Support pile and engineering pile integrated design and detection method based on multi-parameter fusion

Abstract

The present application relates to the field of engineering design construction informatization, and discloses a supporting pile and engineering pile integrated design and detection method based on multi-parameter fusion, which comprises the following steps: S1, collecting design parameters and determining the initial number and initial arrangement of the pile foundation; S2, constructing a supporting pile-engineering pile dual-function coupling stress model, performing stress calculation, and determining the pile foundation parameters; S3, performing pile foundation integrity detection during the design of the test pile, obtaining multi-dimensional detection parameters, performing data fusion, and performing integrity determination on the pile foundation; S4, performing single-pile vertical compression static load test on the test pile by using an anchor pile counterforce device, and obtaining the single-pile vertical compression ultimate bearing capacity; S5, determining the single-pile vertical bearing capacity characteristic value according to the measured single-pile vertical compression ultimate bearing capacity, and optimizing the pile foundation scheme; and S6, performing pile foundation detection, data collection and analysis after the completion of construction, and forming an acceptance report. The present application proposes the supporting pile and engineering pile integrated design and detection method based on multi-parameter fusion, and realizes the collaboration, standardization and high efficiency of design and detection.

Description

Technical Field

[0001] This invention relates to the field of information technology in engineering design and construction, specifically to an integrated design and testing method for support piles and engineering piles based on multi-parameter fusion. Background Technology

[0002] Support piles and engineering piles are two key load-bearing components in foundation pit engineering and the main structure. Traditional engineering projects typically employ a separate design and construction model for support piles and engineering piles. That is, engineering piles only bear the vertical load of the superstructure, while support piles only bear the lateral earth pressure of the foundation pit; they are arranged and constructed independently. This traditional model has significant drawbacks: a large number of piles, high material consumption, complex construction procedures, and numerous overlapping operations lead to higher overall project costs and a significantly longer construction period, making it difficult to meet the requirements of efficient, economical, and green construction in modern engineering.

[0003] To address the shortcomings of traditional separate pile design, the industry is gradually promoting the integrated technology of support piles and engineering piles. Its core is that the pile foundation must simultaneously meet the dual mechanical requirements of the vertical bearing capacity of the superstructure and the horizontal resistance of the foundation pit support. This achieves the integration of structural functions and the optimized allocation of engineering resources, significantly reducing the number of engineering piles and lowering the overall project cost.

[0004] Support piles serving as engineering piles represent a key application scenario where structural engineering and geotechnical engineering intersect. Currently, the industry still faces significant challenges in the design, testing, and evaluation of such integrated pile foundations, as detailed below:

[0005] The lack of unified design standards for integrated pile foundations makes it difficult to simultaneously guarantee dual functions: Integrated piles need to meet the requirements of vertical bearing capacity and horizontal resistance (or lateral force), stiffness and deformation control. However, engineering piles and support piles belong to the structural profession and geotechnical profession respectively, and the code systems they implement are independent of each other. There is a lack of unified and coordinated design criteria, which can easily lead to situations where the vertical bearing capacity meets the requirements but the support stiffness and horizontal resistance are insufficient, or the support function meets the standards but the vertical bearing capacity design is excessive. It is difficult to achieve dual functions safely and economically at the same time.

[0006] Methods for testing the vertical bearing capacity of high-bearing-capacity, large-diameter cast-in-place piles are limited, and the surcharge method presents challenges due to insufficient site space and safety risks. For high-bearing-capacity, large-diameter cast-in-place piles that also serve as support piles, the surcharge method is commonly used for testing their vertical bearing capacity. This method requires a large number of counterweights to be placed on top of the piles to simulate vertical loads. On the one hand, this places extremely high demands on the space and bearing capacity of the construction site, making it unsuitable for projects with narrow foundation pits or soft soil foundations. On the other hand, the heavy surcharge during the testing phase can generate additional stress on the soil around the foundation pit, which can easily lead to deformation and settlement of the foundation pit sidewalls, affecting the safety of foundation pit construction. Thirdly, when the support piles that also serve as engineering piles are close to the sidewalls of underground structures such as subways and tunnels, the surcharge method will inevitably place the counterweights on the top slab of the subway tunnel structure, thus affecting the safety of the subway tunnel structure.

[0007] The self-balancing method has inherent flaws and cannot meet the requirements of random sampling in the specifications: It requires pre-embedding load cells at designated locations on the pile during the pile foundation construction phase. Testing involves loading the upper and lower ends of the load cells to measure the pile's bearing capacity. However, this method has significant drawbacks: First, the location of the pre-embedded load cells can easily become a weak point in the pile structure, affecting the actual performance of the pile foundation in the later stages. Second, because the load cells need to be pre-embedded, the pile location must be determined before construction, making it impossible to meet the random sampling requirements of the specifications, resulting in insufficient representativeness and objectivity of the test results. Third, the pre-embedding process increases construction costs and time, and the installation accuracy of the load cells directly affects the test results, resulting in a low tolerance for error.

[0008] Existing testing methods only check the integrity or bearing capacity of the pile body, without verifying the support function at the same time: Conventional pile foundation testing only focuses on the integrity of the pile body and the vertical bearing capacity, and cannot simultaneously verify the support function (horizontal resistance, lateral displacement control). It cannot fully determine whether the integrated pile meets the dual requirements of "structural bearing capacity + foundation pit support", resulting in problems of incomplete testing coverage and failure to identify structural safety hazards.

[0009] The design and testing processes are disconnected, lacking an integrated technical system: In existing technologies, the design parameters of pile foundations are not linked with subsequent testing methods, and the development of testing plans does not take into account the geological, stress, and pile foundation parameters at the design stage. This leads to the need for additional adjustments to testing equipment and plans during the testing process, increasing testing costs. Furthermore, the testing results cannot quickly verify the rationality of the design, resulting in a disconnect between design and testing and a lack of closed-loop management.

[0010] Multi-source testing data is used in isolation without a multi-parameter fusion evaluation model: In actual engineering, various types of testing data such as vertical bearing capacity of pile foundation, pile integrity, and horizontal displacement can be obtained. However, these data are interpreted and used in isolation without establishing a comprehensive evaluation system that integrates multiple parameters. This makes it impossible to achieve closed-loop verification of design-construction-testing, resulting in one-sided and unreliable evaluation results.

[0011] In summary, existing technologies lack an integrated collaborative mechanism in the design phase, and suffer from problems such as site limitations, inability to conduct random sampling, pile damage, limited testing functions, and inability to integrate and evaluate data in the testing phase. There is an urgent need for a solution that can achieve multi-parameter fusion for the integrated design and testing of support piles and engineering piles. Summary of the Invention

[0012] This invention addresses the shortcomings of existing methods that separate the design and testing of retaining piles as engineering piles, proposing an integrated design and testing method for retaining piles and engineering piles based on multi-parameter fusion. It breaks down the design barriers between structural and geotechnical disciplines, combining multiple parameters such as project geological conditions, main structural stress requirements, and foundation pit support requirements for integrated analysis. This allows for the integrated design of retaining piles and engineering piles, ensuring that the pile foundation simultaneously meets vertical bearing capacity and horizontal resistance requirements, achieving an economical, safe, and rational design.

[0013] To achieve the above-mentioned objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides an integrated design and testing method for support piles and engineering piles based on multi-parameter fusion, comprising the following steps: S1. Collect design parameters, including engineering geological parameters, foundation pit support design parameters, pile foundation design parameters and superstructure load parameters. Based on the design parameters, establish the initial engineering conditions for the dual-function integrated pile, estimate the characteristic value of the single pile bearing capacity, and determine the initial number and initial layout of the pile foundation. S2, Based on the initial engineering conditions of the dual-function integrated pile, estimate the characteristic value of the single pile bearing capacity, determine the initial number and initial layout of the pile foundation, construct a dual-function coupled force model of support pile and engineering pile, the dual-function coupled force model of support pile and engineering pile includes the force calculation of the support stage and the force calculation of the service stage of the dual-function integrated pile, and determine the pile diameter, pile length, pile foundation reinforcement, concrete strength and pile foundation spacing of the dual-function integrated pile, and also calculate the length of the anchor piles on both sides of the dual-function integrated pile; S3. During the design and testing of pile foundations, pile foundation integrity testing is carried out to obtain multi-dimensional testing parameters. The multi-dimensional testing parameters are fused, and the integrity of the pile foundation is determined by a dual model of logical judgment criteria and weighted quantitative scoring. S4. A static load test of the vertical compressive strength of a single pile was conducted on the test pile using an anchor pile reaction device to obtain the ultimate vertical compressive bearing capacity of the single pile. S5. Determine the characteristic value of the vertical bearing capacity of the single pile based on the measured vertical compressive ultimate bearing capacity of the single pile; and substitute the characteristic value of the vertical bearing capacity of the single pile into the dual-function coupled force model of the support pile-engineering pile in step S2 to iteratively correct the design parameters and obtain the optimized design scheme of the dual-function integrated pile. S6. After the support piles are constructed, perform pile integrity testing according to step S3, and conduct deformation monitoring during the foundation pit support stage; after the foundation pit is backfilled, perform single pile vertical bearing capacity testing on the dual-function integrated piles according to step S4; complete data collection and analysis, and generate a pile foundation testing and acceptance report.

[0014] Furthermore, the logical determination criteria in step S3 include: Destructive testing priority principle: Destructive testing uses core drilling to directly obtain core samples for observation. If defects are found, it has high reliability and is given priority. When the classification standard for destructive testing is lower than that for non-destructive testing, destructive testing shall prevail. The principle of prioritizing the whole over the part: If the core sample obtained by the core drilling method is intact, but the sonic logging method or low strain method shows anomalies and the classification standard is lower than that of the borehole method, then the test results of the low strain method or sonic logging method shall be accepted, and additional drilling shall be performed at the abnormal point for verification. Spatial complementarity principle: The classification criteria are combined with the location of the defects. Shallow defects within 5 meters of the pile top and defects at the pile bottom are judged by the low strain method, while deep defects beyond 5 meters of the pile top are judged by the sonic projection method. The principle of taking the most severe severity: If different methods yield different results for the same location, the most severe classification standard shall be taken as the final result.

[0015] Furthermore, the weighted quantization score in step S3 is calculated by multiplying the weights and the detection results and then summing them to obtain the comprehensive score, wherein the weights of the low strain method detection, the acoustic projection method, and the core drilling method increase in sequence.

[0016] Furthermore, step S4 specifically includes the following steps: S41, Anchor pile reaction device construction design, specifically including: a steel beam reaction device is set on the top of the steel beam, anchor bars and anchor plates are pre-embedded at the steel beam position corresponding to the anchor pile, the anchor bars are reliably connected to the steel beam, and the anchor plates are flush with the top surface of the steel beam to ensure effective load transfer during testing; S42, Equipment and Instruments and Their Installation, specifically including: the test loading equipment uses hydraulic jacks; the multiple jacks used are of the same model and specifications; the resultant force center of the jacks coincides with the centroid of the cross-section of the pile under test; the reaction force provided by the loading reaction device is not less than 1.2 times the maximum loading value, and the components of the loading reaction device meet the requirements of bearing capacity and deformation; the load is measured directly by a load sensor placed on the jack; the settlement is measured using a large-range displacement sensor. S43, On-site inspection; S44, Detection data analysis and judgment.

[0017] Furthermore, in step S2, the formula for calculating the length of the anchor piles on both sides of the dual-function integrated pile is: ； ； ； ; In the formula: It is the characteristic value of the vertical bearing capacity of a single pile in a dual-function integrated pile; It refers to the pull-out force of a single anchor pile. The anchor pile's own weight is used, and the buoyancy weight is taken below the groundwater level. It is the standard value of the ultimate pull-out bearing capacity of the anchor pile; This is the safety factor; it is 3.0 for the test pile stage and 2.2 for the engineering pile acceptance stage. It refers to the number of anchor piles; It is the pull-out coefficient; It is the first anchor pile below the bottom of the foundation pit. Standard value of ultimate lateral resistance of soil layer; It is the circumference of the anchor pile; It is the anchor pile circumference below the bottom of the foundation pit. The thickness of the soil layer; It refers to the depth of the foundation pit excavation; It is the total design length of the anchor pile.

[0018] Further, in step S4, the anchor pile reaction device includes an anchor pile 8, a static load test pile 7, a hydraulic loading component 5, a steel beam 2, an anchor bar 4, an anchor plate 3, a pressure bearing pad 6, and a steel crossbeam 1; the downward pressure load is transmitted to the top of the static load test pile 7 to be tested through the hydraulic loading component 5, and the corresponding reverse upward pull force is transmitted from the upper end of the hydraulic loading component (5) to both ends of the steel crossbeam (1). The top pressure bearing surface of the hydraulic loading component (5) is in contact with the thickened pressure bearing pad (6) of the lower flange of the steel beam (2), and the bottom pressure bearing surface of the hydraulic loading component (5) is in contact with the thickened circular pressure bearing pad (6) at the top of the test pile. The load at both ends of the steel crossbeam (1) is transmitted to the steel beam (2) and the anchor pile (8) through the anchor plate (3) and the anchor bar (4). Finally, the lateral resistance between the anchor pile (8) and the surrounding soil balances all the upward pull force, forming a closed-loop force transmission system.

[0019] Furthermore, in step S2, the vertical compressive bearing capacity calculation was performed during the stage stress calculation. This calculation considered the horizontal displacement of the pile top of the dual-function integrated pile during the support stage. The calculation formula is as follows: Under the action of axial vertical force: ； Under the action of eccentric vertical force: ; ; ; Under the action of axial vertical force: ; Under the action of eccentric vertical force: ; ; ; ; In the formula: It is the average vertical force of the foundation pile under the action of the axial vertical force of the standard combination of load effects; It is the first load effect under the standard combination of eccentric vertical force. Vertical force on the foundation pile; It is the maximum vertical force at the pile top under the action of eccentric vertical force in the standard combination of load effects; It is the standard value of the self-weight of the pile cap and the soil above the pile cap; It is the axial force at the bottom of the upper structural column acting on the top surface of the foundation under the standard combination of load effects; 、 It refers to the load effect standard combination acting on the top surface of the pier cap for the upper structural columns around the pier. 、 The torque of the spindle; It refers to the load effect standard combination acting on the upper structural column edge of the top surface of the foundation. Shear force on the shaft; Under the standard combination of load effects, the transfer beam end acting on the edge of the pier cap is... The torque of the spindle; It is the shear force at the end of the transfer beam acting on the edge of the pier under the standard combination of load effects; 、 Under the standard combination of load effects, the load acts on the bottom surface of the pile cap, around the centroid of the pile group. 、 The torque of the spindle; 、 、 、 It is the first , foundation pile to 、 Distance between axes; It is the width of the foundation; It is the height of the foundation; It is the horizontal displacement of the top of the dual-function integrated pile; It is the centroid of the column spacing and pile group of the superstructure. The distance of the spindle; It is the standard value of the vertical ultimate bearing capacity of a single pile, which is calculated based on geotechnical parameters in the preliminary design stage and finally determined based on static load tests. These are the standard values ​​of total limiting side resistance and total limiting end resistance, respectively. It is the first pile side below the bottom of the foundation pit Standard value of ultimate lateral resistance of soil layer; It is the standard value of the ultimate end resistance of the pile; 、 It is the size effect coefficient of the side resistance and end resistance of large-diameter piles; It is the circumference of the pile body; It is the pile perimeter below the bottom of the foundation pit. The thickness of the soil layer; It is the design value of the compressive bearing capacity of the pile body; It is the pile-forming process coefficient; It is the design value of the axial compressive strength of concrete; This is the design value of the compressive strength of the main reinforcement bars; It is the area of ​​the longitudinal reinforcement bars in the pile body; It is the characteristic value of the vertical bearing capacity of a single pile in a dual-function integrated pile; n It refers to the number of piles within the pile cap area, including dual-function integrated piles and engineering piles; It is the area at the pile tip.

[0020] Furthermore, the formula for calculating the characteristic value of the measured vertical bearing capacity of a single pile in step S5 is as follows: ; in, This represents the standard value of the vertical ultimate bearing capacity of a single pile as measured in a static load test. It is the measured characteristic value of the vertical bearing capacity of a single pile in a dual-function integrated pile system; It is the first pile side above the bottom of the foundation pit Standard value of ultimate lateral resistance of soil layer; The pile perimeter above the bottom of the foundation pit i The thickness of the soil layer, It is the circumference of the pile. It is the size effect coefficient of the side resistance of large-diameter piles.

[0021] Furthermore, in step S6, the number of pile foundation tests is determined by the following methods: all piles are tested using the low-strain method; the number of piles tested using the sonic logging method is not less than 10% of the total number of dual-function integrated piles and not less than 10 piles; the number of piles tested using the core drilling method is not less than 20% of the total number of dual-function integrated piles and not less than 10 piles; and the number of piles tested for vertical bearing capacity is not less than 1% of the total number of dual-function integrated piles and not less than 3 piles.

[0022] Furthermore, in step S1: Engineering geological parameters include the physical and mechanical properties of each soil layer and the thickness of each soil layer; The design parameters for foundation pit support include the excavation depth of the foundation pit, the importance coefficient of the support structure, and the limit of horizontal displacement at the top of the piles. The pile foundation design parameters include the proposed pile diameter, pile length, design value of axial compressive strength of pile concrete, pile foundation layout and spacing; The load parameters of the superstructure include the reaction forces transmitted by the superstructure, including the reaction forces at the bottom of the columns, the internal forces at the ends of the transfer beams, and the eccentricity between the superstructure columns and the center of the pile cap.

[0023] Compared with existing technologies, the beneficial effects of this invention are: establishing an integrated technical system for the design and testing of support piles and engineering piles, enabling design parameters to directly guide the formulation of testing schemes, and allowing testing results to quickly verify the rationality of the design, forming a closed-loop management of design and testing, and improving the overall quality and efficiency of pile foundation engineering. Attached Figure Description

[0024] Figure 1 This is the overall flowchart of the integrated design and testing method for support piles and engineering piles based on multi-parameter fusion in Example 1. Figure 2 This is a plan view of the pile foundation layout in Example 1; Figure 3 This is a cross-sectional view AA of the pile foundation layout in Example 1; Figure 4 This is a flowchart of the logic for evaluating the integrity of the pile body in Example 1; Figure 5 This is a diagram showing the anchor pile reaction device and connection relationship in Example 1; Figure 6 This is a flowchart of the integrated design and testing method for support piles and engineering piles based on multi-parameter fusion in Example 2. Figure 7 This is a plan view of the pile foundation layout in Example 2; Figure 8 This is a cross-sectional view AA of the pile foundation layout in Example 2; Figure 9 This is a flowchart of the stress analysis of the dual-function integrated pile in Example 2; Figure 10This is a flowchart of the pile integrity evaluation and judgment process in Example 2; Figure 11 This is a flowchart of the static load test of a single pile vertical compressive strength using an anchor pile reaction device in Example 2; Figure 12 This is the pile foundation layout plan optimized based on the measured characteristic value of the vertical bearing capacity of a single pile in Example 2; Figure 13 This is a diagram of the design and detection system architecture based on multi-parameter fusion, as shown in Example 2.

[0025] Reference numerals: 1-Steel beam, 2-Steel beam, 3-Anchor plate, 4-Anchor bar, 5-Hydraulic loading assembly, 6-Bearing pad, 7-Static load test pile, 8-Anchor pile. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0027] Example 1 This invention is a methodological invention. Its core involves several steps: constructing a dual-functional coupled stress model of support piles and engineering piles; establishing a comprehensive evaluation index for pile integrity; conducting anchor pile bearing capacity testing; and iteratively correcting design parameters by substituting test data into the stress model. This achieves synergy between the design and testing of support piles and engineering piles. The specific steps are as follows, all of which are carried out in conjunction with actual project parameters to complete parameter analysis and scheme design. The overall flowchart is shown below. Figure 1 As shown.

[0028] S1. Collect design parameters, including engineering geological parameters, foundation pit support design parameters, pile foundation design parameters, and superstructure load parameters. Based on the design parameters, establish the initial engineering conditions for the dual-function integrated pile, estimate the characteristic value of the single pile bearing capacity, and determine the initial number and initial layout of the pile foundation.

[0029] Engineering geological parameters include: physical and mechanical properties of each soil layer (unit weight, cohesion, internal friction angle, standard value of ultimate end resistance of pile tip, standard value of ultimate side resistance of pile side, etc.), soil layer thickness, etc.

[0030] The design parameters for foundation pit support include: the depth of the foundation pit. Importance coefficient of support structure Horizontal displacement limit of pile top wait.

[0031] The pile foundation design parameters include: the proposed pile diameter. Pile length Design value of axial compressive strength of pile concrete Pile foundation layout and spacing .

[0032] Superstructure load parameters: The reaction forces transmitted by the superstructure, including column base reactions ( ), Internal forces at the ends of the transfer beam ( ), the eccentricity between the center of the superstructure column and the center of the pile cap wait; Based on the above parameters, and in conjunction with the "Technical Specification for Building Pile Foundations" (JGJ 94-2008) and the "Technical Specification for Foundation Pit Support" (JGJ 120-2012), the bearing capacity of the support piles that also serve as engineering piles is estimated: characteristic value of the vertical compressive bearing capacity of a single pile. Characteristic value of horizontal bearing capacity of a single pile Based on factors such as pile bearing capacity, the number and arrangement of piles were preliminarily determined. The superstructure columns are eccentric relative to the center of the pile cap in the transverse direction of the foundation pit, but not in the longitudinal direction. Figure 2 Pile foundation layout plan and Figure 3 The pile foundation layout is shown in section AA.

[0033] S2: Based on the initial engineering conditions of the dual-function integrated pile, estimate the characteristic value of the single pile bearing capacity, determine the initial number and initial layout of the pile foundation, and construct a dual-function coupled force model of support pile and engineering pile. The dual-function coupled force model of support pile and engineering pile includes the force calculation of the support stage and the force calculation of the service stage of the dual-function integrated pile, and determines the pile diameter, pile length, pile foundation reinforcement, concrete strength and pile foundation spacing of the dual-function integrated pile. It also calculates the length of the anchor piles on both sides of the dual-function integrated pile.

[0034] S21) Stress calculation of dual-function integrated pile support stage: S21-1) Based on the design parameters collected in step S1, establish a calculation and analysis model for the retaining structure: calculate the horizontal displacement of the top of the retaining pile based on the calculation and analysis model for the retaining structure. ,like Then continue to adjust the diameter of the support piles. Pile length Pile spacing Parameters, until satisfied. And read the maximum bending moment design value of the support piles in the calculation and analysis model at this time. Maximum shear design value Horizontal displacement of the top of the support pile ;in, C It is the limit value for horizontal displacement at the top of the pile.

[0035] S21-2) The overall stability calculation shall be performed in accordance with Article 4.2 of the "Technical Specification for Foundation Pit Support" (JGJ 120-2012). This article mainly specifies several core stability verification items that need to be performed on the retaining structure to ensure the safety of the foundation pit during construction and use. Specifically, these include: Embedding depth verification: Ensure that the support structure (such as piles, diaphragm walls) is inserted to a sufficient depth into the bottom of the foundation pit to prevent the structure from overturning or sliding.

[0036] Overall sliding stability verification: Verify the possibility that the support structure, together with the soil behind it, will slide along the sliding surface as a whole.

[0037] Stability verification against heave at the bottom of the pit: Verify the possibility of the soil at the bottom of the pit heaving upwards under the action of lateral earth pressure.

[0038] Groundwater seepage stability calculation: Calculate the potential damage such as piping and quicksand caused by groundwater seepage.

[0039] S21-3) For dual-function integrated piles with longitudinal reinforcement evenly distributed around the perimeter, the bearing capacity of the pile foundation's normal and inclined sections during the support stage is calculated using the following formula: The flexural bearing capacity of the pile foundation section is calculated using the following formula:

[0040] In the formula: ----Design value of bending moment for dual-function integrated piles ( kN·m The maximum bending moment of the pile foundation under the standard combination in the calculation and analysis model of the retaining structure is taken, along with the importance coefficient. and comprehensive component coefficients The product; ----Design value of axial compressive strength of concrete (kN / m 2 ） ; -----Pile cross-sectional area ( m 2 ); ----Relative of the pile ( m ); ----The central angle corresponding to the cross-sectional area of ​​the concrete in the compression zone ( rad The ratio of π to 2π; -----Design value of tensile strength of longitudinal reinforcement ( kN / m 2 ); ----Cross-sectional area of ​​all longitudinal reinforcement bars ( m 2 ); ----Radius of the circle containing the center of the longitudinal reinforcement ( m ); -----The ratio of the cross-sectional area of ​​longitudinal tensile reinforcement to the total cross-sectional area of ​​all longitudinal reinforcement ( m 2 ); The shear capacity of the pile foundation is calculated using the following formula:

[0041]

[0042]

[0043] In the formula: ----Shear force design value of dual-function integrated pile ( kN The maximum shear force of the pile foundation under the standard combination in the calculation and analysis model of the retaining structure is taken, along with the importance coefficient. and comprehensive component coefficients The product; ----Design value of axial tensile strength of concrete ( kN / m 2 ); ----Shear capacity coefficient of inclined concrete; ----The width of a circular cross-section support pile is equivalent to that of a rectangular cross-section; ----The effective height of a circular cross-section retaining pile is equivalent to that of a rectangular cross-section; ----The total cross-sectional area of ​​each leg of the stirrups configured within the same cross-section; ----Relative of the pile ( m ); ---- Spacing of stirrups; --Design value of tensile strength of stirrups ( kN / m 2 ); S22) Stress calculation of dual-function integrated piles during the service stage: Establish the calculation formula for the coupled stress of pile bearing capacity and pile top horizontal displacement, and perform vertical compressive bearing capacity calculation, horizontal bearing capacity calculation and settlement calculation for dual-function integrated piles; S22-1) Vertical compressive bearing capacity calculation: Under the action of axial vertical force:

[0044] Under the action of eccentric vertical force:

[0045]

[0046]

[0047] Under the action of axial vertical force:

[0048] Under the action of eccentric vertical force:

[0049]

[0050]

[0051] ; In the formula: ----The average vertical force of the foundation pile under the action of axial vertical force in the standard combination of load effects; -----The first load effect under the standard combination of eccentric vertical force Vertical force on the foundation pile; - ----Maximum vertical force at the pile top under the action of eccentric vertical force according to the standard combination of load effects; -----Standard value of self-weight of pile foundation cap and soil above pile cap; -----Axial force at the bottom of the upper structural column acting on the top surface of the foundation under the standard combination of load effects; 、 -----Under the standard combination of load effects, the superstructure columns acting on the top surface of the foundation are... 、 The torque of the spindle; -----Under the standard combination of load effects, the upper structural column along the top surface of the foundation... Shear force on the shaft; Under the standard combination of load effects, the transfer beam end acting on the edge of the pier cap... The torque of the spindle; -----Shear force at the end of the transfer beam acting on the edge of the pier under the standard combination of load effects; 、 Under the standard combination of load effects, the load acts on the bottom surface of the pile cap, around the centroid of the pile group. 、 The torque of the spindle; 、 、 、 -----No. 、 foundation pile to 、 The distance between the axes, with the center of the pile cap coinciding with the centroid of the pile group, is defined as the origin of the coordinate system; ----- Width of the foundation; -----Height of the foundation; -----Horizontal displacement of the top of the dual-function integrated pile; -----Cencentricity of the column spacing and pile group of the superstructure The distance of the spindle; The standard value of the vertical ultimate bearing capacity of a single pile is calculated based on geotechnical parameters during the preliminary design stage and ultimately determined based on static load tests. These are the standard values ​​of total limiting side resistance and total limiting end resistance, respectively. -----The pile side below the bottom of the foundation pit Standard value of ultimate lateral resistance of soil layer; -----Standard value of ultimate end resistance of pile; 、 -----Size effect coefficients for side resistance and end resistance of large-diameter piles; -----Pile circumference; -----Pile perimeter below the bottom of the foundation pit The thickness of the soil layer; -----Design value of pile compressive bearing capacity; -----Pile-forming process coefficient; -----Design value of axial compressive strength of concrete; -----Design value of compressive strength of main reinforcement; -----Area of ​​longitudinal reinforcement in pile body; The characteristic value of the vertical bearing capacity of a single pile of a dual-function integrated pile is calculated based on geotechnical parameters during the preliminary design stage and finally determined based on static load tests. n -----The number of piles within the pile cap area, including dual-function integrated piles and engineering piles; -----Pile tip area.

[0052] S22-2) Calculation of horizontal bearing capacity: The reinforcement ratio of the dual-function integrated pile should not be less than 0.65%, and its horizontal bearing capacity should be calculated according to the following formula.

[0053]

[0054]

[0055] In the formula: ----Characteristic value of horizontal bearing capacity of piles in pile group foundation ( kN ); -----Characteristic value of horizontal bearing capacity of a single pile ( kN The calculation is performed according to formula 5.7.2-2 of the "Technical Specification for Building Pile Foundations" (JGJ 94-2008); ----Comprehensive coefficient of pile group effect; -----The coefficient of mutual influence effect of piles; -----The pile top constraint effect coefficient (when the pile top is embedded in the pile cap for 50~100mm) shall be taken from Table 5.7.3-1 of the Technical Specification for Building Pile Foundations (JGJ 94-2008); ----Coefficient of horizontal resistance effect of soil on the lateral side of the foundation; ----Ratio of distance to diameter along the direction of horizontal load; ， -----These represent the number of piles in each row of piles along the horizontal load direction and the vertical horizontal load direction, respectively. -----Total number of piles in a single pile cap; -----Proportional coefficient of horizontal resistance coefficient of soil on the side of the foundation; ----Allowable horizontal displacement of pile top (pile cap); -----Calculated width of the side of the foundation subjected to lateral soil resistance ( m ); -----Height of the foundation ( m ); The horizontal deformation coefficient of the pile shall be calculated according to formula 5.7.5 of the Technical Specification for Building Pile Foundations (JGJ 94-2008); ----Horizontal displacement coefficient at the pile top; --Pile body bending stiffness; -------Under the standard combination of load effects, the upper structural column edge acting on the top surface of the foundation. Shear force of the shaft ( kN ).

[0056] S22-3) Settlement calculation: Settlement calculations for dual-function integrated piles are performed according to Article 5.5 of the Technical Specification for Building Pile Foundations (JGJ 94-2008).

[0057] S23) Calculation of anchor pile lengths on both sides of the dual-function integrated pile:

[0058]

[0059]

[0060]

[0061] In the formula: ----The pull-out force borne by a single anchor pile; ----The self-weight of the foundation pile is taken as the buoyancy weight below the groundwater level; ----Standard value of the ultimate pull-out bearing capacity of anchor piles; ---Characteristic value of vertical bearing capacity of a single pile in a dual-function integrated pile; ---Safety factor: 3.0 for the test pile stage and 2.2 for the acceptance stage of the engineering piles; -----Number of anchor piles; ---- Pull-out coefficient; ---The anchor pile side below the bottom of the foundation pit Standard value of ultimate lateral resistance of soil layer; --Circumference of the anchor pile; -----The anchor piles below the bottom of the foundation pit are around the following number of piles. The thickness of the soil layer; -----Excavation depth of the foundation pit; ----Total design length of anchor piles.

[0062] S3: Design of test piles: Construct 3 test piles and 8 anchor piles, and use low strain method, sonic projection method and core drilling method to test the integrity of the pile foundation and obtain multi-dimensional test parameters; perform data fusion of multi-dimensional test parameters to establish a comprehensive evaluation index of pile integrity and determine the integrity of the pile foundation.

[0063] Pile integrity index: The pile integrity evaluation index should be established based on the "Technical Specification for Testing of Building Foundation Piles" (JGJ106-2014), with a four-class classification system (Class I, Class II, Class III and Class IV) as the core. Quantitative indicators and judgment rules should be set for the low-strain method, sonic logging method and core drilling method respectively. Finally, a comprehensive conclusion is formed through cross-verification of multiple methods to ensure the objectivity and engineering applicability of the evaluation.

[0064] A comprehensive evaluation index is adopted using the envelope of logical judgment model and quantitative calculation model, and the classification standard for poor pile integrity is selected.

[0065] S31, Logical Judgment Model 1) Principle of Priority for Destructive Testing: Core drilling (a form of destructive testing) involves direct observation of the core sample, providing direct, "seeing is believing" evidence. If defects are found using core drilling, the findings have high reliability and are given priority. When the classification criteria for destructive testing (core drilling) are lower than those for non-destructive testing (low-strain dynamics, sonic logging), destructive testing (core drilling) takes precedence. (Class I is the highest, Class IV is the lowest) 2) The principle of prioritizing the overall area over the local: The acoustic wave method tests the area between two acoustic logging tubes, the low-strain method tests the entire pile cross-section, while the core drilling method only tests the concrete along the drilling path. Due to the limitation of "one hole view," it requires additional drilling for verification. If the core sample from the core drilling method is intact (Class I / II), but the acoustic wave projection method or the low-strain method shows anomalies, and the classification standard is lower than that of the core drilling method, then the low-strain method or the acoustic wave projection method should be given priority, and additional drilling should be performed at the abnormal point for verification.

[0066] 3) Spatial Complementarity Principle: The low-strain method, based on the stress wave reflection principle, is sensitive to shallow defects (within 5 meters of the pile top) and pile bottom reflections, but may not show significant results for deep minor defects or localized diameter reduction. The acoustic wave projection method, based on ultrasonic wave propagation, is highly sensitive to the uniformity of concrete within the pile body, localized segregation, or mud inclusions, but has a blind spot in detecting shallow defects at the pile top (near the sonic logging tube opening). The classification criteria must be determined based on the defect location. Shallow defects (within 5 meters of the pile top) and pile bottom defects should be classified using the low-strain method, while deep defects (beyond 5 meters of the pile top) should be classified using the acoustic wave projection method.

[0067] 4) Principle of choosing the most severe: If different methods yield different results for the same location, the most severe classification standard is usually taken as the final result. The flowchart for pile integrity evaluation is as follows: Figure 4 As shown.

[0068] S32, Quantitative Calculation Model The low-strain method, sonic logging method, and core drilling method are assigned scores of 0 to 100 based on the integrity of the pile. The higher the score, the more complete the pile. Different weights are assigned to the test results of different methods, and a comprehensive score is obtained through weighted calculation.

[0069] S=w 1 ×S 1 +w 2 ×S 2 +w 3 ×S 3; Weight values: w 1=0.2 (low strain method) w 2 = 0.3 (sound projection method). w 3 = 0.5 (core drilling method) S1, S2, and S3: Independent index scores for the low-strain method, acoustic projection method, and core drilling method. Category I ≥ 90 points; 80 points ≤ Category II < 90 points; 60 points ≤ Category III < 80 points; Category IV < 60 points.

[0070] S: Comprehensive integrity index. S ≥ 90 points, classified as Category I; 80 points ≤ S < 90 points, classified as Category II; 60 points ≤ S < 80 points, classified as Category III; S < 60 points, classified as Category IV.

[0071] S4: Using an anchor pile reaction device, a static load test of the vertical compressive strength of a single pile was conducted on three test piles to obtain the ultimate vertical compressive bearing capacity of the single pile.

[0072] S41) Anchor pile reaction device structural design: According to the requirements of the anchor pile method testing, the design of the supporting structures required for the testing was completed. The anchor pile reaction device for the dual-function integrated pile vertical compressive static load test is shown below. Figure 5 As shown, the system consists of the anchor pile reaction device, including anchor pile 8, static load test pile 7, hydraulic loading component 5, steel beam 2, anchor bar 4, anchor plate 3, bearing pad 6, and steel crossbeam 1. Through this system, a single pile vertical compressive static load test is performed on the static load test pile 7. The downward pressure load is transferred to the top of the integrated pile to be tested through the hydraulic loading component 5 (generally a jack). The corresponding upward pull-out force is transferred from the upper end of the hydraulic loading component 5 to both ends of the top reaction steel beam. The load at both ends of the steel beam is completely transferred to the anchor pile 8 through the pre-embedded anchors in the steel beam. Finally, the lateral resistance between the anchor pile 8 and the surrounding soil balances all the upward pull-out force, forming a closed-loop force transmission system. The anchorage between each component is reliable, with no slippage or voids.

[0073] The steel beam embedded anchor consists of anchor plate 3 and anchor bar 4, and is embedded as a whole in the steel beam area at the top of the anchor pile. Each embedded anchor bar 4 is welded to the anchor plate 3 by through-hole plug welding process, and the total area of ​​the anchor bar 4 meets the requirements of pull-out bearing capacity verification; the anchor bars 4 are symmetrically and evenly distributed in a rectangular shape, and the distance from the center of the anchor bar 4 to the edge of the anchor plate 3 and the center-to-center spacing of the anchor bars 4 all meet the relevant specifications and structural requirements.

[0074] The tension centers at both ends of the steel beam 1 are strictly aligned with the centroid of the pre-embedded anchor bar group below, ensuring that the load is transferred vertically downward to the pre-embedded anchor of the steel beam, and the geometric center of the steel beam is precisely aligned with the center of the top of the integrated pile to be inspected.

[0075] The hydraulic loading component 5 is arranged below the center of the top reaction steel beam and aligned with the center of the test pile; the top bearing surface of the hydraulic loading component 5 is in contact with the thickened bearing pad 6 of the lower flange of the steel beam 2, and the bottom bearing surface of the hydraulic loading component 5 is in contact with the thickened circular bearing pad 6 at the top of the test pile.

[0076] The specific design details are as follows: S411) Top reaction device: The crossbeam is made of rectangular steel beam to ensure uniform force distribution in contact with the top of the steel beam; The steel beams should be made of Q355 grade steel; The verification load for steel beams should be calculated based on 1.2 times the maximum test load. Under the calculated load, the deflection of the steel beam should not exceed [a certain value]. L / 600, localized areas without plastic deformation, unstable warping; When verifying the bearing capacity under load, the safety factors for bending and shear resistance should be ≥1.5.

[0077] The center of the test pile, the center of the jack, and the geometric center of the steel beam coincide, and the eccentricity is ≤2. mm Uneven loading is strictly prohibited; Thick pads are installed on both the top and bottom of the jacks to ensure full contact of the bearing surfaces and prohibit single-point pressure on the edges of the steel beams. The steel beams are free from warping, suspension, and single-point stress, with all contact surfaces in close contact.

[0078] S412) Steel beam embedded structure: During the steel beam design stage, anchor bars and anchor plates are embedded at the steel beam positions corresponding to the anchor piles. The anchor bars are reliably connected to the steel beam, and the anchor plates are aligned with the top surface of the steel beam to ensure effective load transfer during testing. Anchor plates and anchor bars shall be determined according to the following requirements: The anchor plate should be made of Q355 grade steel, and its thickness should not be less than 60% of the anchor bar diameter; and should preferably be greater than... b / 8, b This refers to the spacing of the anchor bars.

[0079] The anchor bars should be made of HRB400 steel bars, and cold-worked steel bars should not be used. The anchor bars and anchor plates should be connected by through-hole plug welding.

[0080] The total area of ​​the anchor bars is determined by the following formula: ； ; In the formula: ----Total area of ​​anchor bars () ); ----Design value of anchor bar tension; ----- Bending deformation reduction factor of anchor plate; The design value of the tensile strength of the reinforcing steel, and not greater than 300. N / ; ---Safety factor: 3.0 for the test pile stage and 2.2 for the acceptance stage of the engineering piles; ----Characteristic value of vertical bearing capacity of a single pile in a dual-function integrated pile; The diameter of the anchor bar should not be less than 20 mm. mm And should not exceed 28 mm The spacing of the anchor bars and the distance to the edge of the anchor plate should not be less than 3. d and 50 mm ,in d The diameter is the anchor bar diameter.

[0081] S42) Equipment and Instruments and Their Installation: Specifically, this includes: using hydraulic jacks as the test loading equipment; using multiple jacks of the same model and specifications; ensuring the resultant force center of the jacks coincides with the centroid of the cross-section of the pile under test; ensuring the reaction force provided by the loading reaction device is not less than 1.2 times the maximum load value, and that the components of the loading reaction device meet the requirements for bearing capacity and deformation; directly measuring the load using load sensors placed on the jacks; and using large-range displacement sensors for settlement measurement. S43, On-site inspection; S44, Detection data analysis and judgment.

[0082] S5: Determine the characteristic value of the single pile bearing capacity of the dual-function integrated pile based on the static load test of the single pile vertical compressive strength; adjust the pile foundation layout based on the measured characteristic value of the single pile vertical bearing capacity, and substitute the measured value of the single pile vertical bearing capacity characteristic value into the stress model. Iterate and correct the design parameters according to step S2 to form a design-test-optimization closed loop.

[0083] The measured characteristic value of the vertical bearing capacity of a single pile in a dual-function integrated pile is obtained by the following formula: ; Note: In this formula The standard value of the vertical ultimate bearing capacity of a single pile as measured by static load test; It is the measured characteristic value of the vertical bearing capacity of a single pile in a dual-function integrated pile system; It is the first pile side above the bottom of the foundation pit Standard value of ultimate lateral resistance of soil layer; The pile perimeter above the bottom of the foundation pit The thickness of the soil layer; u It is the circumference of the pile. It is the size effect coefficient of the side resistance of large-diameter piles.

[0084] S6: Pile Foundation Testing and Acceptance: After the support piles are constructed, pile integrity testing is performed according to step S3, and deformation monitoring is conducted during the foundation pit support stage. Deformation testing requirements are shown in Table 1. After the tunnel structure construction is completed and the foundation pit backfilling is finished, the single pile bearing capacity test of the dual-function integrated piles is performed according to step S4. The maximum load for the single pile vertical compressive static load test is twice the characteristic value of the single pile bearing capacity. Finally, data collection and analysis are completed to generate a pile foundation testing and acceptance report.

[0085] The number of dual-function integrated piles tested is as follows: all piles are tested using the low-strain method; the number of piles tested using the sonic projection method is no less than 10% of the total number of dual-function integrated piles and no less than 10 piles; the number of piles tested using the core drilling method is no less than 20% of the total number of dual-function integrated piles and no less than 10 piles; and the number of piles tested for single-pile bearing capacity is no less than 1% of the total number of dual-function integrated piles and no less than 3 piles.

[0086] The actual horizontal displacement of the pile top monitored on site should not be greater than the horizontal displacement of the pile top calculated in step S2. If this condition is not met, the bearing capacity of the pile foundation should be recalculated according to step S2 to determine whether it meets the stress requirements.

[0087] Table 1 Deformation Detection Requirements

[0088] Note: 1. Monitoring items 1-3 should preferably be located on the same monitoring profile; 2. In the table H This refers to the depth of the foundation pit excavation.

[0089] Example 2 To further refine the technical solution of this invention and support the scope of protection of the claims, taking a city airport terminal project as an example, the proposed project has a subway rail transit system beneath its main structure, requiring the conversion of the upper main structure columns and the use of some foundation pit support piles as main structure engineering piles. This project will now be used as a specific implementation case to describe in detail the integrated design and testing method of this invention, which can reproduce all the technical solutions of this invention. The flowchart of the integrated design and testing method for support piles and engineering piles based on multi-parameter fusion is shown below. Figure 6 As shown, the specific implementation steps are as follows: S1: Collect engineering geological parameters, foundation pit support design parameters, pile foundation design parameters, and superstructure load parameters to establish the initial engineering conditions for integrated piles, estimate the characteristic value of single pile bearing capacity, and preliminarily determine the initial number and layout of pile foundations.

[0090] Engineering geological parameters: Soil layer distribution According to drilling findings, the soil layers at the site, from top to bottom, are as follows: Miscellaneous fill (①-1), variegated, loose to slightly dense, mainly composed of construction waste, road waste, and domestic waste from villagers' house construction, mixed with a small amount of clay soil, locally containing mudstone breccia and gravel. It is mainly distributed in towns or residential areas, demolition sites, and spoil heaps, etc., with a fill time of less than 5 years and a thickness of 0.30~5.40 mm. m The floor level is between 48.40 and 68.14 meters. m .

[0091] Plain fill (①-2), grayish-brown, reddish-brown, loose to slightly dense, mainly composed of clay and residual soil, containing a small amount of plant roots and stems, locally interspersed with weathered silty mudstone, locally distributed within the site, filled less than 5 years ago, thickness 0.20~-3.00 mm. m The floor level is between 49.72 and 68.49 meters. m .

[0092] The paddy field topsoil (②-1) is yellowish-brown, grayish-brown, and reddish-brown, slightly moist to very moist, and soft to plastic in texture. Its main component is clay, with a high surface content of plant roots. The drilling recovery rate is 95%. It is mainly distributed in valleys and on the surface of fields, with a layer thickness of 0.30~1.60 mm. m The floor level is between 49.22 and 65.51 meters. m .

[0093] The topsoil on the slope (②-2) is yellowish-brown and reddish-brown, loose, and slightly moist, mainly composed of clay and residual soil. The plant root system has a depth of approximately 0.10 meters. m ~0.20 m 0.2 m The following plants generally have sparse root systems. They are mainly distributed on the surface layer of hilltops and slopes, with a thickness of 0.30~3.20 mm. m The floor level elevation is 49.38~71.50. m .

[0094] Silt (③-1), gray to grayish-black, saturated, fluid, containing organic matter and humus, shows no shaking reaction, slightly glossy, low toughness, low dry strength, and has a putrid odor. Mainly distributed at the bottom of some ponds, ditches, and reservoirs, with a layer thickness of 0.30~4.0 mm. m The floor level is between 50.03 and 60.19 meters. m .

[0095] Silty clay (③-2), brownish-gray to grayish-black, saturated, soft plastic to fluid plastic state, containing organic matter and humus, no shaking reaction, slightly glossy, low toughness, and low dry strength. Mainly distributed in some farmland, ponds, ditches, and the bottom of reservoirs, with a layer thickness of 0.30~2.00 mm. m The floor level elevation is 49.13~56.38. m .

[0096] Silty clay (④-1), brownish-yellow, brownish-red, brownish-gray, wet to saturated, soft plastic state, contains iron and manganese oxides, none It exhibits a shaking response, a slightly glossy appearance, low toughness, and low dry strength; the core recovery rate is approximately 90%. It is mainly distributed in major valleys and paddy fields, with a layer thickness of 0.50–3.90 mm. m The bottom elevation of the layer is 47.72~58.15. m .

[0097] Silty clay (④-2), reddish-brown, yellowish-brown, gray, grayish-yellow, in a plastic state, containing iron and manganese oxides and kaolin lumps, slightly lustrous, without shaking reaction, medium dry strength, medium toughness, and a core recovery rate of approximately 95%. Mainly distributed in major valleys, paddy fields, and vegetable gardens, with a thickness of 0.20–7.60 mm. mThe floor level is between 45.75 and 67.44 meters. m .

[0098] Silty clay (④-3), gray, grayish-white, reddish-brown, brownish-red, and brownish-yellow, stiff plastic with a small amount locally plastic, containing iron and manganese oxides and a small amount of kaolinite lumps, slightly lustrous, no shaking reaction, high dry strength, medium toughness, and a core recovery rate of approximately 95%. Widely distributed within the site, with a thickness of 0.50~9.00 mm. m The bottom elevation is 45.69~68.80. m .

[0099] Residual silty clay (⑥), brownish-red to dark brown, stiff to hard, formed from residual argillaceous siltstone, containing a small amount of rock fragments. The original rock structure has been completely destroyed, making it difficult to drill through. It softens easily when exposed to water, has a slight luster, shows no shaking reaction, has high dry strength, and moderate toughness. The core recovery rate is approximately 95%. It is widely distributed within the site, with a layer thickness of 0.30~11.40 mm. m The floor level is between 44.53 and 69.10 meters. m .

[0100] The rock mass is silty mudstone (⑦), fractured to relatively fractured, with most of the structure destroyed, significant changes in mineral composition, and well-developed weathering fissures. The core samples are flattened columnar and fragmented, with visible gray-green streaks. Dry drilling is difficult. It is widely distributed in the area, exhibiting medium to very thick layered structures. The rock quality index (RQD) is 20-30, and the core recovery rate is 60-80%. It is classified as extremely soft rock, with a basic rock mass quality grade of V. Layer thickness ranges from 0.20 to 12.00 mm. m The floor level elevation ranges from 34.46 to 72.62 meters. m .

[0101] Strongly weathered argillaceous siltstone (⑦-1), the rock mass is fractured to relatively fractured, with most of the structure destroyed, significant changes in mineral composition, and well-developed weathering fissures. The core samples are flattened columnar and fragmented, with visible gray-green streaks, making dry drilling difficult. It is widely distributed in the area, with a medium to very thick layered structure. The rock quality index RQD is 20-30, and the core recovery rate is 60-80%. It is classified as extremely soft rock, with a basic rock mass quality grade of V. Layer thickness: 0.20-12.00 mm. m The floor level elevation ranges from 34.46 to 72.62 meters. m .

[0102] The moderately weathered argillaceous siltstone (⑦-2) is relatively intact to complete, with partial structural damage. Secondary minerals are present on joint surfaces, and weathering fissures are well-developed. The rock mass has been cut into blocks, with locally high argillaceous content. Core samples are long columnar with a few short columnar samples, showing grayish-green streaks. Core drilling is possible. This layer is widely distributed in the area and has a medium-thick to very thick layered structure. This layer was not penetrated during the current exploration. The rock quality index RQD value is approximately 60-80, and the core recovery rate is 75-90%. It is classified as soft rock, and the basic quality grade of the rock mass is Class IV.

[0103] Physical and mechanical properties of each soil layer Based on the main physical and mechanical properties and in-situ test indicators of the foundation soil and rock obtained from on-site identification, field tests, and laboratory tests during this investigation, and combined with existing engineering experience in the region, and in accordance with relevant standards such as the "Code for Geotechnical Investigation" (GB50021-2001) (2009 edition), the "Code for Design of Building Foundations" (GB50007-2011), and the "Code for Technical Specifications of Building Pile Foundations" (JGJ 94-2008), the physical and mechanical properties of each soil and rock layer at this site are as follows: Miscellaneous fill (①-1): The standard value of the ultimate side resistance of the pile is 20 kPa; Plain fill (①-2): The standard value of the ultimate side resistance of the pile is 22 kPa; Paddy field topsoil (②-1): The standard value of the ultimate side resistance of the pile is 20 kPa; Sloping topsoil (②-2): The standard value of the ultimate side resistance of the pile is 24 kPa; Silt (③-1): The standard value of the ultimate side resistance of the pile is 12 kPa; Silty clay (③-2): The standard value of the ultimate side resistance of the pile is 20 kPa; Silty clay (④-1): The standard value of the ultimate side resistance of the pile is 30 kPa. kPa; Silty clay (④-2): The standard value of the ultimate side resistance of the pile is 45 kPa; Silty clay (④-3): The standard value of the ultimate side resistance of the pile is 65 kPa; Residual silty clay (⑥): The standard value of the ultimate side resistance of the pile is 80 kPa; Strongly weathered argillaceous siltstone (⑦-1): The standard value of the ultimate side resistance of the pile is 120 kPa, and the standard value of the ultimate end resistance of the pile is 1800 kPa; Moderately weathered argillaceous siltstone (⑦-2): The standard value of the ultimate side resistance of the pile is 220 kPa, and the standard value of the ultimate end resistance of the pile is 4000 kPa. Other parameters are detailed in Table 2.

[0104] Table 2 Recommended values ​​for engineering property parameters of soil and rock

[0105] Excavation pit support design parameters: Excavation depth of foundation pit =20.3 m The support structure adopts a combination of retaining piles and internal bracing. The safety level of the pit sidewall is Grade I, and the importance coefficient of the support structure is [not specified]. =1.1, the foundation pit deformation control and protection level is Level 1, and the horizontal displacement of the top of the support piles is controlled within 0.15%. H Within, and no greater than 20 mm ( H (This refers to the excavation depth of the foundation pit), the horizontal displacement of the top of the support piles is controlled within 0.25%. H Within, and no greater than 20 mm ( H (This refers to the excavation depth of the foundation pit), with the maximum settlement of the top of the support piles controlled at 0.15%. H Within, and no greater than 20 mm ( H (This refers to the depth of the foundation pit excavation).

[0106] Pile foundation design parameters: The pile foundation adopts rotary-drilled cast-in-place piles, with a pile diameter of... D =1000 mm The bearing stratum at the pile tip is moderately weathered silty mudstone (⑦-2), and the concrete strength grade of the pile body is C35. =16.7 Dual-function integrated pile estimated pile length =27 m The pile foundations are arranged in a rectangular pattern, with a pile spacing of [missing information]. =1.4 m For now, two anchor piles will be selected on each side of the dual-function integrated pile foundation.

[0107] Superstructure load parameters: superstructure column base reaction force =582 kN·m , =637 kN·m , =9620 kN , =510 kN , =499 kN Internal forces at the ends of the conversion beam =1690 kN·m , =4583 kN ; Eccentricity between the center of the superstructure column and the center of the pile cap =200 mm pier width =4500 mm pier height =2000 mm ; Based on the above parameters, and in conjunction with the "Technical Specification for Building Pile Foundations" (JGJ 94-2008) and the "Technical Specification for Foundation Pit Support" (JGJ 120-2012), the pile bearing capacity of the dual-function integrated pile is estimated as follows: characteristic value of vertical compressive bearing capacity of a single pile. =4400 kN Characteristic value of horizontal bearing capacity of a single pile =500 kN The compressive bearing capacity of the pile is 13000. kN When designing the pile foundation and pile cap, the superstructure columns are designed to have eccentricity in the transverse direction of the foundation pit, but no eccentricity in the longitudinal direction. The preliminary plan layout of the main structure pile foundation and the cross-sectional form of the foundation pit support are determined as follows: Figure 7 Pile foundation layout plan and Figure 8 The pile foundation layout is shown in section AA.

[0108] S2: Construct a dual-function coupled stress model of support piles and engineering piles, and perform stress calculations for the dual-function integrated pile support stage and the service stage. Determine the pile diameter, pile length, pile foundation reinforcement, concrete strength, and pile spacing of the dual-function integrated pile. Also, calculate the length of the anchor piles on both sides of the dual-function integrated pile. The flowchart of the dual-function integrated pile stress analysis is as follows: Figure 9 As shown.

[0109] S21) Stress calculation of dual-function integrated pile support stage: S21-1) Based on the engineering data collected in step S1, establish a calculation and analysis model for the retaining structure: calculate the horizontal displacement of the top of the retaining pile based on the model. =15.00 mm , =20 mm The calculation requirements are met, and the maximum bending moment design value of the support piles in the calculation and analysis model is read at this time. =1350 kN·m Maximum shear design value =1204 kN ; S21-2) The overall stability calculation shall be performed in accordance with Article 4.2 of the Technical Specification for Foundation Pit Support of Buildings (JGJ 120-2012).

[0110] Substituting the known data into the solution, the minimum embedment depth of the dual-function integrated pile to satisfy the overall stability requirements is obtained. =2.86 m .

[0111] S21-3) For dual-function integrated piles with longitudinal reinforcement evenly distributed around the perimeter, calculate the bearing capacity of the pile foundation's normal and inclined sections during the support stage: The flexural bearing capacity of the pile foundation section is calculated using the following formula:

[0112] Substituting the known data into the solution, we can obtain... =9670 mm² ; Based on the calculation results, 20 longitudinal reinforcement bars of 25 (Grade III steel) are selected for the dual-function integrated pile body.

[0113] The shear capacity of the pile foundation is calculated using the following formula:

[0114]

[0115]

[0116] Substituting the known data into the solution, we can obtain... =1.82 mm² / mm ; Based on the calculation results, the stirrups of the dual-function integrated pile body are selected as 12@100 (grade III steel).

[0117] S22) Stress calculation of dual-function integrated pile during service stage: Establish the single pile bearing capacity calculation formula, and perform vertical compressive bearing capacity calculation, horizontal bearing capacity calculation and settlement calculation for dual-function integrated pile; S22-1) Vertical compressive bearing capacity calculation: superstructure column base reaction force = 582 kN·m , =637 kN·m , = 9620 kN , = 510 kN, = 499 kN Internal forces at the ends of the conversion beam = 1690 kN·m , = 4583 kN ; Substitute the known data into the relevant formulas in step S22-1 to obtain the maximum vertical force of the pile. = 4655 kN = 5280 kN , = 2813 kN = 4400 kN The preliminary estimate of the vertical bearing capacity of a single pile is reasonable and meets the calculation requirements; therefore, it is taken as... = 4400 kN .

[0118] Based on the characteristic value of the vertical compressive bearing capacity of a single pile, the pile length below the bottom elevation of the dual-function integrated pile foundation pit is calculated using the following formula. : ； ; Substituting the known data, we can solve for the following: = 6.5 m The minimum embedment depth is greater than the overall stability requirement. = 2.86 m Overall stability meets the requirements.

[0119] S22-2) Calculation of horizontal bearing capacity: The characteristic value of the horizontal bearing capacity of a single pile is obtained by calculating according to formula 5.7.2-2 of the "Technical Specification for Building Pile Foundations" (JGJ 94-2008) (the backfill around the pile cap is treated as loose backfill). =300 kN .

[0120] The characteristic value of the horizontal bearing capacity of the piles in the pile group foundation is obtained by calculating using the relevant formulas in step S22-2. = 420 kN ; =183 kN ; The horizontal bearing capacity meets the calculation requirements.

[0121] S22-3) Settlement calculation: According to the geological survey report of this project, the bearing stratum of the pile ends is a moderately weathered rock stratum. This rock stratum is an incompressible stratum, so it can be regarded as having a settlement value of 0, and the settlement meets the requirements.

[0122] S23) Calculation of the length of adjacent anchor piles (support piles also serving as anchor piles) of the dual-function integrated pile. Calculation of the length of anchor piles on both sides of the dual-function integrated pile: Substituting the known data into the relevant formula in step S23, we get: =3300kN, =6600kN, =8.5m, meaning the length of the anchor piles on both sides of the dual-function integrated pile below the bottom elevation of the foundation pit is not less than 8.5m. m The minimum embedment depth is greater than the overall stability requirement. =2.86m, the overall stability meets the requirements.

[0123] The integrated pile design scheme that satisfies both functions, obtained through calculation, is as follows: Dual-function integrated pile: pile diameter D =1000 mm The concrete strength grade of the pile body is C35. = 16.7 The longitudinal reinforcement of the pile body consists of 20 strands of 25mm (Grade III steel), and the pile body stirrups consist of 12@100mm (Grade III steel). The length of the pile tip extending below the bottom elevation of the foundation pit is not less than 6.5m. m ; Anchor piles: pile diameter D =1000 mm The concrete strength grade of the pile body is C35. =16.7 The longitudinal reinforcement of the pile body consists of 20 strands of 25mm (Grade III steel), and the pile body stirrups consist of 12@100mm (Grade III steel). The length of the pile tip extending below the bottom elevation of the foundation pit is not less than 8.5m. m ; S3: Test Piling Design: Construct 3 test piles and 8 anchor piles. Use low-strain method, sonic logging method, and core drilling method to test pile foundation integrity and obtain multi-dimensional testing parameters. Fusion of these parameters will establish a comprehensive evaluation index for pile integrity, and the integrity of the pile foundation will be determined. The pile integrity evaluation flowchart is as follows: Figure 10 As shown.

[0124] Low-strain method detection: A small hammer is used to strike the top of the pile, generating a stress wave that propagates downwards along the pile. When the wave encounters a defect in the pile or at the bottom, it generates a reflected wave. A sensor at the top of the pile receives the reflected signal, and by analyzing the arrival time, amplitude, and phase of the reflected wave, the location and nature of the defect can be deduced.

[0125] Acoustic wave projection method detection: Acoustic logging tubes are tied to the reinforcing cage, ensuring the bottom of the tube is sealed, the inside of the tube is unobstructed, and the top of the tube is higher than the top of the pile; before detection, the acoustic logging tubes are filled with clean water as a coupling medium for sound wave propagation; the transmitting and receiving transducers are placed in two separate acoustic logging tubes at the same depth; a fixed step distance (usually 20) is used. cm The transducers are simultaneously raised or lowered to collect acoustic time, amplitude, and waveform data at each measuring point. The changes in acoustic time, amplitude, and waveform of ultrasonic waves propagating in the concrete medium are used to determine the quality of the pile body.

[0126] Core drilling test: Fix the hydraulic drilling rig to the top of the pile, ensuring the drill rod is vertical; use a diamond drill bit to drill to 0.5 meters below the bottom of the pile. m During drilling, record parameters such as drilling speed, core sample length, and return water color; remove core samples, number them sequentially by depth, and photograph them; measure the core sample length and calculate the core recovery rate. Observe whether the core sample is continuous and intact, and whether there are defects such as cracks, mud inclusions, or segregation; cut standard specimens (height-to-diameter ratio 1:1) and conduct compressive strength tests; measure the thickness of sediment at the bottom of the pile. The testing methods, evaluation indicators, and classification standards are shown in Table 3.

[0127] Table 3. Detection methods, evaluation indicators and classification standards

[0128] The following are the indicators for the integrity testing of the test piles in this project: Low strain method shows: waveform is regular, smooth, and without distortion; no defective reflected waves; pile bottom reflected waves are clear and obvious; wave velocity is normal and stable, and the pile integrity is judged as Class I; The acoustic transmission method showed that all acoustic logging parameters and waveforms were normal; the pile integrity was classified as Class I. Core drilling showed that the core sample was continuous, intact, and well-bonded; the concrete was dense, uniform, and free of defects; the compressive strength of the core sample was not less than the design strength of the concrete; and the thickness of the sediment at the bottom of the pile was not greater than 50 mm. mm The pile length and the bearing stratum at the pile tip meet the design requirements, and the integrity of the pile body is judged as Class I. Based on the above test data, according to the S31 logic judgment model, the integrity of the three test piles is classified as Class I.

[0129] According to the S32 quantization calculation model S 1=92、 S 2=95、 S 3=95, according to S=w 1 ×S 1 +w 2 ×S 2 +w 3 ×S 3; Seeking the final S =94.4, the integrity of the three test piles is classified as Class I.

[0130] Based on the above comprehensive evaluation indicators, the integrity of the three test piles was determined to be Class I.

[0131] S4: Using an anchor pile reaction device, a static load test of the vertical compressive strength of a single pile was conducted on three test piles to obtain the ultimate vertical compressive bearing capacity of each pile. The flowchart for the static load test of the vertical compressive strength of a single pile using an anchor pile reaction device is as follows: Figure 11 As shown.

[0132] Anchor pile reaction device structural design: According to the relevant steps in S4, the static load test of the anchor pile method was conducted, with the maximum test load considered as three times the characteristic value of the compressive bearing capacity. The supporting structure was designed and tested accordingly. The top steel beam adopted Q355B 800... 2000 30mm rectangular steel pipe, anchor plate made of Q355 grade steel, anchor plate thickness... t=25mm The anchor bars are made of HRB400 steel bars, and the total area of ​​the anchor bars on one side is [missing information]. =42647 Anchor bar diameter d =25mm, number of anchor bars is 100 (5 20), Anchor bar spacing s =200mm.

[0133] Equipment and Instruments and Key Points for Their Installation: 1) Hydraulic jacks are preferred for testing loading. When two or more jacks are used, they should operate in parallel and synchronously, and should comply with the following regulations: a: The jacks used should be of the same model and specifications; b: The center of the resultant force of the jack should coincide with the centroid of the cross-section of the pile under inspection.

[0134] 2) The reaction force provided by the loading reaction device shall not be less than 1.2 times the maximum load value, and the components of the loading reaction device shall meet the requirements of bearing capacity and deformation.

[0135] 3) Load measurement can be performed directly using a load cell placed on the jack. When measuring oil pressure and converting it to load using a pressure gauge or pressure sensor connected in parallel to the jack's oil circuit, the load conversion should be performed according to the jack calibration curve. The accuracy of the load cell, pressure sensor, or pressure gauge should be better than or equal to 0.5. The pressure of the pressure gauge, oil pump, and oil pipes used in the test should not exceed 80% of the specified working pressure under maximum load.

[0136] 4) Settlement measurement should preferably use large-range displacement sensors or dial gauges, and should comply with the following regulations: a: The measurement error must not exceed 0.1%. FS The scale resolution should be better than or equal to 0.01. mm ; b: Diameter or side width greater than 500 mm For piles, four displacement testing instruments should be symmetrically installed in two directions, with a diameter or side width less than or equal to 500 mm. mm Two displacement testing instruments can be symmetrically installed on the piles; c: The reference beam should have sufficient stiffness; d: The fixtures and reference beams that fix and support the displacement gauges (dial gauges) shall not be affected by temperature, vibration and other external factors; when the reference beam is exposed to sunlight, shading measures shall be taken.

[0137] The settlement measurement plane should be set 200 mm below the pile top. mm The measuring point should be fixed on the pile body at the specified location.

[0138] On-site inspection: Test the addition and unloading methods: 1) Loading should be carried out in stages, and each stage should be applied with equal loads. The load for each stage should be 1 / 10 of the maximum load or the estimated ultimate bearing capacity. The first stage load can be twice the load of the stage. 2) Unloading should be carried out in stages, and the amount of unloading at each stage should be twice the load at the time of loading, and the unloading should be equal at each stage. 3) When loading and unloading, the load transfer should be uniform, continuous and without impact, and the variation of each load level during the maintenance process should not exceed ±10% of the grade load.

[0139] Slow-speed sustained load method for testing: 1) After each load level is applied, it should be handled according to section 5. min 15 min 30 min 45 min 60 min Measure the settlement at the top of the pile, and then every 30 days thereafter. min Measure the settlement at the top of the pile once; 2) Standard for relative stability of pile settlement during test piles: The settlement at the top of the pile shall not exceed 0.1 mm per hour. mm And it occurred twice consecutively (from the 30th day after the application of the graded load). min Begin by pressing 1.5. h Three consecutive times every 30 min (Calculation of settlement observations); 3) When the settlement rate at the top of the pile reaches the relatively stable standard, the next level of load can be applied; 4) During unloading, each load level should be maintained at 1 h According to the 15th min 30 min 60 min After measuring the settlement at the top of the pile, the first-level load can be removed; after unloading to zero, the residual settlement at the top of the pile should be measured, and the maintenance time should not be less than 3 minutes. h The reading times were 15th. min 30 min Every 30 thereafter min Measure the residual settlement at the top of the pile once.

[0140] Loading may be terminated under any of the following conditions: 1) Under a certain load level, the settlement at the pile top is more than 5 times the settlement under the previous load level, and the total settlement at the pile top exceeds 40 mm. mm ; 2) Under a certain load level, the settlement at the pile top is more than twice the settlement under the previous load level, and after 24 hours... h The project has not yet met the relative stability standard stipulated in Section 4.3.5, Paragraph 2 of the "Technical Specification for Testing of Building Foundation Piles" (JGJ 106-2014). The relative stability standard refers to the requirement that the settlement at the top of the pile should not exceed 0.1 mm per hour. mm , and appeared twice in a row; 3) The maximum load value required by the design has been reached and the settlement at the top of the pile has reached a relatively stable standard; 4) When the engineering pile is used as an anchor pile, the pull-out of the anchor pile has reached the allowable value; 5) When the load-settlement curve shows a gradual change, the load can be applied up to 60% of the total settlement at the pile top. mm ~80 mm When the pile end resistance has not been fully utilized, it can be loaded until the cumulative settlement at the pile top exceeds 80%. mm .

[0141] Analysis and judgment of test data: The processing of the detection data is carried out according to the following steps: 1) Based on the test data, plot the vertical load-settlement (Qs) curve and the settlement-logarithm of time (s-lgt) curve; 2) Determine based on the characteristics of settlement variation with load: For steep-drop Qs curves, the load value corresponding to the starting point where a significant steep drop occurs should be taken; 3) Based on the characteristics of settlement change over time, the load value of the previous stage should be taken as the one where the tail of the s-lgt curve shows a significant downward bend. 4) When the conditions meet the requirements of Article 4.3.7, Paragraph 2 of the "Technical Specification for Testing of Building Foundation Piles" (JGJ 106-2014), the previous load value should be used; 5) For a gradually varying Qs curve, s should be taken as 40 based on the total settlement at the pile top. mm The corresponding load value; for D (D is the pile tip diameter) greater than or equal to 800. mm The piles can be taken s Equals 0.05 D The corresponding load value; when the pile length is greater than 40 m When considering this, the elastic compression of the pile body should be taken into account; 6) If conditions 2 to 5 of this step are not met, the maximum load value should be taken as the ultimate vertical compressive bearing capacity of the pile.

[0142] The characteristic value of the vertical compressive bearing capacity of a single pile should be taken as 50% of the ultimate vertical compressive bearing capacity of a single pile.

[0143] After the concrete strength grade of the pile body reaches the design strength, the load is applied using the slow sustained load method, and the vertical load-settlement (Qs) curve and the settlement-time logarithm (s-lgt) curve are plotted based on the relevant test data.

[0144] According to the test data, the load value corresponding to the starting point of the significant steep drop in the three test piles of this project was 13200. kN This value is taken as the standard value of the vertical ultimate bearing capacity of a single pile.

[0145] S5: Determine the characteristic value of the single pile bearing capacity of the dual-function integrated pile based on the static load test of the single pile vertical compressive strength; optimize the pile foundation layout based on the measured characteristic value of the single pile vertical bearing capacity, and substitute the measured value of the single pile vertical bearing capacity characteristic value into the stress model. Iterate and correct the design parameters according to step S2 to form a design-test-optimization closed loop.

[0146] The measured characteristic value of the single pile bearing capacity of the dual-function integrated pile is obtained by the following formula: ; in, This represents the standard value of the vertical ultimate bearing capacity of a single pile as measured in a static load test. It is the measured characteristic value of the vertical bearing capacity of a single pile in a dual-function integrated pile system; It is the first pile side above the bottom of the foundation pit Standard value of ultimate lateral resistance of soil layer; The pile perimeter above the bottom of the foundation pit The thickness of the soil layer, u It is the circumference of the pile. It is the size effect coefficient of the side resistance of large-diameter piles.

[0147] After substituting the relevant data, the measured characteristic value of the single pile bearing capacity of the dual-function integrated pile is obtained. =5800 kN Since the measured value of the characteristic value of the single pile bearing capacity is greater than the calculated value, the six-pile cap can be optimized into a four-pile cap. The eccentricity between the upper structural column of the four-pile cap and the center of the pile cap is... =200 mm pier width =4500 mm pier height =2000 mm The length of the pier cap is 9900. mm Adjusted to 5700 mm ; Perform the vertical compressive bearing capacity calculation and the horizontal bearing capacity calculation again according to step S2.

[0148] Calculation of vertical compressive bearing capacity: Substitute the known data into the relevant formulas in step S22-1 to obtain the maximum vertical force of the pile. =6744 kN =6960 kN , =3936 kN =5800 kN The vertical compressive bearing capacity of a single pile meets the calculation requirements.

[0149] Horizontal bearing capacity calculation: The characteristic value of the horizontal bearing capacity of the piles in the pile group foundation is obtained by calculating using the relevant formulas in step S22-2. = 290 kN ; =275 kN ; The horizontal bearing capacity meets the calculation requirements.

[0150] By iteratively correcting the design parameters according to step S2, the optimal integrated pile design scheme that satisfies both functions is obtained as follows: Dual-function integrated pile: pile diameter D =1000 mm The concrete strength grade of the pile body is C35. =16.7 The longitudinal reinforcement of the pile body consists of 20 strands of 25mm (Grade III steel), and the pile body stirrups consist of 12@100mm (Grade III steel). The length of the pile tip extending below the bottom elevation of the foundation pit is not less than 6.5m. m ; Anchor piles: pile diameter D =1000 mm The concrete strength grade of the pile body is C35. =16.7 The pile's longitudinal reinforcement consists of 20 strands of 25mm (Grade III steel), and the pile's stirrups consist of 12@100mm (Grade III steel). The length of the pile tip extending below the bottom elevation of the foundation pit is no less than 8.5 meters. m The optimized pile foundation layout plan based on the measured characteristic value of the vertical bearing capacity of a single pile is shown below. Figure 12 As shown.

[0151] S6: Pile Foundation Testing and Acceptance: After the support piles are constructed, pile integrity testing is performed according to step S3, and deformation monitoring is conducted during the foundation pit support stage. After the tunnel structure construction is completed and the foundation pit backfilling is finished, the single pile bearing capacity test of the dual-function integrated piles is performed according to step S4. The maximum load for the single pile vertical compressive static load test is twice the characteristic value of the single pile bearing capacity. Finally, data collection and analysis are completed to generate a pile foundation testing and acceptance report.

[0152] After the construction of the support piles and dual-function integrated pile foundations was completed and the concrete strength of the pile body met the requirements, pile integrity testing and single pile vertical compressive bearing capacity testing were conducted. All piles in this project underwent Class I integrity testing. The standard value of the ultimate bearing capacity of a single pile in the anchor pile static load test was 11600. kN, The characteristic value of the single pile bearing capacity is 5800. kN, The requirements are met.

[0153] According to deformation monitoring data, the horizontal displacement of the pile top of the dual-function integrated pile in this project is 13.80 mm. mm Less than the standard limit of 20 mm The horizontal displacement of the pile top of the dual-function integrated pile is 9.60 mm. mm Less than the standard limit of 20 mm The maximum settlement at the top of the dual-function integrated pile is 0. mm Less than the standard limit of 20 mm All monitoring data met the requirements.

[0154] Figure 13 The system architecture diagram for a design and testing system based on multi-parameter fusion is divided into a data layer, a calculation layer, and an output layer. The data layer collects all the original engineering data, the calculation layer realizes dual-function integrated pile foundation design, multi-dimensional parameter fusion pile integrity evaluation, anchor pile length verification, and design parameter optimization and iteration, and the output layer outputs a complete set of design and testing results, realizing full-chain data interoperability.

[0155] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for integrated design and testing of support piles and engineering piles based on multi-parameter fusion, characterized in that, Includes the following steps: S1. Collect design parameters, including engineering geological parameters, foundation pit support design parameters, pile foundation design parameters and superstructure load parameters. Based on the design parameters, establish the initial engineering conditions for the dual-function integrated pile, estimate the characteristic value of the single pile bearing capacity, and determine the initial number and initial layout of the pile foundation. S2, Based on the initial engineering conditions of the dual-function integrated pile, estimate the characteristic value of the single pile bearing capacity, determine the initial number and initial layout of the pile foundation, construct a dual-function coupled force model of support pile and engineering pile, the dual-function coupled force model of support pile and engineering pile includes the force calculation of the support stage and the force calculation of the service stage of the dual-function integrated pile, and determine the pile diameter, pile length, pile foundation reinforcement, concrete strength and pile foundation spacing of the dual-function integrated pile, and also calculate the length of the anchor piles on both sides of the dual-function integrated pile; S3, During the design and test pile period, pile foundation integrity testing is carried out to obtain multi-dimensional testing parameters; Data fusion of multidimensional detection parameters is performed, and the integrity of pile foundations is determined through a dual model of logical judgment criteria and weighted quantitative scoring. S4. A static load test of the vertical compressive strength of a single pile was conducted on the test pile using an anchor pile reaction device to obtain the ultimate vertical compressive bearing capacity of the single pile. S5. Determine the characteristic value of the vertical bearing capacity of the single pile based on the measured vertical compressive ultimate bearing capacity of the single pile; and substitute the characteristic value of the vertical bearing capacity of the single pile into the dual-function coupled force model of the support pile-engineering pile in step S2 to iteratively correct the design parameters and obtain the optimized design scheme of the dual-function integrated pile. S6. After the support piles are constructed, perform pile integrity testing according to step S3, and conduct deformation monitoring during the foundation pit support stage; after the foundation pit is backfilled, perform single pile vertical bearing capacity testing on the dual-function integrated piles according to step S4; complete data collection and analysis, and generate a pile foundation testing and acceptance report.

2. The integrated design and testing method for support piles and engineering piles based on multi-parameter fusion as described in claim 1, characterized in that, The logical decision criteria in step S3 include: Destructive testing priority principle: Destructive testing uses core drilling to directly obtain core samples for observation. If defects are found, it has high reliability and is given priority. When the classification standard for destructive testing is lower than that for non-destructive testing, destructive testing shall prevail. The principle of prioritizing the whole over the part: If the core sample obtained by the core drilling method is intact, but the sonic logging method or low strain method shows anomalies and the classification standard is lower than that of the borehole method, then the test results of the low strain method or sonic logging method shall be accepted, and additional drilling shall be performed at the abnormal point for verification. Spatial complementarity principle: The classification criteria are combined with the location of the defects. Shallow defects within 5 meters of the pile top and defects at the pile bottom are judged by the low strain method, while deep defects beyond 5 meters of the pile top are judged by the sonic projection method. The principle of taking the most severe severity: If different methods yield different results for the same location, the most severe classification standard shall be taken as the final result.

3. The integrated design and testing method for support piles and engineering piles based on multi-parameter fusion as described in claim 2, characterized in that, The weighted quantization score in step S3 is calculated by multiplying the weights and the detection results and then summing them to obtain the comprehensive score. The weights of the low strain method detection, the acoustic projection method, and the core drilling method increase in sequence.

4. The integrated design and testing method for support piles and engineering piles based on multi-parameter fusion as described in claim 1, characterized in that, Step S4 specifically includes the following steps: S41, Anchor pile reaction device construction design, specifically including: a steel beam reaction device is set on the top of the steel beam, anchor bars and anchor plates are pre-embedded at the steel beam position corresponding to the anchor pile, the anchor bars are reliably connected to the steel beam, and the anchor plates are flush with the top surface of the steel beam to ensure effective load transfer during testing; S42, Equipment and Instruments and Their Installation, specifically including: the test loading equipment uses hydraulic jacks; the multiple jacks used are of the same model and specifications; the resultant force center of the jacks coincides with the centroid of the cross-section of the pile under test; the reaction force provided by the loading reaction device is not less than 1.2 times the maximum loading value, and the components of the loading reaction device meet the requirements of bearing capacity and deformation; the load is measured directly by a load sensor placed on the jack; the settlement is measured using a large-range displacement sensor. S43, On-site inspection; S44, Detection data analysis and judgment.

5. The integrated design and testing method for support piles and engineering piles based on multi-parameter fusion according to claim 1, characterized in that, In step S2, the formula for calculating the length of the anchor piles on both sides of the dual-function integrated pile is: ； ； ； ； In the formula: It is the characteristic value of the vertical bearing capacity of a single pile in a dual-function integrated pile; It refers to the pull-out force of a single anchor pile. The anchor pile's own weight is used, and the buoyancy weight is taken below the groundwater level. It is the standard value of the ultimate pull-out bearing capacity of the anchor pile; This is the safety factor; it is 3.0 for the test pile stage and 2.2 for the engineering pile acceptance stage. It refers to the number of anchor piles; It is the pull-out coefficient; It is the first anchor pile below the bottom of the foundation pit. Standard value of ultimate lateral resistance of soil layer; It is the circumference of the anchor pile; It is the anchor pile circumference below the bottom of the foundation pit. The thickness of the soil layer; It refers to the depth of the foundation pit excavation; It is the total design length of the anchor pile.

6. The integrated design and testing method for support piles and engineering piles based on multi-parameter fusion according to claim 1, characterized in that, In step S4, the anchor pile reaction device includes an anchor pile (8), a static load test pile (7), a hydraulic loading assembly (5), a steel beam (2), anchor bars (4), an anchor plate (3), a pressure pad (6), and a steel crossbeam (1). The downward pressure load is transmitted to the top of the static load test pile (7) to be tested through the hydraulic loading assembly (5), and the corresponding reverse upward pull force is transmitted from the upper end of the hydraulic loading assembly (5) to both ends of the steel crossbeam (1). The top bearing surface of the hydraulic loading assembly (5) is in contact with the thickened pressure pad (6) of the lower flange of the steel beam (2), and the bottom bearing surface of the hydraulic loading assembly (5) is in contact with the thickened circular pressure pad (6) at the top of the test pile. The loads at both ends of the steel crossbeam (1) are transmitted to the steel beam (2) and the anchor pile (8) through the anchor plate (3) and the anchor bars (4). Finally, the side resistance between the anchor pile (8) and the surrounding soil balances all the upward pull force, forming a closed-loop force transmission system.

7. The integrated design and testing method for support piles and engineering piles based on multi-parameter fusion according to claim 1, characterized in that, In step S2, the vertical compressive bearing capacity calculation was performed during the stage stress calculation. This calculation considered the horizontal displacement of the pile top during the support stage of the dual-function integrated pile. The calculation formula is as follows: Under the action of axial vertical force: ； Under the action of eccentric vertical force: ； ； ； Under the action of axial vertical force: ； Under the action of eccentric vertical force: ； ； ； ； In the formula: It is the average vertical force of the foundation pile under the action of the axial vertical force of the standard combination of load effects; It is the first load effect under the standard combination of eccentric vertical force. Vertical force on the foundation pile; It is the maximum vertical force at the pile top under the action of eccentric vertical force in the standard combination of load effects; It is the standard value of the self-weight of the pile cap and the soil above the pile cap; It is the axial force at the bottom of the upper structural column acting on the top surface of the foundation under the standard combination of load effects; 、 It refers to the load effect standard combination acting on the top surface of the pier cap for the upper structural columns around the pier. 、 The torque of the spindle; It refers to the load effect standard combination acting on the upper structural column edge of the top surface of the foundation. Shear force on the shaft; Under the standard combination of load effects, the transfer beam end acting on the edge of the pier cap is... The torque of the spindle; It is the shear force at the end of the transfer beam acting on the edge of the pier under the standard combination of load effects; 、 Under the standard combination of load effects, the load acts on the bottom surface of the pile cap, around the centroid of the pile group. 、 The torque of the spindle; 、 、 、 It is the first , foundation pile to 、 Distance between axes; It is the width of the foundation; It is the height of the foundation; It is the horizontal displacement of the top of the dual-function integrated pile; It is the centroid of the column spacing and pile group of the superstructure. The distance of the spindle; It is the standard value of the vertical ultimate bearing capacity of a single pile, which is calculated based on geotechnical parameters in the preliminary design stage and finally determined based on static load tests. These are the standard values ​​of total limiting side resistance and total limiting end resistance, respectively. It is the first pile side below the bottom of the foundation pit Standard value of ultimate lateral resistance of soil layer; It is the standard value of the ultimate end resistance of the pile; 、 It is the size effect coefficient of the side resistance and end resistance of large-diameter piles; It is the circumference of the pile body; It is the pile perimeter below the bottom of the foundation pit. The thickness of the soil layer; It is the design value of the compressive bearing capacity of the pile body; It is the pile-forming process coefficient; It is the design value of the axial compressive strength of concrete; This is the design value of the compressive strength of the main reinforcement bars; It is the area of ​​the longitudinal reinforcement bars in the pile body; It is the characteristic value of the vertical bearing capacity of a single pile in a dual-function integrated pile; n It refers to the number of piles within the pile cap area, including dual-function integrated piles and engineering piles; It is the area at the pile tip.

8. The integrated design and testing method for support piles and engineering piles based on multi-parameter fusion according to claim 1, characterized in that, The formula for calculating the characteristic value of the measured vertical bearing capacity of a single pile in step S5 is as follows: ； in, This represents the standard value of the vertical ultimate bearing capacity of a single pile as measured in a static load test. It is the measured characteristic value of the vertical bearing capacity of a single pile in a dual-function integrated pile system; It is the first pile side above the bottom of the foundation pit Standard value of ultimate lateral resistance of soil layer; The pile perimeter above the bottom of the foundation pit The thickness of the soil layer, It is the circumference of the pile. It is the size effect coefficient of the side resistance of large-diameter piles.

9. The integrated design and testing method for support piles and engineering piles based on multi-parameter fusion according to claim 1, characterized in that, In step S6, the number of pile foundation tests is determined by the following methods: all piles are tested using the low-strain method; the number of piles tested using the sonic logging method is no less than 10% of the total number of dual-function integrated piles and no less than 10 piles; the number of piles tested using the core drilling method is no less than 20% of the total number of dual-function integrated piles and no less than 10 piles; and the number of piles tested for vertical bearing capacity is no less than 1% of the total number of dual-function integrated piles and no less than 3 piles.

10. The integrated design and testing method for support piles and engineering piles based on multi-parameter fusion according to claim 1, characterized in that, In step S1: Engineering geological parameters include the physical and mechanical properties of each soil layer and the thickness of each soil layer; The design parameters for foundation pit support include the excavation depth of the foundation pit, the importance coefficient of the support structure, and the limit of horizontal displacement at the top of the piles. The pile foundation design parameters include the proposed pile diameter, pile length, design value of axial compressive strength of pile concrete, pile foundation layout and spacing; The load parameters of the superstructure include the reaction forces transmitted by the superstructure, including the reaction forces at the bottom of the columns, the internal forces at the ends of the transfer beams, and the eccentricity between the superstructure columns and the center of the pile cap.

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