A method for optimizing the self-restrained stress design of a gradient combined anti-cracking earth retaining wall concrete

Abstract

This invention discloses a gradient-combination crack-resistant diaphragm wall concrete self-constrained stress optimization design method. The method first constructs a BIM three-dimensional structural model including material properties, temperature gradient, and stress state through three-dimensional laser scanning and core sample testing. Then, based on the model, stress zoning is performed, and the self-constrained stress value and stress transmission attenuation coefficient of each zone are calculated. Next, an expansion agent ratio optimization model is established, and the stress redistribution under different dosage gradients is simulated using the finite element algorithm to screen the minimum effective dosage that meets the stress homogenization index. After verifying the crack resistance effect through dynamic simulation, the final mix design is output. This invention combines BIM technology with material gradient design, achieving precise control of the self-constrained stress of diaphragm wall concrete and active optimization of its crack resistance performance. It solves the technical problem that traditional homogeneous material design cannot adapt to complex stress distributions, significantly improving the durability and safety of diaphragm wall structures.

Description

Technical Field

[0001] This invention relates to the field of self-constrained stress optimization design technology for diaphragm wall concrete, and more specifically, to a gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method. Background Technology

[0002] As an important support method for deep foundation pit engineering and underground structures, the crack resistance of diaphragm walls directly affects the safety and durability of the project. Traditional diaphragm wall concrete design methods mainly adopt the assumption of homogeneous materials, failing to fully consider the uneven distribution characteristics of temperature stress gradient and self-restraint stress during construction, leading to problems such as temperature cracks and shrinkage cracks in the structure.

[0003] Especially in diaphragm wall projects under complex geological conditions, the self-constrained stress generated during the concrete hardening process and the external constraint stress superimpose each other, forming a complex stress field distribution. This stress redistribution phenomenon leads to the following technical problems: (1) the surface concrete generates large tensile stress due to rapid heat dissipation; (2) the constraint difference between different pouring layers causes interface stress concentration; (3) the asynchronous release of the expansion agent and stress development causes compensation failure. These problems make it difficult for traditional design methods to meet high standards of crack resistance requirements.

[0004] After solving the problems of the above-mentioned traditional design methods, the design methods in existing engineering practice still have the following technical problems: (1) Existing stress analysis methods are mostly based on two-dimensional simplified models, which are difficult to accurately reflect the complex stress state in three-dimensional space; (2) The expansion agent usage scheme often adopts a single ratio, which cannot adapt to the differentiated stress requirements of different depth areas; (3) The determination of construction parameters depends on empirical formulas, and lacks quantitative analysis of the multi-field coupling effect of materials-structure-environment; (4) Crack early warning mainly relies on post-monitoring, and lacks pre-prediction and active prevention and control measures. Summary of the Invention

[0005] The purpose of this invention is to provide a gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method to solve the above-mentioned problems existing in the prior art.

[0006] The application is as follows:

[0007] A gradient-combination crack-resistant diaphragm wall concrete self-constrained stress optimization design method, the method comprising:

[0008] Geological environment data, structural design parameters and historical construction data of the diaphragm wall project area are obtained, and a BIM three-dimensional structural model including material performance parameters, temperature gradient distribution and stress state is constructed through three-dimensional laser scanning and concrete core sample testing.

[0009] The diaphragm wall is stress-zoned according to the BIM 3D structural model. The self-constrained stress value of the concrete at a single point is calculated based on the temperature gradient and constraint conditions of the stress zones. The attenuation coefficient of stress transfer is determined based on the material continuity between adjacent areas. An expansion agent ratio optimization model is established based on the attenuation coefficient and the self-constrained stress value. An initial material ratio scheme is generated based on the expansion agent ratio optimization model. The initial material ratio scheme is input into the BIM 3D structural model, and the stress redistribution under different expansion agent dosage gradients is simulated using the finite element method. The critical dosage that meets the preset stress homogenization index is selected as the minimum effective dosage. The minimum effective dosage is dynamically simulated using the BIM 3D structural model to obtain simulation results. When the simulation results meet the preset crack resistance constraint conditions, the final ratio scheme is output. The simulation results include temperature stress cloud maps and crack propagation paths.

[0010] Construction parameters are generated based on the final mix design and mapped to the spatial coordinates of the BIM 3D structural model. High-risk areas are output through a visualization interface. The construction parameters include the layer pouring thickness, curing regime, and temperature control standards.

[0011] Furthermore, the method for obtaining the simulation results by dynamically simulating the minimum effective admixture using a BIM three-dimensional structural model, and outputting the final mix design when the simulation results meet the preset crack resistance constraints, includes:

[0012] Based on the spatial distribution of material zones and the curing time and temperature development rate, the synergistic effect of stress fields in adjacent areas under different construction sequences is calculated, and the construction sequence with a synergistic effect greater than the preset synergistic threshold is selected as the optimal construction scheme.

[0013] When the peak temperature stress or crack propagation length in the simulation results exceeds the preset safety threshold, the minimum effective dosage and synergistic effect are recalculated until the simulation results meet the preset crack resistance constraints.

[0014] Furthermore, the method for establishing an expansion agent ratio optimization model based on the attenuation coefficient and the self-constraining stress value, and generating an initial material ratio scheme based on the expansion agent ratio optimization model, includes:

[0015] Based on the attenuation coefficient and the self-constraint stress value, a multi-objective optimization function is constructed with the objectives of minimizing the total expansion dose and maximizing the stress superposition uniformity of adjacent regions.

[0016] The multi-objective optimization function is iteratively generated using a particle swarm optimization algorithm to generate a candidate solution set for the material mix ratio; Pareto front solutions are extracted from the candidate solution set, and the optimal material mix ratio is selected from the Pareto front solutions according to a preset construction economic weight; the optimal material mix ratio is then mapped to the material system of the BIM three-dimensional structural model to obtain an initial mix ratio scheme.

[0017] The initial mix design is verified using a BIM 3D structural model to determine whether the material continuity between adjacent areas causes the stress transfer attenuation coefficient to exceed a preset attenuation threshold. If it exceeds the preset attenuation threshold, the material mix is ​​adjusted to meet the attenuation coefficient constraint.

[0018] Furthermore, the method for verifying whether the material continuity between adjacent regions causes the stress transfer attenuation coefficient to exceed a preset attenuation threshold includes:

[0019] Based on the material distribution data in the BIM 3D structural model, the material performance gradient and transition section length between adjacent construction zones are extracted, and the material continuity index is calculated. The material continuity index is the ratio of the transition section length to the distance between adjacent zones. The material continuity index and temperature gradient data are used to simulate the stress transmission path in heterogeneous materials through the finite difference method, and the actual attenuation coefficient is calculated.

[0020] If the actual attenuation coefficient is greater than the preset attenuation threshold, the material ratio is adjusted according to the angle between the material performance gradient and the stress transmission direction, and the continuity index and actual attenuation coefficient of the adjusted area are recalculated. If the actual attenuation coefficient is still greater than the preset attenuation threshold after a preset number of adjustments, the adjusted area is marked as a high stress concentration area in the BIM three-dimensional structural model, and a ratio compensation command is triggered.

[0021] Furthermore, the method of adjusting the material ratio based on the angle between the material property gradient and the stress transmission direction and recalculating the continuity index and actual attenuation coefficient of the adjustment region includes:

[0022] Based on the geometric relationship between the material property gradient and the stress transmission direction in the three-dimensional space of the BIM three-dimensional structural model, the cosine value of the included angle is calculated. If the cosine value of the included angle is greater than a preset angle cosine value threshold, the proportion is adjusted along the direction perpendicular to the material gradient; if the cosine value of the included angle is less than or equal to the preset angle cosine value threshold, the proportion is adjusted along the direction parallel to the material gradient.

[0023] After each adjustment, the material continuity index of adjacent intervals is recalculated based on the updated proportioning scheme; if the actual attenuation coefficient after adjustment is greater than the preset attenuation threshold, the material proportioning is adjusted incrementally according to the preset step size.

[0024] Furthermore, the method for calculating the synergistic effect of stress fields in adjacent areas under different construction sequences based on the spatial distribution of material zones, curing time, and temperature development rate, and selecting the construction sequence with a synergistic effect greater than a preset synergistic threshold as the optimal construction scheme includes:

[0025] Based on the material zoning spatial distribution generated by the expansion agent ratio optimization model, the three-dimensional stress transfer vector between adjacent regions is calculated based on the zoning spatial distribution, and the theoretical time reference for temperature stress development between adjacent regions is determined based on the temperature development rate corresponding to the material properties of each stress zone in the BIM three-dimensional structural model.

[0026] Based on the theoretical time reference, a dynamic candidate interval for the maintenance sequence is established to obtain a set of candidate schemes for the arrangement and combination of construction sequences. The matching degree between the construction time difference and stress development time of each construction sequence in the candidate scheme set is calculated based on the three-dimensional stress transfer vector and temperature development rate. The ratio of the superimposed stress peak value to the single-zone stress peak value is quantified as a synergistic effect through numerical simulation.

[0027] If the synergistic effect of multiple construction sequence combinations exceeds the preset synergistic threshold, the optimal construction scheme is selected based on the principle of minimizing the total sum of maintenance time.

[0028] Furthermore, the method for obtaining a set of candidate schemes for arranging and combining construction sequences by establishing dynamic candidate intervals for maintenance time based on the theoretical time benchmark includes:

[0029] Based on the maintenance time sequence range within the dynamic candidate interval, a set of candidate construction time points is generated for each construction area. The set of candidate construction time points is evenly distributed according to a preset interval based on the theoretical time benchmark of stress development.

[0030] Based on the spatial distribution topology of the material partitions, adjacency constraint rules for the construction sequence are established. The adjacency constraint rules and the set of candidate construction time points are traversed through all construction sequence permutations and combinations using a depth-first search algorithm to obtain a set of candidate schemes. Conflict analysis is then performed on the construction sequence permutations and combinations in the set of candidate schemes.

[0031] Furthermore, the method for conflict analysis of the construction sequence arrangement and combination in the candidate scheme set includes:

[0032] Based on the spatial distribution and temperature development rate data of the construction area in the BIM 3D structural model, a spatiotemporal influence relationship matrix of the construction area is constructed. Each element in the spatiotemporal influence relationship matrix indicates whether the construction time difference between adjacent areas is less than the theoretical time required for temperature stress to develop to the adjacent area.

[0033] Each construction sequence arrangement is iterated through. When the construction time difference between adjacent areas is less than the theoretical time reference, resulting in an abnormal stress increase in the stress superposition area exceeding the preset abnormal stress increase threshold, it is determined to be a time superposition interference. Based on the spatial coordinates of the construction area in the BIM 3D structural model, the spatial overlap area of ​​the temperature stress development path of adjacent areas under different construction sequences is calculated. If the stress concentration coefficient in the spatial overlap area exceeds the preset concentration coefficient threshold, it is determined to be a path overlap interference conflict. Construction sequence arrangements with time superposition interference or path overlap interference conflicts are marked and removed.

[0034] Furthermore, the method for generating construction parameters based on the final mix design and mapping them to the spatial coordinates of the BIM 3D structural model includes:

[0035] The coordinate data and corresponding stress zones of each construction area are extracted from the BIM 3D structural model. The material parameters of a single area are generated by combining the final mix design. The material parameters of a single area are dynamically corrected according to the initial dosage threshold and material gradient of the stress zone to which the construction area belongs.

[0036] The material parameters of the single zone are mapped to the corresponding construction zone coordinates to form a structured construction parameter set, which is then stored in the material parameter database of the BIM three-dimensional structural model.

[0037] Compared with the prior art, the present invention achieves the following beneficial effects:

[0038] This invention first constructs a BIM 3D structural model incorporating material properties, temperature gradients, and stress states through 3D laser scanning and core sample testing. Then, based on the model, stress zoning is performed, and the self-constraining stress values ​​and stress transmission attenuation coefficients of each zone are calculated. Next, an expansion agent ratio optimization model is established, and the finite element method is used to simulate stress redistribution under different dosage gradients, selecting the minimum effective dosage that meets the stress homogenization index. After verifying the crack resistance through dynamic simulation, the final ratio scheme is output. This invention combines BIM technology with material gradient design, achieving precise control of the self-constraining stress of diaphragm wall concrete and proactive optimization of its crack resistance performance. It solves the technical problem that traditional homogeneous material design cannot adapt to complex stress distributions, significantly improving the durability and safety of diaphragm wall structures. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating a gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method provided in an embodiment of the present invention. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings.

[0041] Example 1

[0042] This invention provides a gradient-combined crack-resistant diaphragm wall concrete self-constrained stress optimization design method, the method comprising:

[0043] S1. Obtain geological environment data, structural design parameters and historical construction data of the diaphragm wall project area, and construct a BIM three-dimensional structural model containing material performance parameters, temperature gradient distribution and stress state through three-dimensional laser scanning and concrete core sample testing.

[0044] Geological environmental data includes groundwater level changes, soil thermal conductivity, and seasonal temperature variations; structural design parameters include wall thickness, reinforcement ratio, and constraints of adjacent structures; historical construction data includes crack distribution and temperature monitoring records from similar projects. Three-dimensional laser scanning uses a high-precision scanner to collect point cloud data of the constructed section, achieving millimeter-level accuracy and covering the entire construction area. Concrete core samples are taken at 50m intervals. 2 A set of standard samples were drilled for testing, including material performance parameters such as elastic modulus and coefficient of thermal expansion. By integrating this data, a BIM 3D structural model was constructed, which includes material performance parameters, temperature gradient distribution, and stress state, accurately reflecting the actual working conditions of the diaphragm wall.

[0045] A full-section scan of the constructed section was performed using a 3D laser scanner (accuracy ±1mm) to obtain surface topography data of the diaphragm wall. Simultaneously, data was collected every 50m... 2 Take a set of standard drilled concrete core samples, and test the following: elastic modulus (28d value 35-45GPa), coefficient of thermal expansion (8-12×10⁻⁶). -6 The data includes: temperature (°C), tensile strength (2.5-3.5MPa), and creep coefficient (1.5-2.5). The scanning data and core sample test results are integrated to construct a BIM three-dimensional structural model. The model includes: material performance parameter matrix (resolution 0.5m×0.5m), temperature gradient field (monitoring point spacing 2m), and stress state cloud map (based on initial finite element calculation).

[0046] S2. Based on the BIM 3D structural model, stress zoning is performed on the diaphragm wall. The self-constrained stress value of the concrete at a single point is calculated based on the temperature gradient and constraint conditions of the stress zoning. The attenuation coefficient of stress transmission is determined based on the material continuity between adjacent areas. An expansion agent ratio optimization model is established based on the attenuation coefficient and the self-constrained stress value. An initial material ratio scheme is generated based on the expansion agent ratio optimization model. The initial material ratio scheme is input into the BIM 3D structural model, and the stress redistribution under different expansion agent dosage gradients is simulated using the finite element algorithm. The critical dosage that meets the preset stress homogenization index is selected as the minimum effective dosage. The minimum effective dosage is dynamically simulated using the BIM 3D structural model to obtain simulation results. When the simulation results meet the preset crack resistance constraint conditions, the final ratio scheme is output. The simulation results include temperature stress cloud maps and crack propagation paths.

[0047] Based on temperature gradients, constraint conditions, and material properties, the diaphragm wall is divided into a high-stress zone (e.g., the surface layer 0-30cm), a medium-stress zone (30-60cm), and a low-stress zone (60cm to the wall center). For each stress zone, the self-constraining stress value of the concrete at a single point is calculated. The stress value in the surface area can reach 2.5-3.5MPa, while it drops to 0.8-1.2MPa in the core area. Simultaneously, considering the material continuity between adjacent areas, the stress transfer attenuation coefficient is determined, typically between 0.7 and 0.95. The finite element method can simulate the coupling effect of the temperature and stress fields of concrete with millimeter-level accuracy. By analyzing the stress distribution under 4-6 different expansion agent dosage gradients (e.g., 3%, 5%, 7%), the critical dosage that meets the preset stress homogenization index (e.g., stress difference not exceeding 0.5MPa) is selected and determined as the minimum effective dosage.

[0048] S3. Based on the final mix design, generate construction parameters and map them to the spatial coordinates of the BIM 3D structural model. Output high-risk areas through a visualization interface. The construction parameters include layer pouring thickness, curing regime, and temperature control standards. The final mix design is optimized according to stress zoning. The expansion agent dosage can reach 6-8% in high-stress areas, 3-5% in medium-stress areas, and 1-2% in low-stress areas. The layer pouring thickness is controlled within the range of 30-50cm. A zone-differentiated curing regime is adopted, with the surface area kept moist for more than 7 days and the core area using thermal insulation curing. The high-risk areas are presented intuitively through the visualization interface, including high tensile stress areas and potential crack propagation paths, with different color indicators to represent risk levels. This allows construction personnel to take targeted preventive measures and effectively control the cracking risk of the diaphragm wall concrete.

[0049] Specifically, firstly, a BIM 3D structural model incorporating material properties, temperature gradients, and stress states is constructed using 3D laser scanning and core sample testing. Then, stress zoning is performed based on the model, and the self-constraining stress values ​​and stress transmission attenuation coefficients of each zone are calculated. Next, an expansion agent ratio optimization model is established, and the stress redistribution under different dosage gradients is simulated using the finite element method to screen the minimum effective dosage that meets the stress homogenization index. After verifying the crack resistance effect through dynamic simulation, the final mix design is output. This invention combines BIM technology with material gradient design, achieving precise control of the self-constraining stress of diaphragm wall concrete and proactive optimization of its crack resistance performance. It solves the technical problem that traditional homogeneous material design cannot adapt to complex stress distributions, significantly improving the durability and safety of diaphragm wall structures.

[0050] In the above embodiments, specifically, the method of obtaining the simulation result by dynamically simulating the minimum effective admixture through a BIM three-dimensional structural model, and outputting the final mix proportion scheme when the simulation result meets the preset crack resistance constraint conditions, includes:

[0051] Based on the spatial distribution of material zones and the curing time and temperature development rate, the synergistic effect of stress fields in adjacent areas under different construction sequences is calculated, and the construction sequence with a synergistic effect greater than the preset synergistic threshold is selected as the optimal construction scheme.

[0052] When the peak temperature stress or crack propagation length in the simulation results exceeds the preset safety threshold, the minimum effective dosage and synergistic effect are recalculated until the simulation results meet the preset crack resistance constraints.

[0053] It should be noted that the implementation details of the synergy effect analysis include:

[0054] (1) Material zoning parameter settings include surface compensation zone (0-30cm thickness range), middle transition zone (30-65cm thickness range), and core stability zone (>65cm thickness range):

[0055] Surface compensation zone (0-30cm thickness range): A double-layer expansion agent system is adopted. The outer 5cm range uses fast-reacting CSA expansion agent (dosage 8%), and the inner 25cm range uses slow-release MgO expansion agent (dosage 3%).

[0056] A temperature sensor array with a spacing of 1.5m × 1.5m was set up to monitor changes in temperature gradient in real time.

[0057] The middle transition zone (thickness range of 30-65cm): adopts a gradient decreasing ratio, with the amount of expansion agent decreasing by 0.7% for every 10cm of thickness; stress monitoring optical fibers are installed, with one set every 3m along the length of the wall;

[0058] Core stability zone (thickness > 65cm): uses a single MgO expanding agent (dosage 1.5%); pre-embedded cooling water pipe system, pipe spacing 0.8m;

[0059] (2) Temperature development monitoring includes monitoring of key periods after pouring and real-time early warning triggered by abnormal conditions;

[0060] Monitoring during key periods after pouring: 0-12h: data collected every 30 minutes; 12-72h: data collected every hour; after 72h: data collected every 6 hours.

[0061] Real-time warning triggered by abnormal conditions: An alarm is activated when the temperature difference between adjacent measuring points exceeds 5℃ / m.

[0062] The construction sequence optimization process includes initial scheme generation, synergy effect evaluation, and optimal scheme selection criteria;

[0063] Initial scheme generation: Three basic construction sequences are automatically generated based on the BIM model:

[0064] Option A: Segmented construction from east to west;

[0065] Option B: Construction proceeds symmetrically from the center outwards;

[0066] Option C: Divide construction into blocks according to structural units;

[0067] Synergistic effect assessment: Three-dimensional simulation was performed for each scheme, with a focus on analyzing: stress transfer efficiency at the joints of adjacent construction sections; temperature gradient at the interface between new and old concrete; and the matching degree of the reaction time of the expansion agent.

[0068] The optimal solution selection criteria must simultaneously meet the following conditions: stress transfer efficiency ≥ 0.85; interface temperature difference ≤ 8℃; and peak reaction time difference of the expanding agent ≤ 2h.

[0069] Through refined zoning control, real-time monitoring and feedback, and dynamic adjustment mechanisms, a systematic improvement in the crack resistance of concrete structures, precise control of the construction process, and reliable assurance of project quality have been achieved.

[0070] In the above embodiments, specifically, the method for establishing an expansion agent ratio optimization model based on the attenuation coefficient and the self-constraining stress value, and generating an initial material ratio scheme based on the expansion agent ratio optimization model, includes:

[0071] Based on the attenuation coefficient and the self-constraint stress value, a multi-objective optimization function is constructed with the objectives of minimizing the total expansion dose and maximizing the stress superposition uniformity of adjacent regions.

[0072] The multi-objective optimization function is iteratively generated using a particle swarm optimization algorithm to generate a candidate solution set for the material mix ratio; Pareto front solutions are extracted from the candidate solution set, and the optimal material mix ratio is selected from the Pareto front solutions according to a preset construction economic weight; the optimal material mix ratio is then mapped to the material system of the BIM three-dimensional structural model to obtain an initial mix ratio scheme.

[0073] The initial mix design is verified using a BIM 3D structural model to determine whether the material continuity between adjacent areas causes the stress transfer attenuation coefficient to exceed a preset attenuation threshold. If it exceeds the preset attenuation threshold, the material mix is ​​adjusted to meet the attenuation coefficient constraint.

[0074] It should be noted that the construction of a multi-objective optimization model includes setting the optimization objective and setting the constraints;

[0075] Optimize target settings:

[0076] Objective 1: Minimize total expansion dose;

[0077] Calculate the total amount of expansion agent used in each zone, including: CSA expansion agent (unit price 12 yuan / kg) and MgO expansion agent (unit price 8 yuan / kg);

[0078] Objective 2: Maximize stress uniformity: Evaluated using the stress coefficient of variation;

[0079] Constraint settings: Surface stress limit: ≤3.0MPa; Core stress limit: ≤1.5MPa; Stress difference between adjacent zones: ≤0.5MPa; Expansion agent dosage range: CSA: 3-8%; MgO: 1-3%;

[0080] The implementation of the particle swarm optimization algorithm includes parameter setting and particle encoding;

[0081] Parameter settings: Number of particles: 80; Number of iterations: 150 generations; Learning factor c1 = 1.5; Inertia weight w = 0.9 → 0.4, decreasing linearly.

[0082] Particle coding: Each particle represents a set of proportions: Surface compensation zone: 1% CSA content + 1% MgO content; Middle transition zone: 2% CSA content + 2% MgO content; Core stable zone: 3% CSA content + 3% MgO content;

[0083] Pareto solution set processing includes frontier solution extraction and optimal solution selection;

[0084] Frontier solution extraction: 50 non-dominated solutions were selected from the final generation population after processing by the particle swarm optimization algorithm;

[0085] Optimal solution selection: Based on the economic weight (0.65), the overall score is calculated as follows: Comprehensive score = 0.65 × (cost standardized value) + 0.35 × (uniformity standardized value); the highest-scoring scheme is selected as the optimal material ratio.

[0086] This implementation process achieves an optimal balance between the economy and performance of material proportions, and precise control over stress transfer effects.

[0087] In the above embodiments, specifically, the method for verifying whether the material continuity between adjacent regions causes the stress transfer attenuation coefficient to exceed a preset attenuation threshold includes:

[0088] Based on the material distribution data in the BIM 3D structural model, the material performance gradient and transition section length between adjacent construction zones are extracted, and the material continuity index is calculated. The material continuity index is the ratio of the transition section length to the distance between adjacent zones. The material continuity index and temperature gradient data are used to simulate the stress transmission path in heterogeneous materials through the finite difference method, and the actual attenuation coefficient is calculated.

[0089] If the actual attenuation coefficient is greater than the preset attenuation threshold, the material ratio is adjusted according to the angle between the material performance gradient and the stress transmission direction, and the continuity index and actual attenuation coefficient of the adjusted area are recalculated. If the actual attenuation coefficient is still greater than the preset attenuation threshold after a preset number of adjustments, the adjusted area is marked as a high stress concentration area in the BIM three-dimensional structural model, and a ratio compensation command is triggered.

[0090] It should be noted that the material continuity testing process includes: using a BIM model to extract parameters from adjacent construction areas (such as the section from chainage K2+100 to K2+150), including material property gradient, transition section characteristics, and temperature gradient data;

[0091] The material property gradient is defined as: the rate of change of elastic modulus (0.3-0.5 GPa / m); the transition section characteristics are defined as: length (1.2-1.8 m) and inclination angle (15-35°); the temperature gradient data is defined as: temperature difference along the thickness direction (8-12℃ / m).

[0092] The continuity index is calculated using the moving window method:

[0093] Continuity index = Measured length of transition section / Theoretical smooth transition length;

[0094] Example: When the transition section is 1.5m long and the theoretical value is 1.6m, the continuity index is 0.94;

[0095] Through the above steps, a BIM-based continuous dynamic evaluation system was established, which achieved precise matching between material properties and structural response, effectively improved the stress transfer efficiency of heterogeneous material interfaces, and ensured the integrity of the structure.

[0096] In the above embodiments, specifically, the method of adjusting the material ratio according to the angle between the material property gradient and the stress transmission direction and recalculating the continuity index and actual attenuation coefficient of the adjustment area includes:

[0097] Based on the geometric relationship between the material property gradient and the stress transmission direction in the three-dimensional space of the BIM three-dimensional structural model, the cosine value of the included angle is calculated. If the cosine value of the included angle is greater than a preset angle cosine value threshold, the proportion is adjusted along the direction perpendicular to the material gradient; if the cosine value of the included angle is less than or equal to the preset angle cosine value threshold, the proportion is adjusted along the direction parallel to the material gradient.

[0098] After each adjustment, the material continuity index of adjacent intervals is recalculated based on the updated proportioning scheme; if the actual attenuation coefficient after adjustment is greater than the preset attenuation threshold, the material proportioning is adjusted incrementally according to the preset step size.

[0099] It should be noted that the process for adjusting the material ratio includes:

[0100] The parameters extracted from the BIM model include the material property gradient direction vector (based on the rate of change of elastic modulus) and the principal stress transfer direction vector (based on the finite element analysis results);

[0101] The cosine value between the material property gradient direction vector and the stress transfer direction vector is calculated by the angle in three-dimensional space. The calculation is performed using the vector dot product formula, with a preset cosine value threshold of 0.7, corresponding to an angle of 45 degrees.

[0102] When the cosine value is greater than 0.7, the specific implementation measures are as follows: the CSA content in the surface compensation zone is increased from 7% to 7.5%, and the MgO content in the middle transition zone is increased from 2% to 2.3%.

[0103] When the cosine value is less than or equal to 0.7, the specific implementation measure is to adjust the gradient change rate from 0.5 GPa / m to 0.4 GPa / m;

[0104] The above steps established an intelligent adjustment algorithm based on three-dimensional spatial relationships, developed an iterative optimization mechanism for quantitative control, and achieved precise coordination between material properties and structural stress.

[0105] In the above embodiments, specifically, the method of calculating the synergistic effect of stress fields in adjacent areas under different construction sequences based on the spatial distribution of material zones, curing time sequence, and temperature development rate, and selecting the construction sequence with a synergistic effect greater than a preset synergistic threshold as the optimal construction scheme includes:

[0106] Based on the material zoning spatial distribution generated by the expansion agent ratio optimization model, the three-dimensional stress transfer vector between adjacent regions is calculated based on the zoning spatial distribution, and the theoretical time reference for temperature stress development between adjacent regions is determined based on the temperature development rate corresponding to the material properties of each stress zone in the BIM three-dimensional structural model.

[0107] Based on the theoretical time reference, a dynamic candidate interval for the maintenance sequence is established to obtain a set of candidate schemes for the arrangement and combination of construction sequences. The matching degree between the construction time difference and stress development time of each construction sequence in the candidate scheme set is calculated based on the three-dimensional stress transfer vector and temperature development rate. The ratio of the superimposed stress peak value to the single-zone stress peak value is quantified as a synergistic effect through numerical simulation.

[0108] If the synergistic effect of multiple construction sequence combinations exceeds the preset synergistic threshold, the optimal construction scheme is selected based on the principle of minimizing the total sum of maintenance time.

[0109] In the above embodiments, specifically, the method for obtaining a set of candidate schemes for construction sequence arrangement and combination based on the dynamic candidate interval of the maintenance time sequence established according to the theoretical time reference includes:

[0110] Based on the maintenance time sequence range within the dynamic candidate interval, a set of candidate construction time points is generated for each construction area. The set of candidate construction time points is evenly distributed according to a preset interval based on the theoretical time benchmark of stress development.

[0111] Based on the spatial distribution topology of the material partitions, adjacency constraint rules for the construction sequence are established. The adjacency constraint rules and the set of candidate construction time points are traversed through all construction sequence permutations and combinations using a depth-first search algorithm to obtain a set of candidate schemes. Conflict analysis is then performed on the construction sequence permutations and combinations in the set of candidate schemes.

[0112] It should be noted that, based on the material zoning spatial distribution generated by the expansion agent ratio optimization model, the three-dimensional stress transfer vector between adjacent regions (including horizontal distance, vertical height difference, and material contact surface orientation information) is calculated. This is then combined with the material properties of each stress zone in the BIM three-dimensional structural model (such as concrete strength grade, expansion agent dosage, thermal conductivity, etc.) to determine the temperature development rate. For example, when C50 high-strength concrete contains 8% magnesium oxide expansion agent, the temperature stress development rate is 1.2 MPa / day; when C30 ordinary concrete contains 5% expansion agent, it is 0.8 MPa / day; and in the lightweight aggregate concrete region, it drops to 0.5 MPa / day. Based on this, a theoretical time benchmark for temperature stress development between adjacent regions is established.

[0113] Based on the theoretical time baseline, a dynamic candidate range for the curing sequence is established (e.g., ±20% of the theoretical value, with candidate time points set at 2-day intervals), forming a set of candidate schemes for arranging and combining construction sequences. For each scheme, the matching degree between the construction time difference between adjacent areas and the stress development time is calculated.

[0114] The peak value of superimposed stress is quantified by finite element numerical simulation. For example, when the construction interval between adjacent areas is equal to the theoretical stress transfer time, the ratio of the peak value of superimposed stress to the peak value of stress in a single area can reach 0.9-1.1 (ideal coordinated range).

[0115] If the time difference deviates from the theoretical value by more than 15%, the ratio may exceed the safe range of 0.7-1.3, resulting in adverse cumulative effects.

[0116] Set a synergy effect threshold (e.g., a ratio between 0.8 and 1.2 indicates effective synergy), screen qualified solutions, and when multiple solutions meet the criteria, prioritize the solution with the shortest total curing period. For example, in the construction of a large-volume concrete structure:

[0117] Option A: Total maintenance period of 42 days, synergy ratio of key areas 1.05;

[0118] Option B: Total maintenance period 38 days, synergy ratio 0.95;

[0119] Option C: Total maintenance period 45 days, synergy ratio 1.10;

[0120] Option B is chosen as the optimal construction option because it achieves the shortest construction period while meeting the synergy requirements (synergy effect ratio > 0.9).

[0121] Construction sequence constraints include:

[0122] The core tube is constructed before the outer frame structure (prioritizing high-constraint areas);

[0123] Vertical components should be cured earlier than horizontal components (to avoid the superposition of gravity loads);

[0124] Thick, large-section areas are constructed using a layered, progressive construction method (to control the temperature rise gradient);

[0125] By analyzing the spatial topology of the 3D BIM model, permutations and combinations that violate basic construction logic are automatically eliminated, thus improving computational efficiency.

[0126] In the above embodiments, specifically, the method for conflict analysis of the construction sequence arrangement and combination in the candidate scheme set includes:

[0127] Based on the spatial distribution and temperature propagation rate data of the construction area in the BIM 3D structural model, a spatiotemporal influence matrix of the construction area is constructed. Each element in the spatiotemporal influence matrix indicates whether the construction time difference between adjacent areas is less than the theoretical time required for temperature stress to develop to the adjacent area. For example, for two construction areas 5 meters apart, if the temperature stress propagation rate is 2 meters / day and the theoretical propagation time is 2.5 days, then the matrix is ​​marked to indicate whether the time difference is less than this value.

[0128] Each construction sequence arrangement is iterated through. When the construction time difference between adjacent areas is less than the theoretical time reference, resulting in an abnormal stress increase in the stress superposition area exceeding the preset abnormal stress increase threshold (e.g., exceeding 15% of the design strength), it is determined to be a time superposition interference. Based on the spatial coordinates of the construction area in the BIM 3D structural model, the spatial overlap area of ​​the temperature stress development path of adjacent areas under different construction sequences is calculated. If the stress concentration coefficient in the spatial overlap area exceeds the preset concentration coefficient threshold (e.g., 1.5 times the average stress), it is determined to be a path overlap interference conflict. Construction sequence arrangements with time superposition interference or path overlap interference conflicts are marked and removed.

[0129] Based on the spatial topology of the construction area, adjacency constraint rules for the construction sequence are established. These adjacency constraint rules and the spatiotemporal influence matrix are then combined using a depth-first search algorithm to traverse all construction sequences, resulting in a set of candidate solutions. The adjacency constraint rules consider construction process requirements, such as principles like "progressing from the core tube to the cantilever" and "construction from the substructure to the superstructure." For example, in the concrete pouring of high-rise buildings, a constraint is set that "lower-level vertical components must be constructed before upper-level horizontal components" to ensure structural stability. The depth-first search algorithm can efficiently handle constraint calculations for medium-sized projects (e.g., 20-30 construction areas), typically completing solution selection within minutes.

[0130] In the above embodiments, specifically, the method for generating construction parameters based on the final mix design and mapping them to the spatial coordinates of the BIM three-dimensional structural model includes:

[0131] The coordinate data and corresponding stress zones of each construction area are extracted from the BIM 3D structural model. The material parameters of a single area are generated by combining the final mix design. The material parameters of a single area are dynamically corrected according to the initial dosage threshold and material gradient of the stress zone to which the construction area belongs.

[0132] The material parameters of the single zone are mapped to the corresponding construction zone coordinates to form a structured construction parameter set and stored in the material parameter database of the BIM three-dimensional structural model.

[0133] It should be noted that the coordinate data of each construction zone and the corresponding stress zones (such as high-constraint zones, transition zones, free deformation zones, etc.) are extracted from the BIM 3D structural model, and combined with the final mix design to generate single-zone material parameters (such as concrete strength grade, expansion agent dosage, fiber dosage, etc.). These single-zone material parameters are dynamically corrected based on the initial dosage threshold and material gradient of the stress zone to which the construction zone belongs.

[0134] The initial expansion agent dosage threshold in highly constrained areas (such as core tubes and thick shear walls) may be set at 8%-10%, and adjusted by ±1% according to the material gradient of adjacent areas to ensure a smooth stress transition.

[0135] The initial dosage in the transition zone (such as the junction of the floor slab and the wall) is set at 5%-7%, and then finely adjusted by ±0.5% based on the results of temperature stress simulation.

[0136] The initial dosage in the free deformation zone (such as cantilever slabs and thin-walled structures) is reduced to 3%-5%, and dynamically optimized based on deformation monitoring data;

[0137] The material parameters of each single zone (including material proportions, curing start time, temperature control indicators, etc.) are mapped to the corresponding construction zone coordinates to form a structured construction parameter set, which is then stored in the material parameter database of the BIM 3D structural model. The structured parameter set includes: construction zone ID (e.g., B1-3F-CORE-01); 3D coordinates (X / Y / Z axis positioning); stress zoning type (high / medium / low constraint level); and material parameters (e.g., C40P8 concrete, MgO content 9%, polypropylene fiber 1.2kg / m³). 3 Construction sequence (pouring sequence number, curing start time);

[0138] This database allows construction teams to access parameters in real time via mobile devices, ensuring precise execution on-site. It also provides a complete data chain for subsequent structural health monitoring and parameter retrospective analysis. For example, in the skip-construction method for super high-rise buildings, the difference in expansion agent gradient between the core tube and the outer frame can be strictly controlled based on the mapped data to avoid localized stress concentration.

[0139] It should be understood that the above embodiments are one or more embodiments of the present invention, and there are many other embodiments and variations based on the present invention; any variations and modifications made by those skilled in the art through the present invention without making pioneering innovations are all within the protection scope of the present invention.

Claims

1. A gradient-combination crack-resistant diaphragm wall concrete self-constrained stress optimization design method, characterized in that, The method includes: Geological environment data, structural design parameters and historical construction data of the diaphragm wall project area are obtained, and a BIM three-dimensional structural model including material performance parameters, temperature gradient distribution and stress state is constructed through three-dimensional laser scanning and concrete core sample testing. The diaphragm wall is stress-zoned according to the BIM 3D structural model. The self-constrained stress value of the concrete at a single point is calculated based on the temperature gradient and constraint conditions of the stress zones. The attenuation coefficient of stress transfer is determined based on the material continuity between adjacent areas. An expansion agent ratio optimization model is established based on the attenuation coefficient and the self-constrained stress value. An initial material ratio scheme is generated based on the expansion agent ratio optimization model. The initial material ratio scheme is input into the BIM 3D structural model, and the stress distribution under different expansion agent dosage gradients is simulated using the finite element method. The critical dosage that meets the preset stress homogenization index is selected as the minimum effective dosage. The minimum effective dosage is dynamically simulated using the BIM 3D structural model to obtain simulation results. When the simulation results meet the preset crack resistance constraint conditions, the final ratio scheme is output. The simulation results include temperature stress cloud maps and crack propagation paths. Based on the final mix design, construction parameters are generated and mapped to the spatial coordinates of the BIM 3D structural model. High-risk areas are output through a visualization interface. The construction parameters include the layer thickness, curing regime, and temperature control standards. The method for establishing an expansion agent ratio optimization model based on the attenuation coefficient and the self-constraining stress value, and generating an initial material ratio scheme based on the expansion agent ratio optimization model, includes: Based on the attenuation coefficient and the self-constraint stress value, a multi-objective optimization function is constructed with the objectives of minimizing the total expansion dose and maximizing the stress superposition uniformity of adjacent regions. The multi-objective optimization function is iteratively generated using a particle swarm optimization algorithm to generate a candidate solution set for the material mix ratio; Pareto front solutions are extracted from the candidate solution set, and the optimal material mix ratio is selected from the Pareto front solutions according to a preset construction economic weight; the optimal material mix ratio is then mapped to the material system of the BIM three-dimensional structural model to obtain an initial mix ratio scheme. The initial mix design is verified using a BIM 3D structural model to determine whether the material continuity between adjacent areas causes the stress transfer attenuation coefficient to exceed a preset attenuation threshold. If it exceeds the preset attenuation threshold, the material mix is ​​adjusted to meet the attenuation coefficient constraint.

2. The gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method according to claim 1, characterized in that, The method for obtaining the simulation results by dynamically simulating the minimum effective admixture using a BIM three-dimensional structural model, and outputting the final mix design when the simulation results meet the preset crack resistance constraints, includes: Based on the spatial distribution of material zones and the curing time and temperature development rate, the synergistic effect of stress fields in adjacent areas under different construction sequences is calculated, and the construction sequence with a synergistic effect greater than the preset synergistic threshold is selected as the optimal construction scheme. When the peak temperature stress or crack propagation length in the simulation results exceeds the preset safety threshold, the minimum effective dosage and synergistic effect are recalculated until the simulation results meet the preset crack resistance constraints.

3. The gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method according to claim 1, characterized in that, The method for verifying whether the material continuity between adjacent regions causes the stress transfer attenuation coefficient to exceed a preset attenuation threshold includes: Based on the material distribution data in the BIM 3D structural model, the material performance gradient and transition section length between adjacent construction zones are extracted, and the material continuity index is calculated. The material continuity index is the ratio of the transition section length to the distance between adjacent zones. The material continuity index and temperature gradient data are used to simulate the stress transmission path in heterogeneous materials through the finite difference method, and the actual attenuation coefficient is calculated. If the actual attenuation coefficient is greater than the preset attenuation threshold, the material ratio is adjusted according to the angle between the material performance gradient and the stress transmission direction, and the continuity index and actual attenuation coefficient of the adjusted area are recalculated. If the actual attenuation coefficient is still greater than the preset attenuation threshold after a preset number of adjustments, the adjusted area is marked as a high stress concentration area in the BIM three-dimensional structural model, and a ratio compensation command is triggered.

4. The gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method according to claim 3, characterized in that, The method of adjusting the material ratio based on the angle between the material property gradient and the stress transmission direction, and recalculating the continuity index and actual attenuation coefficient of the adjustment region, includes: Based on the geometric relationship between the material property gradient and the stress transmission direction in the three-dimensional space of the BIM three-dimensional structural model, the cosine value of the included angle is calculated. If the cosine value of the included angle is greater than a preset angle cosine value threshold, the proportion is adjusted along the direction perpendicular to the material gradient; if the cosine value of the included angle is less than or equal to the preset angle cosine value threshold, the proportion is adjusted along the direction parallel to the material gradient. After each adjustment, the material continuity index of adjacent intervals is recalculated based on the updated proportioning scheme; if the actual attenuation coefficient after adjustment is greater than the preset attenuation threshold, the material proportioning is adjusted incrementally according to the preset step size.

5. The gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method according to claim 2, characterized in that, The method for calculating the synergistic effect of stress fields in adjacent areas under different construction sequences based on the spatial distribution of material zones, curing time, and temperature development rate, and selecting the construction sequence with a synergistic effect greater than a preset synergistic threshold as the optimal construction scheme includes: Based on the material zoning spatial distribution generated by the expansion agent ratio optimization model, the three-dimensional stress transfer vector between adjacent regions is calculated based on the zoning spatial distribution, and the theoretical time reference for temperature stress development between adjacent regions is determined based on the temperature development rate corresponding to the material properties of each stress zone in the BIM three-dimensional structural model. Based on the theoretical time reference, a dynamic candidate interval for the maintenance sequence is established to obtain a set of candidate schemes for the arrangement and combination of construction sequences. The matching degree between the construction time difference and stress development time of each construction sequence in the candidate scheme set is calculated based on the three-dimensional stress transfer vector and temperature development rate. The ratio of the superimposed stress peak value to the single-zone stress peak value is quantified as a synergistic effect through numerical simulation. If the synergistic effect of multiple construction sequence combinations exceeds the preset synergistic threshold, the optimal construction scheme is selected based on the principle of minimizing the total sum of maintenance time.

6. The gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method according to claim 5, characterized in that, The method for obtaining a set of candidate schemes for construction sequence arrangement and combination based on the dynamic candidate interval of the maintenance time sequence according to the theoretical time benchmark includes: Based on the maintenance time sequence range within the dynamic candidate interval, a set of candidate construction time points is generated for each construction area. The set of candidate construction time points is evenly distributed according to a preset interval based on the theoretical time benchmark of stress development. Based on the spatial distribution topology of the material partitions, adjacency constraint rules for the construction sequence are established. The adjacency constraint rules and the set of candidate construction time points are traversed through all construction sequence permutations and combinations using a depth-first search algorithm to obtain a set of candidate schemes. Conflict analysis is then performed on the construction sequence permutations and combinations in the set of candidate schemes.

7. The gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method according to claim 6, characterized in that, The method for conflict analysis of the construction sequence arrangement and combination in the candidate scheme set includes: Based on the spatial distribution and temperature development rate data of the construction area in the BIM 3D structural model, a spatiotemporal influence relationship matrix of the construction area is constructed. Each element in the spatiotemporal influence relationship matrix indicates whether the construction time difference between adjacent areas is less than the theoretical time required for temperature stress to develop to the adjacent area. Each construction sequence arrangement is iterated through. When the construction time difference between adjacent areas is less than the theoretical time reference, resulting in an abnormal stress increase in the stress superposition area exceeding the preset abnormal stress increase threshold, it is determined to be a time superposition interference. Based on the spatial coordinates of the construction area in the BIM 3D structural model, the spatial overlap area of ​​the temperature stress development path of adjacent areas under different construction sequences is calculated. If the stress concentration coefficient in the spatial overlap area exceeds the preset concentration coefficient threshold, it is determined to be a path overlap interference conflict. Construction sequence arrangements with time superposition interference or path overlap interference conflicts are marked and removed.

8. The gradient combination anti-cracking diaphragm wall concrete self-constrained stress optimization design method according to claim 1, characterized in that, The method for generating construction parameters based on the final mix design and mapping them to the spatial coordinates of the BIM 3D structural model includes: The coordinate data and corresponding stress zones of each construction area are extracted from the BIM 3D structural model. The material parameters of each area are generated by combining the final mix design. The material parameters of each area are dynamically corrected according to the initial dosage threshold and material gradient of the stress zone to which the construction area belongs. The material parameters of the single zone are mapped to the corresponding construction zone coordinates to form a structured construction parameter set, which is then stored in the material parameter database of the BIM three-dimensional structural model.

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