A BIM Automatic Optimization Method for Road Composite Foundation Based on Finite Element

Abstract

The present invention discloses a BIM automatic optimization method for road composite foundation based on finite element, belonging to the field of information model. The optimization method includes: obtaining embankment, stratum and relevant information; determining the pile type and the overall pile distribution type, setting the initial values of pile spacing and pile length, and determining the lateral distribution type of pile body at the calculation section; then calling the finite element to read the parametric text file through the developed program for calculation; calculating the safety factor according to the strength reduction method, and performing the first optimization of pile length and pile spacing according to the safety factor; performing the second optimization of pile length and pile spacing according to the maximum settlement at the top of the embankment; generating the pile body BIM according to the set pile type and the optimized pile length and pile spacing. The present invention uses the finite element method to improve the optimization accuracy of the composite foundation scheme, disassembles the multi-constraint index optimization problem to reduce the difficulty, formulates the parameter optimization path to improve the efficiency, and at the same time provides a method that can be used for reference for the BIM of other types of projects to automatically optimize with the help of finite element.

Description

Technical Field

[0001] The present invention relates to the field of information models, and in particular to an automatic optimization method for BIM of road composite foundation based on finite element. Background Art

[0002] With the development of digitalization of transportation infrastructure, the demand for BIM (Building Information Model) delivery in the design of transportation infrastructure solutions is increasing. As an important part of transportation infrastructure, the road composite foundation project has the problem of large BIM modeling workload. How to improve its BIM modeling efficiency through computer technology has gradually become one of the current problems.

[0003] To solve this problem, some scholars have proposed corresponding technical solutions. For example, the invention patent CN113012287A published in June 2021 proposed a rapid modeling and automatic optimization method for road pile-type composite foundation projects, mainly using the calculation methods proposed in existing specifications as constraint conditions to establish an objective function with the engineering quantity as the dependent variable to realize the automatic optimization of road composite foundation solutions. However, this method still has the following disadvantages:

[0004] (1) In the specification, the settlement calculation adopts the layer-wise summation method provided by the specification. The accuracy of its calculation method depends on the calculation method of additional stress. At present, the additional stress calculation of existing composite foundations still adopts approximate calculation methods such as the stress diffusion method, the equivalent entity method, and the Boussinesq solution, and there is no accurate calculation method;

[0005] (2) In the specification, the stability calculation methods include the Bishop method, the Janbu general slice method, the improved total strength method, and the effective consolidation stress method, etc. These calculation methods use the equivalent shear strength to estimate the shear strength of the composite foundation soil in the calculation of the shear strength of the composite foundation. This estimation method has good calculation effects for pile types such as granular material piles and flexible piles that are well combined with the original foundation soil, but will overestimate the stability of rigid piles such as CFG piles and pipe piles;

[0006] (3) This method combines different pile diameters, pile lengths, and pile spacings into multiple schemes for cyclic calculation to solve the optimal scheme. The influence of the changes in pile length and pile spacing on the stability and settlement changes is not comprehensively considered in the solution process to formulate a reasonable optimization path, resulting in excessive resource consumption in the calculation. Summary of the Invention

[0007] In order to overcome the defects in the above technology, the present invention provides an automatic optimization method for BIM of road composite foundation based on finite element, which calls the finite element platform for calculation through the program of BIM secondary development, and formulates a parameter optimization path in combination with the influence of the changes in pile length and pile spacing on the calculation results to realize the rapid optimization of the BIM scheme of the road composite foundation.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A BIM automatic optimization method for road composite foundation based on finite element, comprising the following steps:

[0010] Step 1, obtain the physical parameter information and geometric information of the embankment and the formation at the calculation section, and obtain the vehicle load intensity information of the embankment;

[0011] Step 2, determine the pile type and the overall pile distribution type; set the initial value s0 of the pile spacing and the initial value d0 of the pile length; determine the lateral pile distribution type at the calculation section according to the overall pile distribution type;

[0012] Step 3, design and develop a program. The developed program calls the finite element to read the parametric text file containing modeling, mesh generation, boundary condition setting, and calculation analysis for calculation, and outputs the calculation process information and the maximum settlement at the top of the embankment at the calculation section;

[0013] Step 4, call the finite element to read the parametric text file through the developed program, calculate the safety factor according to the strength reduction method, perform the first optimization of the pile length and the pile spacing according to the safety factor, obtain the optimized pile length d1 and pile spacing s1 after the first optimization, and update the parametric text file after the optimization is completed;

[0014] Step 5, call the finite element to read the updated parametric text file through the developed program again, calculate the maximum settlement at the top of the embankment, perform the second optimization of the pile length and the pile spacing according to the maximum settlement at the top of the embankment, and obtain the optimized pile length d2 and pile spacing s2 after the second optimization;

[0015] Step 6, generate the pile body BIM according to the optimized pile length d2 and pile spacing s2 after the second optimization.

[0016] Preferably, in step 2, the pile type includes the pile diameter and the physical parameter information of the pile; the overall pile distribution type includes two types: staggered distribution and aligned distribution;

[0017] Set the distribution of the piles along the cross-section direction of the embankment as rows. The spacing between adjacent piles in a row is the pile spacing, and the spacing between rows is the row spacing. And let the row spacing = k times the pile spacing. The piles in the same row are distributed according to the lateral distribution type, and the rows are evenly distributed according to the row spacing;

[0018] The lateral distribution type is the distribution type of the piles in the row, including two types: lateral distribution type one and lateral distribution type two; the lateral distribution type one is: in this row, the piles are evenly distributed according to the pile spacing, and there is one pile located on the center plane of the roadbed; the lateral distribution type two is: in this row, the pile bodies are evenly distributed according to the pile spacing, and the midpoint of the center connection line of two piles is located on the center plane of the roadbed;

[0019] When the overall distribution type of the piles is staggered distribution, , the piles in each row are arranged alternately according to the transverse distribution type 1 and the transverse distribution type 2;

[0020] When the overall distribution type of the piles is aligned distribution, k =1, the piles in each row are uniformly aligned according to the transverse distribution type 1 or the transverse distribution type 2;

[0021] Select the transverse distribution type of the row of piles closest to the calculation section according to the position of the calculation section as the transverse distribution type of the piles at the calculation section.

[0022] Preferably, in step 3, the modeling includes creating geometric models of the embankment, formation, and piles at the calculation section and assigning physical parameter information; among them, the geometric model of the piles is created according to the pile type, pile transverse distribution type, pile spacing, and pile length obtained in step 2; the boundary condition setting means applying constraints with zero normal displacement on both sides and the bottom of the soil layer, and applying a pressure equal to the vehicle load intensity information on the top surface of the embankment; the physical parameter information includes elastic modulus, Poisson's ratio, unit weight, cohesion, and internal friction angle; the formation includes soft soil formation.

[0023] Preferably, the implementation process of step 4 is as follows:

[0024] Step 4.1, call the finite element to read the parametric text file through the developed program, and obtain the safety factor E according to the strength reduction method, specifically as follows:

[0025] Step 4.1.1, set the initial value of the reduction coefficient β0 = 1.0;

[0026] Step 4.1.2, first reduce the cohesion and internal friction angle of the embankment and formation in the parametric text file by dividing them by the initial value of the reduction coefficient β0 through the developed program, and then call the finite element to read the parametric text file through the developed program for calculation to obtain the calculation process information;

[0027] Step 4.1.3, make the following judgment:

[0028] If the calculation non-convergence information appears in the calculation process information, take E < 1.0 and enter step 4.2; otherwise, enter step 4.1.4;

[0029] Step 4.1.4, increase the initial value of the reduction coefficient β0 by a coefficient increment Δβ to obtain a new reduction coefficient β1, then reduce the cohesion and internal friction angle of the embankment and formation in the parametric text file by dividing them by the new reduction coefficient β1 through the developed program, and then call the finite element to read the parametric text file through the developed program for calculation to obtain the calculation process information, and make the following judgment:

[0030] If the calculation non - convergence information appears in the calculation process information, end the calculation, and use the bisection method to search for a maximum reduction coefficient β that makes the calculation converge between β1 and β0 max , and take E = β max ;

[0031] If the calculation non - convergence information still does not appear in the calculation process information, then add a coefficient increment Δβ to the new reduction coefficient β1 to obtain a second - updated reduction coefficient β2, and divide the cohesion and internal friction angle of the embankment and formation in the parametric text file by the new reduction coefficient β2 through the developed program for reduction, and then call the finite element through the developed program to read the parametric text file for calculation to obtain the calculation process information until the calculation non - convergence information is obtained in the calculation process information, end the calculation, and record the reduction coefficient obtained at this time as the reduction coefficient β updated for the nth time n , and record the reduction coefficient of the previous calculation as the reduction coefficient β updated for the (n - 1)th time n-1 , and use the bisection method to search for a maximum reduction coefficient β that makes the calculation converge between β n and β n-1 , and take E = β nmax , and take E = β nmax ;

[0032] Step 4.2, given a safety threshold F, make the following judgment: If E > F, then it is determined that d1 = d0, s1 = s0, the first optimization ends, and enter Step 5; otherwise, enter Step 4.3;

[0033] Step 4.3, adjust the pile length and pile spacing according to the safety factor E obtained in Step 4.1, specifically as follows:

[0034] Step 4.3.1, increase the pile length in the parametric text file by a given pile - length increment Δd1 through the developed program to obtain a current pile length d0 * , and recalculate the safety factor according to the strength reduction method described in Step 4.1 to obtain a new safety factor E1;

[0035] Step 4.3.2, make the following judgment:

[0036] If E1 > F, then it is determined that d1 = d0 * , s1 = s0, the first optimization ends, and enter Step 5; otherwise, enter Step 4.3.3;

[0037] Step 4.3.3, if any one of the length stop criteria is met, then it is determined that d1 = d0 * , and enter Step 4.4; otherwise, use the current pile length d0 * to update the pile length in the parametric text file and return to Step 4.3.1;

[0038] The length stopping criterion includes two items. The first item is that the pile length penetrates the soft soil layer. The second item is that the contribution of the increase in pile length to the growth of the safety factor reaches the inflection point of the pile length.

[0039] Step 4.4, if a critical pile spacing value s between the minimum pile spacing s and the initial pile spacing value s0 is obtained through the development program search min then it is determined that s1 = s L ; otherwise, it is determined that the optimization fails and this optimization ends. L During the search process of Step 4.4, when the pile spacing changes, the pile lateral distribution type at the calculation section is updated synchronously, and the pile geometric model in the modeling part of the parametric text file is also updated synchronously.

[0040] Preferably, the critical pile spacing value s in Step 4.4

[0041] satisfies: when the pile spacing in the parametric text file is less than or equal to the critical pile spacing value s L the new safety factor E1 calculated according to Step 4.3 is greater than the safety threshold F, and when the pile spacing in the parametric text file is greater than the critical pile spacing value s L the new safety factor E1 calculated according to Step 4.3 is less than or equal to the safety threshold F. L

[0042] Preferably, the implementation process of Step 5 is as follows:

[0043] Step 5.1, establish an optimization folder and place the parametric text file updated in Step 4 in the optimization folder;

[0044] Step 5.2, call the finite element through the development program to read the parametric text file in the optimization folder and calculate the maximum settlement C at the top of the embankment;

[0045] Step 5.3, given a settlement threshold G and make the following judgment:

[0046] If C < G, then it is determined that d2 = d1, s2 = s1, the second optimization ends, and enter Step 6;

[0047] If C ≥ G, then copy the parametric text file into two copies, which are called copy file A and copy file B respectively, and enter Step 5.4;

[0048] Step 5.4, increase the pile length d1 in copy file A by a pile length increment Δd2 to obtain the increased pile length d1 * reduce the pile spacing s1 in copy file B by a pile spacing increment Δs to obtain the reduced pile spacing s1 * and given the minimum pile spacing s​min , make the following judgments:

[0049] If s1 * < s min , the optimization fails, and this optimization ends;

[0050] If s1 * ≥ s min , enter step 5.5;

[0051] In step 5.4, when the pile spacing in copy file B changes, the pile lateral distribution type at the cross-section is calculated and updated synchronously, and the pile geometric model in the modeling part of copy file B is also updated synchronously;

[0052] Step 5.5, call the finite element through the development program to read the two copy files, calculate the maximum settlement at the top of the embankment respectively, and record them as maximum settlement A and maximum settlement B. At the same time, calculate the increased engineering quantity of the two copy files compared with the parametric text file in the optimization folder through the development program, and record them as engineering quantity increment I and engineering quantity increment J; calculate ratio A * and ratio B * , A * = A / I, B * = B / J;

[0053] Step 5.6, compare the values of ratio A * and ratio B * , and update the parametric text file in the optimization folder with the copy file corresponding to the larger value, and return to step 5.2 for calculation until the optimization fails or the determination of the pile length d2 and pile spacing s2 after the second optimization is obtained.

[0054] Preferably, the calculation cross-section refers to the cross-section that can represent the embankment and formation in the corresponding section for scheme calculation, and the vehicle load intensity information of the embankment refers to the vehicle load that needs to be applied on the top of the embankment during the calculation process.

[0055] Preferably, the development program refers to a plug-in created by secondary development of the BIM platform.

[0056] The present invention also provides a computer program product, which includes a computer program / instructions. When the computer program / instructions are executed by a processor, the above-mentioned method for automatic optimization of road composite foundation BIM based on finite element is implemented.

[0057] The beneficial effects of the present invention include:

[0058] (1) Using the finite element method with higher accuracy to calculate the stability of the embankment slope and the settlement of the composite foundation and optimize them, effectively improving the accuracy of the composite foundation scheme optimization.

[0059] (2) The optimization problem of multiple constraint indicators such as stability and settlement is disassembled, reducing the difficulty of parameter optimization. At the same time, according to the contribution characteristics of pile length and pile spacing to stability and settlement, the corresponding parameter optimization path is formulated, improving the optimization efficiency.

[0060] (3) Based on the reconstruction idea, a BIM secondary development plug-in is used to transfer data from BIM to the finite element platform. Then, the plug-in reads the finite element calculation and output files to realize the feedback of data from the finite element to the BIM plug-in, providing a method for other types of engineering BIM to achieve automatic optimization with the help of the finite element. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a flowchart of a BIM automatic optimization method for a road composite foundation based on the finite element of the present invention;

[0062] Figure 2 It is a schematic diagram of the pile distribution Figure 1 ;

[0063] Figure 3 It is a schematic diagram of the pile distribution Figure 2 ;

[0064] Figure 4 It is a schematic diagram of the geometric information of the embankment, formation and piles of the calculated cross-section obtained by the BIM platform;

[0065] Figure 5 It is a schematic diagram of a pseudo-three-dimensional calculation model generated by the finite element platform reading a parametric text file;

[0066] Figure 6 It is a schematic diagram of adjusting the pile length according to the safety factor;

[0067] Figure 7 It is a schematic diagram of the inflection point of the increase in pile length and the increase in safety factor; DETAILED DESCRIPTION OF THE INVENTION

[0068] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0069] As Figure 1 shown, a BIM automatic optimization method for a road composite foundation based on the finite element includes the following steps:

[0070] Step 1, obtain the physical parameter information and geometric information of the embankment and formation at the calculated cross-section, and obtain the vehicle load intensity information of the embankment; the physical parameter information of the embankment and formation at the calculated cross-section includes their elastic modulus, Poisson's ratio, specific weight, cohesion and internal friction angle; the formation includes the soft soil formation.

[0071] In this embodiment, the calculation cross-section refers to a typical cross-section that can represent the embankment and formation of the corresponding section for scheme calculation, and the vehicle load intensity information of the embankment refers to the vehicle load that needs to be applied to the top of the embankment during the calculation process.

[0072] Figure 4 It is a schematic diagram of the geometric information of the embankment, formation, and piles at the calculation cross-section obtained by the BIM platform. Figure 5 It is a schematic diagram of a pseudo-three-dimensional calculation model generated by the finite element platform reading a parameterized text file. Among them, 1 is the embankment, 2 is the formation, 3 is the pile, 4 is the vehicle load intensity, and 7 is the center line of the roadbed.

[0073] Step 2: Select the pile type, including the material and diameter of the pile; select the overall distribution type of the piles. The overall distribution type of the piles includes two types: staggered distribution and aligned distribution; set the maximum pile spacing given in the code provisions as the initial pile spacing s0, and give the initial pile length d0; determine the lateral distribution type of the piles at the calculation cross-section according to the position of the calculation cross-section.

[0074] In this embodiment, the process of determining the lateral distribution type of the piles at the calculation cross-section according to the position of the calculation cross-section is as follows:

[0075] Set the distribution of the piles along the cross-section direction of the embankment as rows. The spacing between adjacent piles in a row is the pile spacing, and the spacing between rows is the row spacing. And let the row spacing = k times the pile spacing. The piles in the same row are distributed according to the lateral distribution type, and the rows are evenly distributed according to the row spacing.

[0076] The lateral distribution type of the piles is the distribution type of the piles in the row, including two types: lateral distribution type one and lateral distribution type two; the lateral distribution type one is that in this row, the piles are evenly distributed according to the pile spacing, and there is a pile located on the center plane of the roadbed; the lateral distribution type two is that in this row, the piles are evenly distributed according to the pile spacing, and the midpoint of the center connection of two piles is located on the center plane of the roadbed.

[0077] When the overall distribution type of the piles is staggered distribution, , the piles in each row are arranged alternately according to the lateral distribution type one and lateral distribution type two.

[0078] When the overall distribution type of the piles is aligned distribution, k = 1, and the piles in each row are uniformly arranged in alignment according to the lateral distribution type one or lateral distribution type two.

[0079] Select the lateral distribution type of the row of piles closest to the calculation cross-section according to the position of the calculation cross-section as the lateral distribution type of the piles at the calculation cross-section.

[0080] Figure 2 It is a schematic diagram of the pile distribution Figure 1 ,Figure 3 Schematic diagram of pile distribution Figure 2 . In the figure, 9 is the first type of lateral distribution, 10 is the second type of lateral distribution, 12 is the calculation section, 13 is a triangle, and 14 is a square. From Figure 2 and Figure 3 it can be seen that in Figure 2 , the two types of lateral distributions are arranged alternately, and any one pile in the second type of lateral distribution and the two nearest piles in the adjacent row form a triangle 13, and it is an equilateral triangle. In Figure 3 , only the first type of lateral distribution is included, and the four nearest piles between adjacent rows form a square 14

[0081] Step 3: Design and develop a program. By calling the finite element through the developed program, read a parametric text file containing modeling, mesh generation, boundary condition setting, and calculation analysis and conforming to the finite element parametric language format for calculation, and output the calculation process information and the maximum settlement of the embankment top at the calculation section

[0082] The developed program refers to a plug-in created through secondary development of the BIM platform; the modeling includes creating geometric models of the embankment, formation, and piles at the calculation section and assigning physical parameter information; the geometric model of the piles is created according to the lateral distribution type, pile diameter, pile length, and pile spacing obtained in Step 2; the boundary condition setting refers to applying constraints with zero normal displacement on both sides and the bottom of the soil layer, and applying a pressure equal to the vehicle load intensity information on the top surface of the embankment; the result output of the finite element includes the output of the maximum settlement C of the embankment top and the calculation process information, and the output files of the results are respectively recorded as the displacement result file and the calculation process file

[0083] Step 4: Call the finite element through the developed program to read the parametric text file, calculate the safety factor E according to the strength reduction method, perform the first optimization of the pile length and pile spacing according to the safety factor E, obtain the first optimized pile length d1 and the first optimized pile spacing s1, and update the parametric text file after the optimization is completed

[0084] In this embodiment, the implementation process of Step 4 is as follows

[0085] Step 4.1: Call the finite element through the developed program to read the parametric text file and obtain the safety factor E according to the strength reduction method, specifically as follows

[0086] Step 4.1.1: Set the initial value of the reduction coefficient β0 = 1.0

[0087] Step 4.1.2: First, reduce the cohesion and internal friction angle of the embankment and formation in the parametric text file by the initial value of the reduction coefficient β0 through the developed program, and then call the finite element through the developed program to read the parametric text file for calculation to obtain the calculation process file

[0088] Step 4.1.3, make the following judgment:

[0089] If the calculation process file shows information of non - convergent calculation, take E < 1.0. In this embodiment, E is taken as 0.9, and go to Step 4.2; otherwise, go to Step 4.1.4;

[0090] Step 4.1.4, increase the initial value of the reduction coefficient β0 by a coefficient increment Δβ to obtain a new reduction coefficient β1. Then, through the developed program, divide the cohesion and internal friction angle of the embankment and formation in the parametric text file by the new reduction coefficient β1 for reduction. Then, through the developed program, call the finite element to read the parametric text file for calculation to obtain the calculation process file, and make the following judgment:

[0091] If the calculation process file shows information of non - convergent calculation, end the calculation, and use the bisection method to search for a maximum reduction coefficient β for convergent calculation between β1 and β0 max , and take E = β max ;

[0092] If the calculation process file still does not show information of non - convergent calculation, then increase a coefficient increment Δβ on the basis of the new reduction coefficient β1 to obtain a second updated reduction coefficient β2, and through the developed program, divide the cohesion and internal friction angle of the embankment, formation in the parametric text file by the new reduction coefficient β2 for reduction. Then, through the developed program, call the finite element to read the parametric text file for calculation to obtain the calculation process file, and so on, until information of non - convergent calculation is obtained in the calculation process file, end the calculation, and record the reduction coefficient obtained at this time as the reduction coefficient β updated for the nth time n , and record the reduction coefficient of the previous calculation as the reduction coefficient β updated for the (n - 1)th time n-1 . Use the bisection method to search for a maximum reduction coefficient β for convergent calculation between β n and β n-1 , and take E = β nmax ; nmax .

[0093] Step 4.2, given a safety threshold F, make the following judgment: If E > F, then it is determined that d1 = d0, s1 = s0, the first optimization ends, and go to Step 5; otherwise, go to Step 4.3.

[0094] Step 4.3, adjust the pile length and pile spacing according to the safety factor E obtained in Step 4.1, specifically as follows:

[0095] Step 4.3.1, through the developed program, increase the pile length in the parametric text file by a given pile length increment Δd1 to obtain a current pile length d0 *, and recalculate the safety factor according to the strength reduction method described in step 4.1 to obtain a new safety factor E1;

[0096] Step 4.3.2, make the following judgment:

[0097] If E1 > F, then it is determined that d1 = d0 * , s1 = s0, the first optimization ends, and enter step 5; otherwise, enter step 4.3.3;

[0098] Step 4.3.3, if any one of the length stop criteria is met, then it is determined that d1 = d0 * , enter step 4.4; otherwise, use the current pile length d0 * Update the pile length in the parametric text file and return to step 4.3.1;

[0099] The length stop criteria include two items. The first item is that the pile length penetrates the soft soil layer; the second item is that the growth contribution of the pile length increase to the safety factor reaches the pile length inflection point.

[0100] Step 4.4, if a pile spacing critical value s that is between the minimum pile spacing s given in the code provisions min and the initial pile spacing value s0 can be searched through the development program L , then it is determined that s1 = s L ; otherwise, it is determined that the optimization fails and this optimization ends.

[0101] In this embodiment, the pile spacing critical value s described in step 4.4 L satisfies: when the pile spacing in the parametric text file is less than or equal to this value, the new safety factor E1 calculated according to step 4.3 is greater than the safety threshold F, and when the pile spacing in the parametric text file is greater than this value, the new safety factor E1 calculated according to step 4.3 is less than or equal to the safety threshold F.

[0102] In this embodiment, step 4.4 uses the bisection method to search for the pile spacing critical value between the minimum pile spacing s min and the initial pile spacing value s0. Among them, first change the pile spacing in the parametric text file to s min , and then recalculate the safety factor according to the strength reduction method described in step 4.1 to obtain a new safety factor. If the new safety factor is not greater than the safety threshold F, it is considered that the pile spacing critical value s cannot be searched L ; if the new safety factor is greater than the safety threshold F, then search for the pile spacing critical value s according to the bisection method between the minimum pile spacing s min and the initial pile spacing value s0 L ;

[0103] During the search process in Step 4.4, each time the pile spacing changes, it is necessary to refer to the method of specifying the lateral distribution type of piles at the calculation section according to the position of the calculation section in Step 2, update the lateral distribution type of piles at the calculation section, and synchronously update the pile geometric model in the modeling part of the parametric text file.

[0104] Figure 6 It is a schematic diagram of adjusting the pile length according to the safety factor. Among them, 5 is the potential slip surface, and 6 is the given pile length increment Δd1. Figure 7 It is a schematic diagram of the inflection point of the increase in pile length and the growth of the safety factor. Among them, the abscissa is the number of times of pile length increase, the ordinate is the safety factor, and 8 is the inflection point. Specifically, in Step 4.3.3, when using the current pile length d0 * Update the pile length in the parametric text file and return to Step 4.3.1 for calculation. Record the number of times of pile length increase and the corresponding safety factor each time, automatically give the corresponding data points in the plane coordinate system and draw the pile length increase coefficient - safety factor curve. When the curve has an inflection point, it is regarded as meeting the second length stop criterion.

[0105] Step 5, call the updated finite element again through the development program to read the parametric text file to calculate the maximum settlement C at the top of the embankment, and perform the second optimization of the pile length and pile spacing according to the maximum settlement C at the top of the embankment to obtain the second optimized pile length d2 and the second optimized pile spacing s2.

[0106] In this embodiment, the implementation process of Step 5 is as follows:

[0107] Step 5.1, establish an optimization folder and place the parametric text file updated in Step 4 in the optimization folder.

[0108] Step 5.2, call the finite element through the development program to read the parametric text file in the optimization folder to obtain the displacement result file, and calculate the maximum settlement C at the top of the embankment according to the preset program in the displacement result file.

[0109] Step 5.3, specify a settlement threshold G and make the following judgments:

[0110] If C < G, it is determined that d2 = d1, s2 = s1, the second optimization ends, and enter Step 6;

[0111] If C ≥ G, copy the parametric text file into two copies, which are called copy file A and copy file B respectively, and enter Step 5.4.

[0112] Step 5.4, increase the pile length d1 in copy file A by a pile length increment Δd 2 to obtain the increased pile length d1 *, reduce the pile spacing s1 in the copied file B by a pile spacing increment Δs to obtain the reduced pile spacing s1 * , and denote the minimum pile spacing given in the code provisions as s min , make the following judgment:

[0113] If s1 * <s min , the optimization fails and this optimization is ended;

[0114] If s1 * ≥s min , go to step 5.5.

[0115] When the pile spacing in the copied file B changes, it is necessary to refer to the method of specifying the pile lateral distribution type at the calculation section according to the position of the calculation section in step 2 to update the lateral distribution type, and synchronously update the geometric model of the pile body in the modeling part of the copied file B;

[0116] Step 5.5, call the finite element through the developed program to read the two copied files, calculate the maximum settlement at the top of the embankment for each of them, and denote them as maximum settlement A and maximum settlement B. At the same time, calculate the increased engineering quantity of the two copied files compared with the parametric text file in the optimization folder through the developed program, which is called engineering quantity increment I and engineering quantity increment J; Introduce ratio A * and ratio B * , A * =A / I, B * =B / J.

[0117] Step 5.6, compare the values of ratio A * and ratio B * , and update the parametric text file in the optimization folder described in step 5.1 with the copied file corresponding to the larger value, and return to step 5.2 for calculation until the optimization fails or the determination of the second optimized pile length d2 and the second optimized pile spacing s2 is obtained.

[0118] Step 6, if the situation of optimization failure does not occur, generate the pile body BIM in the BIM platform according to the pile type and the overall pile distribution type set in step 2, the second optimized pile length d2 and the second optimized pile spacing s2 obtained in step 5.

[0119] In the above steps, the code provisions refer to the relevant provisions in the current national standards for composite foundations and the industry standards of the Ministry of Transport.

[0120] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A finite element-based BIM automatic optimization method for road composite foundation, characterized in that: The following steps are involved: Step 1, obtaining physical parameter information and geometric information of the embankment and the stratum at the calculation section, and obtaining vehicle load strength information of the embankment; the vehicle load strength information of the embankment refers to the vehicle load that needs to be applied to the top of the embankment during the calculation process; Step 2, determine the pile type and overall pile distribution type; Set the initial value of pile spacing s0 and the initial value of pile length d0; determine the lateral distribution type of piles at the calculation section according to the overall distribution type of piles; Step 3, design and develop a program, the development program calls the finite element to read the parametric text file containing modeling, meshing, boundary condition setting, and calculation analysis to perform calculations, and outputs the calculation process information and the maximum settlement of the embankment top at the calculation section; Step 4, calling the finite element to read the parameterized text file through the development program, calculating the safety factor according to the strength reduction method, performing the first optimization of the pile length and the pile spacing according to the safety factor, obtaining the first optimized pile length d1 and pile spacing s1, and updating the parameterized text file after the optimization is completed; Step 5, again calling the finite element through the development program to read the updated parameterized text file, calculating the maximum settlement of the embankment top, performing a second optimization of the pile length and pile spacing according to the maximum settlement of the embankment top, and obtaining the second optimized pile length d2 and pile spacing s2; Step 6: Generate the pile body BIM according to the pile length d2 and pile spacing s2 after the second optimization.

2. The method for BIM automatic optimization of composite road foundation based on finite element according to claim 1 is characterized in that: In step 2, the pile type includes pile diameter and physical parameter information of the pile; the overall distribution type of the pile includes two types: staggered distribution and aligned distribution; The distribution of piles along the cross section of the embankment is set as rows, the spacing between adjacent piles in a row is the pile spacing, the spacing between rows is the row spacing, and the row spacing = k Double the pile spacing, the piles in the same row are distributed according to the horizontal distribution type, and the rows are evenly distributed according to the row spacing; The lateral distribution type is the distribution type of piles in the row, including lateral distribution type 1 and lateral distribution type 2; the lateral distribution type 1 is: in the row, the piles are evenly distributed according to the pile spacing, and one pile is located on the center plane of the roadbed; the lateral distribution type 2 is: in the row, the piles are evenly distributed according to the pile spacing, and the midpoint of the line connecting the centers of two piles is located on the center plane of the roadbed; When the overall distribution type of the piles is staggered distribution, , each row of piles is arranged alternately according to transverse distribution type one and transverse distribution type two; When the overall distribution type of the piles is aligned distribution, k =1, each row of piles is uniformly arranged according to lateral distribution type 1 or lateral distribution type 2; According to the location of the calculated section, the lateral distribution type of a row of piles closest to the calculated section is selected as the lateral distribution type of piles at the calculated section.

3. The method for BIM automatic optimization of composite road foundation based on finite element according to claim 2 is characterized in that: In step 3, the modeling includes creating a geometric model of the embankment, stratum and piles at the calculation section and assigning physical parameter information; wherein the geometric model of the pile is created according to the pile type, pile lateral distribution type, pile spacing and pile length obtained in step 2; the boundary condition setting refers to applying a constraint of zero normal displacement on both sides and the bottom of the soil layer, and applying a load equal to the pressure of the vehicle-load strength information on the top surface of the embankment; the physical parameter information includes elastic modulus, Poisson's ratio, gravity, cohesion and internal friction angle; the stratum includes a soft soil stratum.

4. The method for BIM automatic optimization of composite road foundation based on finite element according to claim 3 is characterized in that: The implementation process of step 4 is as follows: Step 4.1, call the finite element to read the parameterized text file through the development program, and obtain the safety factor E according to the strength reduction method, as follows: Step 4.1.1, set the initial value of the reduction factor β0=1.0; Step 4.1.2, firstly, the cohesion and internal friction angle of the embankment and the stratum in the parameterized text file are reduced by the initial value of the reduction coefficient β0 through the development program, and then the finite element is called through the development program to read the parameterized text file for calculation to obtain the calculation process information; Step 4.1.3, make the following judgment: If the calculation process information shows that the calculation does not converge, take E<1.0 and go to step 4.2; otherwise, go to step 4.1.4; Step 4.1.4, increase the initial value of the reduction coefficient β0 by a coefficient increment Δβ to obtain a new reduction coefficient β1, and then use the development program to divide the cohesion and internal friction angle of the embankment and stratum in the parameterized text file by the new reduction coefficient β1 for reduction, and then use the development program to call the finite element to read the parameterized text file for calculation, obtain the calculation process information, and make the following judgment: If the calculation process information shows that the calculation does not converge, the calculation is terminated and a maximum reduction factor β that makes the calculation converge is searched between β1 and β0 using the binary search method. max , and take E = β max ; If the calculation process information still does not contain information about non-convergence, then a coefficient increment Δβ is added to the new reduction coefficient β1 to obtain a second updated reduction coefficient β2, and the cohesion and internal friction angle of the embankment and stratum in the parameterized text file are divided by the new reduction coefficient β2 through the development program for reduction, and then the finite element is called through the development program to read the parameterized text file for calculation to obtain the calculation process information until the calculation process information contains information about non-convergence, the calculation is terminated, and the reduction coefficient obtained at this time is recorded as the nth updated reduction coefficient β n , the reduction factor calculated last time is recorded as the reduction factor β of the n-1th update n-1 , using the dichotomy method in β n and β n-1 Search for a maximum reduction factor β that makes the calculation converge nmax , and take E = β nmax ; Step 4.2, given a safety threshold F, make the following judgment: if E>F, then d1=d0, s1=s0, the first optimization is completed, and go to step 5; otherwise, go to step 4.3; Step 4.3, adjust the pile length and pile spacing according to the safety factor E obtained in step 4.1, as follows: Step 4.3.1: Increase the pile length in the parameterized text file by a given pile length increment Δd1 through the development program to obtain a current pile length d0. * , and recalculate the safety factor according to the strength reduction method described in step 4.1 to obtain a new safety factor E1; Step 4.3.2, make the following judgment: If E1>F, then d1=d0 * , s1=s0, the first optimization is completed and go to step 5; otherwise, go to step 4.3.3; Step 4.3.3: If any of the length stopping criteria is met, then d1=d0 * , go to step 4.4; Otherwise use the current pile length d0 * Update the pile length in the parametric text file and return to step 4.3.1; The length stopping criteria include two: first, the pile length penetrates the soft soil layer; second, the contribution of the increase in pile length to the growth of the safety factor reaches the inflection point of the pile length; Step 4.4: If a minimum pile spacing s is obtained through the development program search min The critical value of pile spacing s between the initial value of pile spacing s0 L , then we assume that s1=s L ; Otherwise, the optimization is deemed to have failed and the optimization is terminated; During the search process of step 4.4, when the pile spacing changes, the pile lateral distribution type at the calculation section is updated synchronously, and the pile geometry model of the modeling part in the parametric text file is also updated synchronously.

5. The method for BIM automatic optimization of composite road foundation based on finite element according to claim 4 is characterized in that: The critical value of pile spacing s mentioned in step 4.4 L Satisfaction: When the pile spacing in the parameterized text file is less than or equal to the pile spacing critical value s L When the new safety factor E1 calculated according to step 4.3 is greater than the safety threshold F, the pile spacing in the parameterized text file is greater than the critical pile spacing s L , the new safety factor E1 calculated according to step 4.3 is less than or equal to the safety threshold F.

6. The method for BIM automatic optimization of composite road foundation based on finite element according to claim 3 is characterized in that: The implementation process of step 5 is as follows: Step 5.1, create an optimization folder and place the parameterized text file updated in step 4 in the optimization folder; Step 5.2, calling the finite element to read the parameterized text file in the optimization folder through the development program, and calculating the maximum settlement C of the embankment top; Step 5.3, given the sedimentation threshold G, and make the following judgment: If C<G, it is determined that d2=d1, s2=s1, the second optimization is completed, and the process goes to step 6; If C ≥ G, the parameterized text file is copied into two copies, which are called copy file A and copy file B respectively, and the process goes to step 5.4; Step 5.4, increase the pile length d1 in the copied file A by a pile length increment Δd2 to obtain the increased pile length d1 * , reduce the pile spacing s1 in the copy file B by a pile spacing increment Δs to obtain the reduced pile spacing s1 * , and give the minimum pile spacing s min , make the following judgment: If s1 * <s min , optimization failed, end this optimization; If s1 * ≥s min , go to step 5.5; In step 5.4, when the pile spacing in the copied file B changes, the pile lateral distribution type at the calculation section is updated synchronously, and the pile geometry model of the modeling part in the copied file B is also updated synchronously; Step 5.5, call the finite element to read the two copy files through the development program, calculate the maximum settlement of the top of the embankment, and record it as the maximum settlement A and the maximum settlement B. At the same time, the development program calculates the increase in the engineering quantity of the two copy files compared with the parameterized text file in the optimization folder, and records it as the engineering quantity increment I and the engineering quantity increment J; calculate the ratio A * and ratio B * , A * =A / I,B * =B / J; Step 5.6, compare the ratio A * and ratio B * The value of , and the copy file corresponding to the larger value is used to update the parameterized text file in the optimization folder, and return to step 5.2 for calculation until the optimization fails, or the pile length d2 and pile spacing s2 after the second optimization are determined.

7. A finite element based BIM automatic optimization method for composite road foundation according to any one of claims 1 to 6, characterized in that: The calculation section refers to the cross section that can represent the embankment and stratum of the section for scheme calculation.

8. A finite element based BIM automatic optimization method for composite road foundation according to any one of claims 1 to 6, characterized in that: The development program refers to a plug-in created through secondary development of the BIM platform.

9. A computer program product, characterized in that It includes a computer program / instruction, which, when executed by a processor, implements a finite element-based BIM automatic optimization method for a road composite foundation as described in any one of claims 1 to 8.

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