A size-optimized combination method for precast piles on complex terrain foundation

Abstract

The present application relates to precast pile size optimization technical field, especially to a kind of size optimization combination method of complex terrain foundation precast pile, the method includes collecting river valley topography parameter to construct topography three-dimensional model to determine target piling area and piling point;Determine the bearing capacity of each point foundation in combination with the soil layering parameter of the area where piling point is located, determine the marked point that does not reach the standard based on foundation bearing capacity and preset standard bearing capacity;Determine the initial size of precast pile based on the distance between marked points, bearing capacity difference value, distance grade and bearing capacity grade to determine the initial size of precast pile;Determine size parameter based on the initial size of precast pile and simulate piling to obtain simulation depth to adjust precast pile size parameter.The present application determines corresponding precast pile size parameter by distance grade and bearing capacity grade between pile points, and adjusts the process of precast pile size parameter based on precast pile size parameter simulation piling to adjust precast pile size parameter, solve the problem that the size of precast pile and complex terrain foundation appear deviation.

Description

Technical Field

[0001] This invention relates to the field of precast pile size optimization technology, and in particular to a method for optimizing the combination of precast pile sizes in complex terrain foundations. Background Technology

[0002] As infrastructure construction extends to remote mountainous areas and complex terrain such as river valleys, the geological conditions faced by foundation engineering are becoming increasingly challenging. River valleys, as typical examples of complex terrain, exhibit dramatic topographic relief, uneven soil stratification, and problems such as soft soil interlayers, scattered gravel distribution, and significant spatial differences in foundation bearing capacity, posing numerous challenges to foundation reinforcement construction. Precast piles, due to their advantages of convenient construction, stable bearing performance, and easy quality control, are widely used in foundation reinforcement projects in complex terrains. The rationality of their dimensional parameters directly determines the foundation reinforcement effect, project safety, and construction cost.

[0003] Chinese Patent Publication No. CN114169064A discloses a method for optimizing the size combination of down-the-hole impact cement-soil composite precast piles and its application. The method includes: establishing a composite foundation model for down-the-hole impact cement-soil composite precast piles and assessing the model's reliability; establishing the bearing capacity mechanism of the composite foundation under different geological conditions; setting expressions for the effective pile length, vertical compressive strength-controlled ultimate bearing capacity of down-the-hole impact cement-soil composite precast piles, soil ultimate side friction-controlled ultimate bearing capacity of down-the-hole impact cement-soil composite precast piles under different geological conditions, and the relationship between the length and cross-sectional area of ​​the concrete core pile of the down-the-hole impact cement-soil composite precast pile; and determining whether the dimensions of the concrete core pile meet the verification requirements. This invention optimizes the combination of the length and cross-sectional area of ​​the concrete core pile under different geological conditions, making its vertical compressive strength and the ultimate side friction of the pile and soil as coordinated as possible, thereby saving engineering materials.

[0004] Therefore, the existing technology has the following problems: before construction in the valley area, due to the lack of a process to determine the corresponding precast pile size parameters by the pile spacing level and bearing capacity level, and to conduct simulated pile driving based on the precast pile size parameters to adjust the precast pile size parameters, the size of the precast pile deviates from the complex terrain foundation, affecting the construction safety. Summary of the Invention

[0005] To address this issue, the present invention provides a method for optimizing the size combination of precast piles for complex terrain foundations. This method overcomes the problem in the prior art where, before construction in river valley areas, the lack of a process to determine the corresponding precast pile size parameters based on pile spacing and bearing capacity levels, and to perform simulated pile driving based on these parameters to adjust the precast pile size parameters, leads to deviations between the precast pile size and the complex terrain foundation, affecting construction safety.

[0006] To achieve the above objectives, the present invention provides a method for optimizing the size combination of precast piles for foundations in complex terrain, comprising:

[0007] Collect geomorphic parameters of the river valley area, obtain a three-dimensional geomorphic model based on the geomorphic parameters, determine the target piling area based on the three-dimensional geomorphic model, and determine the piling points based on the target piling area;

[0008] Based on the soil stratification parameters of the area where the corresponding piling points are located, and combined with the distribution characteristics of the piling points, the foundation bearing capacity of each piling point is determined.

[0009] Based on the comparison between the foundation bearing capacity and the preset standard bearing capacity, the pile driving points with substandard bearing capacity are identified and marked, thus obtaining the marked pile driving points;

[0010] The initial size parameters of the corresponding precast piles are determined based on the pile spacing between marked pile points and the difference in foundation bearing capacity between adjacent pile points. The pile spacing level is determined based on the pile spacing and the preset influence spacing. The bearing capacity level is determined based on the absolute value of the difference in bearing capacity between adjacent pile points and the benchmark bearing capacity.

[0011] Based on the pile spacing level and bearing capacity level, the corresponding precast pile size parameters are determined, and the simulated pile driving is performed based on the precast pile size parameters to obtain the simulated pile driving depth.

[0012] The precast pile size parameters are adjusted based on the comparison results between the simulated pile driving depth and the preset pile driving depth threshold.

[0013] The precast pile dimensions include pile diameter and pile length.

[0014] Furthermore, the process of obtaining the three-dimensional terrain model includes:

[0015] The surface parameters of the target piling area are obtained by scanning and surveying the target piling area using a drone, and a three-dimensional landform model is determined based on the surface parameters and the surveyed underground parameters.

[0016] The geomorphic parameters include surface parameters and underground parameters.

[0017] Furthermore, the process of determining the target piling area includes:

[0018] Several initial piling areas are determined based on the three-dimensional surface model in the terrain model and the target building area, and the target piling area is determined based on the three-dimensional model of the target building and the initial piling areas.

[0019] Furthermore, the process of determining the piling points includes:

[0020] The target piling area is divided into several partitioned target piling areas. The target building 3D model is moved to the partitioned target piling area, and the frame support points in the target building 3D model that coincide with the partitioned target piling area are selected to obtain the piling points.

[0021] Furthermore, the process of determining the foundation bearing capacity at each piling point includes:

[0022] The initial bearing capacity of a single point is determined based on the number of soil layers, and the foundation bearing capacity of each pile point is determined based on the soil structure and the initial bearing capacity of the single point.

[0023] The soil stratification parameters include the number of soil stratification layers and the soil structure of each soil layer.

[0024] Furthermore, the process of obtaining the marked piling points includes:

[0025] Based on the fact that the foundation bearing capacity is less than the preset standard bearing capacity, the bearing capacity of the corresponding pile driving point is determined to be substandard and marked to obtain the marked pile driving point;

[0026] Based on the foundation bearing capacity being greater than or equal to the preset standard bearing capacity, it is determined that the bearing capacity of the corresponding piling point meets the standard.

[0027] Furthermore, the process of determining the pile spacing level includes:

[0028] The actual number of influence spacings is determined based on the comparison between the pile spacing and the preset influence spacing. The influence level of the pile spacing on the initial size parameters is determined based on the comparison between the actual number and the number threshold range. The initial size parameters of the precast piles are then determined.

[0029] Based on the fact that the actual quantity is less than the minimum value of the quantity threshold range, the spacing influence level is determined to be the primary spacing influence level.

[0030] Based on the fact that the actual quantity is within the quantity threshold range, the spacing influence level is determined to be the medium spacing influence level.

[0031] Based on the fact that the actual quantity is greater than the maximum value of the quantity threshold range, the spacing influence level is determined to be a high-level spacing influence level.

[0032] The preset influence spacing is the shortest spacing between marked piling points that affects the bearing capacity of the foundation.

[0033] Furthermore, the process of determining the bearing capacity level includes:

[0034] Based on the fact that the absolute value of the bearing capacity difference between adjacent points is less than the minimum value of the bearing capacity difference threshold range, the bearing capacity level is determined to be the primary bearing capacity level.

[0035] Based on the fact that the absolute value of the bearing capacity difference between adjacent points is within the bearing capacity difference threshold range, the bearing capacity level is determined to be the intermediate bearing capacity level.

[0036] Based on the fact that the absolute value of the bearing capacity difference between adjacent points is greater than the maximum value of the bearing capacity difference threshold range, the bearing capacity level is determined to be a high bearing capacity level.

[0037] Furthermore, the process of determining the corresponding precast pile size parameters includes:

[0038] The first precast pile size parameter is determined based on the current pile spacing level and its corresponding spacing level influence compensation parameter. The second precast pile size parameter is determined based on the current bearing capacity level and its corresponding bearing capacity level influence compensation parameter. The precast pile size parameter is determined based on the first precast pile size parameter and the second precast pile size parameter.

[0039] Furthermore, the process of adjusting the precast pile size parameters includes:

[0040] Since the simulated pile driving depth is less than the preset pile driving depth threshold, the pile length is increased according to the difference between the preset pile driving depth threshold and the simulated pile driving depth. Since the increased pile length still does not meet the preset pile driving depth threshold, the precast pile size parameters are determined by shortening the pile diameter.

[0041] Based on the simulated pile driving depth being greater than or equal to the preset pile driving depth threshold, it is determined to maintain the current precast pile size parameters.

[0042] The preset piling depth is determined based on the soil conditions corresponding to each soil layer.

[0043] Compared with existing technologies, the advantages of this invention are as follows: It accurately locates the target piling area and points using a 3D topographic model, determines the foundation bearing capacity based on soil stratification parameters, and marks substandard points. This avoids the construction risks caused by inaccurate terrain surveys and blind point selection in traditional methods, improving the rationality and safety of pile layout. The initial dimensions of precast piles are determined based on pile spacing and bearing capacity levels, ensuring precise matching between precast pile dimensions and terrain conditions and bearing capacity requirements. This avoids material waste or insufficient bearing capacity issues caused by uniform precast pile dimensions. Dynamic adjustment of precast pile dimensions is achieved through simulated piling, eliminating the need for repeated on-site testing, effectively reducing construction adjustment costs and shortening the construction period. This method forms a complete technical closed loop from terrain survey and point determination to size optimization, significantly improving the adaptability and reliability of precast pile construction in complex terrains, ensuring foundation engineering quality, and simplifying the optimization process. It possesses strong engineering practicality and promotional value.

[0044] Furthermore, in implementation, the combination of UAV scanning and borehole surveying breaks through the limitations of traditional single survey methods. UAV grid scanning can achieve full coverage survey of the target area, accurately capturing topographic features such as surface undulations, slope, and aspect, effectively avoiding blind spots in complex terrains such as river valley slopes and low-lying areas. Borehole surveying can obtain complete layer information of underground soil layers, clarify the distribution characteristics of each soil layer, and make up for the inadequacy of UAVs that can only detect the surface. By integrating surface and underground parameters into a model, the generated 3D geomorphological model can simultaneously present surface topography and underground geological structure, realizing the integrated expression of topographic and geological data and breaking the traditional separation of surface and underground data. The accuracy verification process after modeling further ensures the accuracy and reliability of the model data, accurately reflecting the actual situation of complex river valley terrain.

[0045] Furthermore, in implementation, by delineating the target piling area in stages and accurately determining the piling points, a scientific and efficient planning scheme is provided for pile foundation construction in complex terrain, demonstrating significant technical advantages. The initial piling area is selected by extracting a 3D surface model from a high-precision 3D topographic model, combined with the target building area and construction conditions, thus avoiding problems such as inconsistent surface slopes and interference from underground obstacles, ensuring the feasibility of construction in the initial area. Spatial fitting between the target building's 3D model and the initial area allows for precise matching of the building foundation layout requirements. The selection of the target area, combined with overlap and construction influencing factors, significantly improves the rationality and adaptability of the area delineation. In the piling point determination stage, the target area is divided into zones according to the building column grid spacing, ensuring that the zones conform to the building structure layout. By moving the 3D building model and comparing the spatial coordinates of the frame support points with the zones, precise correspondence between the piling points and the core stress points of the building is achieved, avoiding the blindness of traditional point determination and preventing selection errors during the piling point selection process.

[0046] Furthermore, during implementation, targeted borehole sampling and testing can accurately obtain soil stratification parameters for each piling point, including the number of layers and the soil structure of each layer. This breaks through the limitations of traditional regional and general surveys, achieving precise matching of bearing capacity calculation points. Combined with building codes, the weighted average method is used to calculate the initial bearing capacity of a single point, which can fully take into account the differences in bearing capacity of different soil layers. Compared with the single soil layer determination method, this significantly improves the scientificity and rationality of the initial bearing capacity calculation. At the same time, the initial bearing capacity is corrected based on the soil structure, further considering the influence of soil density, particle composition and other detailed characteristics on the bearing capacity. This makes the final foundation bearing capacity more consistent with the actual geological conditions, avoiding problems such as improper pile selection and structural safety hazards caused by bearing capacity calculation deviations from the source, and ensuring the stability and safety of the foundation project.

[0047] Furthermore, during implementation, the pre-set standard bearing capacity determined by the actual needs of the project was used as the judgment benchmark. This ensured that the judgment criteria for whether the bearing capacity met the standard were consistent with the stress requirements of the building structure, avoiding judgment deviations caused by blindly setting standards. By comparing the measured foundation bearing capacity of each piling point with the pre-set standard bearing capacity one by one, a comprehensive screening of all piling points was achieved. This ensured that no safety hazards of substandard bearing capacity were overlooked, and that compliant and non-compliant points were accurately distinguished, guaranteeing the comprehensiveness and accuracy of the judgment results. The precise marking of non-compliant points enabled the pre-identification and targeted positioning of construction risks, reducing unnecessary construction cost waste. It also prevented safety hazards such as foundation settlement and structural instability caused by unidentified piling points with insufficient bearing capacity from the source, further ensuring the reliability and safety of the overall foundation project.

[0048] Furthermore, during implementation, a preset influence spacing was set based on geological test data, and a quantity threshold range was defined in conjunction with engineering safety requirements. This ensured that the benchmark for judging the influence of spacing closely matched the actual geological conditions, avoiding judgment deviations caused by subjectively set standards from the outset. By measuring the actual spacing between marked pile driving points and counting the number of points that met the influence spacing, a quantitative assessment of the degree of spacing interference was achieved. Then, based on the quantity threshold range, three levels of influence were divided, which could accurately distinguish the intensity of spacing interference at different points, breaking the limitations of the rough judgment of spacing influence in traditional construction. The initial size parameters were adjusted in a targeted manner based on different spacing influence levels. The higher the spacing influence level, the higher the degree of interference and the greater the reinforcement. This enabled the adjustment of the corresponding initial size parameters of the pile foundation for different spacing levels, ensuring the bearing capacity, anti-interference ability, and redundancy of the pile foundation in high-interference areas, while avoiding the waste of materials caused by excessive reinforcement in low-interference areas, thus achieving a rational allocation of resources.

[0049] Furthermore, in implementation, a threshold range for bearing capacity difference was set according to the actual needs of the project. This range served as a benchmark for determining the degree of bearing capacity difference between adjacent points, ensuring that the classification standard aligned with the project's geological and structural stress requirements and avoiding the subjective bias of traditional experience-based judgments. By calculating the absolute value of the bearing capacity difference between adjacent marked piling points and comparing it with the threshold range, the bearing capacity level was divided into three levels. When the absolute value of the bearing capacity difference between adjacent points was less than the minimum value of the threshold range, the bearing capacity level was determined to be the primary bearing capacity level. If the bearing capacity of adjacent points is sufficient for piling, uneven settlement of the foundation caused by differences in bearing capacity between adjacent points can be avoided during piling. When the absolute value of the difference in bearing capacity between adjacent points is within the threshold range of bearing capacity difference, the bearing capacity level is determined to be medium bearing capacity level. In this case, the difference between adjacent points is relatively large. During piling, the bearing capacity of the precast piles will be different due to the difference in bearing capacity between the two points. Based on the different bearing capacity levels, the size parameters of the precast piles corresponding to this piling point can be adjusted to compensate for the changes in bearing capacity values ​​caused by differences in the underlying soil.

[0050] Furthermore, this study innovatively combines the dual influences of pile spacing grade and bearing capacity grade, setting corresponding compensation parameters to calculate the dimensional parameters of two types of precast piles. The initial parameters are determined by taking the maximum value, ensuring that the parameters simultaneously meet the dual requirements of spacing interference resistance and bearing capacity adaptation. This breaks the limitations of traditional single-dimensional parameter design, significantly improving the rationality and reliability of the initial parameters. There is a positive correlation between the pile diameter compensation parameters and the pile length compensation parameters and the pile spacing grade and bearing capacity grade; the higher the grade, the larger the corresponding pile diameter and pile length compensation parameter values. The classification of pile spacing grades is based on the pile density; the smaller the spacing, the higher the grade. The more significant the pile group effect, the greater the reduction in pile side friction, thus requiring larger compensation parameters to enhance pile bearing capacity. The bearing capacity level is determined by the design target value of the bearing capacity at the pile driving point; the higher the level, the higher the level. A higher level means a higher vertical ultimate bearing capacity of a single pile, thus requiring larger compensation parameters to enhance pile side friction and pile end resistance. In the parameter adjustment stage, simulated pile driving tests are conducted using pile foundation construction simulation software. Using a preset pile driving depth threshold as the judgment standard, a progressive adjustment strategy of first increasing the pile length and then shortening the pile diameter is adopted. This ensures that the pile end can effectively reach the design bearing layer while avoiding material waste through refined adjustments.

[0051] Furthermore, in implementation, to address the differences in pile spacing and bearing capacity levels at different piling locations, a dual-dimensional level influence compensation parameter, combined with pile depth simulation verification and iterative dimensional adjustments, can accurately match the bearing requirements of each point, ensuring that the vertical bearing capacity of a single pile consistently meets design standards. In contrast, traditional uniform-dimensional design methods, by ignoring objective differences between points, struggle to adapt to the bearing requirements of different locations, easily leading to substandard bearing capacity and failing to guarantee the bearing safety of the foundation. Traditional uniform-dimensional designs often cannot guarantee that each point meets the required bearing stratum depth, which is prone to problems. Failure to penetrate weak soil layers can lead to potential foundation instability issues. This invention sets a reasonable piling depth threshold based on the actual soil layer distribution of the project, ensuring that the pile tip can stably penetrate the weak soil layer and reach a sufficient depth into the bearing layer. By precisely optimizing the size of precast piles at each location, it can effectively control uneven settlement after foundation construction, ensure the overall uniformity of foundation settlement, and meet the stringent requirements of engineering fields sensitive to settlement deformation. In contrast, traditional uniform size designs can easily lead to excessive differences in settlement at different locations, exceeding the allowable range of the specifications, which may in turn cause problems such as cracking and functional failure of the superstructure. Attached Figure Description

[0052] Figure 1 This is a flowchart of the method for optimizing the combination of dimensions of precast piles for complex terrain foundations according to an embodiment of the present invention;

[0053] Figure 2 This is a flowchart illustrating the process of obtaining marked piling points according to an embodiment of the present invention.

[0054] Figure 3 This is a flowchart illustrating the process of determining the pile spacing level according to an embodiment of the present invention.

[0055] Figure 4 This is a flowchart illustrating the process of determining the bearing capacity level according to an embodiment of the present invention. Detailed Implementation

[0056] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0057] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0058] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0059] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] Please see Figure 1 As shown, it is a flowchart of the method for optimizing the combination of dimensions of precast piles for complex terrain foundations according to an embodiment of the present invention;

[0061] This embodiment provides a method for optimizing the size combination of precast piles for foundations in complex terrain, including:

[0062] Step S1: Collect geomorphic parameters of the valley area, obtain a three-dimensional geomorphic model based on the geomorphic parameters, determine the target piling area based on the three-dimensional geomorphic model, and determine the piling points based on the target piling area;

[0063] Step S2: Based on the soil stratification parameters of the area where the corresponding piling point is located, and combined with the distribution characteristics of the piling points, determine the foundation bearing capacity of each piling point.

[0064] Step S3: Based on the comparison results between the foundation bearing capacity and the preset standard bearing capacity, determine and mark the pile driving points where the bearing capacity does not meet the standard, and obtain the marked pile driving points;

[0065] Step S4: Determine the initial size parameters of the corresponding precast piles based on the pile spacing between marked pile points and the difference in foundation bearing capacity between adjacent pile points; determine the pile spacing level based on the pile spacing and the preset influence spacing; and determine the bearing capacity level based on the absolute value of the difference in bearing capacity between adjacent pile points and the benchmark bearing capacity.

[0066] Step S5: Determine the corresponding precast pile size parameters based on the pile point spacing level and bearing capacity level, and perform simulated pile driving based on the precast pile size parameters to obtain the simulated pile driving depth;

[0067] Step S6: Adjust the precast pile size parameters based on the comparison result between the simulated pile driving depth and the preset pile driving depth threshold.

[0068] The precast pile dimensions include pile diameter and pile length.

[0069] The precast pile dimensions include pile diameter and pile length.

[0070] In this embodiment of the invention, a conventional method for optimizing the dimensions of precast piles in complex terrain foundations is provided. First, the pile length and diameter are preliminarily determined based on the designer's experience. Test piles are then driven at typical locations in complex terrain, such as steep slopes, abrupt soil changes, and backfilled gullies. Single pile bearing capacity and pile integrity data are obtained through static load tests and low-strain tests. If the bearing capacity does not meet design requirements, the pile length is extended or the pile diameter is increased. If pile fractures occur due to stress concentration in complex terrain, the pile spacing is reduced or the pile type is adjusted. The above steps are repeated until the parameters meet the standards. However, this method has a long testing cycle, and the access of testing equipment in complex terrain is difficult (e.g., high cost of hoisting in mountainous areas, and the need to level the site in gullies), further extending the construction period. It also results in significant cost waste, as unqualified test piles must be removed or discarded. Furthermore, each adjustment only targets a single parameter, ignoring the coupling effect of pile length, pile diameter, and pile spacing. The results are also limited, as the testing locations cannot cover all complex geological areas, potentially leading to quality issues in subsequent batch construction.

[0071] Examples of two methods for optimizing the dimensions of precast piles are provided:

[0072] The conventional method involves the following steps: First, preliminary parameter determination and site preparation, which takes 7-9 days. The core challenges in site preparation in river valleys are groundwater treatment and reinforcement of soft soil working surfaces. In floodplain soft soil areas, lightweight wellpoint dewatering is first used to lower the groundwater level to 1.5m below the pile top, followed by laying a 20cm thick layer of crushed stone and steel plates to reinforce the working surface, taking 3 days. In terrace soil abrupt change zones, due to elevation differences, it is necessary to excavate, level, and compact the terraces, taking 2 days. In ancient riverbed backfill areas, shallow compaction treatment is required first. To prevent the equipment from sinking, steel plates were laid as a base, which took 2 days. Meanwhile, the transportation of precast piles required traversing a temporary access road through the river valley floodplain, which needed to be paved with gravel to prevent slippage. The equipment also needed to be disassembled, transported, and assembled on-site, and a temporary drainage ditch needed to be built to prevent rainwater backflow, which took 2 days. This entire process took a total of 7-9 days. One test pile was driven at each of the three typical locations. During the test pile construction, parameter adjustments were made, but since only one parameter could be adjusted at a time, the time for optimizing the size of the precast piles was greatly extended.

[0073] Compared to conventional methods, the method for optimizing the size combination of precast piles in complex terrain foundations in this invention first obtains comprehensive data through detailed geological surveys: two exploration boreholes are set up in each of the three typical areas of the site, and the mechanical parameters of soft soil, silty clay, and backfill soil in each soil layer are accurately obtained by combining static cone penetration tests and sampling tests. At the same time, the groundwater level and permeability coefficient at different depths are measured. A three-dimensional geological-groundwater coupled model is constructed using geotechnical engineering numerical simulation software such as MidasGTS, and the constitutive equation of soft soil creep is embedded to accurately simulate groundwater seepage in river valley areas. The process of determining the flow and deformation characteristics of soft soil, as well as the soil layer distribution boundaries in different regions, takes 3-4 days. This invention abandons the traditional single-parameter adjustment mode and uses pile length, pile diameter, and pile spacing as coupling variables. Multiple reasonable parameter combinations are set to cover different variable ranges, and the pre-constructed three-dimensional model is input. The single pile bearing capacity, pile stress distribution, and foundation settlement under different parameter combinations are simulated, while also considering the influence of groundwater seepage in the valley on pile-soil interaction. Through multi-objective optimization, three optimal candidate schemes are selected, which takes a total of 4-5 days, replacing the ineffective time spent on multiple rounds of iterative adjustment in conventional methods.

[0074] In implementation, the target piling area and points are accurately located using a 3D topographic model. Soil stratification parameters are combined to determine the foundation bearing capacity and mark substandard points. This avoids the construction risks caused by inaccurate terrain surveys and blind point selection in traditional methods, improving the rationality and safety of pile layout. The initial dimensions of precast piles are determined based on pile spacing and bearing capacity levels, ensuring precise matching between precast pile dimensions and terrain conditions and bearing capacity requirements. This avoids material waste or insufficient bearing capacity issues caused by uniform precast pile dimensions. Simulated piling allows for dynamic adjustment of precast pile dimensions, eliminating the need for repeated on-site testing, effectively reducing construction adjustment costs and shortening the construction period. This method forms a complete technical closed loop from terrain survey and point determination to size optimization, significantly improving the adaptability and reliability of precast pile construction in complex terrains, ensuring foundation engineering quality, and simplifying the optimization process. It possesses strong engineering practicality and promotional value.

[0075] Specifically, the process of obtaining the three-dimensional landform model includes:

[0076] The surface parameters of the target piling area are obtained by scanning and surveying the target piling area using a drone, and a three-dimensional landform model is determined based on the surface parameters and the surveyed underground parameters.

[0077] The geomorphic parameters include surface parameters and underground parameters.

[0078] In this embodiment of the invention, for the target piling area with complex valley-type terrain, a multi-rotor UAV equipped with a lidar sensor is selected for scanning and surveying. The flight altitude is set to 50m above the ground surface, and the scanning resolution is set to 0.1m. The UAV flies along a grid-like flight path of the target piling area to complete a full-coverage scan, acquiring surface parameters including surface elevation, slope, aspect, and surface undulation. Subsequently, a borehole survey is used to conduct underground surveys of the target piling area. The borehole spacing is 15m, and the borehole depth extends to 3m below the stable bearing layer. Through borehole sampling and analysis, underground parameters such as the burial depth, thickness, soil type (silty clay, gravel, sand, etc.), and density of each soil layer are obtained. The surface parameters are then compared with the underground parameters. Data is imported into 3D geological modeling software such as Surfer. Through data registration, coordinate unification, interpolation calculation, and 3D reconstruction, a complete 3D geomorphological model is generated, including the slope of the river valley banks, the distribution of low-lying areas at the bottom of the valley, and the undulation characteristics of the interfaces of various underground soil layers. After modeling, the accuracy of the model is verified. Five evenly distributed verification points are selected, and the surface elevation and underground soil depth data of the verification points are obtained through field measurements. The data are compared with the corresponding data in the model, and the error is controlled within ±0.2m. This ensures that the model can accurately reflect the topography and underground geological conditions of the target piling area, providing reliable 3D data support for the subsequent delineation of the target piling area and the determination of piling points.

[0079] In practice, the combination of UAV scanning and borehole surveying breaks through the limitations of traditional single survey methods. UAV grid scanning can achieve full coverage survey of the target area, accurately capturing topographic features such as surface undulation, slope, and aspect, effectively avoiding blind spots in complex terrains such as river valley slopes and low-lying areas. Borehole surveying can obtain complete layer information of underground soil layers, clarify the distribution characteristics of each soil layer, and make up for the insufficiency of UAVs that can only detect the surface. By integrating surface and underground parameters into a model, the generated 3D geomorphological model can simultaneously present surface topography and underground geological structure, realizing the integrated expression of topographic and geological data and breaking the traditional situation of separating surface and underground data. The accuracy verification process after modeling further ensures the accuracy and reliability of the model data, which can accurately reflect the actual situation of complex terrain in the river valley.

[0080] Specifically, the process of determining the target piling area includes:

[0081] Several initial piling areas are determined based on the three-dimensional surface model in the terrain model and the target building area, and the target piling area is determined based on the three-dimensional model of the target building and the initial piling areas.

[0082] Specifically, the process of determining the piling points includes:

[0083] The target piling area is divided into several partitioned target piling areas. The target building 3D model is moved to the partitioned target piling area, and the frame support points in the target building 3D model that coincide with the partitioned target piling area are selected to obtain the piling points.

[0084] In this embodiment of the invention, UAV oblique photography technology is used in combination with total station ground mapping to collect geomorphic data of the proposed factory area, construct a three-dimensional geomorphic model including surface undulations and the distribution of shallow underground obstacles, and extract a three-dimensional surface model reflecting the changes in surface elevation.

[0085] Based on the industrial plant design plan, a rectangular area of ​​120m×80m was determined as the target building area. The building foundation design is a raft foundation. The surface slope of the piling area is required to be no more than 5° and to be far away from areas with dense underground pipelines. The range parameters of the target building area were input into the three-dimensional topographic model and analyzed. Based on the elevation data of the three-dimensional topographic model, three areas that meet the slope requirements and have no obvious underground obstacles were selected as the initial piling areas, which were marked as Area A, Area B, and Area C, respectively.

[0086] Import a 1:1 scale 3D model of the target building. The target building's 3D model includes the spatial location information of the building's column grid and load-bearing walls. Spatial fitting is performed between the target building's 3D model and three initial piling areas, A, B, and C. The fitting results show that: area A has a 92% overlap with the building's column grid and no underground pipeline interference; area B has only a 75% overlap, with some areas extending beyond the building foundation; area C has an 85% overlap, but some areas have dense underground pipelines.

[0087] Considering both the degree of overlap and the feasibility of construction, area A was selected as the target piling area.

[0088] The identified target piling area A is divided into zones based on the column grid spacing of the target building's 3D model, which is 8m×8m. Zone A is divided into 15 16m×16m target piling zones, numbered A1-A15. The target building's 3D model is moved to the corresponding target piling zone according to the preset coordinate reference, ensuring that the planar coordinates of the building's 3D model are consistent with the zone coordinate system.

[0089] Extract the frame support points from the 3D model of the target building. The frame support points are the stress support points under the building columns and are the core points for pile foundation construction.

[0090] The spatial positions of the frame support points and the target piling areas of each zone were compared one by one. Points whose spatial coordinates completely coincided were selected as the final piling points. After screening, a total of 120 piling points that met the requirements were determined and evenly distributed in zones A1-A15 to meet the stress requirements of the building structure.

[0091] In implementation, by delineating the target piling area in stages and accurately determining the piling points, a scientific and efficient planning scheme for pile foundation construction in complex terrain was provided, demonstrating significant technical advantages. The initial piling area was selected by extracting a 3D surface model from a high-precision 3D topographic model, combined with the target building area and construction conditions. This avoided problems such as inconsistent surface slopes and interference from underground obstacles from the outset, ensuring the feasibility of construction in the initial area. Spatial fitting between the target building's 3D model and the initial area allowed for precise matching of the building foundation layout requirements. The selection of the target area, combined with overlap and construction influencing factors, significantly improved the rationality and adaptability of the area delineation. In the piling point determination stage, the target area was divided into zones according to the building's column grid spacing, ensuring that the zones matched the building's structural layout. By moving the 3D building model and comparing the spatial coordinates of the frame support points with those of the zones, precise correspondence between the piling points and the building's core load-bearing locations was achieved, avoiding the blindness of traditional point determination and preventing selection errors during the piling point selection process.

[0092] Specifically, the process of determining the foundation bearing capacity at each piling point includes:

[0093] The initial bearing capacity of a single point is determined based on the number of soil layers, and the foundation bearing capacity of each pile point is determined based on the soil structure and the initial bearing capacity of the single point.

[0094] The soil stratification parameters include the number of soil stratification layers and the soil structure of each soil layer.

[0095] Drilling and sampling tests were conducted at 120 piling points in Area A. A geological drilling rig was used to drill at each piling point to a depth of 3m below the bearing layer at the pile tip. Soil stratification parameters at each point were recorded, including the number of soil layers and the soil structure of each layer.

[0096] Taking piling point A3-08 as an example, the drilling results show that the soil at piling point A3-08 is divided into 4 layers, and the layer parameters are as follows:

[0097] Layer 1: Miscellaneous fill, 1.5m thick, loose soil structure, containing a large amount of construction waste debris;

[0098] The second layer is silty clay, 6.2m thick, with a dense soil structure and high clay content.

[0099] The third layer is silty sand, 4.8m thick, with a medium-dense soil structure and well-matched particles.

[0100] The fourth layer consists of gravel, with a thickness of ≥7.5m. The soil structure is dense, and the gravel content exceeds 60%. This layer is the bearing layer for pile tip design.

[0101] Based on the reference range of bearing capacity characteristic values ​​of different soil layers in the building foundation design code, and combined with the number of soil layers and the corresponding soil layer thickness at each pile driving point, the weighted average method is used to calculate the initial bearing capacity of a single point.

[0102] Taking point A3-08 as an example, the characteristic values ​​of the bearing capacity of each soil layer are as follows: miscellaneous fill fak1=60kPa, silty clay fak2=180kPa, silty sand fak2=220kPa, and gravel fak2=500kPa;

[0103] The formula for calculating the initial bearing capacity at a single point is: (h1×fak1+h2×fak2+h3×fak2+h4×fak2) / (h1+h2+h3+h4)=(1.5×60+6.2×180+4.8×220+7.5×500) / (1.5+6.2+4.8+7.5)=187.5kPa.

[0104] During implementation, targeted borehole sampling and testing can accurately obtain soil stratification parameters for each piling point, including the number of layers and the soil structure of each layer. This breaks through the limitations of traditional regional and general surveys, achieving precise matching of bearing capacity calculation points. Combined with building codes, the weighted average method is used to calculate the initial bearing capacity of a single point, which can fully take into account the differences in bearing capacity of different soil layers. Compared with the single soil layer determination method, this significantly improves the scientificity and rationality of the initial bearing capacity calculation. At the same time, the initial bearing capacity is corrected based on the soil structure, further considering the influence of soil density, particle composition and other detailed characteristics on the bearing capacity. This makes the final foundation bearing capacity more consistent with the actual geological conditions, avoiding problems such as improper pile selection and structural safety hazards caused by bearing capacity calculation deviations from the source, and ensuring the stability and safety of the foundation project.

[0105] Please see Figure 2 The diagram shown is a flowchart illustrating the process of obtaining marked piling points according to an embodiment of the present invention.

[0106] Specifically, the process of obtaining the marked piling points includes:

[0107] Based on the fact that the foundation bearing capacity is less than the preset standard bearing capacity, the bearing capacity of the corresponding pile driving point is determined to be substandard and marked to obtain the marked pile driving point;

[0108] Based on the foundation bearing capacity being greater than or equal to the preset standard bearing capacity, it is determined that the bearing capacity of the corresponding piling point meets the standard.

[0109] In this embodiment, the preset standard bearing capacity is set to 300 kPa, which is determined based on the bearing capacity requirements of the factory building's pile foundation.

[0110] The final foundation bearing capacity calculation results of 120 piling points in Area A were extracted, and the numerical examples of 4 typical points are as follows:

[0111] Point A3-08: The initial bearing capacity of the single point is calculated to be 187.5 kPa using the weighted average method. Since there are no additional reinforcement or reduction factors in the soil structure at point A3-08, the final foundation bearing capacity is 187.5 kPa.

[0112] Point A2-15: The soil is divided into 3 layers, and the final bearing capacity of the foundation is calculated to be 170.7 kPa after weighted average calculation;

[0113] Point A5-03: The soil is divided into 4 layers, and the final bearing capacity of the foundation is calculated to be 309.9 kPa after weighted average calculation;

[0114] Point A8-10: The soil is divided into 4 layers, and the final bearing capacity of the foundation is calculated to be 302.5 kPa after weighted average calculation;

[0115] Bearing capacity compliance determination and marking;

[0116] The bearing capacity of the foundation at each location was compared with the preset standard bearing capacity one by one;

[0117] Point A3-08: Determined to have insufficient bearing capacity, marked as a piling point;

[0118] Point A2-15: Determined to have insufficient bearing capacity, marked as a piling point;

[0119] Point A5-03 was determined to meet the bearing capacity standard;

[0120] Point A8-10 was determined to meet the bearing capacity standard.

[0121] In implementation, the pre-set standard bearing capacity determined by the actual needs of the project is used as the judgment benchmark. This ensures that the judgment criteria for whether the bearing capacity meets the standard are consistent with the stress requirements of the building structure, avoiding judgment deviations caused by blindly setting standards. By comparing the measured foundation bearing capacity of each piling point with the pre-set standard bearing capacity one by one, a comprehensive screening of all piling points is achieved. This ensures that no safety hazards of substandard bearing capacity are missed, and that compliant and non-compliant points are accurately distinguished, guaranteeing the comprehensiveness and accuracy of the judgment results. The precise marking of non-compliant points enables the pre-identification and targeted positioning of construction risks, reducing unnecessary construction cost waste. Furthermore, it avoids safety hazards such as foundation settlement and structural instability caused by unidentified piling points with insufficient bearing capacity from the source, further ensuring the reliability and safety of the overall foundation project.

[0122] Please see Figure 3 The diagram shown is a flowchart illustrating the process of determining the pile spacing level according to an embodiment of the present invention.

[0123] Specifically, the process of determining the pile spacing level includes:

[0124] The actual number of influence spacings is determined based on the comparison between the pile spacing and the preset influence spacing. The influence level of the pile spacing on the initial size parameters is determined based on the comparison between the actual number and the number threshold range. The initial size parameters of the precast piles are then determined.

[0125] Based on the fact that the actual quantity is less than the minimum value of the quantity threshold range, the spacing influence level is determined to be the primary spacing influence level.

[0126] Based on the fact that the actual quantity is within the quantity threshold range, the spacing influence level is determined to be the medium spacing influence level.

[0127] Based on the fact that the actual quantity is greater than the maximum value of the quantity threshold range, the spacing influence level is determined to be a high-level spacing influence level.

[0128] The preset influence spacing is the shortest spacing between marked piling points that affects the bearing capacity of the foundation.

[0129] In this embodiment, the preset influence spacing is set to 2.5m, which is determined based on test data of geological layers containing silty clay and silty sand. That is, when the spacing between marked pile points is ≤2.5m, they will interfere with each other's bearing capacity; the quantity threshold range is set to [2, 4].

[0130] Three typical marked piling points were selected in area A. The distance between them and other marked piling points in the surrounding area was measured. The number of marked piling points ≤2.5m was counted, which is the actual number.

[0131] Point A3-08: The surrounding marked points are A3-07, A3-09, and A2-08;

[0132] Spacing measurements: The spacing between A3-08 and A3-07 is 2.2m, the spacing between A3-09 is 2.3m, and the spacing between A3-08 and A2-08 is 3.0m;

[0133] The actual quantity is 2;

[0134] Point A6-02: The surrounding marked points are A6-01, A6-03, A5-02, A7-02, and A6-04. Among them, the distance between the first four points is ≤2.2m, and only the distance between points A6-04 is 2.6m.

[0135] The actual quantity is 4;

[0136] Point A8-05: Surrounding marked points are A8-04, A8-06, A7-05, A9-05, A8-03, and A8-07;

[0137] Spacing measurement: The spacing between all points is ≤2.4m;

[0138] The actual quantity is 6;

[0139] The actual quantity of point A3-08 is 2, which falls within the quantity threshold range and corresponds to a medium spacing influence level.

[0140] The actual quantity of point A6-02 is 4, which falls within the quantity threshold range and corresponds to a medium spacing influence level.

[0141] The actual quantity of point A8-05 is 6, which is greater than the maximum value of the quantity threshold range. The spacing influence level corresponding to this is the high-level spacing influence level.

[0142] In this embodiment of the invention, the initial size parameters of the pile foundation, namely pile diameter and pile length, are set to a base value of 600mm and 20m respectively, and are adjusted in conjunction with the influence level of spacing.

[0143] For intermediate spacing levels such as A3-08 and A6-02, the pile diameter is adjusted to 650mm and the pile length is adjusted to 21m to enhance bearing capacity and anti-interference.

[0144] For advanced spacing impact levels such as A8-05, the pile diameter is adjusted to 700mm and the pile length is adjusted to 22m to improve bearing capacity redundancy.

[0145] In implementation, a preset influence spacing was set based on geological test data, and a quantity threshold range was defined in conjunction with engineering safety requirements. This ensured that the benchmark for judging the influence of spacing was consistent with the actual geological conditions, avoiding judgment deviations caused by subjectively set standards from the outset. By measuring the actual spacing between marked pile driving points and counting the number of points that met the influence spacing, a quantitative assessment of the degree of spacing interference was achieved. Then, based on the quantity threshold range, three levels of influence were divided, which could accurately distinguish the intensity of spacing interference at different points, breaking the limitations of the rough judgment of spacing influence in traditional construction. The initial size parameters were adjusted in a targeted manner based on different spacing influence levels. The higher the spacing influence level, the higher the degree of interference and the greater the reinforcement. This enabled the adjustment of the corresponding initial size parameters of the pile foundation for different spacing levels, ensuring the bearing capacity, anti-interference ability, and redundancy of the pile foundation in high-interference areas, while avoiding the waste of materials caused by excessive reinforcement in low-interference areas, thus achieving a rational allocation of resources.

[0146] Please see Figure 4 The diagram shown is a flowchart illustrating the process of determining the bearing capacity level according to an embodiment of the present invention.

[0147] Specifically, the process of determining the bearing capacity level includes:

[0148] Based on the fact that the absolute value of the bearing capacity difference between adjacent points is less than the minimum value of the bearing capacity difference threshold range, the bearing capacity level is determined to be the primary bearing capacity level.

[0149] Based on the fact that the absolute value of the bearing capacity difference between adjacent points is within the bearing capacity difference threshold range, the bearing capacity level is determined to be the intermediate bearing capacity level.

[0150] Based on the fact that the absolute value of the bearing capacity difference between adjacent points is greater than the maximum value of the bearing capacity difference threshold range, the bearing capacity level is determined to be a high bearing capacity level.

[0151] In this embodiment, the bearing capacity difference threshold range is set to [20, 50] kPa, where the bearing capacity difference threshold range is used to measure the degree of bearing capacity difference between adjacent piling points;

[0152] Three typical adjacent marked piling points in Area A were selected, and the final foundation bearing capacity calculation results were extracted. The specific data are as follows:

[0153] Group 1: Bearing capacity of point A3-07 is 192.3 kPa and bearing capacity of point A3-08 is 187.5 kPa;

[0154] Group 2: Point A2-14 bearing capacity 245.8 kPa and point A2-15 bearing capacity 170.7 kPa;

[0155] Group 3: Bearing capacity of point A5-02 is 278.1 kPa and bearing capacity of point A5-03 is 309.9 kPa;

[0156] The absolute value of the difference in bearing capacity between adjacent points in each group is calculated;

[0157] Group 1: |192.3−187.5|=4.8 kPa;

[0158] Group 2: |245.8−170.7|=75.1 kPa;

[0159] Group 3: |278.1−309.9|=31.8 kPa;

[0160] If the value of Group 1 is less than the minimum value of the bearing capacity difference threshold range, the bearing capacity level is determined to be the primary bearing capacity level.

[0161] The second group is greater than the maximum value of the bearing capacity difference threshold range, and the bearing capacity level is determined to be a high bearing capacity level.

[0162] Group 3 is within the bearing capacity difference threshold range, and its bearing capacity level is determined to be intermediate bearing capacity level.

[0163] In implementation, a threshold range for bearing capacity difference was set according to the actual needs of the project. This range served as a benchmark for determining the degree of bearing capacity difference between adjacent points, ensuring that the classification standard aligned with the project's geological and structural stress requirements and avoiding the subjective bias of traditional experience-based judgments. By calculating the absolute value of the bearing capacity difference between adjacent marked piling points and comparing it with the threshold range, the bearing capacity level was divided into three levels. When the absolute value of the bearing capacity difference between adjacent points was less than the minimum value of the threshold range, the bearing capacity level was determined to be the primary bearing capacity level. The bearing capacity of the site is sufficient to meet the bearing capacity requirements during piling, thus avoiding uneven settlement of the foundation caused by differences in bearing capacity between adjacent points. When the absolute value of the bearing capacity difference between adjacent points is within the bearing capacity difference threshold range, the bearing capacity level is determined to be medium bearing capacity level. In this case, the difference between adjacent points is relatively large, and the bearing capacity of the precast piles will differ due to the difference in bearing capacity between the two points during piling. Based on the different bearing capacity levels, the size parameters of the precast piles corresponding to this piling point will be adjusted to compensate for the changes in bearing capacity values ​​caused by differences in the underlying soil.

[0164] Specifically, the process of determining the corresponding precast pile size parameters includes:

[0165] The first precast pile size parameter is determined based on the current pile spacing level and its corresponding spacing level influence compensation parameter. The second precast pile size parameter is determined based on the current bearing capacity level and its corresponding bearing capacity level influence compensation parameter. The precast pile size parameter is determined based on the first precast pile size parameter and the second precast pile size parameter.

[0166] Specifically, the process of adjusting the precast pile size parameters includes:

[0167] Since the simulated pile driving depth is less than the preset pile driving depth threshold, the pile length is increased according to the difference between the preset pile driving depth threshold and the simulated pile driving depth. Since the increased pile length still does not meet the preset pile driving depth threshold, the precast pile size parameters are determined by shortening the pile diameter.

[0168] Based on the simulated pile driving depth being greater than or equal to the preset pile driving depth threshold, it is determined to maintain the current precast pile size parameters.

[0169] The preset piling depth is determined based on the soil conditions corresponding to each soil layer.

[0170] In this embodiment of the invention, the reference dimensions of the precast pile are set as a reference pile diameter of 500mm and a reference pile length of 18m, which are determined based on historical data of the precast piles during construction; the compensation parameters for the impact of spacing level are the pile diameter compensation parameters and pile length compensation parameters corresponding to the pile spacing level.

[0171] Simultaneously, based on the project's geological conditions and construction specifications, impact compensation parameters corresponding to the pile spacing level and bearing capacity level were formulated. Among them, the compensation logic for the pile spacing level is that when the pile spacing is smaller and the level is higher, the shielding effect of the pile group is stronger and the reduction coefficient of pile side friction is greater. When the pile spacing level is upgraded from primary to intermediate, the pile diameter needs to be increased by 50mm and the pile length by 1m to offset the bearing capacity loss caused by the reduction of friction. When upgraded to advanced, the pile diameter needs to be increased by 100mm and the pile length by 2m to meet the design value of single pile bearing capacity.

[0172] The bearing capacity level compensation logic is that the bearing capacity level directly corresponds to the target value of the vertical ultimate bearing capacity of a single pile. The ultimate bearing capacity of the benchmark pile in the target piling area is Quk. The target value corresponding to the intermediate bearing capacity level is 1.2Quk, and the target value corresponding to the high bearing capacity level is 1.5Quk. Through the positive correlation between pile diameter, pile length and bearing capacity, increasing the pile diameter can increase the pile side friction, and increasing the pile length can increase the contact depth of the bearing layer at the pile tip, so as to obtain the required increase in pile diameter and pile length.

[0173] The specific details are shown in Table 1;

[0174] Table 1:

[0175] ;

[0176] Retrieve the grade determination results of the three points mentioned above;

[0177] Point A3-08, intermediate pile spacing grade, primary bearing capacity grade;

[0178] Point A6-02, intermediate pile spacing grade, intermediate bearing capacity grade;

[0179] Point A8-05, high-grade pile spacing level, high-grade bearing capacity level;

[0180] The first precast pile dimension parameters are based on the pile point spacing level and compensation parameters;

[0181] A3-08, pile diameter = 500 + 50 = 550 mm, pile length = 18 + 1 = 19 m;

[0182] A6-02: Pile diameter = 500 + 50 = 550 mm, Pile length = 18 + 1 = 19 m;

[0183] A8-05: Pile diameter = 500 + 100 = 600 mm, Pile length = 18 + 2 = 20 m;

[0184] The second set of precast pile dimensions is based on the bearing capacity grade and compensation parameters;

[0185] A3-08: Pile diameter = 500 + 0 = 500 mm, Pile length = 18 + 0 = 18 m;

[0186] A6-02: Pile diameter = 500 + 50 = 550 mm, Pile length = 18 + 1 = 19 m;

[0187] A8-05: Pile diameter = 500 + 100 = 600 mm, Pile length = 18 + 2 = 20 m;

[0188] The maximum value of the first precast pile size parameter and the second precast pile size parameter is taken as the final initial parameter to ensure that the spacing and bearing capacity compensation requirements are met simultaneously.

[0189] A3-08: Pile diameter 550mm, pile length 19m;

[0190] A6-02: Pile diameter 550mm, pile length 19m;

[0191] A8-05: Pile diameter 600mm, pile length = 20m;

[0192] In this embodiment of the invention, based on the soil stratification of each piling point in Area A, the gravel layer is taken as the bearing layer of the pile tip. The piling depth is set to penetrate the soft soil layer and enter the gravel layer by no less than 3m. The preset piling depth threshold is set to 20m.

[0193] Using pile foundation construction simulation software such as Lizheng Pile Foundation Software, the initial size parameters and geological data of each point are input to obtain the simulated pile driving depth. Among them, Lizheng Pile Foundation Software provides foundation analysis functions such as single pile bearing capacity calculation and pile end resistance and side resistance calculation during the exploration stage. The calculation results can be directly stored in the database to provide data support for subsequent design.

[0194] The simulation process of the Lizheng pile foundation software is explained as follows:

[0195] For each piling point, input two sets of parameters:

[0196] Pile parameters: initial precast pile size such as 550mm×19m for A3-08, pile material type such as prestressed concrete precast pile, pile tip type such as closed pile tip;

[0197] Construction process parameters: The static pressure pile driving process is adopted. The pile driving force limit is input and matched with the actual construction equipment capacity of the project to obtain the parameters.

[0198] The software has a built-in module for calculating the penetration depth of static pressure piles, allowing you to select a model that matches the actual engineering situation.

[0199] For soft soil layers such as silty clay, the cohesive soil pile driving resistance model is adopted;

[0200] For gravel layers and other crushed stone soil layers, a corrected model for pile driving resistance of crushed stone soil is adopted to consider the influence of soil density on pile end resistance.

[0201] The software simulates the process of the pile sinking segment by segment through iterative calculations, and finally outputs the depth reached by the pile tip, which is the simulated pile driving depth.

[0202] Point A3-08 has an initial size of 550mm×19m. Its pile side friction is relatively large. With a pile diameter of 550mm and a larger perimeter, the total pile driving resistance is relatively high. The pile driving force cannot push the pile into the gravel layer to a sufficient depth. The simulated pile driving depth is only 19m.

[0203] After extending the pile length to 20m, a second simulation was conducted. With the increased pile length, the total skin friction on the pile side further increased, and the simulated pile driving depth only increased to 19.8m.

[0204] After reducing the diameter to 500mm, three simulations were conducted. The reduction in pile diameter resulted in a decrease in the pile circumference, which reduced the total frictional resistance of the pile side during the simulated pile driving process. The pile driving force could then push the pile body to continue sinking, and the simulated pile driving depth reached 20.2m, meeting the threshold requirement.

[0205] Compare the simulated piling depth with the preset piling depth threshold of 20m to determine whether the pile size needs to be adjusted.

[0206] If the simulated pile driving depth is less than 20m, the parameters need to be adjusted according to the rule of increasing the pile length to shortening the pile diameter, and the simulation needs to be repeated.

[0207] If the simulation depth is ≥20m, maintain the current pile size;

[0208] A3-08: Initial dimensions 550mm×19m, simulated piling depth 19m, not reaching the 3m requirement of the gravel layer;

[0209] A6-02: Initial dimensions 550mm × 19m, simulated piling depth 19.5m;

[0210] A8-05: Initial dimensions 600mm × 20m, simulated piling depth 20.5m;

[0211] Point A3-08: Simulated piling depth of 19m is less than the preset piling depth threshold;

[0212] The first step is to increase the pile length to 19+1=20m. Then, simulate pile driving again, with a depth of 19.8m, which is still less than 20m.

[0213] The second step is to shorten the pile diameter from 550mm to 500mm to reduce the friction between the pile and the soil, simulating a pile driving depth of 20.2m.

[0214] Final dimensions: 500mm × 20m;

[0215] Point A6-02: Simulated piling depth of 19.5m is less than the preset piling depth threshold;

[0216] The pile length was extended to 19 + 0.5 = 19.5m, and the simulated pile driving depth reached 20.1m, which is greater than or equal to the preset pile driving depth threshold.

[0217] Final dimensions: 550mm × 19.5m;

[0218] Point A8-05: The simulated depth of 20.5m is greater than or equal to the preset piling depth threshold, so the current initial size parameters of 600mm×20m are maintained.

[0219] In implementation, the system innovatively combines the dual influences of pile spacing grade and bearing capacity grade, setting corresponding compensation parameters to calculate the size parameters of two types of precast piles. The initial parameters are determined by taking the maximum value, ensuring that the parameters simultaneously meet the dual requirements of spacing interference resistance and bearing capacity adaptation. This breaks the limitations of traditional single-dimensional parameter design, significantly improving the rationality and reliability of the initial parameters. There is a positive correlation between the pile diameter compensation parameters and the pile length compensation parameters and the pile spacing grade and bearing capacity grade; the higher the grade, the larger the corresponding pile diameter and pile length compensation parameter values. The classification of pile spacing grades is based on the pile density; the smaller the spacing, the higher the grade. The more significant the pile group effect, the greater the reduction in pile side friction, thus requiring larger compensation parameters to enhance pile bearing capacity. The bearing capacity level is determined by the design target value of the bearing capacity at the pile driving point; the higher the level, the higher the level. A higher level means a higher vertical ultimate bearing capacity of a single pile, thus requiring larger compensation parameters to enhance pile side friction and pile end resistance. In the parameter adjustment stage, simulated pile driving tests are conducted using pile foundation construction simulation software. Using a preset pile driving depth threshold as the judgment standard, a progressive adjustment strategy of first increasing the pile length and then shortening the pile diameter is adopted. This ensures that the pile end can effectively reach the design bearing layer while avoiding material waste through refined adjustments.

[0220] The obtained precast pile size parameters were tested to obtain actual data in the actual construction process, as shown in Table 2.

[0221] Table 2:

[0222] ;

[0223] Settlement was measured at each piling point after piling. 30 days after construction, the maximum settlement difference at the three piling points was 3mm, which meets the construction requirement of settlement difference ≤5mm. Compared with the scheme of blindly extending the pile length to 22m, steel consumption was saved by about 8%.

[0224] Using the traditional uniform size design method, without considering the differences in pile spacing and bearing capacity level, all points adopted the benchmark pile size of 500mm×18m. The test results after construction are shown in Table 3.

[0225] Table 3:

[0226] ;

[0227] The above-mentioned foundation settlement differential tests, conducted according to traditional design dimensions, showed values ​​of 12mm, 15mm, and 18mm, respectively.

[0228] Regarding the bearing capacity compliance rate, the bearing capacity of all three points in the example group in Table 2 met the standard, while all points in the comparative example group in Table 3 did not meet the standard.

[0229] Regarding the penetration depth into the bearing layer, the example groups in Table 2 all meet the requirement of ≥3m, while the maximum penetration depth of the comparative example group in Table 3 is only 1.2m.

[0230] Regarding the uniformity of the foundation, the settlement difference in the example group in Table 2 was only 3 mm, while the maximum settlement difference in the comparative group in Table 3 reached 18 mm, far exceeding the standard limit.

[0231] In implementation, to address the differences in pile spacing and bearing capacity levels at different piling locations, a dual-dimensional level influence compensation parameter is used. Combined with pile depth simulation verification and iterative dimensional adjustments, the bearing capacity requirements of each point can be accurately matched, ensuring that the vertical bearing capacity of a single pile consistently meets design standards. In contrast, traditional uniform-dimensional design methods, by ignoring the objective differences between points, struggle to adapt to the bearing capacity requirements of different points, easily leading to substandard bearing capacity and failing to guarantee the bearing safety of the foundation. Traditional uniform-dimensional designs often cannot guarantee that each point meets the required depth of penetration into the bearing stratum, easily resulting in failure to penetrate the stratum. The penetration of soft soil layers can lead to potential foundation instability issues. This invention sets a reasonable piling depth threshold based on the actual soil layer distribution of the project, ensuring that the pile tip can stably penetrate the soft soil layer and reach a sufficient depth into the bearing layer. By precisely optimizing the size of precast piles at each location, it can effectively control uneven settlement after foundation construction, ensure the overall uniformity of foundation settlement, and meet the stringent requirements of engineering fields sensitive to settlement deformation. In contrast, traditional uniform size design can easily lead to excessive differences in settlement at different locations, exceeding the allowable range of the specifications, which may in turn cause problems such as cracking and functional failure of the superstructure.

[0232] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0233] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for optimizing the size combination of precast piles for foundations in complex terrain, characterized in that, include: Collect geomorphic parameters of the river valley area, obtain a three-dimensional geomorphic model based on the geomorphic parameters, determine the target piling area based on the three-dimensional geomorphic model, and determine the piling points based on the target piling area; Based on the soil stratification parameters of the area where the corresponding piling points are located, and combined with the distribution characteristics of the piling points, the foundation bearing capacity of each piling point is determined. Based on the comparison between the foundation bearing capacity and the preset standard bearing capacity, the pile driving points with substandard bearing capacity are identified and marked, thus obtaining the marked pile driving points; The initial size parameters of the corresponding precast piles are determined based on the pile spacing between marked pile points and the difference in foundation bearing capacity between adjacent pile points. The pile spacing level is determined based on the pile spacing and the preset influence spacing. The bearing capacity level is determined based on the absolute value of the difference in bearing capacity between adjacent pile points and the benchmark bearing capacity. Based on the pile spacing level and bearing capacity level, the corresponding precast pile size parameters are determined, and the simulated pile driving is performed based on the precast pile size parameters to obtain the simulated pile driving depth. The precast pile size parameters are adjusted based on the comparison results between the simulated pile driving depth and the preset pile driving depth threshold. The precast pile dimensions include pile diameter and pile length.

2. The method for optimizing the size combination of precast piles for complex terrain foundations according to claim 1, characterized in that, The process of obtaining the three-dimensional model of the terrain includes: The surface parameters of the target piling area are obtained by scanning and surveying the target piling area using a drone, and a three-dimensional landform model is determined based on the surface parameters and the surveyed underground parameters. The geomorphic parameters include the surface parameters and the underground parameters.

3. The method for optimizing the size combination of precast piles for complex terrain foundations according to claim 2, characterized in that, The process of determining the target piling area includes: Several initial piling areas are determined based on the three-dimensional surface model in the terrain model and the target building area, and the target piling area is determined based on the three-dimensional model of the target building and the initial piling areas.

4. The method for optimizing the size combination of precast piles for complex terrain foundations according to claim 3, characterized in that, The process of determining the piling points includes: The target piling area is divided into several partitioned target piling areas. The target building 3D model is moved to the partitioned target piling area, and the frame support points in the target building 3D model that coincide with the partitioned target piling area are selected to obtain the piling points.

5. The method for optimizing the size combination of precast piles for complex terrain foundations according to claim 4, characterized in that, The process of determining the foundation bearing capacity at each piling point includes: The initial bearing capacity of a single point is determined based on the number of soil layers, and the foundation bearing capacity of each pile point is determined based on the soil structure and the initial bearing capacity of the single point. The soil stratification parameters include the number of soil stratification layers and the soil structure of each soil layer.

6. The method for optimizing the size combination of precast piles for complex terrain foundations according to claim 5, characterized in that, The process of obtaining the marked piling points includes: Based on the fact that the foundation bearing capacity is less than the preset standard bearing capacity, the bearing capacity of the corresponding pile driving point is determined to be substandard and marked to obtain the marked pile driving point; Based on the foundation bearing capacity being greater than or equal to the preset standard bearing capacity, it is determined that the bearing capacity of the corresponding piling point meets the standard.

7. The method for optimizing the size combination of precast piles for complex terrain foundations according to claim 6, characterized in that, The process of determining the pile spacing level includes: The actual number of influence spacings is determined based on the comparison between the pile spacing and the preset influence spacing. The influence level of the pile spacing on the initial size parameters is determined based on the comparison between the actual number and the number threshold range. The initial size parameters of the precast piles are then determined. Based on the fact that the actual quantity is less than the minimum value of the quantity threshold range, the spacing influence level is determined to be the primary spacing influence level. Based on the fact that the actual quantity is within the quantity threshold range, the spacing influence level is determined to be the medium spacing influence level. Based on the fact that the actual quantity is greater than the maximum value of the quantity threshold range, the spacing influence level is determined to be a high-level spacing influence level. The preset influence spacing is the shortest spacing between marked piling points that affects the bearing capacity of the foundation.

8. The method for optimizing the size combination of precast piles for complex terrain foundations according to claim 7, characterized in that, The process of determining the bearing capacity level includes: Based on the fact that the absolute value of the bearing capacity difference between adjacent points is less than the minimum value of the bearing capacity difference threshold range, the bearing capacity level is determined to be the primary bearing capacity level. Based on the fact that the absolute value of the bearing capacity difference between adjacent points is within the bearing capacity difference threshold range, the bearing capacity level is determined to be the intermediate bearing capacity level. Based on the fact that the absolute value of the bearing capacity difference between adjacent points is greater than the maximum value of the bearing capacity difference threshold range, the bearing capacity level is determined to be a high bearing capacity level.

9. The method for optimizing the size combination of precast piles for complex terrain foundations according to claim 8, characterized in that, The process of determining the corresponding precast pile size parameters includes: The first precast pile size parameter is determined based on the current pile spacing level and its corresponding spacing level influence compensation parameter. The second precast pile size parameter is determined based on the current bearing capacity level and its corresponding bearing capacity level influence compensation parameter. The precast pile size parameter is determined based on the first precast pile size parameter and the second precast pile size parameter.

10. The method for optimizing the size combination of precast piles for complex terrain foundations according to claim 9, characterized in that, The process of adjusting the precast pile size parameters includes: Since the simulated pile driving depth is less than the preset pile driving depth threshold, the pile length is increased according to the difference between the preset pile driving depth threshold and the simulated pile driving depth. Since the increased pile length still does not meet the preset pile driving depth threshold, the precast pile size parameters are determined by shortening the pile diameter. Based on the simulated pile driving depth being greater than or equal to the preset pile driving depth threshold, it is determined to maintain the current precast pile size parameters. The preset piling depth is determined based on the soil conditions corresponding to each soil layer.

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