Analytical method for soil pressure under supporting condition in foundation pit and influence effect of soil pressure

Abstract

The invention discloses a method for analyzing soil pressure under a supporting condition in a foundation pit and an influence effect of the soil pressure, and relates to the technical field of foundation pit engineering, and the method comprises the following steps: constructing an inter-pit soil pressure analysis model based on a basic assumption of a soil pressure theory, and calculating the soil pressure and the influence effect of the soil pressure; performing sensitivity analysis on the influence factors of the influence effects to obtain a main effect sequence of the influence factors; and performing finite element simulation, and comparing and verifying the consistency between a simulation result and a theoretical result. The inter-pit soil pressure analysis model constructed by the method can well reflect the soil pressure distribution and disturbance influence effect in the excavation process of the foundation pit; and sensitivity analysis and finite element analysis are performed, a simulation result and a theoretical result are compared and verified, the correctness of construction of the inter-pit soil pressure analysis model is verified, accurate calculation of the soil pressure and the influence effect of the soil pressure is realized, and accurate prediction of the soil pressure and the influence effect of the soil pressure in actual foundation pit engineering is facilitated.

Description

Technical Field

[0001] This invention relates to the field of foundation pit engineering technology, and more specifically, to an analytical method for earth pressure and its effects under support conditions within a foundation pit. Background Technology

[0002] As underground resource development continues to expand to deeper levels, and with the ongoing development of open-pit to underground mining and ultra-deep foundation pit engineering, the construction difficulty is increasing exponentially. For mine foundation pits, the need to erect internal supports and retaining structures during excavation significantly alters the displacement pattern of the soil and rock mass within a limited area, resulting in stress-strain paths that differ markedly from conventional conditions, exhibiting highly nonlinear stress-strain behavior. Accurately characterizing the surrounding rock pressure within a limited domain under such complex stress states has become a critical scientific problem urgently needing breakthroughs in fields such as energy infrastructure, mining development, and urban geotechnical engineering.

[0003] Currently, a series of studies have been conducted on earth pressure in finite soil masses. However, although the analysis of slip surfaces and earth pressure in finite soil masses is relatively mature, further research is needed on the distribution patterns and affected areas of earth pressure. Regarding the calculation of earth pressure and analysis of various influencing factors in foundation pit engineering, there is currently no earth pressure calculation model that comprehensively considers multiple factors and their interrelationships. This makes it impossible to quantify the disturbance range of foundation pit excavation. Furthermore, the lack of precise analysis of each influencing factor results in the absence of operational basis for predicting earth pressure distribution and disturbance effects during foundation pit excavation, thus affecting the implementation of actual projects. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide an analytical method for earth pressure and its influence under the condition of internal support in foundation pit, which solves the problem that the calculation of earth pressure and the analysis of its influencing factors under the condition of support in foundation pit engineering are unreliable and cannot meet the needs of engineering implementation.

[0005] To achieve the above objectives, embodiments of the present invention provide an analytical method for earth pressure and its effects under conditions of internal support in a foundation pit, comprising: Based on the basic assumptions of earth pressure theory, an earth pressure analysis model between pits is constructed to calculate earth pressure and its effects. Sensitivity analysis was performed on the factors influencing the effect to obtain the ranking of the main effects of the factors. Based on the ranking of the earth pressure and its effects with the main effects of the influencing factors, finite element simulation was performed to verify the consistency between the simulation results and the theoretical results.

[0006] In a preferred embodiment, the inter-pit earth pressure analysis model comprehensively considers the wall-soil interface friction effect, soil shear strength parameters, excavation depth, and support axial force.

[0007] In a preferred embodiment, the calculation of earth pressure and its effects includes: Calculate the soil pressure caused by excavation disturbance under unsupported conditions and its impact. Based on the soil pressure and its effects under unsupported conditions, a distribution force correction coefficient is introduced to calculate the soil pressure and its effects caused by excavation disturbance under supported conditions.

[0008] In a preferred embodiment, the calculation of soil pressure and its effects caused by excavation disturbance under unsupported conditions includes: Based on the principle of limit equilibrium and the geometric relationship of closed forces, the resultant earth pressure under unsupported conditions is derived. Based on the angular relationship between soil forces and closing forces, the numerical method is used to solve for the influence effect and the distribution of earth pressure along the wall height under unsupported conditions.

[0009] In a preferred embodiment, the calculation of soil pressure and its effects caused by excavation disturbance under supported conditions includes: By introducing a distributed force correction factor and using the distributed force simplification method, the internal forces of the support structure under supported conditions are calculated. Based on the earth pressure and its effects under unsupported conditions, the influence of the axial force of the foundation pit support is introduced. Based on the active earth pressure distribution pattern of the retaining wall under supported conditions, the earth pressure and its effects under supported conditions are obtained. Based on the theoretical calculation formula of the impact effect, the influencing factors of the impact effect and the law of change of the impact effect with respect to its influencing factors are obtained.

[0010] In a preferred embodiment, the earth pressure and its effects include the resultant earth pressure under supported conditions, the effects, and the distribution of earth pressure along the wall height; the influencing factors include the internal friction angle of the soil, the excavation depth of the foundation pit, and the wall-soil friction angle.

[0011] In a preferred embodiment, a sensitivity analysis is performed on the influencing factors of the impact effect to obtain the ranking of the main effects of the influencing factors, specifically: With the goal of obtaining the ranking of the main effects of influencing factors with the minimum number of experiments, orthogonal experimental design was used to obtain orthogonal results. Solve for the range of each influencing factor in the orthogonal results and sort them to obtain the main effect ranking of the influencing factors.

[0012] In a preferred embodiment, under supported conditions, the main effects of the influencing factors are ranked as follows: excavation depth of the foundation pit > internal friction angle of the soil > wall-soil friction angle.

[0013] In a preferred embodiment, based on the ranking of the earth pressure and its effects with the main effects of the influencing factors, finite element simulation is performed to compare and verify the consistency between the simulation results and the theoretical results. Specifically: Based on the theoretical calculation formula of earth pressure and its influence under supported conditions and the main effect ranking parameters of influencing factors, a three-dimensional finite element overall analysis model of the foundation pit is constructed. Taking into account the actual environmental data, the model size and boundary conditions of the three-dimensional finite element overall analysis model of the foundation pit were determined. Based on the three-dimensional finite element overall analysis model of the foundation pit, the finite element numerical simulation of a single soil layer and multiple soil layers is performed to obtain numerical solutions. By comparing the numerical and theoretical solutions of active earth pressure, the consistency between the simulated and theoretical variation laws of the influence effects of influencing factors is verified.

[0014] In a preferred embodiment, the actual environmental data includes: The complexity of foundation pit engineering, sensitivity to the surrounding environment, numerical accuracy, and simulation efficiency.

[0015] The beneficial effects of this invention are: By constructing an earth pressure analysis model between pits, a quantitative formula for earth pressure and its impact caused by excavation disturbance is proposed to calculate earth pressure and its impact. Sensitivity analysis of the influencing factors is then conducted to clarify the order of significance of each influencing factor under supported conditions, i.e., the ranking of the main effects of the influencing factors, revealing the variation law of the impact effect under different finite element analysis conditions and excavation stages. The simulation results obtained from finite element analysis are then compared and verified with the theoretical results obtained from theoretical calculations to confirm the correctness of the earth pressure analysis model and the consistency between the theoretical and simulation results calculated based on the model. This effectively reflects the earth pressure distribution and disturbance impact effect during foundation pit excavation, providing a theoretical basis for related foundation pit design and analysis. It enables accurate calculation of earth pressure and its impact under supported conditions, facilitating accurate prediction of earth pressure and its impact in actual foundation pit engineering to meet practical engineering needs. Attached Figure Description

[0016] Figure 1 A flowchart illustrating the analytical method for determining earth pressure and its effects under support conditions within an excavation pit. Figure 2 This is a schematic diagram of the soil stress during the excavation of the foundation pit; Figure 3 This is a schematic diagram of the forces during the excavation of the foundation pit; Figure 4 The graph shows the effect of the wall-soil friction angle on the curve. Figure 5 The graph shows the effect of friction angle within the soil as a function of the soil's internal friction angle. Figure 6 The graph shows the effect of the impact on the excavation depth. Figure 7 The graph shows the effect of the wall-soil friction angle on the curve. Figure 8 The graph shows the effect of friction angle within the soil as a function of the soil's internal friction angle. Figure 9 The graph shows the effect of the impact on the excavation depth. Figure 10 This is a schematic diagram of a cross-section of a single soil mass model; Figure 11 This is a cross-sectional view of a multi-layered soil foundation pit support structure. Figure 12 This is a diagram showing the distribution of soil pressure with burial depth for a single soil mass. Figure 13 This is a diagram showing the distribution of soil pressure with burial depth in multi-layered soil structures. Figure 14 The distribution of numerical earth pressure solution with excavation depth under the influence of internal friction angle; Figure 15 The numerical solution of earth pressure under the influence of wall-soil friction angle is shown as the distribution of earth pressure with excavation depth. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figure 1 An analytical method for earth pressure and its effects under internal support conditions in a foundation pit includes: constructing an earth pressure analysis model between pits based on the basic assumptions of earth pressure theory, calculating earth pressure and its effects; performing sensitivity analysis on the influencing factors of the effects, obtaining the main effect ranking of the influencing factors; and verifying the consistency between the simulation results and the theoretical results by comparing the earth pressure and its effects with the main effect ranking of the influencing factors through finite element simulation.

[0019] Based on the fundamental assumptions of earth pressure theory, an earth pressure analysis model for pit excavation is constructed, and a quantitative formula for earth pressure and its effects caused by excavation disturbance is proposed to calculate earth pressure and its effects. Sensitivity analysis of the influencing factors is then conducted to clarify the order of significance of each influencing factor under supported conditions, i.e., the ranking of the main effects of the influencing factors, revealing the variation law of the effects under different finite element analysis conditions and excavation stages. The simulation results obtained from finite element analysis are then compared and verified with the theoretical results obtained from theoretical calculations to confirm the correctness of the pit excavation earth pressure analysis model and the consistency between the theoretical and simulation results calculated based on the model. This effectively reflects the earth pressure distribution and disturbance effects during foundation pit excavation, providing a theoretical basis for related foundation pit design and analysis. It enables accurate calculation of earth pressure and its effects under supported conditions, facilitating accurate prediction of earth pressure and its effects in actual foundation pit engineering to meet practical engineering needs.

[0020] To improve the modeling accuracy of the inter-pit earth pressure analysis model, the model is constructed based on the basic assumptions of earth pressure theory, taking into account factors such as wall-soil interface friction effect, soil shear strength parameters, excavation depth, and support axial force.

[0021] To improve the accuracy of theoretical calculations, this embodiment further defines the calculation of earth pressure and its effects. The calculation of earth pressure and its effects includes: calculating the earth pressure and its effects caused by excavation disturbance under unsupported conditions; and, based on the earth pressure and its effects under unsupported conditions, introducing a distributed force correction coefficient to calculate the earth pressure and its effects caused by excavation disturbance under supported conditions. Specifically: S1 constructs an earth pressure analysis model between pits, theoretically calculates and analyzes earth pressure and its effects. The basic assumptions of S11 Coulomb's earth pressure theory Before constructing the earth pressure analysis model between pits, to simplify the derivation of earth pressure, the following basic assumptions are proposed based on Coulomb's earth pressure theory: (1) The potential rupture surface of a finite soil mass is simplified to a plane, and the fill slides along this sliding surface as a whole.

[0022] (2) The soil is homogeneous clay and homogeneous sand. Only gravity is considered, and there is no cohesion or the cohesion can be ignored. Among them, the clay is assumed to be in a dry state or under short-term non-drainage conditions, and the influence of pore water pressure on earth pressure is ignored; the friction effect between the interface between the flexible support structure and the soil is considered in the analysis of homogeneous sand.

[0023] (3) Treat the sliding soil wedge as a rigid body. When the retaining wall is displaced, the backfill behind the wall slides along a certain plane to form a rigid sliding wedge. The stress redistribution and deformation inside the wedge are not considered.

[0024] (4) Assume that the soil wedge is in a state of limit equilibrium and meets the Mohr-Coulomb strength criterion, that is, the shear stress reaches the shear strength and the internal and external action relationship satisfies the static equilibrium requirement.

[0025] S12 Calculation of Earth Pressure Caused by Excavation Disturbance and Its Impact under Unsupported Conditions The calculation of soil pressure and its effects caused by excavation disturbance under unsupported conditions includes: deriving the resultant soil pressure under unsupported conditions based on the principle of limit equilibrium and the geometric relationship of closing forces; and using numerical methods to solve for the effects and the distribution of soil pressure along the wall height under unsupported conditions based on the angular relationship between soil forces and closing forces.

[0026] Calculate the soil pressure and its effects, and analyze the factors influencing these effects: S121 Calculation of the resultant earth pressure on the soil Please see Figure 2 During the excavation of the foundation pit, when the finite soil mass between the pits slides, the soil fracturing surface extends and unfolds towards the ground surface, forming a sliding wedge with a stable triangular boundary. Based on the principle of limit equilibrium, the weight of soil per meter of the sliding wedge can be derived. The expression is as follows:

[0027] In the formula, This refers to the depth of the foundation pit excavation. The impact of excavation; The unit weight of the soil is given.

[0028] At this point, the soil fracture angle The expression is:

[0029] Please see Figure 3 ,gravity Earth pressure resultant force and reaction force The resultant earth pressure can be obtained from geometric relationships forming a closed triangle of forces. for:

[0030] Where: internal friction angle of soil Wall-soil friction angle ; soil fracture angle .

[0031] S122 calculates the impact effect and the distribution of earth pressure along the wall height, and analyzes the parameters of the impact effect based on the impact effect. Due to the weight of the earth wedge Too The function, therefore when and After setting a fixed value, Just A single-valued function, soil rupture angle It can be determined by the resultant force of earth pressure. The extreme value is obtained, that is:

[0032] Solved using numerical methods ,make ,but ,have: Solving for:

[0033]

[0034] Therefore, when the excavation depth H of the foundation pit is increased, the internal friction angle of the soil is increased. Wall-soil friction angle Once determined, the effect B can be calculated.

[0035] Please see Figures 4-6 Under different conditions without internal support, the effect B is influenced by the soil internal friction angle. Wall-soil friction angle The impact is influenced by three factors: the depth of the foundation pit (H), and the excavation depth (H). Specifically: Please see Figure 4 When the excavation depth of the foundation pit is H=13 m and the internal friction angle of the soil is... When the angle is 20°, the effect B varies with the friction angle of the wall back-fill interface. Corresponding curves showing the changes; Please see Figure 5 When the excavation depth of the foundation pit is H=13 m and the friction angle of the wall-soil interface is... When the angle is 5°, the effect B varies with the internal friction angle of the soil. Corresponding curves showing the changes; Please see Figure 6 When the internal friction angle of the soil Take 20°, wall-soil friction angle The curve showing the relationship between the influence effect B and the excavation depth H under the condition of 7°. from Figure 4 and Figure 6 It can be seen that, with the wall-soil friction angle As the excavation depth H of the foundation pit increases, the impact effect B also increases, which is consistent with engineering practice and confirms the correctness of the theoretical calculation of the impact effect B under unsupported conditions; from Figure 5 It can be known that the internal friction angle of the soil The increase is negatively correlated with the effect B; therefore, soil reinforcement can effectively reduce the effect B.

[0036] The distribution pattern of earth pressure along the wall height can be derived by differentiating the formula for calculating the resultant earth pressure E under unsupported conditions:

[0037] To facilitate the determination of the excavation effect B and the wall-soil friction angle and the angle of rupture of the soil The relationship between B and its effect simplifies the formula for calculating the effect B to B and , The relevant function is denoted as .

[0038]

[0039] S13, based on the earth pressure and its effects caused by excavation disturbance under unsupported conditions, introduces a distributed force correction coefficient to calculate the earth pressure and its effects caused by excavation disturbance under supported conditions. The calculation of soil pressure and its effects caused by excavation disturbance under supported conditions includes: introducing a distributed force correction coefficient and using a distributed force simplification method to calculate the internal forces of the support structure under supported conditions; based on the soil pressure and its effects under unsupported conditions, introducing the influence of the axial force of the foundation pit support, and obtaining the soil pressure and its effects under supported conditions based on the active soil pressure distribution pattern of the retaining wall under supported conditions; and obtaining the influencing factors of the effects and the law of change of the effects with respect to the influencing factors based on the theoretical calculation formula of the effects.

[0040] The earth pressure and its effects include the resultant earth pressure under supported conditions, the effects, and the distribution of earth pressure along the wall height; the influencing factors include the internal friction angle of the soil, the excavation depth of the foundation pit, and the wall-soil friction angle.

[0041] Calculate the soil pressure and its effects, and analyze the factors influencing these effects: S131 Calculation of the resultant earth pressure on the soil In the design of foundation pits, a distribution force correction factor is introduced, and the distribution force simplification method is used to calculate the internal forces of the support structure. The distribution force simplification method refers to converting the earth pressure distribution into an equivalent distribution force.

[0042] By introducing a distributed force correction factor, it can be reflected that the actual earth pressure distribution is not completely linear or triangular; at the same time, it can also reflect the influence of factors such as the deformation mode of the support structure, pit depth, excavation conditions, and soil parameters on the earth pressure distribution. In the correction calculation, it is ensured that the calculated internal forces and deformations of the support structure are closer to reality. Assume... ,in, For distributed force, This is the distributed force correction factor.

[0043] When calculating the distribution pattern of active earth pressure on the retaining wall under supported conditions, the influence of the axial force of the foundation pit support is introduced, namely: Calculation When the earth pressure is in an active state When the earth pressure is in a passive state .

[0044] in accordance with Figure 3 Given a polygon with moderate forces, the expression for the resultant earth pressure E under supported conditions is:

[0045] S132 calculates the impact effect and the distribution of earth pressure along the wall height, and analyzes the parameters of the impact effect based on the impact effect. Similarly, the angle of rupture of soil It can be achieved through combined force The extreme value is obtained, that is:

[0046] Substituting into the formula for calculating effect B, we get:

[0047] Therefore, when the excavation depth H of the foundation pit is increased, the internal friction angle of the soil is increased. Wall-soil friction angle Once determined, the effect B can be calculated.

[0048] Please see Figures 7-9 Under different internal support conditions, the effect B is influenced by the soil internal friction angle. Wall-soil friction angle The impact of three factors is on the excavation depth H of the foundation pit. Please refer to Table 1, where the parameters of the internal support are given under the condition of support: Table 1: Support Parameter Table for the Case Study under Supported Conditions

[0049] Please see Figure 7 When the excavation depth of the foundation pit is H=13 m and the internal friction angle of the soil is... When the angle is 20°, the effect B varies with the wall-soil friction angle. A curve showing the corresponding relationship between the changes; Please see Figure 8 When the excavation depth of the foundation pit is H=13 m and the friction angle of the wall-soil interface is... At that time, the effect B varies with the internal friction angle of the soil. Corresponding curves showing the changes; Please see Figure 9 When the internal friction angle of the soil =20°, friction angle at the wall-soil interface The curve showing the relationship between the influence effect B and the excavation depth H of the foundation pit at a depth of 7°.

[0050] from Figures 7-9 It can be seen that the larger the distributed force correction coefficient, the more obvious the reduction in the impact effect, which is consistent with engineering practice and confirms the correctness of the theoretical calculation of the impact effect B under supported conditions.

[0051] The distribution pattern of earth pressure along the wall height can be derived by differentiating the formula for calculating the resultant earth pressure E under supported conditions, i.e.:

[0052] To better perform sensitivity analysis on the influencing factors of the impact effect, this embodiment further specifies the requirements. Sensitivity analysis is performed on the influencing factors to obtain the ranking of their main effects. Specifically, with the goal of obtaining the ranking of the main effects of the influencing factors with the minimum number of experiments, an orthogonal experimental method is used to obtain orthogonal results. The range of each influencing factor in the orthogonal results is calculated and ranked to obtain the ranking of the main effects of the influencing factors. Under supported conditions, the ranking of the main effects of the influencing factors is: excavation depth > soil internal friction angle > wall-soil friction angle. Specifically: S2 conducts a sensitivity analysis on the factors influencing the effect to obtain the ranking of the main effects of the factors on the effect and the changing patterns of the effect. Please refer to Tables 2 and 3 to obtain the wall-soil friction angle with minimal experimental data using orthogonal design. , soil internal friction angle The main effects of the excavation depth H on the influence effect B were ranked, and the optimal combination was selected through comparison. This orthogonal experiment included nine working conditions, among which the wall-soil friction angle... Including three levels: 5°, 7°, and 9°, the internal friction angle of the soil. The pits are divided into three levels: 18°, 20°, and 22°, and the excavation depth H is divided into three types: 11m, 13m, and 15m.

[0053] Table 2: Level Table of Influencing Factors

[0054] Table 3: Orthogonal Experimental Design Scheme

[0055] According to the orthogonal experimental design scheme in Table 3, nine working conditions were generated using the orthogonal array, and the influence effect B under supported conditions was calculated. Then, the range of each influencing factor was obtained and ranked to determine the order of significance of the influence.

[0056] The formula for calculating the K1 value of a single factor level is:

[0057] in, The average index is the average value of the test results, i.e.:

[0058]

[0059] Wall-soil friction angle , soil internal friction angle The three influencing factors, namely, the excavation depth H, were analyzed, and the orthogonal results were processed. The following table shows the ranking of the influence of the three factors on the experimental indicators: Table 4: Range of Impact Effects under Supported Conditions

[0060] Therefore, the order of the main effects of the above three influencing factors on effect B is: excavation depth H > soil internal friction angle. > Wall-soil friction angle Constrained by the internal support system of the foundation pit, the internal friction angle of the soil... The contribution of the wall-soil friction angle to effect B is greater than that to effect B. .

[0061] To verify the accuracy of the earth pressure analysis model constructed between pits, and to verify the obtained earth pressure and its effects, as well as the variation law of earth pressure and its effects, this example, based on the aforementioned methods, conducts a finite element simulation analysis and compares the consistency between the simulation results and the theoretical results of earth pressure and its effects. Specifically: S3 constructs a three-dimensional finite element overall analysis model of the foundation pit and simulates and verifies the consistency between the numerical solution and the theoretical solution. Based on the earth pressure and its effects, and the ranking of the main effects of the influencing factors, finite element simulation was conducted to verify the consistency between the simulation results and the theoretical results. Specifically, a three-dimensional finite element overall analysis model of the foundation pit was constructed based on the theoretical calculation formula of earth pressure and its effects under supported conditions and the ranking parameters of the main effects of the influencing factors. The model size and boundary conditions of the three-dimensional finite element overall analysis model of the foundation pit were determined by comprehensively considering actual environmental data. Based on the three-dimensional finite element overall analysis model of the foundation pit, finite element numerical simulations of single soil layers and multiple soil layers were performed to obtain numerical solutions. The numerical solutions and theoretical solutions of the active earth pressure were compared to verify the consistency between the simulated and theoretical variation laws of the effects of the influencing factors. The actual environmental data included: the complexity of the foundation pit project, the sensitivity of the surrounding environment, numerical accuracy, and simulation efficiency.

[0062] S31 Numerical Simulation S311 Finite Element Numerical Simulation of a Single Soil Mass Based on the calculation results of the earth pressure and its effects, and the ranking of the main effects of the influencing factors, a three-dimensional finite element overall analysis model of the foundation pit is constructed. This analysis model comprehensively considers the complexity of the project, the sensitivity of the surrounding environment, numerical accuracy, and computational efficiency, and the dimensions and boundary conditions of the analysis model are determined accordingly. Specifically: Based on practice, the lateral soil disturbance range induced by foundation pit excavation is approximately 2–5H, and the vertical disturbance range is approximately 3–5H, where H is the excavation depth. The farther the boundary is from the excavation area, the weaker the boundary effect. The influence effect is 2–5H along the perimeter of the foundation pit and 3–5H at the bottom, with the constraint decreasing further away from the boundary.

[0063] Analysis model dimensions: Based on the maximum excavation depth H of 13 m, the final analysis model is 132 m (length) × 24 m (width) × 40 m (depth) to balance calculation accuracy and boundary independence.

[0064] Analysis of model boundary conditions: Taking into account the complexity of the foundation pit excavation project, environmental sensitivity, and computational efficiency, the model size and boundaries are determined.

[0065] Please see Figure 10 A three-dimensional finite element overall analysis model of the foundation pit was constructed, with 110,000 mesh elements and 20,000 nodes. Solid elements were used for the soil layer; 2D elements were used for the diaphragm wall; and 1D structural elements were used for the steel support. The modified MC constitutive model was adopted for the soil layer, and the basic soil parameters are shown in Table 5. The parameters for the diaphragm wall and steel support are shown in Table 6.

[0066] Table 5: Physical and Mechanical Parameters of Soil

[0067] Table 6: Physical and Mechanical Parameters of Diaphragm Wall and Steel Support

[0068] Finite element numerical simulation of S312 multi-layer soil In actual engineering projects, foundation pit excavation generally involves multiple layers of soil. The weighted average of relevant parameters is calculated based on the proportion of the thickness of each soil layer to the excavation depth of the foundation pit.

[0069] Similarly, the maximum depth of the excavation pit was selected to be approximately 13 m, and the final analysis model was 132m (length) × 24m (width) × 40m (depth).

[0070] Please see Figure 11 A three-dimensional finite element overall analysis model of the foundation pit was constructed, with 110,000 mesh elements and 20,000 nodes. Solid elements were used for the soil layer; 2D elements were used for the diaphragm wall; and 1D structural elements were used for the steel support. The modified MC constitutive model was adopted for the soil layer, and the basic soil parameters are shown in Table 7. The parameters for the diaphragm wall and steel support are shown in Table 8.

[0071] Table 7: Physical and Mechanical Parameters of Soil

[0072] Table 8: Physical and Mechanical Parameters of Diaphragm Wall and Steel Support

[0073] S32 Verification Analysis Active earth pressure analysis of single and multi-layered soil masses in S321: Verification of the consistency between numerical and theoretical solutions. Please see Figure 12 and Figure 13 Based on the theoretically calculated earth pressure and its effects, as well as the influencing factors affecting these effects, a comparison diagram of the distribution of active earth pressure numerical solution and theoretical solution along the excavation and depth of the foundation pit is constructed using a three-dimensional finite element overall analysis model of the foundation pit.

[0074] Please see Figure 12 Under single soil conditions, although the numerical solutions of earth pressure and its effects differ from the theoretical solutions in terms of numerical values, the distribution trends of the numerical and theoretical earth pressure solutions along the depth are consistent, which verifies the rationality of the theoretical solution calculation.

[0075] Please see Figure 13Under multi-layered soil conditions, the soil pressure variations observed in the numerical simulation at excavation depths of 2m and 7m are due to the presence of steel supports at these depths. At depths of 0m and 13m, the numerical and theoretical solutions for soil pressure at the top and bottom of the pit show minimal difference, with the overall distribution trend remaining highly consistent. Compared to the calculations of Rankine and Coulomb earth pressures, the theoretical and numerical solutions obtained in this application show the smallest discrepancy, thus verifying the rationality of the theoretical earth pressure calculations presented in this application.

[0076] S322 Analysis of Influencing Factors and Earth Pressure Distribution Along Wall Height in Influence Effects; Verification of the Theoretical Variation Law of Influencing Factors in Effect Effects. Please see Figure 14 When the internal friction angle of the soil The numerical solution of active earth pressure in the three-dimensional finite element global analysis model varies with excavation depth for angles of 16°, 18°, 20°, 22°, and 24°. Based on the variation curves, it can be obtained that as the internal friction angle of the soil increases... As the soil pressure increases, the active earth pressure gradually decreases, verifying that soil reinforcement has a significant effect on reducing earth pressure. This is consistent with the theoretical conclusion in S1, which is based on the constructed pit earth pressure analysis model, that "soil reinforcement can effectively reduce the impact effect B".

[0077] Please see Figure 15 When the wall-soil friction angle The numerical solution of active earth pressure in the three-dimensional finite element global analysis model varies with excavation depth for angles of 3°, 6°, 9°, 12°, and 15°. Based on the variation curves, it can be obtained that as the wall-soil friction angle increases... As the value increases, the active earth pressure gradually increases, showing good consistency with the theoretical analysis in the earth pressure calculation formula based on the constructed pit earth pressure analysis model in S1.

[0078] In summary, through theoretical analysis and numerical simulation of the earth pressure and its effects under foundation pit excavation, we have concluded that: using the assumptions of Coulomb earth pressure, a calculation model for soil pressure under internal support conditions is established, and the excavation depth H, the friction angle between the wall back and the fill, and other parameters are derived. Angle of friction with soil The relevant expressions for calculating soil pressure and effect B are presented. Sensitivity analysis of the influencing factors reveals that, under supported conditions, the order of significance of the influence on effect B is: excavation depth H > soil internal friction angle. > Angle of friction between the wall back and the backfill Finite element numerical simulations show that the numerical solution of earth pressure agrees well with the theoretical solution in terms of distribution. Compared with the calculation results of Rankine earth pressure and Coulomb earth pressure, the theoretical solution of this application has the smallest difference, which shows that the calculation of earth pressure and its influence effect in this application is reasonable and can provide a reference for the division of influence effects in actual engineering.

[0079] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0080] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0081] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0082] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0083] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0084] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An analytical method for earth pressure and its influence under internal support conditions in a foundation pit, characterized in that, include: Based on the basic assumptions of earth pressure theory, an earth pressure analysis model between pits is constructed to calculate earth pressure and its effects. Sensitivity analysis was performed on the factors influencing the effect to obtain the ranking of the main effects of the factors. Based on the ranking of the earth pressure and its effects with the main effects of the influencing factors, finite element simulation was performed to verify the consistency between the simulation results and the theoretical results.

2. The analytical method for earth pressure and its influence under the condition of internal support in the foundation pit according to claim 1, characterized in that, The earth pressure analysis model between pits comprehensively considers the wall-soil interface friction effect, soil shear strength parameters, excavation depth, and support axial force.

3. The analytical method for earth pressure and its influence under the condition of internal support in the foundation pit as described in claim 2, characterized in that, The calculation of earth pressure and its effects includes: Calculate the soil pressure caused by excavation disturbance under unsupported conditions and its impact. Based on the soil pressure and its effects under unsupported conditions, a distribution force correction coefficient is introduced to calculate the soil pressure and its effects caused by excavation disturbance under supported conditions.

4. The analytical method for earth pressure and its influence under the condition of internal support in the foundation pit as described in claim 3, characterized in that, The calculation of soil pressure and its effects caused by excavation disturbance under unsupported conditions includes: Based on the principle of limit equilibrium and the geometric relationship of closed forces, the resultant earth pressure under unsupported conditions is derived. Based on the angular relationship between soil forces and closing forces, the numerical method is used to solve for the influence effect and the distribution of earth pressure along the wall height under unsupported conditions.

5. The analytical method for earth pressure and its influence under the condition of internal support in the foundation pit according to claim 4, characterized in that, The calculation of soil pressure and its effects caused by excavation disturbance under supported conditions includes: By introducing a distributed force correction factor and using the distributed force simplification method, the internal forces of the support structure under supported conditions are calculated. Based on the earth pressure and its effects under unsupported conditions, the influence of the axial force of the foundation pit support is introduced. Based on the active earth pressure distribution pattern of the retaining wall under supported conditions, the earth pressure and its effects under supported conditions are obtained. Based on the theoretical calculation formula of the impact effect, the influencing factors of the impact effect and the law of change of the impact effect with respect to its influencing factors are obtained.

6. The analytical method for earth pressure and its influence under the condition of internal support in a foundation pit according to any one of claims 1-5, characterized in that, The earth pressure and its effects include the resultant earth pressure under supported conditions, the effects, and the distribution of earth pressure along the wall height; the influencing factors include the internal friction angle of the soil, the excavation depth of the foundation pit, and the wall-soil friction angle.

7. The analytical method for earth pressure and its influence under the condition of internal support in a foundation pit as described in claim 6, characterized in that, Sensitivity analysis was performed on the factors influencing the aforementioned effects to obtain the ranking of the main effects of these factors, specifically: With the goal of obtaining the ranking of the main effects of influencing factors with the minimum number of experiments, orthogonal experimental design was used to obtain orthogonal results. Solve for the range of each influencing factor in the orthogonal results and sort them to obtain the main effect ranking of the influencing factors.

8. The analytical method for earth pressure and its influence under the condition of internal support in the foundation pit according to claim 7, characterized in that, Under supported conditions, the main effects of the influencing factors are ranked as follows: excavation depth of the foundation pit > internal friction angle of the soil > wall-soil friction angle.

9. The analytical method for earth pressure and its influence under the condition of internal support in a foundation pit according to claim 1, characterized in that, Based on the ranking of the earth pressure and its effects with the main effects of the influencing factors, finite element simulation was performed to verify the consistency between the simulation results and the theoretical results. Specifically: Based on the theoretical calculation formula of earth pressure and its influence under supported conditions and the main effect ranking parameters of influencing factors, a three-dimensional finite element overall analysis model of the foundation pit is constructed. Taking into account the actual environmental data, the model size and boundary conditions of the three-dimensional finite element overall analysis model of the foundation pit were determined. Based on the three-dimensional finite element overall analysis model of the foundation pit, the finite element numerical simulation of a single soil layer and multiple soil layers is performed to obtain numerical solutions. By comparing the numerical and theoretical solutions of active earth pressure, the consistency between the simulated and theoretical variation laws of the influence effects of influencing factors is verified.

10. The analytical method for earth pressure and its influence under the condition of internal support in a foundation pit according to claim 9, characterized in that, The actual environmental data includes: The complexity of foundation pit engineering, sensitivity to the surrounding environment, numerical accuracy, and simulation efficiency.

Images