Pile foundation simulation device for soft foundation and test method

Abstract

The invention discloses a pile foundation simulation device and a test method for a soft foundation in the technical field of roadbed settlement tests, the pile foundation simulation device comprises a base plate, a model pile and a displacement sensor, the simulation device capable of simulating a real roadbed can simulate the real roadbed, and the base plate of the simulation device can rotate mutually through a hinge. According to the device, the model pile can be hoisted and positioned in a beam frame suspension mode, so that the model pile can be kept stable in the soil filling process, the position of the model pile can be accurately positioned, the levelness and perpendicularity of the model pile can be guaranteed, and the construction efficiency is improved. The device is simple in structure, stable in structure and high in test efficiency, the roadbed can be conveniently adjusted to be in different gradients for detection, the base plate is additionally provided with a bag body, the base plate can simulate the rheological roadbed, the simulation range is wide, and test data are more accurate.

Description

Technical Field

[0001] The invention relates to the technical field of roadbed settlement testing, in particular to a pile foundation simulation device and a testing method for soft foundation. Background Art

[0002] A weak foundation is one composed primarily of silt, muddy soil, backfill, miscellaneous fill, or other highly compressible soil layers. This type of foundation has excessive natural moisture content, low bearing capacity, and is prone to sliding or consolidation settlement under load.

[0003] Dense gully-type soft steep slope foundations, with many gullies, may result in a undulating road surface, with the road surface mostly tilted. Furthermore, the roadbed contains a large amount of silt, some of which has a high water content and is highly fluid, resulting in rheological properties within the roadbed, posing a significant challenge to road use. When constructing super-high embankments on dense gully-type soft steep slope foundations, the pile foundation, as a key bearing structure, has a stability that directly impacts project safety. However, this type of foundation is characterized by large terrain undulations, uneven soil distribution, and numerous weak interlayers, making pile foundations prone to settlement and lateral displacement during construction and operation. Therefore, it is necessary to pre-test the roadbed in such geological conditions to predict the impact of the actual settlement and rheological state of the roadbed on the pile foundation at the bottom of the roadbed after construction. This can help determine how the size and other parameters of the pile foundation should be adjusted during construction to improve settlement after the roadbed is completed.

[0004] Existing pile foundation model test devices are mostly designed for homogeneous foundations and lack the ability to simulate complex terrain and soft foundations, making it difficult to accurately reflect the true mechanical behavior of pile foundations in dense gully-type soft steep slope foundations. In the existing technology, a flat plate is generally used with displacement sensors to locate the road surface and roadbed, that is, a conventional cement or asphalt hard base plate with a soft roadbed buried at the bottom. This method and structure cannot simulate the height difference changes of steep slope terrain, and does not consider the impact of the rheological properties of the soft foundation on the positioning of the pile foundation. In addition, traditional detection devices only detect the displacement changes of the road surface base plate, making it difficult to dynamically monitor the displacement and stress changes of the pile foundation during the filling process. This filling process will cause a large deviation between the test data and the actual project.

[0005] Based on this, the present invention designs a pile foundation simulation device and test method for soft foundation to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a pile foundation simulation device and test method for soft foundation, which can simulate the real roadbed with a more realistic test device, and the provided base plates can rotate with each other through hinges, so that the entire foundation road surface forms a wavy undulating structure. The device can also lift and position the model piles by means of a suspended beam frame, so that the model piles can remain stable during the filling process, and can accurately locate the position of the model piles and ensure the horizontality and verticality of the model piles, thereby ensuring the accurate position of the model piles during the test, providing effective guarantee for the accuracy of the test data. The device has a simple structure, a stable structure, and is easy to disassemble, has strong practicality, can conveniently adjust the roadbed to different slopes for testing, and has high test efficiency.

[0007] The present invention is achieved by: a pile foundation simulation device and a test method for soft foundation, comprising:

[0008] Base plate, model piles, displacement sensors, foundation pits and adjustment struts;

[0009] The foundation pit is a deep pit with an open top and a flat bottom;

[0010] A suspension beam is stably erected above the foundation pit in the front-rear direction, a traveling crane is hung on the suspension beam, and the traveling crane is erected directly above the foundation pit in a horizontally movable manner;

[0011] The upper and lower surfaces of the substrate are hard flat plates, a hollow tough capsule is sandwiched in the middle of the substrate, a material injection hole is opened on the side wall of the substrate, and a connecting pipe is installed in the material injection hole with a detachable seal;

[0012] The plurality of substrates are sequentially spliced ​​into a long strip structure along the front-to-back direction, and adjacent substrates are rotatably connected by hinges;

[0013] The injection hole of one of the substrates is also connected to an external water pump, and the inner cavities of the other substrates are sealed and connected in sequence through connecting pipes;

[0014] The model piles and the adjustment struts are stably and vertically arranged in the foundation pit;

[0015] The adjusting support rod is a hydraulic rod, and the adjusting support rod can be detachably supported vertically at the bottom of any base plate;

[0016] The model pile is a pile rod of fixed length, and a limit plate is locked on the top of the model pile. The limit plate is a support pad. The limit plate can be supported between the model pile and the base plate with an adjustable angle.

[0017] The model pile can be detachably hung on a sling under the vehicle;

[0018] The top of the model pile is stably supported on the bottom of any base plate through a limiting plate, and the lower end of the model pile is stably inserted into the bottom of the foundation pit;

[0019] A displacement sensor is installed on each of the model piles, and a pressure sensor is also provided at the bottom of each of the base plates;

[0020] The test method includes the following steps:

[0021] Step S1: First, the slope inclination and undulation shape of the road surface to be simulated are designed, and the support height of each base plate is planned, thereby obtaining the support point and length of each model pile on the base plate, and then pouring concrete to make the model pile according to the design;

[0022] Step S2, vertically placing an adjustment support rod in the foundation pit, stably installing the adjustment support rod below the base plate at the highest design point of the simulated road surface, and allowing the adjustment support rod to raise the base plate to a designed height;

[0023] Step S3: hoisting the model piles of matching lengths at their designed positions, and adjusting the angles of the limit plates by adjusting rods so that the top slope of the limit plates is consistent with the inclination angle of the bottom of the matching substrates, and then making the model piles and the bottom of the matching substrates form a stable support, and ensuring that each substrate is supported at the corresponding designed height position by a model pile;

[0024] Step S4: All the model piles are translated forward, backward, left, and right by a crane, and each model pile is hoisted to a preset position and height, and the bottom of the model pile is buried and stabilized at the bottom of the foundation pit. Displacement sensors are embedded in the top and side walls of the model piles, and each model pile is positioned by reading the position parameters of the displacement sensors, and the displacement sensor reading data on each model pile is recorded as its three-dimensional position parameter;

[0025] Step S5, filling the foundation pit with soil. When the soil is filled to the middle height position and the model piles in the foundation pit are sufficiently stably supported by the soil filling, the adjusting support rods are removed and the soil filling is continued until the soil layer material in the foundation pit is filled and compacted to the designed height.

[0026] Step S6: laying the base plates, ensuring that the bottom of each base plate is stably supported by the model piles and fill soil, and forming the designed undulating road surface after the base plates are laid, simulating the dense valley terrain;

[0027] Step S7: injecting a silica gel composite into the capsule of the substrate by a water pump to change the flow state of the inner cavity of the substrate so that the medium pressure of the capsule inside the substrate changes from small to large, dynamically simulating the long-term deformation characteristics of the weak foundation;

[0028] Step S8, checking the position parameters of the displacement sensor on each of the model piles, adjusting the position of the displaced model piles, and adjusting the horizontality and verticality of the model piles to ensure that the final position of each model pile after filling is completed is consistent with the set initial position;

[0029] Step S9, adding a load on the substrate;

[0030] In step S10, the parameter changes of each pressure sensor and each displacement sensor during step S7 and step S8 are recorded to obtain test data.

[0031] Furthermore, the suspension beam frame and the crane form a complete bridge crane.

[0032] Furthermore, a plurality of stake holes are provided at the bottom of the limiting plate, a plurality of adjustment rods are provided at the top of the model pile, and the model pile is locked with the stake holes through the adjustment rods;

[0033] The height gap between the model pile and the limiting plate in each direction is adjusted by lifting and lowering the adjusting rod, and at least four adjusting rods are provided on each model pile.

[0034] Furthermore, the connecting pipe is a high-pressure hose or a fixedly connected PVC high-pressure pipeline;

[0035] The upper and lower surfaces of the base plate are covered with concrete flat plates, and the middle layer of the base plate is a hollow rubber capsule.

[0036] Furthermore, the displacement sensor is embedded in the top of the model pile, and the top of the model pile has a groove, and the displacement sensor can be locked in the groove of the top of the model pile;

[0037] The pressure sensor is closely attached between the bottom of the substrate and the filling soil.

[0038] Furthermore, a plurality of cranes are hung on the suspension beam frame, and each of the model piles is hoisted and positioned by a crane.

[0039] Furthermore, the method further includes step S11, hoisting the model pile by the crane to tilt the model pile forward, backward, left and right, and recording parameter changes of the pressure sensor and each displacement sensor when each model pile forms different tilt angles.

[0040] The beneficial effects of the present invention are as follows: 1. The present invention adds multiple substrates, which can form a slope surface by coordinating the undulations between different substrates, thereby achieving the effect of accurately simulating and reproducing dense valley terrain, forming a more realistic complex height difference and slope road surface, and improving the authenticity of the test scene;

[0041] 2. The upper and lower surfaces of the substrate are made of rigid materials, and a capsule is sandwiched in the middle layer, which enables the device to simulate rheological properties. Variable stiffness material is injected into the middle capsule of the substrate. Combined with hydraulic control, it can dynamically simulate the long-term deformation characteristics of weak foundations, filling a technical gap that cannot be achieved by conventional tests.

[0042] 3. The model piles supported by the suspended beam frame are equipped with displacement sensors and pressure sensors, which can collect and analyze data in real time, provide a quantitative basis for pile foundation stability assessment, and reduce engineering risks. In addition, this device detects the bearing pressure of the base plate and the settlement of the model piles, which can more accurately understand the settlement state of the roadbed soil after being loaded. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] Figure 1 It is a schematic top view of the overall structure of the present invention;

[0045] Figure 2 This is a schematic side structural diagram of a flat substrate of the present invention;

[0046] Figure 3 This is a schematic diagram of the side structure of the sloped surface splicing of the substrate of the present invention;

[0047] Figure 4 This is a schematic diagram of a single substrate structure of the present invention;

[0048] Figure 5 This is a schematic diagram of the bottom structure of the limiting plate of the present invention;

[0049] Figure 6 It is a structural schematic diagram of the splicing state of the limiting plate and the model pile of the present invention.

[0050] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0051] 1-base plate, 11-hinge, 12-injection hole, 13-connecting pipe, 2-model pile, 21-limiting plate, 22-fixed pile hole, 23-adjusting rod, 3-displacement sensor, 31-pressure sensor, 4-foundation pit, 41-suspension beam, 42-crane, 5-adjusting support rod. DETAILED DESCRIPTION

[0052] See also Figures 1 to 6 As shown, the present invention provides a pile foundation simulation device and test method for soft foundation. In order to better understand the above technical solution, the above technical solution will be described in detail below in combination with the drawings and specific implementation methods of the specification.

[0053] In a specific embodiment of the technical solution of the present invention:

[0054] It includes a base plate 1, a model pile 2, a displacement sensor 3, a foundation pit 4 and an adjustment support rod 5;

[0055] The foundation pit 4 is a deep pit with an open top and a flat bottom;

[0056] A suspension beam 41 is stably mounted above the foundation pit 4, extending forward and backward. A crane 42 is suspended from the suspension beam 41, mounted directly above the foundation pit 4 and capable of horizontal movement. The crane 42 forms a complete bridge crane. The crane 42 moves horizontally, left and right, forward and backward, along the suspension beam 41, and has its own lifting ropes for lifting and lowering. This allows the model pile 2 to be raised and lowered vertically and laterally displaced, achieving precise positioning of the pile foundation in three dimensions and adapting to uneven settlement in weak foundations.

[0057] The upper and lower surfaces of the substrate 1 are hard flat plates, and a hollow tough capsule is sandwiched in the middle of the substrate 1. The side wall of the substrate 1 is provided with an injection hole 12, and a detachable sealing connection pipe 13 is installed in the injection hole 12; the connection pipe 13 is a high-pressure hose or a fixed PVC high-pressure pipe;

[0058] The upper and lower surfaces of the substrate 1 are covered with concrete flat plates, and the middle layer of the substrate 1 is a hollow rubber capsule. The internal pressure change makes the overall pressure state of the substrate 1 different. When the internal fluid is filled with a large pressure, a more stable roadbed is formed. When the internal capsule of the substrate 1 has less fluid, it forms a deformation, and there is still fluid flowing inside, forming a soft base rheological state. The inner cavity of the substrate 1 is connected to the external water pump through a hydraulic pipeline, so that the silicone compound is injected into the interior of the substrate 1. By changing its internal pressure, the bearing strength of the substrate 1 is adjusted, and then the road surface state with different hardness of the roadbed is simulated to achieve a simulation effect. When the internal pressure of the substrate 1 is small, the strength of the substrate 1 is relatively high. Low level, simulating a softer soil road surface. When the internal pressure of the substrate 1 is high, the surface of the substrate 1 is propped up to form a stable supporting road surface, and it cannot collapse and fluctuate, simulating cement or asphalt road surfaces. Road surfaces of different materials have different weights and surface firmness. As for the upper and lower surfaces of the substrate 1, the hard materials can be steel plates with a certain toughness or concrete flat plates. The middle layer is a high-pressure resistant rubber capsule. The material injected into the capsule can be a silicone composite. The pressure will not be particularly large. Generally, it only needs to achieve a stable support effect. If a completely hard substrate 1 is required, it can be replaced with a completely cement-cast substrate 1. This device simulates the road base surface in a rheological state.

[0059] It is precisely because this fluid is injected into the capsule of the substrate 1 that the device can simulate the rheological properties of a weak foundation, making the simulation of actual conditions more diverse.

[0060] Multiple base plates 1 are sequentially spliced ​​in the front-to-back direction to form a long strip structure. Adjacent base plates 1 are rotatably connected by hinges 11. The hinges 11 allow the base plates 11 to float up and down within a 70° range. That is, when the base plates 1 are horizontal, they can float up and down by 35° along the hinges 11.

[0061] The injection hole 12 of one of the substrates 1 is also connected to an external water pump. Generally, the water pump is connected to the substrate 11 at the middle position. The inner cavities of adjacent substrates 1 are sealed and connected through a connecting pipe 13. The inner cavities of other substrates 1 are sealed and connected in sequence through the connecting pipe 13. The injection holes 12 that do not need to be connected can be plugged with sealing plugs to ensure the airtightness of the injection holes 12.

[0062] The interior of the substrate 1 is injected with a liquid filler, which may be a composite silica gel;

[0063] The model piles 2 and the adjustable struts 5 are both stably and vertically arranged in the foundation pit 4; the model piles 2 are buried at different depths according to the experimental design to achieve the purpose of adjusting and supporting the base plate 1, and to adjust the base plate at different angles. The model piles 2 can adjust the support position left and right, or front and back, and then adjust the support position by adjusting the struts 5 to make the base plate 1 tilt left and right, or front and back, to achieve the effect of simulating a soft base road surface;

[0064] The adjusting support rod 5 is a hydraulic rod. The adjusting support rod 5 can be detachably supported vertically at the bottom of any substrate 1. A flat plate is fixedly installed on the top of the adjusting support rod 5. The flat plate can stably support the substrate 1 on the top of the adjusting support rod 5.

[0065] The model pile 2 is a pile rod of fixed length, and a limit plate 21 is locked on the top of the model pile 2. The limit plate 21 is a support pad, which can be a flat steel pad with greater versatility. The limit plate 21 can be supported between the model pile 2 and the base plate 1 with an adjustable angle.

[0066] A plurality of fixing holes 22 are provided at the bottom of the limiting plate 21, and a plurality of adjusting rods 23 are provided at the top of the model pile 2. The model pile 2 is locked with the fixing holes 22 through the adjusting rods 23;

[0067] The height gap between the model pile 2 and the limit plate 21 in each direction is adjusted by raising and lowering the adjusting rod 23. At least four adjusting rods 23 are set on each model pile 2. The supporting height between the model pile 2 and the limit plate 21 in each direction is adjusted by fitting the adjusting rod 23 and the nut to achieve the effect of adjusting the supporting angle of the limit plate 21, ensuring that the top of the model pile 2 remains in contact with the inclined or horizontal base plate 1.

[0068] The model pile 2 can be detachably hung on a sling below the crane 42 ; a plurality of cranes 42 are hung on the suspension beam 41 , and each model pile 2 is hoisted and positioned by a crane 42 .

[0069] The top of the model pile 2 is stably supported on the bottom of any base plate 1 by the limiting plate 21, and the lower end of the model pile 2 is stably inserted into the bottom of the foundation pit 4;

[0070] A displacement sensor 3 is installed on each model pile 2, and a pressure sensor 31 is also set at the bottom of each substrate 1; the displacement sensor 3 and the pressure sensor 31 are both wirelessly connected to a signal receiver, which is connected to the controller data, which can be Bluetooth, mobile network or LoRa network, as long as there is a wireless data connection.

[0071] The displacement sensor 3 is embedded in the top of the model pile 2. There is a groove on the top of the model pile 2. The displacement sensor 3 can be locked in the groove on the top of the model pile 2.

[0072] The pressure sensor 31 is closely attached between the bottom of the substrate 1 and the filling soil.

[0073] It should be noted that:

[0074] 1. In actual construction, after the pile foundation is completed, the roadbed will not be filled. Only before the pile foundation construction will the reinforcement material be filled to make the roadbed more stable. During construction, the pile foundation construction will be carried out after the filling is completed. In simulation testing, it is just the opposite. The pile foundation needs to be set first, and then the soil is filled into the simulated experimental foundation pit 4. The filling process will also cause force changes on the test model pile 2, and even the force on the left, right, front and back is uneven. In real soil, the stress base plate inside the roadbed soil remains stable. The existing testing method ignores the force and position changes of the model pile 2 during the filling process, resulting in the pile body itself being unbalanced. The subsequent natural data of the test cannot reach the design accuracy. The present device limits the position of the model pile 2 to ensure that the model pile 2 remains fixed in the filling process. After the filling is completed, the model pile 2 has remained stable. Then the positioning suspension beam frame 41 and other positioning structures are removed. In the process of simulating the roadbed filling and compaction in the foundation pit 4, it is effectively ensured that the position of the model pile 2 remains stable, and the base plate 1 is stably supported.

[0075] 2. Existing test roadbeds are all complete hard flat plate substrates 1, resulting in either a flat road or a unilaterally inclined slope, which is completely unable to simulate the undulating road surface formed in the dense gully-type soft steep slope foundation. This type of road surface has a very different pressure on the roadbed soil and the pressure change on the pile foundation, resulting in a significant difference in force change and settlement. Such a hard complete substrate 1 sometimes has technical deficiencies in simulating actual roadbed settlement. The roadbed of this device is composed of multiple separate substrates 1 that are movably connected to each other, so that the substrate 1 of the road surface can form a wavy state for simulation, thereby more realistically simulating the actual state of the dense gully-type soft steep slope foundation;

[0076] 3. Existing test devices are all for flat roads, and wavy roads have not been considered. Therefore, there is no need for the support and coordination of the base plate 1. Because this device needs to adjust the wavy road surface, each model pile 2 can control its height individually, and instead of slowly piling up soil for reinforcement, it is adjusted by the suspension beam 41 and the crane 42 to control the front and rear position of the model pile 2, as well as its left and right support position. After positioning is completed, the adjustment rod 23 can also be used to adjust the coordination angle between the limit plate 21 and the base plate 1, thereby adjusting the road slope state of the base plate 1.

[0077] The present invention completes the test by following steps:

[0078] Step S1: First, the slope inclination and undulation shape of the road surface to be simulated are designed, and the support height of each base plate 1 is planned to correspond to the simulated shape of the road surface design. Then, the support point and length of each model pile 2 on the base plate 1 are obtained, and the model pile 2 is cast with concrete according to the design;

[0079] Step S2: vertically placing the adjusting support rod 5 in the foundation pit 4, stably installing the adjusting support rod 5 below the base plate 1 at the highest design point of the simulated road surface, and allowing the adjusting support rod 5 to support and raise the base plate 1 to the designed height;

[0080] Step S3: hoist the model pile 2 of matching length to its designed position, and adjust the angle of the limit plate 21 through the adjustment rod 23 so that the top inclined surface of the limit plate 21 is consistent with the inclination angle of the bottom of the matching base plate 1. Then, the model pile 2 and the bottom of the matching base plate 1 form a stable support, and ensure that each base plate 1 is supported at the corresponding designed height position by a model pile 2;

[0081] Step S4: All model piles 2 are translated forward, backward, left, and right by the crane 42, and each model pile 2 is hoisted to a preset position and height, and the bottom of the model pile 2 is firmly buried at the bottom of the foundation pit 4. Displacement sensors 3 are embedded in the top and side walls of the model piles 2. Each model pile 2 is positioned by reading position parameters of the displacement sensors 3, and the data read by the displacement sensors 3 on each model pile 2 is recorded as its three-dimensional position parameter.

[0082] Step S5: Fill the foundation pit 4 with soil. The compaction degree and material of the soil in the foundation pit 4 also simulate the actual soil layer test data. When the soil is filled to the middle height, the model piles 2 in the foundation pit 4 form a sufficiently stable support state through the soil filling. The adjusting support rods 5 are removed and the soil filling is continued until the soil material in the foundation pit 4 is filled and compacted to the designed height.

[0083] Step S6: Laying the base plate 1, ensuring that the bottom of each base plate 1 is stably supported by the model piles 2 and fill soil. After the base plate 1 is laid, the designed undulating road surface is formed to simulate the dense valley terrain;

[0084] Step S7: injecting a silica gel composite into the capsule of the substrate 1 by a water pump, changing the flow state of the inner cavity of the substrate 1 so that the medium pressure of the capsule inside the substrate 1 changes from small to large, dynamically simulating the long-term deformation characteristics of the weak foundation;

[0085] Step S8, checking the position parameters of the displacement sensor 3 on each model pile 2, adjusting the position of the displaced model pile 2, adjusting the horizontality and verticality of the model pile 2, ensuring that the final position of each model pile 2 after the filling is completed is consistent with the set initial position, and confirming that the position of the model pile 2 is not affected by the filling process;

[0086] Step S9, adding a load to the substrate 1, which can be a heavy object pressing continuously or a vehicle running;

[0087] In step S10, the parameter changes of each pressure sensor 31 and each displacement sensor 3 during the process of step S7 and step S8 are recorded to obtain test data.

[0088] The method further includes step S11 of hoisting the model pile 2 by the crane 42 to tilt the model pile 2 forward, backward, left, and right, and recording parameter changes of the pressure sensor 31 and each displacement sensor 3 when each model pile 2 forms different tilt angles.

[0089] This device can obtain accurate experimental results through this test method, and can simulate the internal rheological state of the roadbed, simulate the road surface into a one-way inclined road surface, and simulate the undulating wavy road surface with dense valley terrain. It can also monitor the bearing state of road surfaces of different forms, as well as the rising and falling conditions of the model pile 2 when buried in the soil layer. It is flexible to use and can obtain more comprehensive terrain data.

[0090] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A pile foundation simulation device and test method for soft foundation, characterized in that: The simulation device comprises: a base plate (1), a model pile (2), a displacement sensor (3), a foundation pit (4) and an adjustment support rod (5); The foundation pit (4) is a deep pit with an open top, and the bottom of the foundation pit (4) is flat; A suspension beam (41) is stably erected above the foundation pit (4) in the front-rear direction, a traveling crane (42) is hung on the suspension beam (41), and the traveling crane (42) is erected directly above the foundation pit (4) in a horizontally movable manner; The upper and lower surfaces of the substrate (1) are hard flat plates, a hollow tough capsule is sandwiched in the middle of the substrate (1), a material injection hole (12) is provided on the side wall of the substrate (1), and a connecting pipe (13) is installed in the material injection hole (12) in a detachable seal; The plurality of substrates (1) are sequentially spliced ​​in the front-to-back direction to form a long strip structure, and adjacent substrates (1) are rotatably connected via hinges (11); The injection hole (12) of one of the substrates (1) is also connected to an external water pump, and the inner cavities of the other substrates (1) are sealed and connected in sequence through connecting pipes (13); The model pile (2) and the adjustment support rod (5) are both stably and vertically arranged in the foundation pit (4); The adjusting support rod (5) is a hydraulic rod, and the adjusting support rod (5) can be detachably supported vertically at the bottom of any base plate (1); The model pile (2) is a pile rod of fixed length, and a limit plate (21) is locked on the top of the model pile (2). The limit plate (21) is a support pad. The limit plate (21) is supported between the model pile (2) and the base plate (1) in an adjustable angle. The model pile (2) can be detachably hung on a sling below the traveling crane (42); The top of the model pile (2) is stably supported on the bottom of any base plate (1) through a limiting plate (21), and the lower end of the model pile (2) is stably inserted into the bottom of the foundation pit (4); A displacement sensor (3) is installed on each of the model piles (2), and a pressure sensor (31) is also provided at the bottom of each of the base plates (1); The test method includes the following steps: Step S1, first designing the slope inclination and undulating shape of the road surface to be simulated, and planning the support height of each base plate (1), thereby obtaining the support point and length of each model pile (2) required for the base plate (1), and casting concrete to make the model pile (2) according to the design; Step S2, vertically placing an adjusting support rod (5) in the foundation pit (4), stably installing the adjusting support rod (5) below the base plate (1) at the highest design point of the simulated road surface, and allowing the adjusting support rod (5) to support and raise the base plate (1) to a designed height; Step S3, hoisting the model pile (2) of matching length at its designed position, and adjusting the angle of the limit plate (21) through the adjusting rod (23) so that the top inclined surface of the limit plate (21) is consistent with the bottom inclined angle of the matched base plate (1), and then forming a stable support between the model pile (2) and the bottom of the matched base plate (1), and ensuring that each base plate (1) is supported at the corresponding designed height position by a model pile (2); Step S4, all the model piles (2) are translated forward, backward, left, and right by a traveling crane (42), and each model pile (2) is hoisted to a preset position and height, and the bottom of the model pile (2) is stably buried at the bottom of the foundation pit (4), and displacement sensors (3) are embedded in the top sidewalls of the model piles (2). Each model pile (2) is positioned by reading the position parameters of the displacement sensors (3), and the data read by the displacement sensors (3) on each model pile (2) is recorded as its three-dimensional position parameter; Step S5, filling the foundation pit (4) with soil. When the soil is filled to an intermediate height, the model piles (2) in the foundation pit (4) are in a sufficiently stable supporting state by the filling. The adjusting support rods (5) are removed, and the soil filling is continued until the soil layer material in the foundation pit (4) is filled and compacted to the designed height. Step S6, laying the base plate (1), ensuring that the bottom of each base plate (1) is stably supported by the model piles (2) and fill soil, and forming a designed undulating road surface after paving the base plate (1), simulating a dense valley terrain; Step S7, injecting a silica gel composite into the capsule of the substrate (1) by a water pump, changing the flow state of the inner cavity of the substrate (1), causing the medium pressure of the capsule inside the substrate (1) to change from small to large, and dynamically simulating the long-term deformation characteristics of the weak foundation; Step S8, checking the position parameters of the displacement sensor (3) on each of the model piles (2), adjusting the position of the displaced model piles (2), adjusting the horizontality and verticality of the model piles (2), and ensuring that the final position of each model pile (2) after filling is completed is consistent with the set initial position; Step S9, adding a load on the substrate (1); Step S10, recording the parameter changes of each pressure sensor (31) and each displacement sensor (3) during step S7 and step S8 to obtain test data.

2. The pile foundation simulation device and test method for soft foundation according to claim 1, characterized in that: The suspension beam frame (41) and the crane (42) form a complete bridge crane.

3. The pile foundation simulation device and test method for soft foundation according to claim 1, characterized in that: A plurality of pile holes (22) are provided at the bottom of the limiting plate (21), a plurality of adjustment rods (23) are provided at the top of the model pile (2), and the model pile (2) is locked with the pile holes (22) via the adjustment rods (23); The height gap between the model pile (2) and the limiting plate (21) in each direction is adjusted by raising and lowering the adjusting rod (23), and at least four adjusting rods (23) are provided on each model pile (2).

4. The pile foundation simulation device and test method for soft foundation according to claim 1, characterized in that: The connecting pipe (13) is a high-pressure hose or a fixedly connected PVC high-pressure pipeline; The upper and lower surfaces of the base plate (1) are covered with concrete flat plates, and the middle layer of the base plate (1) is a hollow rubber capsule.

5. The pile foundation simulation device and test method for soft foundation according to claim 1, characterized in that: The displacement sensor (3) is embedded in the top of the model pile (2). The top of the model pile (2) has a groove, and the displacement sensor (3) can be locked in the groove at the top of the model pile (2). The pressure sensor (31) is tightly attached between the bottom of the substrate (1) and the fill.

6. The pile foundation simulation device and test method for soft foundation according to claim 1, characterized in that: A plurality of cranes (42) are hung on the suspension beam frame (41), and each model pile (2) is hoisted and positioned by a crane (42).

7. The soft foundation pile foundation simulation device and test method according to claim 6, characterized in that: The method further comprises step S11, wherein the model pile (2) is hoisted by the crane (42), so that the position of the model pile (2) is tilted forward, backward, left, and right, and parameter changes of the pressure sensor (31) and each displacement sensor (3) are recorded when each model pile (2) forms different tilt angles.

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