Calculation method and device of bearing capacity of coral sand expanded pile and storage medium

Abstract

The application relates to the technical field of geotechnical engineering pile foundation, in particular to a method and device for calculating the bearing capacity of a coral sand expansion pile and a storage medium, wherein the method comprises the following steps: acquiring the mechanical parameters of coral sand and pile body design parameters; calculating the spatial range of expansion-crushing coupling and the boundary crushing rate according to the ratio of expansion pressure to critical expansion pressure; calculating the particle crushing rate at each position along the radial direction within the spatial range; respectively correcting the initial internal friction angle and the initial compression modulus according to the crushing rate at each position; calculating the unit area side resistance at each depth of the pile body according to the corrected mechanical parameters; and integrating along the full length of the pile body to obtain the ultimate bearing capacity of a single pile. The application realizes accurate calculation of the bearing capacity of an HSCA expansion pile in a coral sand foundation by introducing expansion-crushing coupling effect and performing radial partition correction on the mechanical parameters of the soil around the pile.

Description

Technical Field

[0001] This application relates to the field of geotechnical engineering pile foundation technology, and in particular to a method, apparatus and storage medium for calculating the bearing capacity of coral sand expansion piles. Background Technology

[0002] HSCA expansive piles are a novel pile foundation technology. They utilize the HSCA expansive agent incorporated into the pile concrete, which exerts radial pressure on the surrounding soil through the volumetric expansion caused by the hydration reaction of the agent, thereby increasing the pile's side friction and end bearing capacity. The maximum expansion pressure of the HSCA expansive agent can reach 120 MPa. Studies have shown that HSCA expansive piles exhibit excellent bearing capacity enhancement effects in both cohesive soils and quartz sands; a 20% HSCA content can increase the ultimate bearing capacity by 56%.

[0003] Coral sand is a carbonate sand formed from coral reef debris through weathering, transportation, and deposition, and is widely distributed in tropical and subtropical marine engineering areas. Coral sand particles possess the following engineering characteristics: brittle, low strength, rich in internal porosity, irregular particle shape, and easily broken. When HSCA (High-Speed ​​Carbonate Collar) expansion piles are applied to coral sand foundations, the following specific problems arise:

[0004] (1) Synergistic effect of particle crushing and expansion filling. Coral sand particles are crushed under the expansion pressure of the pile body. The shrinkage space generated by the crushing is filled by the volume expansion of the expansion pile, forming a dynamic balance of "crushing-expansion". This synergistic effect makes the lateral resistance improvement effect of the expansion pile in coral sand better than that in quartz sand.

[0005] (2) Matching of expansion pressure and fracture threshold. The maximum expansion pressure of HSCA expansion agent can reach 120 MPa, while the particle fracture threshold stress of coral sand is only 100 kPa to 800 kPa. Excessive expansion pressure may lead to over-fracture, which will deteriorate the soil structure around the pile; excessive expansion pressure will not make full use of the fracture filling effect.

[0006] (3) Mechanical properties of the expansion-fracture coupling zone. An expansion-fracture coupling zone is formed near the pile-soil interface. The soil in this zone has undergone the processes of fracturing, rearrangement and compaction, and its mechanical parameters are significantly different from those of the soil in the far field.

[0007] (4) Long-term performance stability. The expansion effect of expansion piles is time-dependent, while the crushing of coral sand is gradual. The time-varying coupling of the two determines the long-term bearing capacity of the pile foundation.

[0008] However, existing HSCA expansion pile design methods are mainly based on pile-soil interaction theory of quartz sand or cohesive soil, and have the following key drawbacks:

[0009] First, the enhancement effect of coral sand particle crushing on the expansion effect was not considered, resulting in a conservative design of the expansion agent dosage.

[0010] Second, the quantitative relationship between expansion pressure and breakage rate has not been established, making it impossible to optimize the amount of expansion agent to achieve the optimal design that just fills the constricted space of the broken body.

[0011] Third, the special mechanical properties of the expansion-fracture coupling zone were not considered, and the pile side resistance calculation still used far-field soil parameters, which led to calculation errors.

[0012] Fourth, there is a lack of methods for predicting the long-term bearing capacity of HSCA expansion piles in coral sand. Summary of the Invention

[0013] To address this, the present invention provides a method, apparatus, and storage medium for calculating the bearing capacity of coral sand expansion piles, thereby overcoming the problems in the prior art that do not consider the dynamic coupling effect between coral sand particle breakage and expansion agent expansion, resulting in large deviations in bearing capacity calculation, inaccurate design of expansion agent dosage, and lack of long-term performance prediction methods.

[0014] To achieve the above objectives, this invention provides a method for calculating the bearing capacity of coral sand expansion piles. It includes:

[0015] Step S1: Obtain the initial internal friction angle, initial compression modulus, unit weight, coefficient of earth pressure at rest, swelling pressure and critical swelling pressure of the coral sand, as well as the pile diameter and pile length.

[0016] Step S2: Calculate the spatial range of the pile perimeter expansion-fracture coupling effect based on the ratio of the expansion pressure to the critical expansion pressure, and calculate the boundary fracture rate at the outer boundary of the spatial range.

[0017] Step S3: Within the spatial range, calculate the particle breakage rate at each radial position within the spatial range based on the boundary breakage rate;

[0018] Step S4: Based on the particle breakage rate at each location, correct the initial internal friction angle and the initial compression modulus to obtain the corrected internal friction angle and the corrected compression modulus.

[0019] Step S5: Calculate the side resistance per unit area at each depth of the pile body based on the corrected internal friction angle, the corrected compression modulus, the unit weight, the static earth pressure coefficient, the calculation depth, and the expansion enhancement coefficient.

[0020] Step S6: Integrate the lateral resistance per unit area along the entire length of the pile to obtain the ultimate bearing capacity of a single pile;

[0021] Step S7, calculate the long-term bearing capacity:

[0022] ;

[0023] in, For long-term load-bearing capacity, This refers to the ultimate bearing capacity of a single pile. The contribution coefficient to expansion. The expansion time constant is This is the creep reduction factor. t is the creep time constant, and t is the service time.

[0024] Further, in step S1, the formula for calculating the expansion pressure is:

[0025] ;

[0026] in, For expansion pressure, The dosage of HSCA expansion agent, To correct the compression modulus, For expansion strain.

[0027] Further, in step S2, the spatial range of the pile perimeter expansion-fracture coupling effect is calculated based on the ratio of the expansion pressure to the critical expansion pressure, including:

[0028] Step S21: Calculate the ratio of the expansion pressure to the critical expansion pressure;

[0029] Step S22: Based on the ratio and a preset attenuation index, calculate the distance from the outer boundary of the spatial range to the center of the pile.

[0030] Step S23: Determine the spatial range as an annular area between the pile center and the pile surface, with the preset distance as the radius.

[0031] The formula for calculating the preset distance is:

[0032] ;

[0033] in, The distance is the preset distance, and d is the diameter of the pile. For expansion pressure, The critical expansion pressure is denoted as , and m is the decay exponent; the critical expansion pressure The value range is from 200 kPa to 600 kPa; the value range of the attenuation index m is from 0.3 to 0.8.

[0034] Further, in step S2, the formula for calculating the boundary breakage rate is:

[0035] ;

[0036] in, For boundary breakage rate, and For expansion-fracture coupling parameters, The reference pressure; the reference pressure The value ranges from 100 kPa to 500 kPa.

[0037] Further, in step S3, the formula for calculating the particle breakage rate at each radial position within the spatial range is:

[0038] ;

[0039] Wherein, Br(r) is the particle breakage rate at a radial distance r from the pile center. The boundary breakage rate, Let be the distance from the outer boundary of the spatial range to the center of the pile, β be the attenuation coefficient, and r be the radial distance from the center of the pile, with the value of r ranging from 1 to 2. The attenuation coefficient β ranges from 0.5 to 2.0.

[0040] Further, in step S4, the formulas for calculating the corrected internal friction angle and the corrected compression modulus are as follows:

[0041] ,

[0042] ;

[0043] in, This is the corrected internal friction angle at a radial distance r. The initial internal friction angle is... Here, Br(r) is the friction angle reduction factor, and Br(r) is the particle breakage rate at a radial distance r. This is the corrected compressive modulus at a radial distance r. The initial compression modulus, The coefficient for growth of the compression modulus; the coefficient for reduction of the friction angle. The value range is from 1° to 10°; the compression modulus growth coefficient The value range is from 2 to 8.

[0044] Further, in step S5, the formula for calculating the side resistance per unit area is:

[0045]

[0046] in, Let r be the side drag per unit area at depth z and radial distance r. Here, γ is the static earth pressure coefficient, γ is the unit weight, and z is the calculation depth. η is the corrected internal friction angle at a radial distance r, η is the expansion enhancement coefficient, and Br(r) is the particle breakage rate at a radial distance r.

[0047] The formula for calculating the expansion enhancement coefficient is as follows:

[0048] ;

[0049] in, For calibration coefficients, The initial void ratio, The minimum porosity; the calibration coefficient The value range is from 2.0 to 4.0.

[0050] Furthermore, in step S6, the formula for calculating the ultimate bearing capacity of a single pile is:

[0051] ,

[0052] ;

[0053] in, The value represents the ultimate bearing capacity of a single pile, where L is the pile length and d is the pile diameter. Let z be the side resistance per unit area of ​​the pile surface at depth z. For the bearing capacity of the pile tip, γ is the bearing capacity coefficient, and γ is the unit weight. This represents the cross-sectional area of ​​the pile tip.

[0054] Compared with the prior art, the beneficial effects of the present invention are that, by establishing a quantitative relationship between the ratio of expansion pressure to critical expansion pressure and the range of the coupling zone and the boundary breakage rate, this embodiment achieves accurate quantification of the spatial range and outer boundary breakage rate of the expansion-breakage coupling effect of HSCA expansion piles in coral sand foundations. This provides accurate physical boundaries and benchmark values ​​for the subsequent radial zoning correction of the mechanical parameters of the soil around the pile, thereby ensuring that the bearing capacity calculation can fully consider the synergistic effect of coral sand particle breakage and expansion, and solving the problem of bearing capacity calculation deviation caused by ignoring the spatial distribution characteristics of the expansion-breakage coupling zone in the prior art.

[0055] Furthermore, this embodiment quantifies the non-uniform distribution characteristics of the expansion-fracture coupling effect in the space around the pile by establishing a power function decay distribution of the fracture rate along the radial direction, providing an accurate spatial variability data basis for the differentiated correction of soil mechanical parameters at different locations in subsequent steps.

[0056] Furthermore, this embodiment establishes a quantitative correction relationship between particle breakage rate and internal friction angle and compression modulus, thereby achieving differentiated correction of soil mechanical parameters at different locations within the coupling zone. The corrected internal friction angle decreases with increasing breakage rate, while the corrected compression modulus increases with increasing breakage rate. This accurately reflects the synergistic effect of two opposing mechanical effects: the deterioration of frictional performance caused by coral sand particle breakage and the increase in stiffness caused by filling and compaction. This provides material parameter inputs with continuous radial variation and clear physical meaning for the refined calculation of side resistance in subsequent steps.

[0057] Furthermore, this embodiment establishes a calculation formula for the quantitative improvement of pile side resistance by introducing the expansion enhancement coefficient η and the particle breakage rate Br(r). This fully reflects the enhancing effect of the filling compaction effect after the coral sand particles are broken on the side resistance, and avoids the underestimation problem caused by the use of far-field soil parameters to calculate the side resistance in the prior art.

[0058] Furthermore, this embodiment achieves a precise quantitative assessment of the ultimate bearing capacity of a single HSCA expansion pile in coral sand foundation by integrating the lateral resistance per unit area along the entire length of the pile and combining it with the calculation of the pile tip bearing capacity. This fully reflects the comprehensive influence of the expansion-fracture coupling effect along the depth direction and the radial direction of the pile, providing an accurate calculation basis for the design and construction of HSCA expansion piles in coral sand foundation.

[0059] This application provides a device for calculating the bearing capacity of coral sand expansion piles, including:

[0060] The parameter input module is used to obtain the initial internal friction angle, initial compression modulus, unit weight, coefficient of earth pressure at rest, swelling pressure and critical swelling pressure of coral sand, as well as the pile diameter and pile length.

[0061] The coupling zone calculation module is used to calculate the spatial range of the pile perimeter expansion-fracture coupling effect based on the ratio of the expansion pressure to the critical expansion pressure, and to calculate the boundary fracture rate at the outer boundary of the spatial range.

[0062] A breakage rate calculation module is used to calculate the particle breakage rate at each position along the radial direction within the spatial range, based on the boundary breakage rate.

[0063] The parameter correction module is used to correct the initial internal friction angle and the initial compression modulus according to the particle breakage rate at each position, so as to obtain the corrected internal friction angle and the corrected compression modulus.

[0064] The side resistance calculation module is used to calculate the side resistance per unit area at each depth of the pile body based on the corrected internal friction angle, the corrected compression modulus, the unit weight, the static earth pressure coefficient, the calculation depth, and the expansion enhancement coefficient.

[0065] The bearing capacity calculation module is used to integrate the lateral resistance per unit area along the entire length of the pile to obtain the ultimate bearing capacity of a single pile.

[0066] The results output module is used to output the calculated ultimate bearing capacity and / or long-term bearing capacity of a single pile.

[0067] This application provides a computer-readable storage medium storing a computer program thereon, which, when executed in a computer, causes the computer to perform the method provided in this application. Attached Figure Description

[0068] Figure 1 This is a flowchart illustrating the calculation method for the bearing capacity of coral sand expansion piles according to an embodiment of this application;

[0069] Figure 2 This is a flowchart illustrating the method for determining the spatial range in the calculation of the bearing capacity of coral sand expansion piles in this application embodiment;

[0070] Figure 3 This is a structural block diagram of the calculation device for the bearing capacity of coral sand expansion piles according to an embodiment of this application. Detailed Implementation

[0071] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0072] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0073] like Figures 1-3 As shown, Figure 1 This is a flowchart illustrating the calculation method for the bearing capacity of coral sand expansion piles according to an embodiment of this application; Figure 2 This is a flowchart illustrating the method for determining the spatial range in the calculation of the bearing capacity of coral sand expansion piles in this application embodiment; Figure 3 This is a structural block diagram of the calculation device for the bearing capacity of coral sand expansion piles according to an embodiment of this application.

[0074] The technical solution provided in this application includes the following steps:

[0075] Step S1: Obtain the initial internal friction angle, initial compression modulus, unit weight, coefficient of earth pressure at rest, swelling pressure and critical swelling pressure of the coral sand, as well as the pile diameter and pile length.

[0076] Step S2: Calculate the spatial range of the pile perimeter expansion-fracture coupling effect based on the ratio of the expansion pressure to the critical expansion pressure, and calculate the boundary fracture rate at the outer boundary of the spatial range.

[0077] Step S3: Within the spatial range, calculate the particle breakage rate at each radial position within the spatial range based on the boundary breakage rate;

[0078] Step S4: Based on the particle breakage rate at each location, correct the initial internal friction angle and the initial compression modulus to obtain the corrected internal friction angle and the corrected compression modulus.

[0079] Step S5: Calculate the side resistance per unit area at each depth of the pile body based on the corrected internal friction angle, the corrected compression modulus, the unit weight, the static earth pressure coefficient, the calculation depth, and the expansion enhancement coefficient.

[0080] Step S6: Integrate the lateral resistance per unit area along the entire length of the pile to obtain the ultimate bearing capacity of a single pile;

[0081] Step S7, calculate the long-term bearing capacity:

[0082] ;

[0083] in, For long-term load-bearing capacity, This refers to the ultimate bearing capacity of a single pile. The contribution coefficient to expansion. The expansion time constant is This is the creep reduction factor. t is the creep time constant, and t is the service time.

[0084] Specifically, in step S1, the formula for calculating the expansion pressure is:

[0085] ;

[0086] in, For expansion pressure, The dosage of HSCA expansion agent, To correct the compression modulus, For expansion strain.

[0087] In this embodiment, the physical and mechanical parameters of the coral sand are obtained as follows: the initial internal friction angle of the coral sand. Initial compressive modulus , unit weight γ and coefficient of earth pressure at rest The coral sand foundation was tested through in-situ field tests or laboratory geotechnical tests. Specifically, in-situ mechanical parameters of the coral sand strata were obtained using static cone penetration tests or standard penetration tests. Simultaneously, borehole samples were taken at the site to be constructed, and laboratory tests were conducted according to the "Standard for Geotechnical Testing Methods": the initial internal friction angle of the coral sand was determined using direct shear tests or triaxial compression tests. The initial compressive modulus was determined by consolidation test. The unit weight γ and the coefficient of earth pressure at rest of coral sand were determined using the ring sampler method. According to the initial internal friction angle Calculation determined.

[0088] Obtaining expansion pressure and critical expansion pressure: Expansion pressure and critical expansion pressure The expansion pressure is determined based on the dosage of HSCA expanding agent and the gradation characteristics of the coral sand. The calculation method is based on the dosage of HSCA expanding agent. The free expansion strain of the expanding agent at different dosages was determined by free expansion test. The actual expansion pressure is obtained by reducing the constraint stiffness of the soil around the pile. Critical expansion pressure The critical expansion pressure was determined by conducting a lateral confined compression-expansion coupling test on coral sand samples. The samples were placed in a lateral confined compression apparatus, and vertical loads were applied in stages while simultaneously measuring the volume change. When the applied expansion pressure exceeded a certain threshold, the coral sand particles began to break significantly, and the volume compression increased sharply. This threshold pressure was defined as the critical expansion pressure. Or, critical expansion pressure. The critical expansion pressure is determined by the statistical distribution characteristics of the single-particle crushing strength of coral sand, and the median value of the single-particle crushing strength distribution is taken as the critical expansion pressure. The value of .

[0089] Obtaining the expansion-fracture coupling parameters: Expansion-fracture coupling parameters and Calibration was determined through indoor expansion-fracture coupling tests: multiple groups of coral sand samples with different densities were prepared, and different levels of expansion pressure were applied to each sample. The changes in particle size distribution before and after the test were measured, and the particle breakage rate Br was calculated. The test data were then analyzed according to... Perform a regression fit and obtain the calibration results. and The values ​​of are determined as follows: The pile diameter d and pile length L are determined directly from the engineering design drawings or design scheme. Other preset parameters include: attenuation index m, attenuation coefficient β, and friction angle reduction coefficient. Compression modulus growth factor Expansion enhancement coefficient η, expansion strain Reference pressure These parameters are preset based on the engineering characteristics of the coral sand or the range of values ​​obtained through experience.

[0090] Specifically, in step S2, the spatial range of the pile perimeter expansion-fracture coupling effect is calculated based on the ratio of the expansion pressure to the critical expansion pressure, including:

[0091] Step S21: Calculate the ratio of the expansion pressure to the critical expansion pressure;

[0092] Step S22: Based on the ratio and a preset attenuation index, calculate the distance from the outer boundary of the spatial range to the center of the pile.

[0093] Step S23: Determine the spatial range as an annular area between the pile center and the pile surface, with the preset distance as the radius.

[0094] The formula for calculating the preset distance is:

[0095] ;

[0096] in, The distance is the preset distance, and d is the diameter of the pile. For expansion pressure, The critical expansion pressure is denoted as , and m is the decay exponent; the critical expansion pressure The value range is from 200 kPa to 600 kPa; the value range of the attenuation index m is from 0.3 to 0.8.

[0097] In this embodiment, based on the expansion pressure obtained in step S1 and critical expansion pressure Calculate the ratio of the two. For example, if the expansion pressure Critical expansion pressure Then the ratio This ratio reflects the relative level of expansion pressure to the particle breakage threshold of coral sand. When λ≤1, it indicates that the expansion pressure has not yet reached the particle breakage threshold, and the soil around the pile is mainly elastically compressed without significant particle breakage. When λ>1, it indicates that the expansion pressure exceeds the breakage threshold, and the coral sand particles around the pile begin to break, forming an expansion-breakage coupling zone.

[0098] Calculate the distance from the outer boundary of the spatial range to the center of the pile: Based on the ratio λ obtained in step S21 and combined with the preset attenuation index m, calculate the distance from the outer boundary of the expansion-fracture coupling spatial range to the center of the pile using the following formula. : Where d is the pile diameter and m is the attenuation index, reflecting the radial attenuation rate of the expansion-fracture coupling effect. For example, continuing the previous example, if the pile diameter d = 0.8m (then the pile radius...), then... ),ratio Decay index ,but: That is, the outer boundary of the expansion-fracture coupling effect space is approximately 0.693m from the pile center and the distance from the pile surface is... .

[0099] As can be seen from the above formula, the larger the ratio λ of the expansion pressure to the critical expansion pressure, the wider the coupling range; the larger the attenuation index m, the slower the radial attenuation of the influence of the expansion pressure, and the larger the coupling range.

[0100] Determine the spatial range: The spatial range of the pile periphery expansion-fracture coupling effect is defined as follows: with the pile center as the center, and... The inner boundary is a circular area with radius [radius] between the pile surface and the pile body surface. Specifically: the inner boundary is the pile surface, at a distance [distance] from the pile center. Outer boundary: The outer boundary of the coupling zone, distance from the center of the pile. Spatial range: That is, extending outward from the surface of the pile to The annular region. Within this spatial range, coral sand particles undergo varying degrees of fragmentation, with the fragmentation rate gradually decreasing from the inner boundary to the outer boundary; outside this spatial range ( The effect of expansion pressure on the soil has diminished to the point where it is insufficient to cause significant particle breakage. This area is considered the far field region, and the original, uncorrected mechanical parameters are used.

[0101] Specifically, in step S2, the formula for calculating the boundary breakage rate is:

[0102] ;

[0103] in, For boundary breakage rate, and For expansion-fracture coupling parameters, The reference pressure; the reference pressure The value ranges from 100 kPa to 500 kPa.

[0104] In this embodiment, the boundary breakage rate is calculated simultaneously at the boundary outside the spatial range. The calculation formula is as follows:

[0105] ;

[0106] in, and The expansion-fracture coupling parameters were determined through indoor expansion-fracture coupling tests. For reference pressure.

[0107] For example, take ,but:

[0108] ;

[0109] That is, the particle breakage rate at the outer boundary of the coupling zone is about 79.2%, and this value is used as the benchmark value for calculating the breakage rate at each location in the coupling zone in step S3.

[0110] This embodiment establishes a quantitative relationship between the ratio of expansion pressure to critical expansion pressure and the range of the coupling zone and the boundary breakage rate. This enables precise quantification of the spatial range and outer boundary breakage rate of the expansion-breakage coupling effect of HSCA expansion piles in coral sand foundations. It provides accurate physical boundaries and benchmark values ​​for subsequent radial zoning correction of the mechanical parameters of the soil around the pile, thereby ensuring that the bearing capacity calculation can fully consider the synergistic effect of coral sand particle breakage and expansion. This solves the problem of bearing capacity calculation deviation caused by ignoring the spatial distribution characteristics of the expansion-breakage coupling zone in the prior art.

[0111] Specifically, in step S3, the formula for calculating the particle breakage rate at each radial position within the spatial range is as follows:

[0112] ;

[0113] Wherein, Br(r) is the particle breakage rate at a radial distance r from the pile center. The boundary breakage rate, Let be the distance from the outer boundary of the spatial range to the center of the pile, β be the attenuation coefficient, and r be the radial distance from the center of the pile, with the value of r ranging from 1 to 2. The attenuation coefficient β ranges from 0.5 to 2.0.

[0114] In this embodiment, within the spatial range of the expansion-fracture coupling effect Within the particle breakage rate Br(r) at each location, the following formula is used:

[0115] ;

[0116] Wherein, Br(r) is the particle breakage rate at a radial distance r from the pile center. The boundary breakage rate (i.e., the outer boundary of the coupling zone) calculated in step S2. (breakage rate at the location) Let be the distance from the outer boundary of the coupling zone to the center of the pile, β be the attenuation coefficient, and r be the radial distance from the center of the pile, with the value of r ranging from 1 to 2. .

[0117] For example, the sample data from step S2 is used: The attenuation coefficient β = 1.2. The particle breakage rate at different radial positions within the coupling zone is calculated respectively:

[0118] At the surface of the pile ( ):

[0119] ;

[0120] calculate ;

[0121] ;

[0122] Due to the calculation This indicates that the coral sand particles near the surface of the pile have reached a completely broken state. (i.e., 100% breakage rate).

[0123] At the midpoint of the coupling region (r=0.55m):

[0124] ;

[0125] calculate ;

[0126] ;

[0127] same, ,Pick .

[0128] At the outer boundary of the coupling region ( ):

[0129] .

[0130] At a location near the outer boundary (r=0.65m):

[0131] ;

[0132] calculate ;

[0133] .

[0134] The calculation results show that within the coupling zone, the breakage rate gradually decreases from the pile surface to the outer boundary: the breakage rate reaches 100% near the pile surface (r=0.4m), remains 100% in the middle region (r=0.55m), drops to approximately 85.5% near the outer boundary (r=0.65m), and reaches 79.2% at the outer boundary (r=0.693m). This indicates that the expansion-breakage coupling effect is strongest near the pile surface and gradually decreases radially outward. When the calculated Br(r) > 1, Br(r) = 1 is taken to characterize that the particles have reached a completely broken state. The physical meaning of this upper limit constraint is that the breakage rate of coral sand particles cannot exceed 100%, that is, after all particles have broken at a certain location, further increases in expansion pressure will no longer increase the breakage rate at that location, but will instead be converted into further compaction of particles or rearrangement of breakage products. Outside the spatial range ( When Br(r) = 0, no particle breakage occurs, and this region is the far-field region, where the soil remains in its original state.

[0135] This embodiment quantifies the non-uniform distribution characteristics of the expansion-fracture coupling effect in the space around the pile by establishing a power function decay distribution of the fracture rate along the radial direction, providing an accurate spatial variability data basis for the differentiated correction of soil mechanical parameters at different locations in subsequent steps.

[0136] Specifically, in step S4, the formulas for calculating the corrected internal friction angle and the corrected compression modulus are as follows:

[0137] ,

[0138] ;

[0139] in, This is the corrected internal friction angle at a radial distance r. The initial internal friction angle is... Here, Br(r) is the friction angle reduction factor, and Br(r) is the particle breakage rate at a radial distance r. This is the corrected compressive modulus at a radial distance r. The initial compression modulus, This is the growth factor of the compression modulus.

[0140] In this embodiment, step S4 adjusts the initial internal friction angle of the coral sand based on the particle breakage rate Br(r) at each location calculated in step S3. and initial compressive modulus After correction, the corrected internal friction angles at various radial positions within the coupling region are obtained. and the corrected compression modulus .

[0141] Corrected internal friction angle Calculate using the following formula:

[0142] ;

[0143] in, This is the corrected internal friction angle at a radial distance r. The initial internal friction angle obtained in step S1, Br(r) is the friction angle reduction factor, and Br(r) is the particle breakage rate at the radial distance r calculated in step S3.

[0144] Corrected compressive modulus Calculate using the following formula:

[0145] ;

[0146] in, This is the corrected compressive modulus at a radial distance r. The initial compression modulus obtained in step S1, Br(r) is the growth factor of the compression modulus, and Br(r) is the particle breakage rate at a radial distance r; the friction angle reduction factor is... The value range is from 1° to 10°; the growth coefficient of the compression modulus The value range is from 2 to 8.

[0147] The physical meaning of the two correction formulas mentioned above is that after coral sand particles break down under expansion pressure, the interlocking effect and friction coefficient between particles decrease, leading to a reduction in the internal friction angle. Simultaneously, the small particles generated by the breakage fill the original pores, making the soil skeleton more compact and increasing the compression modulus. Therefore, the internal friction angle is corrected by reduction, and the compression modulus is corrected by enhancement.

[0148] For example, the example data and calculation results from step S3 are used. Initial internal friction angle Initial compressive modulus Friction angle reduction factor growth coefficient of compression modulus .

[0149] Calculate the corrected mechanical parameters at different radial positions within the coupling region:

[0150] At the surface of the pile ( ), :

[0151] ;

[0152] ;

[0153] At the midpoint of the coupling region (r=0.55m), Br(0.55)=1.0:

[0154] ;

[0155] ;

[0156] At a certain location near the outer boundary (r=0.65m), Br(0.65)=0.855:

[0157] ;

[0158] ;

[0159] At the outer boundary of the coupling region ( ), :

[0160] ;

[0161] .

[0162] The calculation results above show that, within the coupling region, the corrected internal friction angle... The angle gradually recovers from 32° at the pile surface to 32.624° towards the outer boundary, but is still lower than the initial value of 35°, indicating that the reduction in internal friction angle caused by particle breakage still exists at the outer boundary of the coupling zone, but the magnitude is small; the corrected compression modulus The pressure gradually decreases from 225 MPa at the pile surface to 187.56 MPa towards the outer boundary, but is still significantly higher than the initial value of 45 MPa, indicating that the effect of the broken filling effect on soil stiffness gradually weakens radially outward.

[0163] Outside the spatial range ( Since Br(r) = 0, no particle breakage occurs, therefore no correction is needed, i.e.:

[0164] ;

[0165] .

[0166] This embodiment establishes a quantitative correction relationship between particle breakage rate and internal friction angle and compression modulus, thereby achieving differentiated correction of soil mechanical parameters at different locations within the coupling zone. The corrected internal friction angle decreases with increasing breakage rate, while the corrected compression modulus increases with increasing breakage rate. This accurately reflects the synergistic effect of two opposing mechanical effects: the deterioration of frictional performance caused by coral sand particle breakage and the increase in stiffness caused by filling and compaction. This provides material parameter inputs with continuous radial variation and clear physical meaning for the refined calculation of side resistance in subsequent steps.

[0167] Specifically, in step S5, the formula for calculating the side resistance per unit area is:

[0168]

[0169] in, Let r be the side drag per unit area at depth z and radial distance r. Here, γ is the static earth pressure coefficient, γ is the unit weight, and z is the calculation depth. η is the corrected internal friction angle at a radial distance r, η is the expansion enhancement coefficient, and Br(r) is the particle breakage rate at a radial distance r.

[0170] The formula for calculating the expansion enhancement coefficient is as follows:

[0171] ;

[0172] in, For calibration coefficients, The initial void ratio, The minimum porosity; the calibration coefficient The value range is from 2.0 to 4.0.

[0173] In this embodiment, step S5 is based on the internal friction angle corrected in step S4. and the corrected compression modulus Combined with the unit weight γ and the coefficient of earth pressure at rest obtained in step S1 The calculation also includes the preset calculation depth z and expansion enhancement coefficient η, to calculate the lateral resistance per unit area at each depth of the pile. .

[0174] Side resistance per unit area The calculation formula is:

[0175] ;

[0176] in, Let r be the side drag per unit area at depth z and radial distance r. γ is the at-rest earth pressure coefficient obtained in step S1, γ is the unit weight of coral sand obtained in step S1, and z is the calculation depth. η is the corrected internal friction angle at the radial distance r calculated in step S4, η is the expansion enhancement coefficient, and Br(r) is the particle breakage rate at the radial distance r calculated in step S3.

[0177] The physical meaning of this formula is that side drag is determined by three factors. Part One The effective vertical stress reflects the basic contribution of the overlying soil weight to the lateral resistance; Part Two The corrected tangent value of the internal friction angle reflects the frictional performance of the pile-soil interface; Part Three The expansion enhancement factor reflects the effect of the expansion-fracture coupling on the side drag. The larger the Br(r), the higher the degree of particle fragmentation at that location, the more complete the expansion filling effect, and the greater the increase in side drag.

[0178] The expansion enhancement coefficient η reflects the overall efficiency of the lateral resistance enhancement of coral sand under the coupled effect of expansion and breakage. Its calculation formula is as follows:

[0179] ;

[0180] in, These are calibration coefficients, determined through indoor model tests. The initial porosity of the coral sand obtained in step S1; The minimum porosity of coral sand can be determined through a maximum dry density test.

[0181] The physical meaning of this formula is: This reflects the density state of the coral sand and its initial porosity. The larger the particle size (i.e., the more porous), the greater the compressible space, the more significant the effect of small particles filling the pores after particle breakage, and the more pronounced the expansion enhancement effect; calibration coefficient This comprehensively reflects the impact of factors such as the type of expansive agent and the characteristics of the pile-soil interface on the reinforcement efficiency.

[0182] Example data following the steps described above. Initial porosity. Minimum porosity Calibration coefficient The expansion enhancement coefficient η is calculated as follows:

[0183] .

[0184] Pick .

[0185] Taking a depth of z=5m as an example, , Calculate the side drag per unit area at each radial location:

[0186] At the surface of the pile (r=0.4m, i.e. at the pile-soil interface). , :

[0187] ;

[0188] Vertical effective stress: ;

[0189] Expansion enhancement factor: ;

[0190] ;

[0191] At the middle position of the coupling region ( ), , :

[0192] ;

[0193] At a location near the outer boundary ( ), , :

[0194] ;

[0195] Expansion enhancement factor: ;

[0196] ;

[0197] At the outer boundary of the coupling region ( ), , :

[0198] ;

[0199] Expansion enhancement factor: ;

[0200] ;

[0201] Outside the spatial range ( (far field region) , : ;

[0202] Expansion enhancement factor: ;

[0203] .

[0204] From the above calculation results, we can see that: First, within the coupling region ( Due to the expansion-fracture coupling effect, the side resistance per unit area (approximately 34.38~36.21 kPa) is significantly higher than that in the far-field region (approximately 26.35 kPa), with an increase of approximately 30% to 37%, indicating that the expansion-fracture coupling effect has a significant enhancing effect on the pile side resistance. Secondly, within the coupling zone, the side resistance gradually decreases from 36.21 kPa at the pile surface to 34.38 kPa towards the outer boundary, showing a decreasing trend from the inside out, consistent with the decay law of the fracture rate Br(r). Thirdly, in the far-field region (… Since there is no expansion-fracture coupling effect, the side resistance is determined solely by the original soil parameters, resulting in the lowest value. When calculating the actual side resistance at the pile surface, r = d / 2 (i.e., at the pile-soil interface) is taken as... As a representative value of the side resistance per unit area of ​​the pile at that depth, it is used for the integral calculation along the entire length of the pile in step S6.

[0205] This embodiment establishes a calculation formula for the quantitative improvement of pile side resistance by introducing the expansion enhancement coefficient η and the particle breakage rate Br(r). It fully reflects the enhancement effect of the filling compaction effect after the coral sand particles are broken on the side resistance, and avoids the underestimation problem caused by the use of far-field soil parameters to calculate the side resistance in the prior art.

[0206] Specifically, in step S6, the formula for calculating the ultimate bearing capacity of a single pile is:

[0207] ;

[0208] ;

[0209] in, The value represents the ultimate bearing capacity of a single pile, where L is the pile length and d is the pile diameter. Let z be the side resistance per unit area of ​​the pile surface at depth z. For the bearing capacity of the pile tip, γ is the bearing capacity coefficient, and γ is the unit weight. This represents the cross-sectional area at the pile tip.

[0210] In this embodiment, step S6 calculates the lateral resistance per unit area of ​​the pile surface at each depth based on the data obtained in step S5. The total skin friction of the pile is obtained by integrating along the entire length of the pile. Then, the pile tip bearing capacity is added to obtain the ultimate bearing capacity of the single pile. .

[0211] ultimate bearing capacity of a single pile The calculation formula is:

[0212]

[0213] in, The value represents the ultimate bearing capacity of a single pile, where L is the pile length and d is the pile diameter. This is the side resistance per unit area of ​​the pile surface at depth z (i.e., the value calculated at r=d / 2 in step S5). This refers to the bearing capacity at the pile end.

[0214] Pile end bearing capacity The calculation formula is:

[0215] ;

[0216] in, The bearing capacity coefficient is determined by referring to a table based on the internal friction angle of the coral sand or by using classical soil mechanics formulas (such as Terzaghi's formula or Meyerhoff's formula); γ is the unit weight of the coral sand obtained in step S1; L is the pile length, i.e., the pile tip embedment depth. For the cross-sectional area of ​​the pile tip, according to calculate.

[0217] The physical meaning of the above formula is that the ultimate bearing capacity of a single pile consists of two parts. The first part is the total skin friction along the pile side, that is, along the entire surface area of ​​the pile (…). The first part is the cumulative sum of lateral resistance at each depth, which is precisely summarized by integral form to represent the distribution of lateral resistance varying along the depth; the second part is the pile tip bearing capacity, that is, the ultimate resistance of the soil at the pile tip under vertical load, which is related to the pile tip embedment depth L and the pile tip cross-sectional area. Proportional.

[0218] For example, using the sample data from the preceding steps: Pile diameter d = 0.8m, pile length L = 12m, pile tip cross-sectional area... Severe Bearing capacity coefficient (according to Consult the Terzaghi bearing capacity coefficient table and take... ).

[0219] In step S5, the side drag per unit area at each depth has been calculated. .because It is linearly related to the computational depth z. The total skin friction of the pile can be calculated using an integral method.

[0220] Taking a depth of z=5m as an example, Based on the linear relationship, As z increases linearly, its expression can be written as:

[0221] ;

[0222] Integrating the pile side friction along the entire length of the pile:

[0223]

[0224] =π×0.8×7.242×(144 / 2)

[0225] =π×0.8×7.242×72

[0226] =3.1416 × 0.8 × 521.424

[0227] =3.1416 × 417.139

[0228] ≈1310.5kN.

[0229] Calculate the bearing capacity of the pile end :

[0230]

[0231] =48×17.5×6.0324

[0232] =48×105.567

[0233] ≈5067.2kN.

[0234] Calculate the ultimate bearing capacity of a single pile : .

[0235] If the uncorrected parameters in the far-field region are used for calculation (i.e., the expansion-fragmentation coupling effect is not considered), then... , ),but The total skin friction of the pile is:

[0236]

[0237] .

[0238] The comparison shows that, considering the expansion-fracture coupling effect, the ultimate bearing capacity of a single pile increases from 6020.8 kN to 6377.7 kN, an increase of approximately (6377.7-6020.8) / 6020.8 ≈ 5.93%. Among these increases, the total skin friction of the pile increases from 953.6 kN to 1310.5 kN, a significant increase of 37.4%, fully demonstrating the significant enhancement effect of the expansion-fracture coupling effect on the skin friction of the pile; while the pile tip bearing capacity remains unchanged. Because the soil at the pile tip is far from the pile body, it is not directly affected by the expansion-fracture coupling effect.

[0239] In practical engineering, the above calculations can be performed using numerical integration methods (such as Simpson's rule or Gauss's quadrature method), that is, discretizing the pile along its length into several infinitesimal segments and summing the side resistance of each infinitesimal segment:

[0240] ;

[0241] in, Let be the representative depth of the i-th infinitesimal segment. Let be the length of the i-th infinitesimal segment.

[0242] This embodiment achieves a precise quantitative assessment of the ultimate bearing capacity of a single HSCA expansion pile in coral sand foundation by integrating the lateral resistance per unit area along the entire length of the pile and combining it with the calculation of the pile tip bearing capacity. It fully reflects the comprehensive influence of the expansion-fracture coupling effect along the depth direction and the radial direction of the pile, providing an accurate calculation basis for the design and construction of HSCA expansion piles in coral sand foundation.

[0243] Specifically, during the service life of expansion piles, the expansion effect of the HSCA expansion agent gradually takes effect over time, while the coral sand particles undergo creep and progressive breakage under long-term loads. To evaluate the evolution of the bearing capacity of expansion piles during their service life, the long-term bearing capacity is calculated using the following formula:

[0244] ;

[0245] Where Q(t) is the bearing capacity of the pile foundation at service time t; The ultimate bearing capacity of a single pile is calculated in step S7; The expansion contribution coefficient reflects the long-term enhancement of bearing capacity due to the expansion effect, and its value ranges from 0.05 to 0.20. The expansion time constant reflects the rate at which the expansion effect takes effect, and its value ranges from 30 days to 180 days. The creep reduction factor reflects the long-term weakening of bearing capacity caused by coral sand creep and progressive fragmentation, with a value ranging from 0.02 to 0.10. is the creep time constant, which reflects the evolution rate of the creep effect, and its value ranges from 90 days to 365 days; t is the service time.

[0246] The above parameters were determined through long-term load tests or indoor creep-expansion coupling tests on HSCA expansion piles in coral sand foundations. As t→∞, the bearing capacity tends to a stable value. .

[0247] Example 1: A coral sand foundation project site requires the design of HSCA expansion pile foundations. The bearing capacity is calculated according to the method of this invention.

[0248] The physical and mechanical parameters and expansion-fracture coupling parameters of coral sand were determined.

[0249] Based on on-site sampling and indoor testing, the physical and mechanical parameters of the coral sand were determined as follows: initial porosity Minimum porosity Severe Initial internal friction angle Initial compressive modulus Energy consumption coefficient of particle crushing .

[0250] Calibrate the expansion-fracture coupling parameters through indoor expansion-fracture coupling tests: , Reference pressure .

[0251] Determine the design parameters for the expansion pile.

[0252] The designed pile diameter is d=0.8m, and the pile length is L=15m. The HSCA expansion agent dosage is 15%. Expansion strain .

[0253] Calculate expansion pressure and coupling region range .

[0254] Corrected compressive modulus Initial selection Then the expansion pressure is:

[0255] .

[0256] Critical expansion pressure The attenuation index m = 0.5.

[0257] Coupling region range:

[0258] .

[0259] Calculate the breakage rate distribution Br(r) within the coupling zone.

[0260] Fragmentation rate at the outer boundary of the coupling region:

[0261] .

[0262] The attenuation coefficient β = 1.0.

[0263] At a distance r = 0.4m from the pile center (pile-soil interface):

[0264] .

[0265] At r=0.6m: .

[0266] At r=0.781m (outer boundary of the coupling region): .

[0267] Calculate the corrected mechanical parameters within the coupling region.

[0268] Friction angle reduction factor growth coefficient of compression modulus .

[0269] At r=0.4m:

[0270] ;

[0271] .

[0272] At r=0.6m:

[0273] ;

[0274] .

[0275] At r = 0.781m:

[0276] ;

[0277] .

[0278] Calculate the pile side resistance.

[0279] coefficient of earth pressure at rest .

[0280] Calibration coefficient Expansion enhancement coefficient:

[0281] .

[0282] At the pile-soil interface at r=0.4m (within the coupling zone), , ):

[0283]

[0284] =0.426×17.5×z×tan(33.08°)×(1+1.179×0.385)

[0285] =7.455×z×0.652×1.454

[0286] =7.068×z (kPa, where z is in meters).

[0287] At a depth of z=15m .

[0288] In contrast, a traditional method (which does not consider expansion and fracturing and uses far-field soil parameters) is employed. (without expansion enhancement coefficient)

[0289]

[0290] =7.455×z×0.700=5.219×z.

[0291] At a depth of z=15m .

[0292] In this embodiment, the pile side resistance increase ratio is 7.068 / 5.219=1.355, that is, the ultimate side resistance is 35.5% higher than the design value of the traditional method.

[0293] Calculate the ultimate bearing capacity of a single pile.

[0294] Pile tip bearing capacity coefficient

[0295] =tan²(62.5°)×exp(π×0.700)=3.69×9.03=33.3.

[0296] Pile tip cross-sectional area .

[0297] Pile end bearing capacity .

[0298] Pile side resistance:

[0299]

[0300] =3.1416×0.8×7.068×(15² / 2)=17.754×112.5=1997kN.

[0301] ultimate bearing capacity of a single pile .

[0302] In contrast, the pile side resistance calculated using traditional methods is as follows:

[0303] .

[0304] Traditional method for ultimate bearing capacity of single pile .

[0305] In this embodiment, the ultimate bearing capacity of a single pile is increased by (6390-5867) / 5867=8.9% compared with the traditional method, of which the pile side resistance is increased by 35.5%.

[0306] Calculate the long-term bearing capacity.

[0307] Inflation contribution coefficient expansion time constant .

[0308] Creep reduction factor Creep time constant .

[0309] When the service time is t=365 days (1 year):

[0310]

[0311] =6390×[1+0.10×(1-0.0176)-0.05×(1-0.131)]

[0312] =6390×[1+0.0982-0.0435]

[0313] =6390×1.0547=6741kN.

[0314] When the service time is t=1095 days (3 years):

[0315]

[0316] =6390×[1+0.10×0.99999-0.05×0.9975]

[0317] =6390×[1+0.10-0.0499]

[0318] =6390×1.0501=6710kN.

[0319] Long-term load-bearing capacity tends to stabilize. .

[0320] Example 2: A coral sand foundation engineering site was designed with HSCA expansion piles. Coral sand parameters: initial void ratio... Minimum porosity Severe Initial internal friction angle Initial compressive modulus Energy consumption coefficient of particle crushing Expansion-fracture coupling parameters: , Reference pressure Design parameters for expansion piles: pile diameter d = 1.0m, pile length L = 20m, HSCA expansion agent dosage is 12%, taken as... Expansion strain .

[0321] Calculate expansion pressure and coupling region range .

[0322] .

[0323] Critical expansion pressure The attenuation index m = 0.55.

[0324] .

[0325] Calculate the breakage rate distribution Br(r) within the coupling zone.

[0326] .

[0327] The attenuation coefficient β = 1.2.

[0328] At r=0.5m: .

[0329] At r=0.8m: .

[0330] At r = 1.053m: Br(1.053) = 0.199.

[0331] Calculate the corrected mechanical parameters within the coupling region.

[0332] Friction angle reduction factor growth coefficient of compression modulus .

[0333] At r=0.5m: ; .

[0334] At r=0.8m: ; .

[0335] At r = 1.053m: ; .

[0336] Calculate the pile side resistance.

[0337] coefficient of earth pressure at rest .

[0338] Calibration coefficient Expansion enhancement coefficient:

[0339] ;

[0340] At the pile-soil interface at r=0.5m (Br=0.507), ):

[0341]

[0342] =6.912×z×0.727×1.365

[0343] =6.859×z (kPa).

[0344] Traditional method: .

[0345] The increase in pile side resistance is 6.859 / 5.398=1.270, which means that the ultimate side resistance is 27.0% higher than the design value of the traditional method.

[0346] Calculate the ultimate bearing capacity of a single pile:

[0347] Pile tip bearing capacity coefficient .

[0348] Pile tip cross-sectional area .

[0349] Pile end bearing capacity .

[0350] Pile side resistance: .

[0351] ultimate bearing capacity of a single pile .

[0352] Traditional methods for pile side resistance .

[0353] Traditional method for ultimate bearing capacity of single pile .

[0354] The ultimate bearing capacity of a single pile increased by (18777-17860) / 17860=5.1%, of which the pile side resistance increased by 27.0%.

[0355] Comparative analysis of the embodiments: Table 1 compares the key parameters and calculation results of the two embodiments.

[0356] Table 1

[0357]

[0358] As shown in Table 1, Example 1, due to its higher initial porosity of coral sand (e0=1.80) and larger amount of expanding agent (15%), has a larger expansion enhancement coefficient, resulting in a 35.5% increase in pile side resistance. Example 2, with its lower initial porosity of coral sand (e0=1.50) and smaller amount of expanding agent (12%), shows a 27.0% increase in pile side resistance. Both examples demonstrate that the pile side resistance calculated by the method of this invention is significantly higher than that of the traditional method, and the increase is positively correlated with the porosity of the coral sand and the amount of expanding agent, consistent with the physical mechanism of the crushing-expansion synergistic effect.

[0359] This application provides a device for calculating the bearing capacity of coral sand expansion piles, including:

[0360] The parameter input module is used to obtain the initial internal friction angle, initial compression modulus, unit weight, coefficient of earth pressure at rest, swelling pressure and critical swelling pressure of coral sand, as well as the pile diameter and pile length.

[0361] The coupling zone calculation module is used to calculate the spatial range of the pile perimeter expansion-fracture coupling effect based on the ratio of the expansion pressure to the critical expansion pressure, and to calculate the boundary fracture rate at the outer boundary of the spatial range.

[0362] A breakage rate calculation module is used to calculate the particle breakage rate at each position along the radial direction within the spatial range, based on the boundary breakage rate.

[0363] The parameter correction module is used to correct the initial internal friction angle and the initial compression modulus according to the particle breakage rate at each position, so as to obtain the corrected internal friction angle and the corrected compression modulus.

[0364] The side resistance calculation module is used to calculate the side resistance per unit area at each depth of the pile body based on the corrected internal friction angle, the corrected compression modulus, the unit weight, the static earth pressure coefficient, the calculation depth, and the expansion enhancement coefficient.

[0365] The bearing capacity calculation module is used to integrate the lateral resistance per unit area along the entire length of the pile to obtain the ultimate bearing capacity of a single pile.

[0366] The results output module is used to output the calculated ultimate bearing capacity and / or long-term bearing capacity of a single pile.

[0367] This application provides a computer-readable storage medium storing a computer program thereon, which, when executed in a computer, causes the computer to perform the method provided in this application.

[0368] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A method for calculating the bearing capacity of coral sand expansion piles, characterized in that, include: Step S1: Obtain the initial internal friction angle, initial compression modulus, unit weight, coefficient of earth pressure at rest, swelling pressure and critical swelling pressure of the coral sand, as well as the pile diameter and pile length. Step S2: Calculate the spatial range of the pile perimeter expansion-fracture coupling effect based on the ratio of the expansion pressure to the critical expansion pressure, and calculate the boundary fracture rate at the outer boundary of the spatial range. Step S3: Within the spatial range, calculate the particle breakage rate at each radial position within the spatial range based on the boundary breakage rate; Step S4: Based on the particle breakage rate at each location, correct the initial internal friction angle and the initial compression modulus to obtain the corrected internal friction angle and the corrected compression modulus. Step S5: Calculate the side resistance per unit area at each depth of the pile body based on the corrected internal friction angle, the corrected compression modulus, the unit weight, the static earth pressure coefficient, the calculation depth, and the expansion enhancement coefficient. Step S6: Integrate the lateral resistance per unit area along the entire length of the pile to obtain the ultimate bearing capacity of a single pile; Step S7, calculate the long-term bearing capacity: ； in, For long-term load-bearing capacity, This refers to the ultimate bearing capacity of a single pile. The contribution coefficient to expansion. The expansion time constant is This is the creep reduction factor. t is the creep time constant, and t is the service time.

2. The method according to claim 1, characterized in that, In step S1, the formula for calculating the expansion pressure is: ； in, For expansion pressure, The dosage of HSCA expansion agent. To correct the compression modulus, For expansion strain.

3. The method according to claim 1, characterized in that, In step S2, the spatial range of the pile perimeter expansion-fracture coupling effect is calculated based on the ratio of the expansion pressure to the critical expansion pressure, including: Step S21: Calculate the ratio of the expansion pressure to the critical expansion pressure; Step S22: Based on the ratio and a preset attenuation index, calculate the distance from the outer boundary of the spatial range to the center of the pile. Step S23: Determine the spatial range as an annular area between the pile center and the pile surface, with the preset distance as the radius and the circular area centered on the pile center. The formula for calculating the preset distance is: ； in, The distance is the preset distance, and d is the diameter of the pile. For expansion pressure, The critical expansion pressure is denoted as , and m is the decay exponent; the critical expansion pressure The value range is from 200 kPa to 600 kPa; the value range of the attenuation index m is from 0.3 to 0.

8.

4. The method according to claim 1, characterized in that, In step S2, the formula for calculating the boundary breakage rate is: ； in, For boundary breakage rate, and For expansion-fracture coupling parameters, The reference pressure; the reference pressure The value ranges from 100 kPa to 500 kPa.

5. The method according to claim 1, characterized in that, In step S3, the formula for calculating the particle breakage rate at each radial position within the spatial range is: ； Wherein, Br(r) is the particle breakage rate at a radial distance r from the pile center. The boundary breakage rate, Let be the distance from the outer boundary of the spatial range to the center of the pile, β be the attenuation coefficient, and r be the radial distance from the center of the pile, with the value of r ranging from 1 to 2. The attenuation coefficient β ranges from 0.5 to 2.

0.

6. The method according to claim 1, characterized in that, In step S4, the formulas for calculating the corrected internal friction angle and the corrected compression modulus are as follows: ， ； in, This is the corrected internal friction angle at a radial distance r. The initial internal friction angle is... Here, Br(r) is the friction angle reduction factor, and Br(r) is the particle breakage rate at a radial distance r. This is the corrected compressive modulus at a radial distance r. The initial compression modulus, The coefficient for growth of the compression modulus; the coefficient for reduction of the friction angle. The value range is from 1° to 10°; the compression modulus growth coefficient The value range is from 2 to 8.

7. The method according to claim 1, characterized in that, In step S5, the formula for calculating the side resistance per unit area is: ； in, Let r be the side drag per unit area at depth z and radial distance r. Here, γ is the static earth pressure coefficient, γ is the unit weight, and z is the calculation depth. η is the corrected internal friction angle at a radial distance r, η is the expansion enhancement coefficient, and Br(r) is the particle breakage rate at a radial distance r. The formula for calculating the expansion enhancement coefficient is as follows: ； in, For calibration coefficients, The initial void ratio, The minimum porosity; the calibration coefficient The value range is from 2.0 to 4.

0.

8. The method according to claim 1, characterized in that, In step S6, the formula for calculating the ultimate bearing capacity of a single pile is: ， ； in, The value represents the ultimate bearing capacity of a single pile, where L is the pile length and d is the pile diameter. Let z be the side resistance per unit area of ​​the pile surface at depth z. For the bearing capacity of the pile tip, γ is the bearing capacity coefficient, and γ is the unit weight. This represents the cross-sectional area at the pile tip.

9. A calculation device for the bearing capacity of coral sand expansion piles, characterized in that, include: The parameter input module is used to obtain the initial internal friction angle, initial compression modulus, unit weight, coefficient of earth pressure at rest, swelling pressure and critical swelling pressure of coral sand, as well as the pile diameter and pile length. The coupling zone calculation module is used to calculate the spatial range of the pile perimeter expansion-fracture coupling effect based on the ratio of the expansion pressure to the critical expansion pressure, and to calculate the boundary fracture rate at the outer boundary of the spatial range. A breakage rate calculation module is used to calculate the particle breakage rate at each position along the radial direction within the spatial range, based on the boundary breakage rate. The parameter correction module is used to correct the initial internal friction angle and the initial compression modulus according to the particle breakage rate at each position, so as to obtain the corrected internal friction angle and the corrected compression modulus. The side resistance calculation module is used to calculate the side resistance per unit area at each depth of the pile body based on the corrected internal friction angle, the corrected compression modulus, the unit weight, the static earth pressure coefficient, the calculation depth, and the expansion enhancement coefficient. The bearing capacity calculation module is used to integrate the lateral resistance per unit area along the entire length of the pile to obtain the ultimate bearing capacity of a single pile. The results output module is used to output the calculated ultimate bearing capacity and / or long-term bearing capacity of a single pile.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 8.

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