Foundation pit excavation model test device with engineering pile at pit bottom and use method

Abstract

The invention belongs to the field of underground space, and provides a foundation pit excavation model test device with an engineering pile at the pit bottom and a use method, and the device comprises a model box, a counterforce device, a monitoring ring positioning mold, a foundation pit positioning mold and the like. The counter-force device is located above the model box, and the model material is embedded into the soil body through the counter-force device; the monitoring ring positioning mold is arranged in the model box; the foundation pit positioning molds are fixed to the two sides of the outer wall of the model box and removed after the model materials are installed, and earth surface monitoring equipment is arranged at the same position; the use method comprises the following steps: preliminarily assembling the model box; filling a soil body in layers; after the soil body is filled to the corresponding elevation, a monitoring ring positioning mold is placed, and a monitoring ring is placed in the mold; after the surface of the model box is filled with soil, a foundation pit positioning mold is placed, and a foundation pit model enclosure structure and an engineering pile are pressed in sections through a counter-force device; and the foundation pit positioning mold is dismantled, and ground surface settlement monitoring equipment is arranged.

Description

Technical Field

[0001] The invention belongs to the field of geotechnical engineering indoor model tests and relates to a foundation pit excavation model test device with engineering piles at the bottom of the pit and a use method thereof. Background Art

[0002] Foundation pit engineering is an important branch of civil engineering. With the continuous acceleration of urban construction, urban foundation pits are often affected by environmental factors. Piles are often found around or at the bottom of foundation pits, and interactions between the piles and the foundation pit are inevitable. Therefore, studying the interaction between foundation pits and piles is of great significance to engineering safety.

[0003] Monitoring deformation and stress changes in foundation pits and piles at construction sites is the most intuitive and effective method. However, since both foundation pits and piles are underground projects, underground monitoring components are difficult to deploy. Furthermore, given the complexity of construction sites, monitoring of underground data is often difficult. Therefore, model testing is widely used as an important research tool. Model testing occupies a small area, allows for repeatable testing, and allows for customizable working conditions, facilitating the analysis of patterns.

[0004] However, although various foundation pit excavation model test devices are disclosed in the prior art, the influence of engineering piles is not taken into consideration, making it difficult to analyze the deformation and stress conditions of the foundation pit under different engineering pile working conditions. Summary of the Invention

[0005] In order to solve the technical problems existing in the prior art, the present invention aims to provide a foundation pit excavation model test device with engineering piles at the bottom of the pit, which has a simple structure and is easy to install, and a method for using the same.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions: A foundation pit excavation model test device with engineering piles at the bottom of the pit, comprising a model box, a reaction device, a monitoring ring positioning mold, a foundation pit positioning mold, soil internal monitoring equipment, surface settlement monitoring equipment, a retaining structure, an internal support and a model pile; It includes a model box, a reaction device, soil internal monitoring equipment, a monitoring ring positioning mold, a foundation pit positioning mold, a surface settlement monitoring device, a retaining structure and a model pile; The reaction device is located on the top of the model box, and the retaining structure and the model pile can be embedded in the soil through the reaction device; The soil body internal monitoring device is arranged inside the soil body, and the monitoring ring positioning mold is placed inside the model box to position the soil body internal monitoring device. The soil body internal monitoring device can be removed after installation. The foundation pit positioning mold is fixed on the model box to position the pressing process of the retaining structure and the model pile; and after the retaining structure and the model pile are pressed in, the foundation pit positioning mold is removed and the surface settlement monitoring equipment is placed at the same position.

[0007] As a further technical solution, a preferred solution for the foundation pit excavation model test device with engineering piles at the bottom of the pit is that the model box is a box structure with an open top and a closed bottom, and one of the sides is a plexiglass plate.

[0008] As a further technical solution, a preferred solution for a foundation pit excavation model test device in which there are engineering piles at the bottom of the pit is provided. The reaction structure includes a main reaction beam, a secondary reaction beam, a slide rail and a hydraulic jack. The main reaction beam is connected to form a frame structure. The secondary reaction beam is fixed in the frame structure, and a slide rail and a driving device are provided inside the secondary reaction beam. A hydraulic jack is provided on the slide rail, and the fixing device drives the hydraulic jack to move in the X / Y plane. As a further technical solution, a preferred solution for the foundation pit excavation model test device in which there are engineering piles at the bottom of the pit is provided, wherein the monitoring ring positioning mold includes a positioning plate, a distance measuring ruler and a positioning mold level bubble, a distance measuring ruler is arranged around the positioning plate, and a level bubble is arranged on the positioning plate; the distance between the monitoring ring and the side wall of the model box can be determined by the distance measuring ruler, and whether the monitoring ring positioning mold is level can be determined by the level bubble.

[0009] As a further technical solution, a preferred solution for the foundation pit excavation model test device in which there are engineering piles at the bottom of the pit is provided, wherein the foundation pit positioning mold includes adjusting screws, connecting grooves, wing plates, a mold outer ring strip, a mold inner plate and a wing plate level bubble; wing plates are connected on both sides of the mold outer ring strip, and adjusting screws and level bubbles are provided at the ends of the wing plates, and a mold inner plate is provided on the inner ring of the mold outer ring strip; there is a certain gap between the mold inner plate and the front, back, left and right four surfaces of the mold outer ring strip, and the two are connected by a plurality of sliding sliders, and the sliders can slide in the four front, back, left and right surfaces.

[0010] As a further technical solution, the soil internal monitoring equipment includes a monitoring ring, a transverse micro-soil pressure box, a transverse micro-displacement sensor, a vertical micro-soil pressure box, and a vertical micro-displacement sensor; the transverse micro-soil pressure box and the transverse micro-displacement sensor are installed on the outer ring of the monitoring ring, and the vertical micro-soil pressure box and the vertical micro-displacement sensor are installed at the bottom of the monitoring ring.

[0011] As a further technical solution, the surface settlement monitoring equipment includes a fixed beam surface deformation displacement sensor, a connecting rod and a slot; a slot is provided at the bottom of the fixed beam; and multiple connecting rods are provided on the side of the fixed beam, each connecting rod being connected to a surface deformation displacement sensor.

[0012] As a further technical solution, an optimal solution for the foundation pit excavation model test device in which there are engineering piles at the bottom of the pit is that the retaining structure is made of PVC board material, and the adjacent retaining structures are connected by concave and convex matching; the model piles are made of hollow aluminum tubes, and the adjacent model piles are connected by concave and convex matching to achieve the connection between the upper and lower model piles.

[0013] As a further technical solution, the preferred solution of the foundation pit excavation model test device with engineering piles at the bottom of the pit also includes an internal support, which is a hollow tube structure with adjustable length and is fixed inside the enclosure structure.

[0014] A second object of the present invention is to provide a method for using a foundation pit excavation model test device with engineering piles at the bottom of the pit. To achieve this object, the present invention is implemented through the following technical solutions: Step 1: Assemble the model box, hang it in the test site, and place the reaction device above the column of the model box; Step 2: Fill the soil layer by layer. After the soil is filled to the corresponding elevation, place the monitoring ring positioning mold at the specified monitoring height; Step 3: Install the micro earth pressure cell and micro displacement sensor monitoring element on the monitoring ring of the soil internal monitoring equipment in advance, place the monitoring ring in the monitoring ring positioning mold, and lead the cable of the monitoring element out from the corner of the mold box; Step 4: After the soil is filled to the surface of the model box, the foundation pit positioning mold is placed. The foundation pit positioning mold is placed on the side wall of the model box and fixed and leveled. The retaining structure is placed in the gap reserved between the mold inner plate and the mold outer ring of the positioning mold. The retaining structure is pressed into the soil in sections by the hydraulic jack in the reaction device. At the same time, the model piles are inserted into the model pile guide holes reserved on the mold inner plate. The model piles are pressed into the soil in sections by the hydraulic jack in the reaction device. Step 5: Remove the foundation pit positioning mold and deploy surface settlement monitoring equipment. The surface settlement monitoring equipment deploys soil surface settlement displacement sensors according to monitoring requirements. Step 6: The foundation pit is excavated in layers and internal supports are set at specified locations. During the excavation process, the soil pressure and displacement changes inside and outside the foundation pit are monitored in real time, and the relevant data are transmitted to the computer terminal.

[0015] The beneficial effects of the present invention are as follows: The present invention can coordinate the retaining structure and the model pile through the mutual cooperation of the model box, the reaction device and the foundation pit positioning mold. Accurately pressed into the soil, the monitoring ring positioning mold can simultaneously accurately position the monitoring equipment within the soil; the foundation pit positioning mold can be used to position the retaining structure and model pile during the pressing process. This invention can maximize the reproduction of the actual on-site construction conditions of the foundation pit retaining structure and engineering piles, and can monitor the soil pressure and displacement changes inside and outside the foundation pit in real time. This invention can be used to consider the working conditions when the pile body and foundation pit excavation interact, and can adjust the foundation pit working conditions and monitoring content according to actual conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0017] Figure 1 This is a schematic diagram of the overall structure of Example 1 of the present invention; Figure 2 This is a schematic diagram of a model box according to embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the reaction force structure of Example 1 of the present invention; Figure 4 and Figure 5 This is a schematic diagram of a monitoring ring positioning mold according to Example 1 of the present invention; Figure 6 and Figure 7 This is a schematic diagram of a foundation pit positioning mold according to Example 1 of the present invention; Figure 8 and Figure 9 This is a schematic diagram of the monitoring device according to Example 1 of the present invention; Figure 10-13 This is a schematic diagram of the model material of Example 1 of the present invention; Wherein: 1. Model box; 2. Reaction device; 3. Monitoring ring positioning mold; 4. Foundation pit positioning mold; 101. Model box bottom plate; 102. Model box column; 103. Side plate; 104. Organic glass plate; 105. Fixing bar; 201. Primary reaction beam; 202. Secondary reaction beam; 203. Slide rail; 204. Hydraulic jack; 301. Distance ruler; 302. Positioning mold level bubble; 303. Positioning plate; 304. Mounting hole; 401. Adjustment screw; 402 .Connecting groove; 403. Wing plate; 404. Mold outer ring strip; 405. Mold inner plate; 406 Wing plate level bubble; 501. Monitoring ring; 502. Horizontal micro earth pressure cell; 503. Horizontal micro displacement sensor; 504. Vertical micro earth pressure cell; 505. Vertical micro displacement sensor; 506. Fixed beam; 507. Surface deformation displacement sensor; 508. Connecting rod; 509. Slot; 601. Enclosure structure; 602. Model pile; 603. Internal support.

[0018] Specific application method The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] In the description of the present invention, terms indicating directions or positions, such as "upper", "lower", "left", "right", "inside", "outside", "bottom", and "top", are based on the directions shown in the accompanying drawings and are only used to simplify the description. They do not indicate or imply that the present invention must have a specific direction or position. All connection / fixing relationships involved in the present invention do not simply refer to direct connection of components, but rather to the optimal connection / fixing method that can be adopted according to the specific implementation situation.

[0020] The present invention is described using the model test of excavation of a foundation pit with existing piles at the bottom as an example, but is not limited to this working condition. The present invention is applicable to all tests involving foundation pit excavation in geotechnical model tests or tests that consider the interaction between foundation pit and piles.

[0021] Example 1 refer to Figures 1-13 This embodiment discloses a foundation pit excavation model test device with engineering piles at the bottom of the pit, including a model box 1, a reaction device 2, a monitoring ring positioning mold 3, and a foundation pit positioning mold 4; the reaction device is located above the model box, and the model material can be embedded into the soil through the reaction device; the monitoring ring positioning mold is placed inside the model box and can be removed after the monitoring equipment inside the soil is installed; the foundation pit positioning mold is fixed on both sides of the outer wall of the model box and is removed after the soil is filled, and the surface monitoring equipment is placed at the same location.

[0022] In this embodiment, the model box includes a model box bottom plate 101, a model box column 102, a model box side plate 103, a plexiglass plate 104 and a fixing strip 105; the model box floor 101 and the model box columns 102 are all steel products, the model box columns 102 are hollow structures, and the model box columns 102 include four, four model box columns 102 are connected to the four corners of the model box bottom plate 101; the model box side plates 103 include three, and the three model box side plates 103 are installed between adjacent columns. The plexiglass plate is divided into three pieces, and the screws are fixed to two of the opposite model box side plates 103 by fixing strips. The model box side plates 103, the plexiglass plates 104, and the model box bottom plate 101 together constitute a model box with an open top and a closed bottom, wherein the plexiglass plates 104 can be assembled when filling the soil and removed when cleaning the soil; In this embodiment, the reaction structure includes a main reaction beam 201, a secondary reaction beam 202, a slide rail 203 and a hydraulic jack 204; the main reaction beam 201 is connected to the model box column 102 by high-strength bolts and can be disassembled and assembled; the main reaction beam 201 is an I-beam structure, the secondary reaction beam 202 is located within the envelope of the main reaction beam 201, and a slide rail is provided inside the secondary reaction beam 202 for the hydraulic jack 204 to move in the X / Y direction, so that the hydraulic jack 204 can be used to press the enclosure structure and the model pile 602; Furthermore, in this embodiment, the monitoring ring positioning mold includes a positioning plate 303, a distance measuring ruler 301 and a positioning mold level bubble 302. The positioning plate 303 is provided with a distance measuring ruler around it, the positioning plate 303 is provided with a level bubble 302, and the positioning plate 303 is provided with a plurality of circular mounting holes 304. The circular mounting holes 304 are used to install the monitoring ring 301. The distance between the monitoring ring and the side wall of the model box is determined by the distance measuring ruler 301, and the level bubble 302 can be used to determine whether the monitoring ring positioning mold is horizontal. After the soil is filled in layers to the specified height, the monitoring ring positioning mold is set, and the monitoring ring can be removed after installation.

[0023] Furthermore, in this embodiment, the foundation pit positioning mold includes an adjusting screw 401, a connecting groove 402, a wing plate 403, a mold outer ring strip 404, a mold inner plate 405 and a wing plate level bubble 406; wing plates 403 are connected to both sides of the mold outer ring strip 404, and adjusting screws 401 are provided at the ends of the wing plates 403. The inner ring of the mold outer ring strip 404 is provided with a mold inner plate 405; the mold inner plate 405 is a rectangular plate, and there is a certain gap between the mold inner plate 405 and the four front, back, left and right surfaces of the mold outer ring strip 404. The two are connected by a plurality of sliding sliders, and the sliders can slide in the four front, back, left and right surfaces. The gap is used to insert the retaining structure. When the retaining structure on the left needs to be inserted, the slider slides to the front, back, and right directions to press the retaining piles. When the retaining structure on the right needs to be inserted, the slider slides to the front, back, and left directions to press the retaining piles. When the retaining structure in front needs to be inserted, the slider slides to the back, left, and right directions to press the retaining piles. When the retaining structure in the back needs to be inserted, the slider slides to the front, left, and right directions to press the retaining piles. At the same time, a plurality of model pile guide holes are provided on the mold inner plate 405. In this embodiment, 9 model pile guide holes are provided to guide the 9 model piles. Furthermore, the positioning mold can be ensured to remain level by adjusting the screws 401 and the wing plate level bubble 406. After the construction of the retaining structure and the model piles is completed, the foundation pit positioning mold is removed and the surface settlement monitoring equipment is installed. In this embodiment, the monitoring equipment is divided into soil internal monitoring equipment and surface settlement monitoring equipment; soil internal monitoring equipment such as Figure 4As shown, it includes a monitoring ring 501, a transverse micro earth pressure cell 502, a transverse micro displacement sensor 503, a vertical micro earth pressure cell 504, and a vertical micro displacement sensor 505; the transverse micro earth pressure cell 502 and the transverse micro displacement sensor 503 are installed on the outer ring of the monitoring ring 501, and the vertical micro earth pressure cell 504 and the vertical micro displacement sensor 505 are installed at the bottom of the monitoring ring 501; the transverse micro earth pressure cell 502, the transverse micro displacement sensor 503, the vertical micro earth pressure cell 504, and the vertical micro displacement sensor 505 are fixed on the monitoring ring in advance according to the monitoring quantity requirements, wherein the transverse micro earth pressure cell 502 is used to monitor the horizontal stress change data of the soil, the transverse micro displacement sensor 503 is used to monitor the horizontal displacement data of the soil, the vertical micro earth pressure cell 504 is used to monitor the vertical stress change data of the soil, and the vertical micro displacement sensor 505 is used to monitor the vertical displacement data of the soil; Further, such as Figure 5 As shown, the surface settlement monitoring equipment in this embodiment includes a fixed beam 506, a surface deformation displacement sensor 507, a connecting rod 508 and a slot 509; a slot 509 is provided at the bottom of the fixed beam 506, and the fixed beam can be fixedly connected to the side wall of the model box through the slot; a plurality of connecting rods 508 are provided on the side of the fixed beam 506, and each connecting rod 508 is connected to a surface deformation displacement sensor 507.

[0024] Furthermore, in this embodiment, the model material includes a retaining structure 601, a model pile 602, and an inner support 603; The enclosure structure 601 is made of PVC board, and the adjacent upper and lower enclosure structures and the left and right enclosure structures are connected by concave and convex fitting. The model piles 602 are made of hollow aluminum tubes, and the adjacent upper and lower model piles 602 are connected by concave and convex fitting; the inner support 603 is a hollow tube structure, and its length is adjustable (it can be set in two sections, and the two sections of the inner support 603 are threadedly connected to achieve adjustable length), and the inner support 603 can be fixed inside the enclosure structure 601 by rotating it.

[0025] In this embodiment, the retaining structure of the foundation pit and the model piles at the bottom of the pit can be determined by the foundation pit positioning mold, and the reaction structure can be pressed down into the soil in layers to simulate the construction process of the foundation pit on-site retaining structure and engineering piles.

[0026] In this embodiment, the model box base, model box columns, model box outer wall, fixing bars, reaction device, monitoring ring, monitoring ring positioning mold and foundation pit positioning mold are all made of steel.

[0027] Example 2 This embodiment discloses a foundation pit excavation model test device and a method for using the device in Example 1, wherein the device includes the following steps: Step 1: Assemble the model box. After hanging the model box at the test site, place the reaction device above the model box column. Fix the corners of the main reaction beam to the model box column with high-strength bolts to complete the preliminary assembly of the model test device.

[0028] Step 2: Fill the soil in layers. After the soil is filled to the corresponding elevation, install the organic glass plate and place the monitoring ring positioning mold at the specified monitoring height; Step 3: Install the micro earth pressure cell and micro displacement sensor monitoring element on the monitoring ring in advance, place the monitoring ring in the monitoring ring positioning mold, and lead the cable of the monitoring element out from the corner of the model box; Step 4: After the soil is filled to the surface of the model box, the foundation pit positioning mold is placed. The two ends of the wing plate of the foundation pit positioning mold are placed on the side walls of the model box. The positioning mold is fixed by adjusting screws and the level of the positioning mold is achieved by adjusting the height. The retaining structure 601 is placed in the gap reserved between the mold inner plate 405 and the mold outer ring strip 404 of the positioning mold. The retaining structure is pressed into the soil in sections by the hydraulic jack in the reaction device; at the same time, the model pile 602 is inserted into the model pile guide hole reserved on the mold inner plate 405, and the model pile is pressed into the soil in sections by the hydraulic jack in the reaction device; it should be noted that the model pile can be constructed first, or the retaining structure can be constructed first, and there is no special requirement for the construction order of the two.

[0029] Step 5: Remove the foundation pit positioning mold and deploy the surface settlement monitoring equipment. Place the fixed beam on the side wall of the model box and connect the fixed beam to the model box using the slot. Slide the surface deformation displacement sensor into the internal groove of the fixed beam through the connecting rod. Deploy the soil surface settlement displacement sensor according to the monitoring requirements. Step 6: The foundation pit is excavated in layers and internal supports 603 are set at specified locations. During the foundation pit excavation process, the soil pressure and displacement changes inside and outside the foundation pit are monitored in real time, and the relevant data are transmitted to the computer terminal.

[0030] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A foundation pit excavation model test device with engineering piles at the bottom of the pit, characterized in that: It includes a model box, a reaction device, soil internal monitoring equipment, a monitoring ring positioning mold, a foundation pit positioning mold, a surface settlement monitoring device, a retaining structure and a model pile; The reaction device is located on the top of the model box, and the retaining structure and the model pile can be embedded in the soil through the reaction device; The soil body internal monitoring device is arranged inside the soil body, and the monitoring ring positioning mold is placed inside the model box to position the soil body internal monitoring device. The soil body internal monitoring device can be removed after installation. The foundation pit positioning mold is fixed in the model box to position the pressing process of the retaining structure and the model pile; and after the retaining structure and the model pile are pressed in, the foundation pit positioning mold is removed and the surface settlement monitoring equipment is placed at the same position.

2. The foundation pit excavation model test device with engineering piles at the bottom of the pit according to claim 1, characterized in that: The model box is a box structure with an open top and a closed bottom, and one of the sides is a plexiglass plate.

3. The foundation pit excavation model test device with engineering piles at the bottom of the pit according to claim 1, characterized in that: The reaction structure includes a main reaction beam, a secondary reaction beam, a slide rail and a hydraulic jack. The main reaction beam is connected to form a frame structure. The secondary reaction beam is fixed in the frame structure, and a slide rail and a driving device are provided inside the secondary reaction beam. A hydraulic jack is provided on the slide rail, and the fixing device drives the hydraulic jack to move in the X / Y plane.

4. The foundation pit excavation model test device with engineering piles at the bottom of the pit according to claim 1, characterized in that: The monitoring ring positioning mold comprises a positioning plate, a distance measuring ruler and a level bubble. The distance measuring ruler is arranged around the positioning plate, and the level bubble is arranged on the positioning plate.

5. The foundation pit excavation model test device with engineering piles at the bottom of the pit according to claim 1, characterized in that: The foundation pit positioning mold includes adjusting screws, connecting grooves, wing plates, mold outer ring strips, mold inner plates and wing plate level bubbles; wing plates are connected on both sides of the mold outer ring strip, and adjusting screws and level bubbles are provided at the ends of the wing plates. The inner ring of the mold outer ring strip is provided with a mold inner plate; there is a certain gap between the mold inner plate and the front, back, left and right four surfaces of the mold outer ring strip, and the two are connected by a plurality of sliding sliders, and the sliders can slide in the four surfaces of the front, back, left and right.

6. The foundation pit excavation model test device with engineering piles at the bottom of the pit according to claim 1, characterized in that: The soil internal monitoring equipment includes a monitoring ring, a transverse micro soil pressure box, a transverse micro displacement sensor, a vertical micro soil pressure box, and a vertical micro displacement sensor; the transverse micro soil pressure box and the transverse micro displacement sensor are installed on the outer ring of the monitoring ring, and the vertical micro soil pressure box and the vertical micro displacement sensor are installed at the bottom of the monitoring ring.

7. The foundation pit excavation model test device with engineering piles at the bottom of the pit according to claim 1, characterized in that: The surface settlement monitoring equipment includes a fixed beam surface deformation displacement sensor, a connecting rod and a slot; a slot is provided at the bottom of the fixed beam; multiple connecting rods are provided on the side of the fixed beam, and each connecting rod is connected to a surface deformation displacement sensor.

8. The foundation pit excavation model test device with engineering piles at the bottom of the pit according to claim 1, characterized in that: The enclosure structure is made of PVC board material, and adjacent enclosure structures are connected by concave and convex matching; the model piles are made of hollow aluminum tubes, and adjacent model piles are connected by concave and convex matching to achieve the connection between the upper and lower model piles.

9. The foundation pit excavation model test device with engineering piles at the bottom of the pit according to claim 1, characterized in that: It also includes an inner support, which is a hollow tube structure with adjustable length and is fixed inside the enclosure structure.

10. A method for using the foundation pit excavation model test device with engineering piles at the bottom of the pit according to any one of claims 1 to 9, characterized in that: as follows: Step 1: Assemble the model box, hang it in the test site, and place the reaction device above the column of the model box; Step 2: Fill the soil layer by layer. After the soil is filled to the corresponding elevation, place the monitoring ring positioning mold at the specified monitoring height; Step 3: Install the micro earth pressure cell and micro displacement sensor monitoring element on the monitoring ring of the soil internal monitoring equipment in advance, place the monitoring ring in the monitoring ring positioning mold, and lead the cable of the monitoring element out from the corner of the mold box; Step 4: After the soil is filled to the surface of the model box, the foundation pit positioning mold is placed. The foundation pit positioning mold is placed on the side wall of the model box and fixed and leveled. The retaining structure is placed in the gap reserved between the mold inner plate and the mold outer ring of the positioning mold. The retaining structure is pressed into the soil in sections by the hydraulic jack in the reaction device. At the same time, the model piles are inserted into the model pile guide holes reserved on the mold inner plate. The model piles are pressed into the soil in sections by the hydraulic jack in the reaction device. Step 5: Remove the foundation pit positioning mold and deploy surface settlement monitoring equipment. The surface settlement monitoring equipment deploys soil surface settlement displacement sensors according to monitoring requirements. Step 6: The foundation pit is excavated in layers and internal supports are set at specified locations. During the excavation process, the soil pressure and displacement changes inside and outside the foundation pit are monitored in real time, and the relevant data are transmitted to the computer terminal.

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