Combined static pressure group pile centrifuge test device and test method

Abstract

This invention discloses a combined static pressure pile centrifuge testing device and method, comprising a model box with an open top, filled with a soft soil sample, and several sensors arranged within the sample; and a track box arranged within the model box, containing a first track and a second track arranged vertically. The first track is coaxially fitted within the second track, wherein a model pile is slidably fitted at the first track, and a counterweight box is slidably fitted at the second track, with a first through hole vertically formed in the counterweight box for the first track to pass through. The combined static pressure pile centrifuge testing device of this invention enables rapid separation of the counterweight box from the model pile, making the movement of the model pile after detaching from the track box more closely resemble the actual stress state of a static pressure pile under the influence of adjacent piles after penetration. This allows for obtaining the stress and displacement changes of the surrounding soil during the actual static pressure pile driving process.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering technology, specifically relating to a combined static pressure pile centrifuge testing device. Background Technology

[0002] Static pressure piles are a widely used pile foundation in foundation engineering in soft soil areas, and their advantages, such as fast construction speed, low noise, and high single pile bearing capacity, have been widely recognized. However, when installing static pressure piles in saturated soft clay foundations, the pile body will displace an equal volume of soil, causing lateral displacement, excess pore water pressure, and lateral soil pressure in the surrounding soil, which in turn affects the safety of adjacent buildings. To address the issues of low controllability and poor repeatability in field tests of static pressure piles, centrifugal testing using a hypergravity physical model is an effective way to simulate static pressure pile construction. The hypergravity field can compensate for the influence of model scaling on stress and strain, and can realistically reproduce the soil displacement effect of static pressure pile groups.

[0003] Existing research on the soil displacement effect of static pressure piles mainly focuses on single piles, while research on the soil displacement effect of static pressure pile groups is relatively limited. Furthermore, existing simulation tests primarily use motors to provide vertical displacement for pile driving; however, the adjusted drive speed of the motor is often constant, regardless of the underlying soil composition or soil conditions, resulting in a constant rate at which the static pressure pile is driven in. This fails to reflect the influence of soil conditions on the installation rate of static pressure piles and cannot obtain the stress and displacement changes of the surrounding soil during the actual static pressure pile driving process. Summary of the Invention

[0004] In response to one or more of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a combined static pressure pile centrifuge test device to solve the problem that the existing static pressure pile test cannot truly reflect the stress and displacement changes of the surrounding soil under the influence of geological conditions.

[0005] To achieve the above objectives, the present invention provides a combined static pressure pile centrifuge testing device, comprising:

[0006] A model box with an opening at the top, the model box being filled with a soft soil sample, and several sensors being arranged inside the soft soil sample.

[0007] A track box is provided inside the model box. A first track and a second track are arranged vertically inside the track box. The first track is coaxially sleeved inside the second track. A model pile is slidably provided on the first track. A counterweight box is slidably provided on the second track. The counterweight box has a first through hole in the vertical direction for the first track to pass through. The counterweight box is located above the model pile.

[0008] The bottom of the track box has a second through hole that communicates with the first track. The second through hole is provided with an elastic element in the circumferential direction. The elastic element and the counterweight box overlap at least partially in the vertical direction, and the elastic force direction of the elastic element is the same as the movement direction of the counterweight box.

[0009] As a further improvement of the present invention, the upper end of the counterweight box is open, the lower end of the counterweight box is provided with the first through hole, and a counterweight pile driver is provided at the first through hole.

[0010] The counterweight pile driver includes a pile driving support and a plurality of metal strips arranged around the pile driving support. The pile driving support includes a horizontally arranged abutment surface for abutting against the downward pressing of the model pile.

[0011] Multiple metal strips are arranged in a "┐" shape, with one end connected to the pile support and the other end extending into the first through hole and attached to the bottom surface of the counterweight box. A strip-shaped window is left between the multiple metal strips for the first track to pass through.

[0012] As a further improvement of the present invention, the first track includes a plurality of vertically arranged slide rails, the plurality of slide rails passing vertically through the strip-shaped window, and the slide rails having a plurality of pile-holding pulleys arranged vertically, the plurality of pile-holding pulleys slidingly engaging with the outer periphery of the model pile.

[0013] As a further improvement of the present invention, the second track is a cylindrical structure, and the inner wall of the second track is provided with a plurality of box-holding pulleys, which are slidably connected to the outer wall of the counterweight box.

[0014] As a further improvement of the present invention, the elastic element includes a plurality of elastic pins arranged circumferentially along the second through hole. Each of the plurality of elastic pins includes an elastic mechanism and a locking mechanism. The locking mechanism is disposed within the elastic mechanism. The locking mechanism is arranged in multiple segments along the vertical direction, and the locking mechanism can extend or lock vertically.

[0015] As a further improvement of the present invention, the track box is also provided with a closing mechanism at the second through hole. The closing mechanism includes multiple snap-lock gates, which are controlled by a remote sensing mechanism to open and close the second through hole under the control of the remote sensing mechanism.

[0016] As a further improvement of the present invention, a plurality of support slots are vertically spaced along the outer periphery of the track box, and the plurality of support slots are circumferentially embedded in the outer wall of the track box. A combined support is mounted on the upper end of the model box, and the combined support forms a plurality of slots that match the support slots, and the support slots are embedded in the combined support.

[0017] As a further improvement of the present invention, the combined support is provided with a plurality of slots that match the support groove, and there are a plurality of track boxes, which are combined and arranged on the combined support.

[0018] As a further improvement of the present invention, at least one drainage valve is provided at the bottom of the model box.

[0019] This application also includes a combined static pressure pile group centrifugal test method, which includes the following steps:

[0020] S1. Test the initial moisture content of the soft soil sample. Adjust the moisture content of the soft soil sample according to the test requirements. Place the soft soil sample with the adjusted moisture content in the model box and embed the sensor in the set soil layer.

[0021] S2. Install the model box on the centrifuge platform, rotate and accelerate to the set acceleration and continue for a preset time, observe the data transmitted by the sensor inside the model box, and judge the degree of consolidation of the soft soil sample based on the data.

[0022] S3. Compress and reset the elastic element, load the model pile, close the first through hole, load the counterweight in the counterweight box, and complete the assembly of each track box in sequence.

[0023] S4. Arrange each track box on the combined support and fix it on the upper part of the model box. Adjust the installation height of the track box so that the bottom of the model pile contacts the surface of the soft soil sample.

[0024] S5. Release the model piles in sequence according to the test requirements, and record the soil pressure and pore water pressure caused by each model pile penetrating the soft soil sample. Stop centrifugation when all model piles have been penetrated and the sensor monitoring data remain unchanged.

[0025] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0026] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include:

[0027] (1) The combined static pressure pile centrifuge test device of the present invention is configured with a counterweight box and a model pile, and a first track and a second track are arranged coaxially in the track box. When the model pile is inside the track box, the counterweight box can press down on the model pile. When the model pile is separated from the track box, the counterweight box is lifted by the elastic element at the bottom of the track box, thereby realizing the rapid separation of the counterweight box and the model pile. After the model pile is separated from the track box, there is no load or constraint on the top of the model pile. When subsequent piles are pressed in, the influence on the previously pressed piles can be truly reflected, and the stress and displacement change law of the surrounding soil during the static pressure pile pressing process can be obtained, thereby improving the authenticity of the simulation test and the accuracy and richness of the data.

[0028] (2) The combined static pressure pile centrifuge test device of the present invention sets a counterweight pile driver at the bottom of the counterweight box. The counterweight pile driver itself only plays a pressing role on the model pile. After the model pile leaves the track box, it separates from the model pile, so that the downward pressing and penetration of the model pile is more in line with the actual penetration of static pressure pile. In addition, the design of the counterweight pile driver realizes the pressing of the model pile and does not hinder the arrangement and design of the first track around the model pile, which improves the stability of the model pile during the falling process and ensures the stable conduct of the simulation test.

[0029] (3) The combined static pressure pile centrifuge test device of the present invention, by setting up a combined support, enables a single model box to carry out pressing tests on multiple model piles at the same time, and can realize various controls on the pile plane layout, including horizontal and vertical pile spacing, rectangular layout and quincunx layout.

[0030] (4) The combined static pressure pile centrifuge test device of the present invention can realize the static pressure pile group pressing test by remotely releasing the model piles through each track box loaded with model piles, thereby achieving different pile arrangements and pressing sequences.

[0031] (5) The combined static pressure pile centrifuge test device of the present invention can adjust the pile driving load by adding or removing weights in the track box counterweight box, and can realize the test of the maximum driving depth of static pressure piles in different strata under different pile driving loads. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the combined static pressure pile centrifuge test device in an embodiment of the present invention;

[0033] Figure 2 This is a top view schematic diagram of one of the combined static pressure pile centrifuge test devices in an embodiment of the present invention;

[0034] Figure 3 This is a top view of another combined static pressure pile centrifuge test device in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the assembly structure of the counterweight box and the second track in an embodiment of the present invention;

[0036] Figure 5 This is a top view of the counterweight box structure in an embodiment of the present invention;

[0037] Figure 6 This is a perspective view of the interior of the track box in an embodiment of the present invention;

[0038] Figure 7 This is a schematic diagram of the assembly structure of the counterweight box and the model pile inside the track box in an embodiment of the present invention;

[0039] Figure 8 This is a schematic diagram of the extended state of the elastic pin in an embodiment of the present invention;

[0040] Figure 9 This is a schematic diagram of the compressed state structure of the elastic pin in an embodiment of the present invention;

[0041] Figure 10 This is a schematic diagram of the snap ring gate structure in an embodiment of the present invention.

[0042] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically:

[0043] 1. Model box; 2. Track box; 3. First track; 4. Second track; 5. Counterweight box; 6. Model pile; 7. Elastic pin; 8. Pile support; 9. Metal strip; 10. Strip window; 11. Pile holding pulley; 12. Second through hole; 13. Box holding pulley; 14. Spring snap gate; 15. Support groove; 16. Combined support; 17. Locking device;

[0044] 701. Flexible mechanism; 702. Locking mechanism. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0046] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0048] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0049] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0050] Example:

[0051] Please see Figures 1-10 The combined static pressure pile centrifuge test device in a preferred embodiment of the present invention includes a model box 1, which has an open top and is filled with a soft soil sample. Several sensors are arranged inside the soft soil sample. A track box 2 is also arranged inside the model box 1. A first track 3 and a second track 4 are vertically arranged inside the track box 2. The first track 3 is coaxially fitted inside the second track 4. A model pile 6 is slidably fitted at the first track 3, and a counterweight box 5 is slidably fitted at the second track 4. A first through hole is vertically opened in the counterweight box 5 for the first track 3 to pass through. This ensures that the counterweight box 5 does not interfere with the first track 3 when pressing down the model pile 6. At the same time, the bottom of the track box 2 is also provided with a second through hole 12 for the model pile 6 to pass through, so as to press the model pile 6 in the track box 2 into the soft soil sample. The second through hole 12 is provided with an elastic element in the circumference. The elastic element and the counterweight box 5 overlap at least partially in the vertical direction, so that when the counterweight box 5 falls to the bottom of the counterweight box 5, it contacts the elastic element. The elastic element applies a reverse elastic force to stop the counterweight box 5 from moving, thereby realizing the separation of the counterweight box 5 and the model pile 6, so that the falling of the model pile 6 is closer to the actual penetration of the static pressure pile.

[0052] The combined static pressure pile centrifuge test device of the present invention uses a counterweight box 5 and a model pile 6, and a first track 3 and a second track 4 are coaxially arranged in a track box 2. When the model pile 6 is inside the track box 2, the counterweight box 5 can press down on the model pile 6 accordingly. After the model pile 6 is separated from the track box 2, the counterweight box 5 is lifted up by the elastic element at the bottom of the track box 2, realizing the rapid separation of the counterweight box 5 and the model pile 6. After the model pile 6 is separated from the track box 2, the top of the model pile 6 is unloaded and unrestrained. When subsequent model piles 6 are pressed in, the influence on the previously pressed model piles 6 can be realistically reflected, and the stress and displacement changes of the surrounding soil during the static pressure pile pressing process can be obtained, thereby improving the realism of the simulation test and the accuracy and richness of the data.

[0053] Furthermore, as a preferred embodiment of the present invention, the upper end of the counterweight box 5 is open, and the aforementioned first through hole is formed at the lower end of the counterweight box 5. A counterweight pile driver is provided at the first through hole. The counterweight pile driver specifically includes a pile support 8 and a plurality of metal strips 9 arranged around the pile support 8. The pile support 8 includes a horizontally arranged abutment surface for abutting against the pressed model pile 6. The metal strips 9 are arranged in a "┐" shape. One end of the metal strip 9 is connected to the pile support 8, and the other end extends into the first through hole and is attached to the bottom surface of the counterweight box 5. A strip-shaped window 10 is reserved between the plurality of metal strips 9 to allow the first track 3 to pass through. Specifically, the bottom surface of the counterweight box 5 forms a first through hole for the first track 3 to pass through, which correspondingly allows the model pile 6 to also pass through the first through hole. Therefore, a counterweight pile driver is provided at the first through hole, and its pile support 8 presses against the model pile 6. The strip-shaped window 10 between the metal strips 9 allows the first track 3 to pass through.

[0054] It is worth noting that the space inside the counterweight box 5 is used to place weights, etc., to apply different pressures to the model pile 6. Simultaneously, the weights can press the metal strip 9 tightly against the bottom surface of the counterweight box 5, ensuring stable pressing of the counterweight pile driver onto the model pile 6. At the same time, the vertical structure of the metal strip 9 expands outward, forming a claw-like structure centered on the pile support 8, so that the first track 3 will not interfere with the pile support 8 when it vertically passes through the strip-shaped window 10. Preferably, the metal strip 9 in this application has a certain degree of extensibility. By compressing the metal strip 9 towards the center of the pile support 8, the metal strip 9 can pass through the first through hole, and then the metal strip 9 expands outwards, allowing the counterweight pile driver to be hung at the bottom of the counterweight box 5.

[0055] More preferably, the first track 3 in this application includes a plurality of vertically arranged slide rails, which pass vertically through the strip window 10. At the same time, a plurality of pile-holding pulleys 11 are arranged vertically on the slide rails. The plurality of pile-holding pulleys 11 slide in contact with the outer periphery of the model pile 6 to guide the model pile 6 to fall steadily vertically and avoid deviation during its fall.

[0056] Furthermore, the second track 4 in this application is a cylindrical structure, and the inner wall of the second track 4 is provided with a plurality of box-holding pulleys 13. The plurality of box-holding pulleys 13 are used to slide and connect with the outer wall of the counterweight box 5, so as to drive the counterweight box 5 to fall vertically and stably and apply the load of the model pile 6.

[0057] More preferably, the aforementioned elastic element includes a plurality of elastic pins 7 arranged circumferentially along the first through hole. Each of the plurality of elastic pins 7 includes an elastic mechanism 701 and a locking mechanism 702, wherein the locking mechanism 702 is disposed within the elastic mechanism 701, and the locking mechanism 702 is arranged in multiple segments along the vertical direction, and can extend or lock vertically. Specifically, the elastic pins 7 are mainly used to lift upwards when the counterweight box 5 descends and contacts the end face of the elastic pin 7, so as to prevent the counterweight box 5 from continuing to descend, and lock after being raised to a specific height, thereby realizing the separation of the counterweight pile driver at the bottom of the counterweight box 5 from the model pile 6. The elastic mechanism 701 can be a spring or other elastic material. When the elastic mechanism 701 is a spring, the spring is sleeved on the outer periphery of the locking mechanism 702. The locking mechanism 702 is set in a multi-segment form to facilitate the overall downward compression of the elastic pin 7. The vertical extension or locking of the locking mechanism 702 is to ensure that the elastic pin 7 can switch between the compressed state and the straightened state to lift the counterweight box 5 and ensure that it will not fall before the next repeated test.

[0058] More preferably, the track box 2 is further provided with a closing mechanism at the second through hole 12. This closing mechanism includes multiple snap-lock gates 14, which are controlled by a remote sensing mechanism to open and close the second through hole 12. Since the first track 3 vertically connects to the second through hole 12, if there is no closing mechanism at the second through hole 12, the model pile 6 will slide out of the track box 2 along the first track 3, making the test impossible. Therefore, this application provides a closing mechanism at the second through hole 12. When the model pile 6 needs to be assembled into the track box 2, the remote sensing mechanism controls the snap-lock gates 14 to close the second through hole 12, and the lower end of the model pile 6 abuts against the snap-lock gates 14, preventing the model pile 6 from falling. When the model pile 6 needs to be released, the remote sensing mechanism controls the snap-lock gates 14 to open, and the model pile 6 falls and slides out from the second through hole 12.

[0059] Furthermore, as a preferred embodiment of the present invention, the track box 2 in this application has multiple support slots 15 arranged vertically at intervals along its outer periphery. These support slots 15 are circumferentially embedded in the outer wall of the track box 2. Simultaneously, a combined support 16 is mounted on the upper end of the model box 1. This combined support 16 has multiple slots that match the support slots 15. The track box 2 is correspondingly embedded in these slots, and the support slots 15 abut against the combined support 16. This application achieves relative fixation between the track box 2 and the model box 1 through the cooperation of the external support slots 15 and the combined support 16. Furthermore, the vertically spaced support slots 15 on the outer wall of the track box 2 allow for corresponding height adjustments between the track box 2 and the model box 1, facilitating the adjustment of the bottom of the track box 2 to be flush with the surface of the soft soil sample for centrifugation testing.

[0060] Furthermore, the aforementioned combined support 16 has multiple slots that match the support groove 15, and multiple track boxes 2 are correspondingly provided. These multiple track boxes 2 can be arbitrarily combined and arranged on the combined support 16 as needed. Specifically, the combined support 16 in this application includes multiple rods arranged side-by-side at the upper end of the model box 1, with the ends of the rods supporting the perimeter of the model box 1, forming a support structure above the soft soil sample. Simultaneously, locking fasteners 17 are also provided around the outer wall of the track box 2. These locking fasteners 17 are screws or other fixing structures. After the track box 2 is relatively fixed on the model box 1, the locking fasteners 17 are used to further fix the track box 2 to the combined support 16, achieving a fixed connection between the track box 2 and the model box 1.

[0061] Preferably, in this application, the bottom of the track box 2 is provided with a disc-shaped cavity, and the stacked cavity is fitted around the second through hole 12. The aforementioned elastic pin 7, snap ring gate 14, etc. are installed in the disc-shaped cavity.

[0062] Furthermore, as a preferred embodiment of the present invention, the bottom of the model box 1 in this application is also provided with at least one drainage valve, which is used to adjust the moisture content in the soft soil test. Meanwhile, the sensors in this application are a pore water pressure gauge and an earth pressure gauge, used to acquire the displacement, earth pressure, and pore water pressure of the soft soil sample.

[0063] Preferably, the model box 1 in this application is welded from aluminum alloy plates, with an open upper end and a closed lower end. The model box 1 has a metal frame structure, with perforated plates around its perimeter. Tempered glass is fixed to the inner side of the perforated areas to facilitate observation of the internal sensor placement. The upper end of the model box 1 has slots on its four sides for mounting the combined bracket 16.

[0064] Based on the combined static pressure pile centrifuge testing device in this application, this application also includes a combined static pressure pile centrifuge testing method, which includes the following steps:

[0065] S1. Test the initial moisture content of the soft soil sample. Adjust the moisture content of the soft soil sample according to the test requirements. Place the soft soil sample with adjusted moisture content in the model box 1 and embed the sensor in the set soil layer.

[0066] S2. Install model box 1 on the centrifuge platform, rotate and accelerate to the set acceleration and continue for a preset time, observe the data transmitted by the sensor inside model box 1, and judge the degree of consolidation of the soft soil sample based on the data.

[0067] S3. Compress and reset the elastic element, load the model pile 6, close the first through hole, load the counterweight in the counterweight box 5, and complete the assembly of each track box 2 in sequence.

[0068] S4. Arrange each track box 2 on the combined support 16 and fix it on the upper part of the model box 1. Adjust the installation height of the track box 2 so that the bottom of the model pile 6 contacts the surface of the soft soil sample.

[0069] S5. Release the model piles 6 sequentially according to the test requirements, and record the soil pressure and pore water pressure caused by each model pile 6 during the penetration of the soft soil sample. Stop the centrifuge when all model piles 6 have been penetrated and the sensor monitoring data remains unchanged. Specifically, in this application, the release of the model piles 6 is controlled by a remote sensing mechanism at the bottom of the track box 2. The remote sensing mechanism controls the opening of the snap ring gate 14 to realize the release of the model piles 6.

[0070] The combined static pressure pile centrifuge test method in this invention is matched with the above-mentioned combined static pressure pile centrifuge test device to realize the simulation test of static pressure piles. This centrifuge test method can simulate the stress and displacement change law of the surrounding soil during the static pressure pile driving process under real conditions, which can improve the realism of the simulation test and the accuracy of the data obtained.

[0071] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A combined static pressure pile centrifuge testing device, characterized in that, include: A model box with an opening at the top, the model box being filled with a soft soil sample, and several sensors being arranged inside the soft soil sample. A track box is disposed inside a model box. A first track and a second track are vertically arranged inside the track box. The first track is coaxially fitted inside the second track, and a model pile is slidably mounted on the first track. A counterweight box is slidably mounted on the second track. The counterweight box has a first through hole vertically for the first track to pass through, and the counterweight box is positioned above the model pile. Multiple support slots are vertically spaced along the outer periphery of the track box, and these slots are circumferentially embedded in the outer wall of the track box. A combined support is mounted on the upper end of the model box, and the combined support has multiple slots that match the support slots. The support slots are embedded in the combined support. Multiple track boxes are combined and arranged on the combined support. The bottom of the track box has a second through hole that communicates with the first track. The second through hole is provided with an elastic element in the circumferential direction. The elastic element and the counterweight box overlap at least partially in the vertical direction, and the elastic force direction of the elastic element is the same as the movement direction of the counterweight box.

2. The combined static pressure pile centrifuge test device according to claim 1, characterized in that, The counterweight box has an opening at the top and the first through hole is provided at the bottom of the counterweight box. A counterweight pile driver is provided at the first through hole. The counterweight pile driver includes a pile driving support and a plurality of metal strips arranged around the pile driving support. The pile driving support includes a horizontally arranged abutment surface for abutting against the downward pressing of the model pile. Multiple metal strips are arranged in a "┐" shape, with one end connected to the pile support and the other end extending into the first through hole and attached to the bottom surface of the counterweight box. A strip-shaped window is left between the multiple metal strips for the first track to pass through.

3. The combined static pressure pile centrifuge test device according to claim 2, characterized in that, The first track includes multiple vertically arranged slide rails, which pass vertically through the strip-shaped window. Multiple pile-holding pulleys are arranged vertically on the slide rails, and the multiple pile-holding pulleys slide in contact with the outer periphery of the model pile.

4. The combined static pressure pile centrifuge testing device according to claim 1, characterized in that, The second track is a cylindrical structure, and the inner wall of the second track is provided with multiple box-holding pulleys, which are slidably connected to the outer wall of the counterweight box.

5. The combined static pressure pile centrifuge testing device according to claim 1, characterized in that, The elastic element includes a plurality of elastic pins arranged circumferentially along the second through hole. Each of the plurality of elastic pins includes an elastic mechanism and a locking mechanism. The locking mechanism is disposed within the elastic mechanism. The locking mechanism is arranged in multiple segments along the vertical direction and can extend or lock vertically.

6. The combined static pressure pile centrifuge testing device according to claim 1, characterized in that, The track box is also provided with a closing mechanism at the second through hole. The closing mechanism includes multiple snap-lock gates, which are controlled by a remote sensing mechanism. Under the control of the remote sensing mechanism, the multiple snap-lock gates open and close the second through hole.

7. The combined static pressure pile centrifuge testing device according to any one of claims 1 to 6, characterized in that, The bottom of the model box is also equipped with at least one drainage valve.

8. A method for centrifugal testing of combined static pressure pile groups, wherein the test is conducted using the combined static pressure pile group centrifuge testing device as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Test the initial moisture content of the soft soil sample. Adjust the moisture content of the soft soil sample according to the test requirements. Place the soft soil sample with the adjusted moisture content in the model box and embed the sensor in the set soil layer. S2. Install the model box on the centrifuge platform, rotate and accelerate to the set acceleration and continue for a preset time, observe the data transmitted by the sensor inside the model box, and judge the degree of consolidation of the soft soil sample based on the data. S3. Compress and reset the elastic element, load the model pile, close the first through hole, load the counterweight in the counterweight box, and complete the assembly of each track box in sequence. S4. Arrange each track box on the combined support and fix it on the upper part of the model box. Adjust the installation height of the track box so that the bottom of the model pile contacts the surface of the soft soil sample. S5. Release the model piles in sequence according to the test requirements, and record the soil pressure and pore water pressure caused by each model pile penetrating the soft soil sample. Stop the centrifuge when all model piles have been penetrated and the sensor monitoring data remain unchanged.

Images