting structure model test device and test method

Abstract

The invention discloses an assembly type supporting structure model test device and test method. The test device comprises a model box base and a model box arranged on the model box base. The model box internally comprises a double-row pile supporting structure located on the periphery of the foundation pit and simulation soil bodies arranged on the double-row pile supporting structure and the periphery of the double-row pile supporting structure in a filling mode. Distributed optical fiber sensors are attached to the double-row pile supporting structure, and the distributed optical fiber sensors are connected with an external optical fiber sensing testing system. A plurality of soil pressure boxes which are longitudinally distributed at equal intervals are attached to the double-row pile supporting structure; the device further comprises a plurality of settlement meters arranged in the simulated soil body, a plurality of dewatering wells extending into the bottom of the foundation pit and a plurality of observation wells arranged on the periphery of the foundation pit, each settlement meter is used for monitoring settlement changes of the surface of the simulated soil body, and each dewatering well is connected with an external water suction pump to achieve foundation pit dewatering. The invention aims to realize a foundation pit layer-by-layer rainfall excavation test for simulating the support of an actual assembly type support structure.

Description

Technical Field

[0001] The present invention relates to the technical field of test devices, and in particular to a test device and a test method for a prefabricated support structure model. Background Art

[0002] At present, in foundation pit projects, in order to ensure the safety and smooth progress of underground construction, it is crucial to choose a suitable support structure. Various support structures play a unique role. Among them, traditional support structures include pile walls, strip anchors, prestressed anchors, etc. In recent years, double-row pile support structures have been widely used due to their unique characteristics. The reason is that the double-row pile support structure has the characteristics of high support strength and strong resistance to deformation, and there is no need to set up braces and angle braces inside the foundation pit, so it is widely used in foundation pit projects of various depths. The traditional double-row pile support structure uses reinforced concrete as the main material, and the resulting disadvantages such as the material cannot be reused and the long construction period need to be treated with caution during construction design.

[0003] The invention patent with the existing patent publication number CN117587824A discloses a double-row pile enclosure structure with a combination of long and short piles, including existing enclosure piles and proposed structure enclosure piles; the proposed structure enclosure piles intrude into the part between two adjacent existing enclosure piles and fit with the two adjacent existing enclosure piles at the same time; the top of the proposed structure enclosure piles and the top of the existing enclosure piles share a joint crown beam, and the spacing between each two adjacent piles of the proposed structure enclosure piles is consistent with the spacing between each two adjacent piles of the existing enclosure piles; the proposed structure enclosure piles are provided with a waist beam, and the waist beam is arranged within a height range of 2-3m above the bottom of the existing short enclosure piles. Although the structure has the corresponding support capacity, the device still needs to be reinforced by grouting, which makes it impossible to reuse the support structure and it is impossible to achieve the actual working condition of first dewatering the foundation pit and then excavating the foundation pit. Summary of the invention

[0004] The main purpose of the present invention is to provide a prefabricated support structure model test device and test method, aiming to solve the technical problem that the existing prefabricated support structure cannot be used for foundation pit excavation operations under precipitation conditions.

[0005] To achieve the above-mentioned object, the present invention provides a prefabricated support structure model test device, wherein the device comprises a model box base and a model box arranged on the model box base;

[0006] The model box includes a double-row pile support structure located around the foundation pit and simulated soil filled in the double-row pile support structure and its surroundings;

[0007] Distributed optical fiber sensors are attached to the double-row pile support structure, and each distributed optical fiber sensor is connected to an external optical fiber sensing test system;

[0008] The double-row pile support structure is provided with a plurality of earth pressure boxes distributed at equal intervals in the longitudinal direction, each earth pressure box is used to monitor the pressure change of the simulated soil at different depths;

[0009] The device also includes a plurality of settlement meters arranged in the simulated soil, a plurality of precipitation wells extending into the bottom of the foundation pit, and a plurality of observation wells arranged around the foundation pit. Each settlement meter is used to monitor the settlement change law on the surface of the simulated soil. Each precipitation well is connected to an external water pump to simulate different precipitation conditions. Each observation well is used to monitor the water level change inside the simulated soil.

[0010] Optionally, the double-row pile support structure comprises a plurality of front-row support piles and rear-row support piles respectively connected in a ring shape, the front-row support piles are connected by a front crown beam, and the rear-row support piles are connected by a rear crown beam;

[0011] Each front row supporting pile is connected to the corresponding rear row supporting pile by a first connecting beam, and each front row supporting pile is also staggeredly connected to two adjacent rear row supporting piles of the corresponding rear row supporting piles by a second connecting beam.

[0012] Optionally, an annular water replenishment cavity is arranged between the inner wall of the model box and the simulated soil body, the annular water replenishment cavity and the simulated soil body are separated by a perforated partition plate, and the base of the model box is placed in a water reservoir.

[0013] Optionally, each observation well is provided with corresponding water pressure gauges at equal axial intervals, and each water pressure gauge is connected to an external dynamic and static test and analysis system.

[0014] Optionally, a dial indicator is provided on the outer wall of the model box.

[0015] Optionally, the front row support piles are connected by a plurality of support panels, and a plurality of drainage holes are arranged on the surface of each support panel.

[0016] Optionally, the settlement meters are arranged at the periphery of the foundation pit and at equal intervals along a preset direction.

[0017] In addition, in order to achieve the above-mentioned purpose, the present invention also provides a test method of a prefabricated support structure model test device, the method comprising the following steps:

[0018] Step 1, assembling and placing the double-row pile support structure at a preset position of the model box, then installing corresponding distributed optical fibers in a preset area of ​​the double-row pile support structure, each distributed optical fiber is externally connected to a fiber optic sensing test system, and multiple perforated partitions are arranged between the double-row pile support structure and the model box to form an annular water replenishment cavity between the perforated partitions and the model box;

[0019] Step 2, placing the model box and the model box base in a water reservoir;

[0020] Step 3: Fill the area with perforated partitions in layers. During the backfilling of each layer of soil, a soil pressure box is buried in the corresponding area, and a precipitation well and an observation well made of PVC wire pipe are placed in the corresponding area. After the soil layer is backfilled to the target thickness, an appropriate amount of water is injected into the annular water replenishment cavity, and the cavity is left to stand for a preset number of days to wait for the soil to consolidate.

[0021] Step 4, after the soil is consolidated, corresponding settlement meters are installed at preset positions on the soil surface, and each settlement meter is zeroed in turn;

[0022] Step 5, using each precipitation well in turn to perform precipitation before excavation, and observing the soil water level through the observation well until it is below the prepared excavation surface to simulate the precipitation environment, and excavating the foundation pit in layers from the soil surface downward for multiple times, the foundation pit is located in the double-row pile support structure area, and after each layer of excavation is completed, a support panel is fixed on the side of the double-row pile support structure close to the foundation pit, and strain gauges are placed on the surface of each support panel, and relevant data are continuously read and recorded at intervals, and the relevant data include excavation depth, excavation surface level, soil pressure, pore water pressure, strain gauge strain and optical fiber displacement;

[0023] Step 6: After excavating to the specified elevation, let it stand for 50 minutes to wait for soil creep and consolidation, output the corresponding monitoring data, and end the model test. The collected data is analyzed and processed to obtain the stress and deformation of the prefabricated support structure model in three-dimensional space during the excavation and dewatering process, and determine the changes in pore water and the settlement law of the soil during the dewatering excavation process.

[0024] Optionally, in step 3, a plurality of through holes are provided on the side wall of each precipitation well, and each through hole is used to place a corresponding water pressure gauge.

[0025] Optionally, before step 1, the method includes determining simulation parameters corresponding to the simulation device according to actual parameters of the actual construction site to design a model box, a model test support structure, laboratory soil preparation, and design a simulated precipitation and a static period after layered support.

[0026] Beneficial effects:

[0027] The prefabricated support structure model test device of the present invention realizes the detachability of the support structure and the setting of the support panel by adopting a double-row pile support structure, thereby improving the stability of the support structure; through the setting of the annular water distribution cavity, the water pressure gauge and the observation well, and the precipitation well, it realizes the foundation pit excavation test under the condition of precipitation effectively simulating, and through the corresponding monitoring setting, it realizes the monitoring of the relevant data of the entire model test device, so as to obtain the stress and deformation of the prefabricated support structure model in the three-dimensional space during the excavation and precipitation process, the change of pore water during the precipitation excavation process and the settlement law of the soil through processing these data, thereby providing an effective basis for the subsequent actual application of the support structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a prefabricated support structure model test device of the present invention;

[0029] Figure 2 for Figure 1 a top view of the structure shown;

[0030] Figure 3 for Figure 1 a cross-sectional view of the structure shown;

[0031] Figure 4 for Figure 1 Schematic diagram of the connection between the supporting steel panel and the front row of pile bolts;

[0032] Figure 5 It is a top view of the structure shown in another embodiment of a prefabricated support structure model test device of the present invention.

[0033] Description of Figure Numbers

[0034] 1-model box; 2-rear crown beam; 3-front crown beam; 4-front row support piles; 5-rear row support piles; 6-first connecting beam; 7-support panel; 8-drainage hole; 9-optical fiber sensing test system; 10-dynamic and static test analysis system; 11-computer; 12-earth pressure box; 13-dial indicator; 14-sedimentation meter; 15-strain gauge; 16-distributed optical fiber; 17-model box base; 18-water reservoir; 19-annular water distribution cavity; 20-perforated partition; 21-precipitation well; 22-observation well; 23-water pressure gauge; 24-water pump; 25-installation hole

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0037] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system 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 system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0038] like Figure 1-4 As shown, the present invention provides a structural schematic diagram of an embodiment of a prefabricated support structure model test device, wherein the device includes a model box base 17 and a model box 1 arranged on the model box base 17; the model box 1 includes a double-row pile support structure located around the foundation pit and a simulated soil filled in the double-row pile support structure and around it, preferably, an annular water replenishment cavity 19 is arranged between the inner wall of the model 1 and the simulated soil, and the annular water replenishment cavity 19 is separated from the simulated soil by a perforated partition 20, thereby realizing the transfer of soil water during precipitation excavation; and the model box base 17 is placed in a reservoir 18, which can effectively cooperate with the annular water replenishment cavity 19 to achieve a moisture content matching between the soil inside the model box 1 and the on-site foundation pit. Preferably, the model box is made of steel, and the components are connected by welding to ensure good sealing. In order to reduce the influence of the soil boundary on the test results, the inner lining of the part where the model box and the soil are in contact is lined with two layers of polytetrafluoroethylene film, and lubricating oil is applied to reduce the error caused by the boundary during the test.

[0039] Furthermore, if Figure 2 As shown, the double-row pile support structure includes a plurality of front-row support piles 4 and rear-row support piles 5 connected in a ring shape, the front-row support piles 4 are connected by a front crown beam 3, the rear-row support piles 5 are connected by a rear crown beam 2, and the front-row support piles 4 are connected to the corresponding rear-row support piles 5 by a first connecting beam 6. Preferably, the front / rear-row support piles are connected by bolts, and the first connecting beam 6 is connected to the front and rear-row support piles by bonding, so as to facilitate subsequent disassembly. In addition, the front / rear-row support piles are mostly made of aluminum.

[0040] Furthermore, in order to analyze the strain and displacement of the support structure under different working conditions, a distributed optical fiber sensor 16 is attached to the double-row pile support structure, and each distributed optical fiber sensor 16 is respectively connected to an external optical fiber sensing test system 9, and the optical fiber sensing test system 9 is also connected to a computer 11. And in order to measure the change of soil pressure during the layer-by-layer dewatering excavation process, a plurality of soil pressure boxes 12 with equal longitudinal spacing are attached to the double-row pile support structure, so that each soil pressure box 12 monitors the pressure change of the simulated soil at different depths.

[0041] Furthermore, each front row support pile 4 is connected by a plurality of support panels 7. Specifically, the front row support pile 4 is connected to the corresponding support panel 7 by bolts, so as to facilitate subsequent disassembly. Preferably, a plurality of drainage holes 8 are also provided on the surface of each support panel 7, so as to facilitate the effective discharge of soil water in the simulated soil, and a plurality of mounting holes 25 for bolt connection are provided around each support panel 7. More preferably, the support panel 7 adopts a rubber plate with a certain rigidity, and a corresponding strain gauge 15 is attached to the side of the support panel 7 close to the simulated soil to monitor the slight deformation of the panel, so as to analyze the deformation law of the support panel at different positions and directions. The provision of the above-mentioned support panels enhances the overall stability of the support structure.

[0042] Furthermore, a plurality of settlement meters 14 are provided in the simulated soil, each settlement meter 14 is used to monitor the settlement change law of the simulated soil surface. Preferably, the plurality of settlement meters 14 are arranged along a specific direction around the foundation pit. Figure 2 As shown, the distance between the settlement meter 14 and the foundation pit gradually increases to observe the settlement of the soil surface; in addition, the settlement meter 14 can also be set in other layout modes, all of which are aimed at obtaining the settlement change law of the simulated soil surface.

[0043] Furthermore, if Figure 2-3 As shown, a plurality of dewatering wells 21 extending into the bottom of the pit are also provided in the foundation pit, and each dewatering well 21 is connected to an external water pump 24. Specifically, the dewatering well is made of PVC wire pipe and extends a certain distance into the bottom of the pit, and an external water pump 24 is connected to realize the dewatering function in the pit.

[0044] Furthermore, a plurality of observation wells 22 are provided in the simulated soil around the foundation pit, and each observation well 22 is used to monitor the water level changes inside the simulated soil. Specifically, each observation well 22 is evenly spaced in the axial direction and equipped with a corresponding water pressure gauge 23. Preferably, a plurality of evenly spaced through holes are provided on the side wall of each precipitation well 21, and each through hole is used to place a corresponding water pressure gauge 23. Each water pressure gauge 23 is connected to an external dynamic and static test and analysis system 10, and the dynamic and static test and analysis system 10 is also connected to a computer 11. Then, the water pressure gauge 23 transmits data to the computer 11 through the external dynamic and static test and analysis system 10 to realize data transmission and analysis functions, so as to monitor the water pressure and changes in the seepage zone in the simulated soil.

[0045] Furthermore, if Figure 2 As shown, a dial gauge 13 may also be provided on the outer wall of the model box 1, and the dial gauge 13 is used to detect the deformation of the model box 1. Generally, if the deformation shown by the dial gauge is less than 1.8 mm, it is considered to meet the specification requirements.

[0046] Furthermore, if Figure 5As shown, in Figure 1 On the basis of the embodiment shown, each front row support pile 4 is further connected to two adjacent rear row support piles 5 of the corresponding rear row support piles 5 by a second connecting beam, thereby enhancing the stability effect of the double row pile support structure.

[0047] In addition, in order to better illustrate the prefabricated support structure model test device of the present invention, taking the experimental device of the first embodiment as an example, the test method is described in detail, and the method includes the following steps:

[0048] Step 1, assemble and place the double-row pile support structure at a preset position of the model box 1, then install the corresponding distributed optical fiber 16 in the preset area of ​​the double-row pile support structure, each distributed optical fiber 16 is externally connected to the optical fiber sensing test system 9, and multiple perforated partitions 20 are arranged between the double-row pile support structure and the model box 1, so that an annular water replenishment cavity 19 is formed between the perforated partitions 20 and the model box 1. During the assembly process, epoxy glue is used as a fixing material to ensure that the distributed optical fiber can be firmly placed at the predetermined pile body position, and the distributed optical fiber 16 is externally connected to the optical fiber sensing measurement system and connected to the computer 11.

[0049] Step 2, placing the model box 1 and the model box base 17 in the water reservoir 18, and cooperating with the surrounding annular water replenishment cavity 19 to achieve a moisture content matching the soil inside the model box and the on-site foundation pit.

[0050] Step 3, the soil filling operation is carried out in the area of ​​the perforated partition 20 in a layered filling manner. During the backfilling process of each layer of soil, the soil pressure box 12 is buried in the corresponding area, and a precipitation well 21 and an observation well 22 made of PVC wire pipe are placed in the corresponding area. After the soil layer is backfilled to the target thickness, an appropriate amount of water is injected into the annular water replenishment cavity 19, and the soil is left to stand for a preset number of days to wait for the soil to consolidate. Specifically, during the layered filling process, the soil is filled according to the preset layers. At the same time, the distributed optical fiber used to measure the settlement is also buried in layers synchronously. The upper and lower parts of the optical fiber are fixed to ensure its stable position in the soil. At the same time, the height of a single filling is strictly controlled at 10 cm. After each layer of filling is completed, it is fully compacted to ensure the compactness and stability of the soil. At a specific height behind the pile, a soil pressure box 12 is buried every 10 cm to monitor the pressure changes of the soil at different depths. Subsequently, the double-row pile support structure and the earth pressure box 12 are buried layer by layer in the soil and compacted to ensure close integration with the surrounding soil. During this period, a water pressure gauge 23, a precipitation well 21 made of PVC wire pipe and an observation well 22 are placed at the corresponding positions. Among them, the precipitation well 21 is 15 cm deep into the bottom of the pit and is connected to an external pump 24 to achieve the precipitation function in the pit. After completing the above steps, let it stand to wait for the soil to further consolidate.

[0051] Step 4, after the soil is consolidated, corresponding settlement meters 14 are installed at preset positions on the soil surface, and each settlement meter 14 is zeroed in turn;

[0052] Step 5, using each dewatering well 21 to dewater before excavation, and observing the soil water level through the observation well 22 until it is below the prepared excavation surface to simulate the dewatering environment, excavating the foundation pit from the soil surface downward for multiple times, the foundation pit excavation area is located in the double-row pile support structure area, and after each layer of excavation is completed, the support panel 7 is fixed on the side of the double-row pile support structure close to the foundation pit, and strain gauges 15 are also placed on the surface of each support panel 7, and relevant data are continuously read and recorded at intervals, and the relevant data include excavation depth, excavation surface level, soil pressure, pore water pressure, strain gauge strain and optical fiber displacement. Specifically, in this embodiment, the dewatering excavation work of the foundation pit is carried out in layers, and the entire dewatering excavation process is divided into five times. First, the dewatering well in the pit is connected to a water pump for dewatering to ensure that the groundwater level in the foundation pit drops to below the current soil layer elevation of 10 cm, and the water pressure at the corresponding position is read. Excavation operation is carried out, and the depth of each excavation is accurately controlled at 10 cm. During the excavation process, make full use of relevant measuring tools such as levels to ensure that the depth of each excavation is accurate and consistent, and the excavation surface remains horizontal. After each excavation, the support panels are installed and fixed with bolts. After each layer of excavation operation is completed, it is left to stand for 50 minutes to wait for soil creep and consolidation. During this period, relevant data is continuously read and recorded at certain time intervals. After the data is stable and no longer changes, the next excavation work is carried out.

[0053] Step 6: After excavating to the specified elevation, let it stand for 50 minutes to wait for soil creep and consolidation, output the corresponding monitoring data, and end the model test. The collected data is analyzed and processed to obtain the stress and deformation of the prefabricated support structure model in three-dimensional space during the excavation and dewatering process, and determine the changes in pore water and the settlement law of the soil during the dewatering excavation process.

[0054] Furthermore, before step 1, it is also necessary to determine the simulation parameters corresponding to the simulation device according to the actual parameters of the actual construction site, so as to design the model box, model test support structure, laboratory soil, design simulated precipitation and static period after layered support. Specifically, in combination with the actual construction site of the prefabricated support structure, determine the duration of each precipitation, excavation, and steel panel installation support step of the actual construction, determine the similarity ratio according to factors such as soil layer properties, support structure properties, and construction time, and design the model box, model test support materials, laboratory soil, design simulated precipitation, and static period after layered support.

[0055] Among them, the design of model test support materials and laboratory soil preparation includes: selecting representative soil layers based on the actual geological information of the construction site, and determining the properties of the model test soil layers based on similarity criteria. According to the properties and dimensions of the support materials and support structures, the excavation dimensions of the foundation pit are determined, specifically:

[0056]

[0057] Where H is the depth of the foundation pit, L is the length of the foundation pit, W is the width of the foundation pit, υ is the Poisson's ratio, ε is the strain, EI is the bending stiffness, δ is the horizontal displacement of the structure, σ is the stress, p is the soil pressure, γ is the gravity, and E is the elastic modulus.

[0058] Furthermore, the method for determining the static period after layered support is as follows: based on the actual installation time of each layer of steel panels in the actual double-row pile construction foundation pit, the static period after layered support in the model test is determined according to the similarity criterion, preferably 50 minutes.

[0059] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0060] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A prefabricated support structure model test device, characterized in that: The device comprises a model box base (17) and a model box (1) arranged on the model box base (17); The model box (1) includes a double-row pile support structure located around the foundation pit and simulated soil filled in the double-row pile support structure and around it; Distributed optical fiber sensors (16) are attached to the double-row pile support structure, and each distributed optical fiber sensor (16) is respectively connected to an external optical fiber sensing test system (9); A plurality of soil pressure boxes (12) are provided in the double-row pile support structure at equal intervals in the longitudinal direction, and each soil pressure box (12) is used to monitor the pressure change of the simulated soil at different depths; The device further comprises a plurality of settlement meters (14) arranged in the simulated soil, a plurality of precipitation wells (21) extending into the bottom of the foundation pit, and a plurality of observation wells (22) arranged around the foundation pit. Each settlement meter (14) is used to monitor the settlement change pattern of the surface of the simulated soil. Each precipitation well (21) is connected to an external water pump (24) to realize the layer-by-layer precipitation function and the simulation of different precipitation conditions. Each observation well (22) is used to monitor the water level change inside the simulated soil.

2. The assembled support structure model test device according to claim 1 is characterized in that: The double-row pile support structure comprises a plurality of front-row support piles (4) and rear-row support piles (5) respectively connected in a ring shape, wherein the front-row support piles (4) are connected by a front crown beam (3), and the rear-row support piles (5) are connected by a rear crown beam (2); Each front row support pile (4) is connected to the corresponding rear row support pile (5) via a first connecting beam (6), and each front row support pile (4) is also staggeredly connected to two adjacent rear row support piles (5) of the corresponding rear row support pile (5) via a second connecting beam (6).

3. The assembled support structure model test device according to claim 1 is characterized in that: An annular water replenishment cavity (19) is arranged between the inner wall of the model box (1) and the simulated soil body. The annular water replenishment cavity (19) and the simulated soil body are separated by a perforated partition plate (20). The model box base (17) is placed in a water reservoir (18).

4. The assembled support structure model test device according to claim 1 is characterized in that: Each observation well (22) is provided with a corresponding water pressure gauge (23) at equal intervals in the axial direction, and each water pressure gauge (23) is connected to an external dynamic and static test analysis system (10).

5. The assembled support structure model test device according to claim 1 is characterized in that: The outer wall of the model box (1) is provided with a dial indicator (13).

6. The assembled support structure model test device according to claim 2 is characterized in that: The front row support piles (4) are connected via a plurality of support panels (7), and a plurality of drainage holes (8) are arranged on the surface of each support panel (7).

7. The assembled support structure model test device according to claim 1 is characterized in that: The settlement meters (14) are arranged at the periphery of the foundation pit and at equal intervals along a preset direction.

8. A test method for a prefabricated support structure model test device, characterized in that: The method comprises the following steps: Step 1, assembling and placing a double-row pile support structure at a preset position of a model box (1), then installing corresponding distributed optical fibers (16) in a preset area of ​​the double-row pile support structure, each distributed optical fiber (16) is externally connected to an optical fiber sensing test system (9), and arranging a plurality of perforated partitions (20) between the double-row pile support structure and the model box (1) so that an annular water replenishment cavity (19) is formed between the perforated partitions (20) and the model box (1); Step 2, placing the model box (1) and the model box base (17) in a water reservoir (18); Step 3, filling soil in the area of ​​the perforated partition (20) in a layered filling manner, burying a soil pressure box (12) in the corresponding area during the backfilling of each layer of soil, and placing a precipitation well (21) and an observation well (22) made of PVC wire pipe in the corresponding area. After the soil layer is backfilled to the target thickness, an appropriate amount of water is injected into the annular water replenishment cavity (19), and the cavity is left to stand for a preset number of days to wait for the soil to consolidate; Step 4, after the soil is consolidated, a corresponding settlement meter (14) is installed at a preset position on the soil surface, and each settlement meter (14) is zeroed in turn; Step 5, using each dewatering well (21) to pump water layer by layer, and observing the soil water level through the observation well (22) until it is below the next excavation surface to simulate the dewatering environment, and excavating the foundation pit in layers from the soil surface downward for multiple times, wherein the foundation pit is located in the area of ​​the double-row pile support structure, and after each layer of excavation is completed, a support panel (7) is fixed on the side of the double-row pile support structure close to the foundation pit, and strain gauges (15) are also placed on the surface of each support panel (7), and relevant data are continuously read and recorded at intervals, and the relevant data include excavation depth, excavation surface levelness, soil pressure, pore water pressure, strain gauge strain and optical fiber displacement; Step 6: After excavating to the specified elevation, let it stand for 50 minutes to wait for soil creep and consolidation, output the corresponding monitoring data, and end the model test. The collected data is analyzed and processed to obtain the stress and deformation of the prefabricated support structure model in three-dimensional space during the excavation and dewatering process, and determine the changes in pore water and the settlement law of the soil during the dewatering excavation process.

9. The test method of the assembled support structure model test device according to claim 9 is characterized in that: In step 3, a plurality of through holes are provided on the side wall of each precipitation well (21), and each through hole is used to place a corresponding water pressure gauge (23).

10. The test method of the assembled support structure model test device according to claim 9, characterized in that: Before step 1, it includes determining the simulation parameters corresponding to the simulation device according to the actual parameters of the actual construction site, so as to design the model box, the model test support structure, the laboratory soil preparation, the design of the simulated precipitation and the static period after the layered support.

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