Reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe pile

Abstract

The invention provides a reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles, and relates to the technical field of pile foundation detection, and the method comprises the steps that the assembled prefabricated steel pipe piles are constructed at preset elevation positions of a target test field; obtaining first record data and second record data; on the basis of the first recorded data and the second recorded data, the total compressive bearing capacity and the total uplift bearing capacity of the prefabricated steel pipe pile are obtained through calculation according to a reverse self-balancing method; wherein a pile body load box in the loading pile body section is used for loading, the upper pile body and the lower pile body are driven to deform oppositely, and at least the stress of the pile body load box and the opposite displacement of the pile body are recorded as first record data; and a pile top load box in the pile cap loading section is loaded, the upper pile body and the lower pile body are driven to deform oppositely, and at least the stress of the pile top load box and the opposite displacement of the pile body are recorded as second record data. The method for detecting the bearing capacity of the pile foundation is simpler, more efficient and quicker.

Description

Technical Field

[0001] The present invention relates to the technical field of pile foundation detection, and in particular to a method and system for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles. Background Art

[0002] The bearing capacity of pile foundations is crucial for pile foundation engineering design. Common methods for determining the bearing capacity include static load tests (direct loading, anchor pile-beam reaction method, and heaped load method), dynamic testing (high-strain and low-strain dynamic testing), in-situ testing (standard penetration test, static cone penetration test), theoretical calculation (load transfer method, empirical formula method), and code recommendations. Each of these methods has its own unique characteristics. Static load tests are accurate but costly, dynamic testing and in-situ testing are rapid and economical, theoretical calculations are suitable for theoretical research and design, and code recommendations are simple and easy to implement. In practical applications, the appropriate method should be selected based on a comprehensive consideration of factors such as project requirements, geological conditions, and economic benefits.

[0003] The self-balancing method is a method used to measure the bearing capacity of pile foundations. The principle of the self-balancing method is to set one or more load boxes inside the pile body, and by applying pressure inside the load box, the pile body is displaced upward, and at the same time the soil on the side of the pile generates a downward reaction force, thereby balancing the applied load. This method reduces the impact of the test on the site and construction progress, and is suitable for a variety of geological conditions and construction environments. Although the self-balancing method for measuring pile bearing capacity does not require an external reaction device and reduces the impact of the site, its disadvantages include theoretical assumption limitations, load box installation problems, complex test result interpretation, soil layer differences, pile body displacement limitations, high cost, and low accuracy due to the conversion of positive and negative friction resistance. These factors may lead to errors in the test results and affect the promotion of the test method.

[0004] To this end, the reverse self-balancing method was proposed. Its core principle is to add a vertical loading device to the pile top in the traditional self-balancing test. This method solves the technical challenge of converting the negative friction in the upper section of the pile into positive friction during the self-balancing pile test. It can also test the pile's tensile bearing capacity. The effectiveness of this method has been verified through theoretical analysis and numerical simulation, which will help promote its application in practical projects and further improve the evaluation method for the vertical bearing capacity of single piles.

[0005] The existing reverse self-balancing method is mainly based on cast-in-place concrete piles to carry out pile foundation bearing capacity testing. It is necessary to bury a load box in the middle and lower part of the pile body during pile foundation construction. In order to place the load box, the steel cage needs to be specially designed. At the same time, pipes for tensioning steel cables and deformable rods need to be reserved. The operation process is complicated and needs to be improved in promotion and application to optimize the detection process of the reverse self-balancing method. Summary of the Invention

[0006] The present invention provides a reverse self-balancing pile foundation bearing capacity detection method and system based on prefabricated steel pipe piles, which is used to solve the defects of cumbersome installation and use steps of pile foundation bearing capacity detection devices in the prior art, and realize a pile foundation bearing capacity detection method and system with simple operation and accurate measurement results.

[0007] The present invention provides a reverse self-balancing pile foundation bearing capacity detection method based on a prefabricated steel pipe pile. The prefabricated steel pipe pile based on the method includes a pile cap loading section, a common pile body section, a loading pile body section, and a pile head section, wherein the common pile body section includes an upper pile body section and a lower pile body section, the pile cap loading section, the upper pile body section, the loading pile body section, the lower pile body section, and the pile head section are sequentially connected along the axial direction to form a steel pipe pile body, the pile cap loading section and the upper pile body section constitute an upper pile body, and the lower pile body section and the pile head section constitute a lower pile body; The method comprises: The assembled prefabricated steel pipe piles are installed at the preset elevation of the target test site; Acquire first record data and second record data; Based on the first recorded data and the second recorded data, calculating the total compressive bearing capacity and the total pull-out bearing capacity of the prefabricated steel pipe pile according to the reverse self-balancing method; wherein the pile body load box in the pile body section is loaded to drive the upper pile body and the lower pile body to deform in opposite directions, and at least the force on the pile body load box and the opposite displacement of the pile body during the opposite deformation process are recorded as first recorded data; The pile top load box in the pile cap loading section is loaded to drive the upper pile body and the lower pile body to deform toward each other, and at least the force of the pile top load box and the opposite displacement of the pile body during the deformation process are recorded as second recorded data.

[0008] According to a method for testing the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles provided by the present invention, before the step of constructing the assembled prefabricated steel pipe piles at a preset elevation position in a target test site, the method further includes: Determining the neutral point position of the prefabricated steel pipe pile according to the design parameters of the prefabricated steel pipe pile and the soil parameters of the target test site; The pile cap loading section, ordinary pile section, loading pile section and pile head section are spliced ​​together according to the neutral point position to obtain the assembled prefabricated steel pipe pile, so that the loading pile section is at the neutral point position after assembly.

[0009] According to a method for detecting the bearing capacity of a reverse self-balancing pile foundation based on a prefabricated steel pipe pile provided by the present invention, the pile cap loading section is connected to the lower pile body via a force transmission rod. After the step of recording the force of the pile top load box and the opposite displacement of the pile body during the opposite deformation as the second recorded data, the method further includes: Release the connection between the force transmission rod and the lower pile body; Recover the force transmission rod.

[0010] According to a method for detecting the bearing capacity of a reverse self-balancing pile foundation based on a prefabricated steel pipe pile provided by the present invention, after the step of recording the force of the pile top load box and the reverse displacement of the pile body during the opposite deformation as the second recorded data, the method further includes: Concrete pouring is performed on the prefabricated steel pipe piles; or The prefabricated steel pipe piles are extracted and recovered.

[0011] According to a method for detecting the bearing capacity of a reverse self-balancing pile foundation based on a prefabricated steel pipe pile provided by the present invention, after the step of extracting and recovering the prefabricated steel pipe pile, the method further includes: The pile load box is removed.

[0012] According to a method for detecting the bearing capacity of a reverse self-balancing pile foundation based on a prefabricated steel pipe pile provided by the present invention, the prefabricated steel pipe pile further comprises a plurality of measuring optical fibers, the measuring optical fibers being attached to the inner wall of the steel pipe pile body along the axial direction of the steel pipe pile body; The first recorded data further includes: first strain data recorded by the measuring optical fiber during the process in which the upper pile body and the lower pile body deform in opposite directions; The second recorded data further includes: second strain data recorded by the measuring optical fiber during the process in which the upper pile body and the lower pile body deform toward each other; The step of calculating the total compressive bearing capacity and the total pull-out bearing capacity of the prefabricated steel pipe pile according to the reverse self-balancing method specifically includes: The first type of total compressive bearing capacity and total pullout bearing capacity of precast steel pipe piles are calculated based on the load box at the pile top and the pile body. Calculating the second type of total compressive bearing capacity and total pullout bearing capacity of the prefabricated steel pipe pile based on the first strain data and the second strain data; The first type of total compressive bearing capacity and total pull-out bearing capacity are compared and calibrated with the second type of total compressive bearing capacity and total pull-out bearing capacity to obtain the total compressive bearing capacity and total pull-out bearing capacity of the prefabricated steel pipe pile.

[0013] The present invention also provides a reverse self-balancing pile foundation bearing capacity detection system based on prefabricated steel pipe piles, comprising: a detection module, configured to record the force on the pile load box and the pile displacement during the opposite deformation process as first recorded data; It is also used to record the force on the pile top load box and the opposite displacement of the pile body during the opposite deformation process as second recorded data; The determination module is configured to calculate the total compressive bearing capacity and the total pull-out bearing capacity of the prefabricated steel pipe pile based on the first recorded data and the second recorded data according to a reverse self-balancing method.

[0014] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the program, it implements any of the above-described reverse self-balancing pile foundation bearing capacity detection methods based on prefabricated steel pipe piles.

[0015] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles as described in any one of the above is implemented.

[0016] The present invention also provides a computer program product, comprising a computer program, which, when executed by a processor, implements any of the above-described methods for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles.

[0017] The reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles provided by the present invention is to construct pre-assembled prefabricated steel pipe piles at a preset elevation of a target test site, then drive the upper pile body and the lower pile body to displace away from each other through the pile body load box of the prefabricated steel pipe pile, and drive the upper pile body and the lower pile body to displace towards each other through the pile top load box. The pile foundation bearing capacity of the prefabricated steel pipe pile can be calculated based on the force data and displacement data recorded during the two loading processes. The detection process optimizes the segmented pouring step in the traditional detection method, thereby realizing a simpler, more efficient and faster pile foundation bearing capacity detection method. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic diagram of the structure of the prefabricated steel pipe piles used in the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles provided by the present invention; Figure 2 1 is a flow chart of a method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles provided by the present invention; Figure 3 (a) is a schematic diagram of a load-displacement curve of a process in which an upper pile and a lower pile generate opposite displacements in a reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles provided by the present invention; Figure 3 (b) is a schematic diagram of a load-displacement curve of the process in which the upper pile and the lower pile generate relative displacement in the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles provided by the present invention; Figure 4 Schematic diagram of the structure of the reverse self-balancing pile foundation bearing capacity detection device based on prefabricated steel pipe piles provided by the present invention; Figure 5 It is a structural schematic diagram of the electronic device provided by the present invention.

[0020] Reference numerals: 1. Pile cap loading section; 2. Ordinary pile body section; 21. Upper pile body section; 22. Lower pile body section; 3. Loading pile body section; 4. Pile head section; 5. Measuring optical fiber. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0022] The following combination Figures 1 to 3 The present invention introduces a reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles. The method is applied to a prefabricated steel pipe pile, such as Figure 1 As shown, the prefabricated steel pipe pile includes a pile cap loading section 1, a common pile body section 2, a loading pile body section 3 and a pile head section 4, wherein the common pile body section 2 includes an upper pile body 21 and a lower pile body 22, and the pile cap loading section 1, the upper pile body 21, the loading pile body section 3, the lower pile body 22 and the pile head section 4 are sequentially connected along the axial direction to form a steel pipe pile body; The pile cap loading section 1 and the upper pile body 21 constitute an upper pile body, and the lower pile body 22 and the pile head section 4 constitute a lower pile body; like Figure 1 As shown, the ordinary pile body section 2 constitutes the pile section of the prefabricated steel pipe pile body, wherein the portion of the loading pile body section 3 close to the pile cap loading section 1 is the upper pile body 21, and the portion of the loading pile body section 3 close to the pile head section 4 is the lower pile body 22.

[0023] Taking the loading pile body section 3 as the boundary, the pile cap loading section 1 and the upper pile body 21 above the loading pile body section 3 are determined as the upper pile body, and the pile head section 4 and the lower pile body 22 below the loading pile body section 3 are determined as the lower pile body, so as to carry out pile foundation bearing capacity testing.

[0024] The loading pile body section 3 includes a pile body load module, which is used to drive the upper pile body and the lower pile body to move away from each other, so as to generate a negative bearing force of the upper pile body and a positive bearing force of the lower pile body; The pile body load module is arranged in the loading pile body section 3 .

[0025] Optionally, the pile load module can be any form of linear drive component, such as an oil cylinder, an air cylinder or a jack. In this embodiment, a load box is selected, and the loading and unloading of the load box can be achieved by remotely controlling the servo motor of the load box.

[0026] The pile cap loading section 1 is equipped with a pile top load module, which is further connected to the lower pile body via a connector. The pile top load module is used to drive the upper pile body and the lower pile body to move toward each other.

[0027] The pile top load module is arranged in the pile cap loading section 1 .

[0028] Optionally, the pile top load module may be the same as or different from the pile body load module. In this embodiment, a load box that is the same as the pile body load module is selected as the pile top load module.

[0029] The connecting piece can be connected to any position inside the lower pile body, such as the lower pile body 22 or the pile head section 4 .

[0030] like Figure 2 As shown, the detection method includes: Step 201: construct the assembled prefabricated steel pipe piles at a preset elevation position in the target test site; It is understandable that, according to design requirements, the pile cap loading section 1, the upper pile body 21, the loading pile body section 3, the lower pile body 22 and the pile head section 4 are pre-assembled to obtain an assembled prefabricated steel pipe pile.

[0031] The prefabricated steel pipe piles obtained by splicing are then constructed at the design elevation of the target soil layer in the target test site to carry out pile foundation bearing capacity testing.

[0032] Alternatively, the prefabricated steel pipe piles may be constructed into the predetermined stratum by using a process such as static pressure sinking, vibration sinking, or borehole vibration sinking, wherein the type of sinking process may be determined based on the type of soil stratum at the target test site.

[0033] In one feasible embodiment, the soil layer of the target test site includes a clay layer and a pebble layer. A vibration hammer composite pile driving method is used accordingly, with construction being carried out in the clay layer at an initial penetration rate of less than or equal to 1 meter per minute to avoid rapid sinking that could cause the pile to tilt or equipment overload. After the pile head section 4 of the prefabricated steel pipe pile is sunk into the pebble layer, high-frequency vibration and high-pressure water jetting are used to assist penetration in order to reduce pile end resistance. The pile head section 4 is then sunk to a preset elevation, completing the sinking of the assembled prefabricated steel pipe pile. Optionally, the frequency of the high-frequency vibration is set to 30 Hz.

[0034] Optionally, the preset elevation is predetermined based on the testing requirements of the pile foundation bearing capacity.

[0035] Step 202, obtaining first record data and second record data; wherein the pile body load box in the pile body section 3 is loaded to drive the upper pile body and the lower pile body to deform in opposite directions, and at least the force on the pile body load box and the opposite displacement of the pile body during the opposite deformation process are recorded as first recorded data; The pile top load box in the pile cap loading section 1 is loaded to drive the upper pile body and the lower pile body to deform toward each other, and at least the force of the pile top load box and the opposite displacement of the pile body during the deformation process are recorded as second recorded data.

[0036] In this embodiment, both the pile body load module and the pile top load module use load boxes, which are named pile body load box and pile top load box respectively. Therefore, before formally conducting the pile foundation bearing capacity test, the servo control lines of the pile body load box and the pile top load box are first connected to the controller, and the equipment is debugged.

[0037] Optionally, the controller is a computer.

[0038] After debugging is completed, the upper and lower piles can be driven to move away from each other or towards each other through the load box, and various data during the movement process can be recorded for calculating the bearing capacity of the pile foundation.

[0039] Optionally, the pile body load box can be loaded first to drive the upper pile body and the lower pile body to displace away from each other, and then the pile top load box can be loaded to drive the upper pile body and the lower pile body to displace toward each other; or, the pile top load box can be loaded first to drive the upper pile body and the lower pile body to displace toward each other, and then the pile body load box can be loaded to drive the upper pile body and the lower pile body to displace away from each other.

[0040] In this embodiment, the specific loading process is introduced by taking the preferred method of first using the pile body load box for loading as an example.

[0041] Optionally, the pile load box is loaded in stages using a slow maintained load method.

[0042] Specifically, the controller activates the pile load box, which loads the pile load box, causing the upper and lower pile bodies to deform in opposite directions. During this deformation process, the force data from the pile load box is recorded as first recorded data, which serves as the basis for calculating the bearing capacity of the pile foundation. The force data from the pile load box and the elongation data at the output end can be directly read from an instrument on the pile load box.

[0043] In addition, it is necessary to obtain the displacement of the pile body during the opposite deformation process to draw the QS curves of the upper and lower pile bodies, thereby realizing the calculation of the bearing capacity of the pile foundation.

[0044] In one feasible embodiment, the connecting member is configured as a force-transfer rod, which axially connects the lower pile body and the pile top load box within the steel pipe pile body. Based on this, a displacement measuring instrument is used to measure the displacement s of the force-transfer rod. The displacement s of the force-transfer rod during the opposite deformation process is recorded to represent the opposite displacement of the pile body and recorded as the first recorded data.

[0045] After the pile body is loaded, the pile body load box is first unloaded to put it in the initial state, and then the pile top load box is started for loading.

[0046] Optionally, the pile body load box is unloaded in stages, specifically in an equal amount at each stage.

[0047] Optionally, the pile top load box is loaded in stages using a slow maintained load method.

[0048] Specifically, a controller activates a load box at the top of the pile. Loading the load box causes the upper and lower pile bodies to deform toward each other. During this deformation, force data from the load box is recorded as second recorded data, serving as the basis for calculating the bearing capacity of the pile foundation. The force data from the load box is directly read from an instrument on the load box.

[0049] In addition, similar to the method of obtaining the opposite displacement of the pile body, the displacement s of the force transmission rod detected by the displacement measuring instrument during the deformation of the upper and lower pile bodies is recorded to represent the opposite displacement of the pile body, and is recorded together as the second recorded data.

[0050] Step 203 : Based on the first recorded data and the second recorded data, the total compressive bearing capacity and the total tensile bearing capacity of the prefabricated steel pipe pile are calculated using a reverse self-balancing method.

[0051] Specifically, in the process of the pile body load box driving the upper and lower pile bodies to deform in opposite directions, the step-by-step loading drives the upper and lower pile bodies to deform in opposite directions. Based on the force of the pile body load box and the opposite displacement of the pile body, the QS curves of the upper and lower pile bodies are drawn, as shown in Figure 2. Figure 3 As shown in (a) in the figure. Based on the QS curve corresponding to the opposite displacement, the negative bearing capacity of the upper pile is determined. Positive bearing capacity of the pile .

[0052] In the process of the pile top load box driving the upper and lower pile bodies to deform toward each other, the step-by-step loading drives the upper and lower pile bodies to deform toward each other. Based on the force of the pile top load box and the relative displacement of the pile body, the QS curves of the upper and lower pile bodies are drawn, as shown in Figure 2. Figure 3 As shown in (b) in the figure. Based on the QS curve corresponding to the relative displacement, the positive bearing capacity of the upper pile is determined. and the negative bearing capacity of the pile .

[0053] On this basis, calculate 、 The deadweight of prefabricated steel pipe piles W The sum of the vertical compressive bearing capacity of the test pile is , .calculate of and the deadweight of prefabricated steel pipe piles W The difference between the two is taken as the total vertical pull-out bearing capacity of the test pile , , thereby realizing the pile foundation bearing capacity detection based on the reverse self-balancing principle.

[0054] The principle is to add a pile top load module to the traditional self-balancing test device. During the test, the pile body load module located in the middle pile is used to make the upper pile (i.e., the upper pile body) and the lower pile (i.e., the lower pile body) move in opposite directions, and the negative bearing capacity of the upper pile is measured. and the positive bearing capacity of the lower pile Then the pile body load box in the pile body load module returns oil, and the pile top load module is loaded, so that the upper and lower piles are displaced toward each other, and the positive bearing capacity of the upper pile is measured. and the negative bearing capacity of the lower pile Finally, the total ultimate vertical compressive bearing capacity of the test pile is the sum of the positive bearing capacity of the upper pile segment and the negative bearing capacity of the lower pile segment plus the pile weight; the total ultimate vertical pullout bearing capacity of the test pile is the sum of the negative bearing capacity of the upper pile segment and the positive bearing capacity of the lower pile segment minus the pile weight.

[0055] The present invention constructs pre-assembled prefabricated steel pipe piles at a preset elevation of a target test site, then drives the upper and lower pile bodies to displace away from each other through the pile body load box of the prefabricated steel pipe pile, and drives the upper and lower pile bodies to displace toward each other through the pile top load box. The pile foundation bearing capacity of the prefabricated steel pipe pile can be calculated based on the force data and displacement data recorded during the two loading processes. The detection process optimizes the segmented pouring steps in the traditional detection method, thereby realizing a simpler, more efficient and faster pile foundation bearing capacity detection method.

[0056] In the method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles of the present invention, before the step of placing the assembled prefabricated steel pipe piles at a preset elevation at a target test site, the method further includes: Determining the neutral point position of the prefabricated steel pipe pile according to the design parameters of the prefabricated steel pipe pile and the soil parameters of the target test site; The pile cap loading section, ordinary pile section, loading pile section and pile head section are spliced ​​together according to the neutral point position to obtain the assembled prefabricated steel pipe pile, so that the loading pile section is at the neutral point position after assembly.

[0057] In the process of realizing pile foundation bearing capacity detection based on the reverse self-balancing method, it is necessary to make the position of pile body loading at the neutral point of the pile foundation as a whole. Therefore, corresponding to the prefabricated steel pipe pile in this embodiment, it is also necessary to predetermine the neutral point position and splice the loading pile body section used for pile body loading at the neutral point of the steel pipe column body.

[0058] Therefore, before constructing prefabricated steel pipe piles, it is necessary to determine the neutral point position of the prefabricated steel pipe piles based on the design parameters of the prefabricated steel pipe piles and the soil parameters of the target test site.

[0059] Optionally, the design parameters of the prefabricated steel pipe pile include the diameter, total length, design bearing capacity, wall thickness, etc. of the steel pipe pile.

[0060] Optionally, the soil parameters of the target test site include the soil layer type of the target test site and the thickness, elastic modulus, friction resistance, basic bearing capacity, etc. of each type of soil layer.

[0061] On this basis, the neutral point position of the prefabricated steel pipe pile is determined according to the neutral point calculation principle, wherein the neutral point calculation principle makes the negative bearing capacity of the upper pile body equal to the positive bearing capacity of the lower pile body.

[0062] In a feasible implementation manner, the common pile body segment includes a plurality of standard pipe segments, and the plurality of standard pipe segments can be sequentially connected along the axial direction to form an upper pile body segment and a lower pile body segment.

[0063] The lengths of the upper and lower pile sections of the standard pile shaft are determined based on the calculated neutral point. The lengths of the upper and lower pile sections are then used to determine the number of standard pipe sections to be used in splicing the upper and lower pile sections, respectively, so that the loaded pile section, after splicing, is located at the neutral point of the steel pipe pile body. This means that, after splicing, the neutral point of the steel pipe pile body is within the range of the loaded pile section.

[0064] In other feasible implementations, the lengths of the upper and lower pile bodies of the ordinary pile body segment can be determined based on the calculated neutral point position, combined with the lengths of the pile cap loading segment, the loading pile body segment, and the pile head segment, and the upper and lower pile bodies can be pre-customized. The pile cap loading segment, the upper pile body, the loading pile body segment, the lower pile body, and the pile head segment can be spliced ​​in sequence, so that after the splicing is completed, the neutral point position is within the range of the loading pile body segment.

[0065] In this embodiment, the prefabricated steel pipe pile has a design diameter of 1 meter, a total length of 20 meters, a design bearing capacity of 4000 kN, and a steel pipe thickness of 20 mm. Based on the design parameters of the prefabricated steel pipe pile, a 1.5-meter-long and 1.5-meter-wide pile cap loading section is selected. Eight 2-meter-long standard pipe sections and one 1-meter-long standard pipe section are spliced ​​together to form the upper and lower pile sections. The standard pipe section closest to the pile cap loading section is embedded within the pile cap loading section. A 2-meter-long loading pile section is selected, which includes two 1-meter-long standard sections with built-in load boxes as the pile body load boxes. A 1-meter-long, 0.5-meter-diameter tapered head is selected as the pile head section.

[0066] The total compressive bearing capacity of the pile foundation is 4000KN, and the total pull-out bearing capacity is 1500KN. The design requires that the compressive safety factor is greater than 2.0 and the pull-out safety factor is greater than 1.25.

[0067] The soil layers at the target test site, from the surface to the subsurface, are: a 6-meter-thick, 200 kPa clay layer, a 1-meter-thick, 400 kPa gravel layer, and a 250 kPa sand layer. The design value for the pile-soil positive friction is 0.3 to 0.4 times the geological bearing capacity, and the design value for the pile-soil negative friction is 10 kPa to 15 kPa, with the higher value being used for deeper soil layers.

[0068] The geological parameters of the target test site are shown in Table 1 below: Table 1

[0069] Corresponding to the design parameters of the prefabricated steel pipe piles and the soil parameters of the target test site, negative friction resistance is accumulated layer by layer from the pile top downward, and positive friction resistance is accumulated layer by layer from the pile bottom upward. Finally, the depth where the two are equal is calculated and used as the neutral point position.

[0070] In the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles of the present invention, the pile cap loading section is connected to the lower pile body via a force transmission rod. After the step of recording the force of the pile top load box and the opposite displacement of the pile body during the opposite deformation as the second recorded data, the method further includes: Release the connection between the force transmission rod and the lower pile body; Recover the force transmission rod.

[0071] It is understandable that after the second recorded data is obtained, the test data required for calculating the bearing capacity of the pile foundation has been obtained. Therefore, the prefabricated steel pipe pile can be used as a permanent pile after concrete pouring. Therefore, before pouring, some equipment located in the pile body can be recovered.

[0072] like Figure 1 As shown, the pile cap loading section is connected to the lower pile body via a force-transfer rod. This rod, located within the steel pipe pile body, is anchored to the lower pile body at one end and connected to the output port of the load box at the pile top at the other end. This allows the force-transfer rod to be sheared off at the end closest to the lower pile body for recovery, or to be unanchored at the end closest to the pile body using hot-melt anchor mortar.

[0073] In the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles of the present invention, after the step of recording the force of the pile top load box and the reverse displacement of the pile body during the opposite deformation as the second recorded data, the method further includes: Concrete pouring is performed on the prefabricated steel pipe piles; or The prefabricated steel pipe piles are extracted and recovered.

[0074] In a feasible implementation, after the pile foundation bearing capacity test data is obtained, the prefabricated steel pipe piles can be poured with concrete to use them as permanent engineering piles, thereby realizing effective utilization of the pile foundation bearing capacity test device. After the test is completed, there is no need to dismantle the test device and re-construct the cast-in-place piles, thereby improving the overall construction efficiency.

[0075] In another feasible implementation, after the pile foundation bearing capacity test data is obtained, the prefabricated steel pipe piles can be extracted and recovered so as to achieve the reuse of the prefabricated steel pipe piles and reduce the cost of pile foundation bearing capacity testing.

[0076] Optionally, the tube can be removed by vibration-based extubation or by inserting a cannula into the steel pipe and removing it using a dedicated extubation machine.

[0077] In the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles of the present invention, after the step of extracting and recovering the prefabricated steel pipe piles, the method further includes: The pile load box is removed.

[0078] It should be noted that the extraction and recovery method can recover the upper pile body of the prefabricated steel pipe pile. Specifically, the portion that can be extracted is the pile cap loading section and the upper section of the conventional pile body, while the loading pile body section, the lower section of the conventional pile body, and the pile head section remain buried in the soil. Furthermore, the load box can be hoisted and recovered using the hoisting holes reserved in the steel pipe pile body, removing the pile body load box from the loading pile body and allowing it to be reused.

[0079] In the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles of the present invention, the prefabricated steel pipe piles further include a plurality of measuring optical fibers 5, which are attached to the inner wall of the steel pipe pile body along the axial direction of the steel pipe pile body; Although the displacement between the upper and lower pile bodies can be characterized by measuring and recording the strain of the force transmission rod during the pile foundation bearing capacity test, it is also preferred to use an optical fiber attached to the steel pipe pile body to record the strain of the optical fiber during the pile foundation bearing capacity test, thereby obtaining more intuitive deformation data of each segment of the steel pipe pile, and calculating more characteristic parameters related to the pile foundation bearing capacity based on the deformation data directly generated by the steel pipe pile body.

[0080] In a specific embodiment, Figure 1 As shown, three measuring optical fibers 5 are evenly arranged on the inner wall of the steel pipe pile body in the circumferential direction of the steel pipe pile body, and the length direction of the measuring optical fibers 5 is parallel to the axial direction of the steel pipe pile.

[0081] Optionally, the measuring optical fiber 5 may be a distributed optical fiber or a temperature compensation optical fiber.

[0082] The first recorded data also includes: first strain data recorded by the measuring optical fiber 5 during the process in which the upper pile body and the lower pile body deform in opposite directions; The second recorded data also includes: second strain data recorded by the measuring optical fiber 5 during the process of the upper pile body and the lower pile body deforming toward each other; On this basis, it can be understood that, in the process of loading the pile body and driving the upper pile body and the lower pile body to deform in opposite directions, the first strain data of the measuring optical fiber 5 is recorded to characterize the pile body strain data of the prefabricated steel pipe pile in this process; in the process of loading the pile top and driving the upper pile body and the lower pile body to deform in opposite directions, the second strain data of the measuring optical fiber 5 is recorded to characterize the pile body strain data of the prefabricated steel pipe pile in this process.

[0083] The step of calculating the total compressive bearing capacity and the total pull-out bearing capacity of the prefabricated steel pipe pile according to the reverse self-balancing method specifically includes: The first type of total compressive bearing capacity and total pullout bearing capacity of precast steel pipe piles are calculated based on the load box at the pile top and the pile body. It can be understood that based on the first strain data and the second strain data, the opposite displacement of the pile body and the opposite displacement of the pile body can be directly calculated, so as to draw the QS diagram of the two loading processes, and the first type of total compressive bearing capacity and total tensile bearing capacity can be calculated according to the process described above, which will not be repeated here.

[0084] Calculating the second type of total compressive bearing capacity and total pullout bearing capacity of the prefabricated steel pipe pile based on the first strain data and the second strain data; The first type of total compressive bearing capacity and total pull-out bearing capacity are compared and calibrated with the second type of total compressive bearing capacity and total pull-out bearing capacity to obtain the total compressive bearing capacity and total pull-out bearing capacity of the prefabricated steel pipe pile.

[0085] In addition, the frictional resistance of the soil around each position of the upper pile and the lower pile can be calculated based on the first strain data and the second strain data, so as to obtain the second type of compressive total bearing capacity of the prefabricated pile just installed based on the frictional resistance.

[0086] The specific calculation formula is as follows: ; Where, Indicates the frictional resistance at any position of the pile axis. represents the elastic modulus of the prefabricated steel pipe pile steel, D represents the diameter of the prefabricated steel pipe pile, t represents the wall thickness of the prefabricated steel pipe column, Indicates the change of axial strain of prefabricated steel pipe pile with depth z, obtained based on the first strain data / second strain data, Indicates the weight of the steel pipe.

[0087] Furthermore, the bearing capacity of the upper and lower pile sections is calculated based on the pile friction resistance as shown below: ; Where, Indicates the axial force at the reference starting point, Indicates depth h L Axial force at position, Indicates the height of the i-th segment in the calculation.

[0088] It is understandable that when calculating the bearing capacity of the upper and lower pile bodies, the corresponding h 0 and h L Just do the calculation.

[0089] The second type of total compressive bearing capacity and total pull-out bearing capacity can be calculated using the above method.

[0090] On this basis, the first type of total compressive bearing capacity and total pull-out bearing capacity and the second type of total compressive bearing capacity and total pull-out bearing capacity calculated by two different methods are compared and calibrated to improve the calculation accuracy of the bearing capacity of the pile foundation.

[0091] Optionally, according to the actual detection situation, the bearing capacities calculated by the two different methods are compared and calibrated by taking the average, maximum, minimum or weighted combination.

[0092] The reverse self-balancing pile foundation bearing capacity detection system based on prefabricated steel pipe piles provided by the present invention is described below. The reverse self-balancing pile foundation bearing capacity detection system based on prefabricated steel pipe piles described below and the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles described above can be referenced to each other.

[0093] like Figure 4 As shown, the reverse self-balancing pile foundation bearing capacity detection system based on prefabricated steel pipe piles includes a detection module 401 and a determination module 402; A detection module 401 is used to record the force on the pile load box and the pile displacement during the opposite deformation process as first recorded data; Both the pile body load module and the pile top load module use load boxes, which are named pile body load box and pile top load box respectively. Therefore, before formally conducting the pile foundation bearing capacity test, the servo control lines of the pile body load box and the pile top load box are first connected to the controller, and the equipment is debugged.

[0094] Optionally, the controller is a computer.

[0095] After debugging is completed, the pile body load box is first used for loading.

[0096] Specifically, a controller activates a pile load box, which loads the pile load box, causing the upper and lower pile bodies to deform in opposite directions. During this deformation, force data from the pile load box is recorded as first recorded data, serving as the basis for calculating the pile foundation bearing capacity. The force data from the pile load box is directly read from an instrument on the pile load box.

[0097] In addition, it is necessary to obtain the displacement of the pile body during the opposite deformation process to draw the QS curves of the upper and lower pile bodies, thereby realizing the calculation of the bearing capacity of the pile foundation.

[0098] In one feasible embodiment, the connecting member is configured as a force-transfer rod, which axially connects the lower pile body and the pile top load box within the steel pipe pile body. Based on this, a displacement measuring instrument is used to measure the displacement s of the force-transfer rod. The displacement s of the force-transfer rod during the opposite deformation process is recorded to represent the opposite displacement of the pile body and recorded as the first recorded data.

[0099] It is also used to record the force on the pile top load box and the opposite displacement of the pile body during the opposite deformation process as second recorded data; After the pile body is loaded, the pile body load box is first unloaded to put it in the initial state, and then the pile top load box is started for loading.

[0100] Specifically, a controller activates a load box at the top of the pile. Loading the load box causes the upper and lower pile bodies to deform toward each other. During this deformation, force data from the load box is recorded as second recorded data, serving as the basis for calculating the bearing capacity of the pile foundation. The force data from the load box is directly read from an instrument on the load box.

[0101] In addition, similar to the method of obtaining the opposite displacement of the pile body, the displacement s of the force transmission rod detected by the displacement measuring instrument during the deformation of the upper and lower pile bodies is recorded to represent the opposite displacement of the pile body, and is recorded together as the second recorded data.

[0102] The determination module 402 is configured to calculate the total compressive bearing capacity and the total pullout bearing capacity of the prefabricated steel pipe pile based on the first recorded data and the second recorded data according to a reverse self-balancing method.

[0103] Specifically, in the process of the pile body load box driving the upper and lower pile bodies to deform in opposite directions, the step-by-step loading drives the upper and lower pile bodies to deform in opposite directions. Based on the force of the pile body load box and the opposite displacement of the pile body, the QS curves of the upper and lower pile bodies are drawn, as shown in Figure 2. Figure 3 As shown in (a) in the figure. Based on the QS curve corresponding to the opposite displacement, the negative bearing capacity of the upper pile is determined. Positive bearing capacity of the pile .

[0104] In the process of the pile top load box driving the upper and lower pile bodies to deform toward each other, the step-by-step loading drives the upper and lower pile bodies to deform toward each other. Based on the force of the pile top load box and the relative displacement of the pile body, the QS curves of the upper and lower pile bodies are drawn, as shown in Figure 2. Figure 3 As shown in (b) in the figure. Based on the QS curve corresponding to the relative displacement, the positive bearing capacity of the upper pile is determined. and the negative bearing capacity of the pile .

[0105] On this basis, calculate 、 The deadweight of prefabricated steel pipe piles W The sum of the vertical compressive bearing capacity of the test pile is , .calculate of and the deadweight of prefabricated steel pipe piles W The difference between the two is taken as the total vertical pull-out bearing capacity of the test pile , , thereby realizing the pile foundation bearing capacity detection based on the reverse self-balancing principle.

[0106] The present invention constructs pre-assembled prefabricated steel pipe piles at a preset elevation of a target test site, then drives the upper and lower pile bodies to displace away from each other through the pile body load box of the prefabricated steel pipe pile, and drives the upper and lower pile bodies to displace toward each other through the pile top load box. The pile foundation bearing capacity of the prefabricated steel pipe pile can be calculated based on the force data and displacement data recorded during the two loading processes. The detection process optimizes the segmented pouring steps in the traditional detection method, thereby realizing a simpler, more efficient and faster pile foundation bearing capacity detection method.

[0107] Figure 5 An example of a physical structure diagram of an electronic device is shown below. Figure 5 As shown, the electronic device may include: a processor 510, a communication interface 520, a memory 530, and a communication bus 540, wherein the processor 510, the communication interface 520, and the memory 530 communicate with each other via the communication bus 540. The processor 510 may call the logic instructions in the memory 530 to execute a reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles, the method comprising: recording the force of the pile body load box and the pile body's reverse displacement during the reverse deformation process as first recorded data; recording the force of the pile top load box and the pile body's reverse displacement during the reverse deformation process as second recorded data; and calculating the total compressive bearing capacity and the total tensile bearing capacity of the prefabricated steel pipe pile according to the reverse self-balancing method based on the first and second recorded data.

[0108] Furthermore, the logic instructions in the aforementioned memory 530 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0109] On the other hand, the present invention also provides a computer program product, which includes a computer program, and the computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles provided by the above-mentioned methods. The method includes: recording the force of the pile body load box and the opposite displacement of the pile body during the opposite deformation process as the first recorded data; recording the force of the pile top load box and the opposite displacement of the pile body during the opposite deformation process as the second recorded data; based on the first recorded data and the second recorded data, calculating the total compressive bearing capacity and the total pull-out bearing capacity of the prefabricated steel pipe pile according to the reverse self-balancing method.

[0110] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it is implemented to execute the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles provided by the above-mentioned methods. The method includes: recording the force of the pile body load box and the opposite displacement of the pile body during the opposite deformation process as the first recorded data; recording the force of the pile top load box and the opposite displacement of the pile body during the opposite deformation process as the second recorded data; based on the first recorded data and the second recorded data, calculating the total compressive bearing capacity and the total pull-out bearing capacity of the prefabricated steel pipe pile according to the reverse self-balancing method.

[0111] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0112] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles, characterized in that: The prefabricated steel pipe pile on which the method is based comprises a pile cap loading section, a common pile body section, a loading pile body section and a pile head section, wherein the common pile body section comprises an upper pile body section and a lower pile body section, the pile cap loading section, the upper pile body section, the loading pile body section, the lower pile body section and the pile head section are sequentially connected along the axial direction to form a steel pipe pile body, the pile cap loading section and the upper pile body section constitute an upper pile body, and the lower pile body section and the pile head section constitute a lower pile body; The method comprises: The assembled prefabricated steel pipe piles are installed at the preset elevation of the target test site; Acquire first record data and second record data; Based on the first recorded data and the second recorded data, calculating the total compressive bearing capacity and the total pull-out bearing capacity of the prefabricated steel pipe pile according to the reverse self-balancing method; wherein the pile body load box in the pile body section is loaded to drive the upper pile body and the lower pile body to deform in opposite directions, and at least the force on the pile body load box and the opposite displacement of the pile body during the opposite deformation process are recorded as first recorded data; The pile top load box in the pile cap loading section is loaded to drive the upper pile body and the lower pile body to deform toward each other, and at least the force of the pile top load box and the opposite displacement of the pile body during the deformation process are recorded as second recorded data.

2. The method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles according to claim 1, characterized in that: Before the step of constructing the assembled prefabricated steel pipe piles at the preset elevation of the target test site, the method further includes: Determining the neutral point position of the prefabricated steel pipe pile according to the design parameters of the prefabricated steel pipe pile and the soil parameters of the target test site; The pile cap loading section, ordinary pile section, loading pile section and pile head section are spliced ​​together according to the neutral point position to obtain the assembled prefabricated steel pipe pile, so that the loading pile section is at the neutral point position after assembly.

3. The method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles according to claim 1, characterized in that: The pile cap loading section is connected to the lower pile body via a force transmission rod. After the step of recording the force of the pile top load box and the opposite displacement of the pile body during the opposite deformation as the second recording data, the method further includes: Release the connection between the force transmission rod and the lower pile body; Recover the force transmission rod.

4. The method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles according to claim 1, wherein: After the step of recording the force of the pile top load box and the pile body displacement in the process of the opposite deformation as the second recorded data, the method further includes: Concrete pouring is performed on the prefabricated steel pipe piles; or The prefabricated steel pipe piles are extracted and recovered.

5. The method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles according to claim 4, characterized in that: After the step of extracting and recovering the prefabricated steel pipe piles, the method further comprises: The pile load box is removed.

6. The method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles according to any one of claims 1 to 5, characterized in that: The prefabricated steel pipe pile further includes a plurality of measuring optical fibers, which are attached to the inner wall of the steel pipe pile body along the axial direction of the steel pipe pile body; The first recorded data further includes: first strain data recorded by the measuring optical fiber during the process in which the upper pile body and the lower pile body deform in opposite directions; The second recorded data further includes: second strain data recorded by the measuring optical fiber during the process in which the upper pile body and the lower pile body deform toward each other; The step of calculating the total compressive bearing capacity and the total pull-out bearing capacity of the prefabricated steel pipe pile according to the reverse self-balancing method specifically includes: The first type of total compressive bearing capacity and total pullout bearing capacity of precast steel pipe piles are calculated based on the load box at the pile top and the pile body. Calculating the second type of total compressive bearing capacity and total pullout bearing capacity of the prefabricated steel pipe pile based on the first strain data and the second strain data; The first type of total compressive bearing capacity and total pull-out bearing capacity are compared and calibrated with the second type of total compressive bearing capacity and total pull-out bearing capacity to obtain the total compressive bearing capacity and total pull-out bearing capacity of the prefabricated steel pipe pile.

7. A reverse self-balancing pile foundation bearing capacity detection system based on prefabricated steel pipe piles, characterized in that: include: A detection module, configured to record the force on the pile body load box and the pile body displacement during the opposite deformation process as first recorded data; It is also used to record the force on the pile top load box and the opposite displacement of the pile body during the opposite deformation process as second recorded data; The determination module is configured to calculate the total compressive bearing capacity and the total pull-out bearing capacity of the prefabricated steel pipe pile based on the first recorded data and the second recorded data according to a reverse self-balancing method.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the reverse self-balancing pile foundation bearing capacity detection method based on prefabricated steel pipe piles is implemented as described in any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles according to any one of claims 1 to 6 is implemented.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the method for detecting the bearing capacity of a reverse self-balancing pile foundation based on prefabricated steel pipe piles according to any one of claims 1 to 6 is implemented.

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