Element body and supergravity test model coupling-based slope stability analysis method

Abstract

The invention discloses a side slope stability analysis method based on coupling of a unit body and a supergravity test model, which comprises the following steps: calibrating unit body mechanical parameters of a side slope soil body through a unit body test, constructing a supergravity test model, and acquiring pore water pressure, displacement and displacement acceleration of the side slope physical model under the action of an external force load; then constructing an elastic-plastic effective stress numerical analysis model, and performing iterative training on the elastic-plastic effective stress numerical analysis model according to data acquired by the supergravity test model; and finally, dividing the potential sliding surface of the slope into a plurality of soil mass units, predicting each soil mass unit by adopting the trained elastic-plastic effective stress numerical analysis model, calculating a time history of a slope stability safety coefficient according to mechanical parameters of the unit mass, and evaluating the slope stability according to the time history to obtain a stability evaluation result. Through coupling of the unit body test and the supergravity test model, the precision and reliability of slope stability analysis under the dynamic effect are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering data processing technology, specifically a slope stability analysis method based on the coupling of unit cells and hypergravity test models. Background Technology

[0002] Currently, domestic and international methods for analyzing the seismic stability of slopes mainly include static analysis methods based on limit equilibrium theory and dynamic response analysis methods based on numerical simulation. Limit equilibrium methods are widely used in engineering design due to their computational simplicity; however, this method cannot fully reflect the stress-strain relationship and pore water pressure evolution characteristics of slope soil under seismic loading, making it difficult to accurately predict deformation processes during and after earthquakes. Numerical simulation methods can consider soil dynamics to some extent, but their parameters are often derived from experience or simplified assumptions, lacking support from real physical experimental data, which limits the reliability and applicability of the calculation results.

[0003] Currently, unit cell tests are an important tool for studying the stress-strain behavior and pore water pressure development characteristics of soil under dynamic loading, providing relatively detailed constitutive relations and parameters, and laying a data foundation for numerical analysis. However, unit cell tests cannot fully reflect the overall response characteristics of actual slopes under strong earthquakes. Meanwhile, hypergravity model tests are considered an important method for verifying slope stability and deformation patterns because they can reproduce the dynamic response of the prototype slope in a scaled-down model. However, single hypergravity tests often fail to consider the micromechanical properties of the soil, and parameter selection relies on experience and is not precise enough.

[0004] Existing studies have adopted equivalent modeling of slopes as homogeneous continuums, which simplifies the calculation process. However, this method struggles to effectively reveal the coupling relationship between dynamic parameters and actual engineering responses at different scales, and cannot accurately reflect the dynamic amplification effect and time-history variation of the safety factor of slopes under seismic loading. Therefore, existing methods still have significant shortcomings in balancing the realism and refinement of slope dynamic responses. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a slope stability analysis method based on the coupling of unit cell and hypergravity test model. While maintaining computational efficiency, the method significantly improves the accuracy and reliability of slope stability analysis under dynamic action by coupling unit cell test and hypergravity test model, and can provide a scientific basis for the seismic safety design and post-earthquake deformation prediction of slopes in various large-scale engineering projects.

[0006] The technical solution of this invention is as follows: The slope stability analysis method based on the coupling of unit cell and hypergravity test model includes the following steps: (1) The stress-strain relationship and pore water pressure evolution characteristics of slope soil under different loading conditions are tested by unit body test, so as to calibrate the unit body mechanical parameters of slope soil; (2) Place the slope physical model on the shaking table, and then place the shaking table together with the slope physical model in the basket inside the hypergravity centrifuge to construct the hypergravity test model. Apply external force load through the shaking table and the hypergravity centrifuge, and at the same time obtain the pore water pressure, displacement and displacement acceleration of the slope physical model under the action of external force load through the sensors in the slope physical model. (3) Construct a numerical analysis model of elastoplastic effective stress. Based on the pore water pressure, displacement and displacement acceleration of the slope physical model obtained from the supergravity test model under the action of external force load, iteratively train the numerical analysis model of elastoplastic effective stress to obtain a trained numerical analysis model of elastoplastic effective stress. (4) The potential sliding surface of the slope is determined by the limit equilibrium method, and the potential sliding surface is divided into several soil units. Each soil unit is predicted by a trained elastoplastic effective stress numerical analysis model. The pore water pressure time history, acceleration time history, displacement time history and effective stress time history of each soil unit are predicted. Then, the time history of the slope stability safety factor is calculated by the limit equilibrium method and based on the mechanical parameters of the unit. The slope stability is evaluated based on the calculated slope stability safety factor to obtain the stability evaluation results under strong earthquake conditions.

[0007] The mechanical parameters of the unit include effective cohesion, effective internal friction angle, dynamic shear modulus, and dynamic damping ratio.

[0008] The slope physical model includes a model box, slope soil set inside the model box, multiple sensor groups set inside the slope soil, multiple displacement sensors set inside the model box facing the slope surface of the slope soil, and a data acquisition module. The multiple displacement sensors are arranged from top to bottom along the slope surface of the slope soil, and the multiple sensor groups are distributed at different horizontal heights inside the slope soil. Each sensor group includes an earth pressure sensor, an acceleration sensor, and a pore water pressure sensor. The multiple sensor groups and displacement sensors are all connected to the data acquisition module, which is wirelessly connected to an external computer.

[0009] The elastoplastic effective stress numerical analysis model is a numerical model, which specifically includes the effective stress equation, the water-soil mixture mass conservation equation and the displacement-external force load relationship equation. The effective stress equation is shown in equation (1), the water-soil mixture mass conservation equation is shown in equation (2), and the displacement-external force load relationship equation is shown in equation (3). (1); In equation (1), This represents the effective stress at time t; The total stress at time t is collected by an earth pressure sensor. This represents the pore water pressure at time t; (2); In equation (2), The water storage coefficient is used to describe the amount of water that can be stored in a unit volume of soil. This represents the Biot coefficient, which describes the coupling effect between the slope soil and pore water. Divergence is used to describe the divergence or convergence of a vector field in space. The first derivative represents the displacement of the slope soil, and the displacement velocity of the soil is also represented. The permeability coefficient of the slope soil; Represents the viscosity of water; Represents the gradient; Represents pore water pressure; The term "source" represents the input, output, or change in water source caused by external factors. (3); In equation (3), The mass matrix representing the slope soil. Represents the damping matrix. Represents the elastic-plastic stiffness matrix. The spatial distribution of slope soil displacement, i.e., the displacement field. The first derivative represents the displacement of the slope soil, and the displacement velocity of the soil is also represented. The second derivative represents the displacement of the slope soil, and the displacement acceleration of the soil is also represented. This represents the external force load applied by the shaking table and the centrifuge. The pore water pressure and displacement are iteratively calculated based on the constructed elastoplastic effective stress numerical analysis model. At the same time, the pore water pressure, displacement acceleration and displacement of the slope physical model under external load obtained from the hypergravity test model are iteratively converged and optimized to obtain a trained elastoplastic effective stress numerical analysis model.

[0010] The elastic-plastic effective stress numerical analysis model iteratively calculates the pore water pressure and displacement at each time step and determines whether it converges. When the following equation (4) is satisfied, it is determined that the iteration has converged. (4); In equation (4), The convergence tolerance represents the pore water pressure; The convergence tolerance represents the displacement; This represents the empirical harmonic parameter, with a value range of 0.85 to 1.32. represent The pore water pressure at that moment, represent The pore water pressure at that time represent Displacement at time t, represent Displacement at time t, Representative norm.

[0011] The method described above involves determining the potential sliding surface of a slope using the limit equilibrium method, dividing the potential sliding surface into several soil elements, and using a trained elasto-plastic effective stress numerical analysis model to predict the pore water pressure time history, displacement acceleration time history, displacement time history, and effective stress time history of each soil element. Then, the method is used to calculate the slope stability safety factor based on the element mechanical parameters. The specific steps include: S41. Update the effective stress of each soil element at different times based on the trained elastoplastic effective stress numerical analysis model. ; S42. Calculate the shear strength of the soil according to the following formula (5): (5); In equation (5), Represents the shear strength at time t; Represents effective cohesion; Represents the effective internal friction angle; Represents the dynamic damping ratio; Represents the dynamic shear modulus; Represents shear strain, indicating the degree of shear deformation of the slope soil; S43. Calculate the shear strength of the slope soil according to the following formula (6): (6); In equation (6), This represents the shear force of the i-th soil element at time t. Shear strength of the i-th soil element at time t Represents the length of the sliding surface of the i-th soil element; S44. Calculate the driving force of each soil element according to the following formula (7). : (7); In equation (7), This represents the self-weight of each soil element; This represents the pore water pressure at time t for each soil element; This represents the seismic load borne by each soil unit, indicating the inertial force caused by the earthquake, which varies with seismic waves. S45. For each time step, calculate the time history of the slope stability safety factor using the limit equilibrium method. The specific calculation is shown in the following formula (8): (8).

[0012] The specific method for assessing slope stability based on the calculated slope stability safety factor is as follows: First, a critical value for the safety factor is set. When the calculated slope stability safety factor Below the set safety factor threshold If the slope is unstable, it indicates that the slope is in an unstable state.

[0013] Advantages of this invention: This invention, through the coupling of unit cell experiments and hypergravity test models, allows the stress-strain relationship and pore water pressure evolution characteristics of slope soil to be reflected in unit cell experiments, significantly improving the accuracy of numerical calculations. Meanwhile, the overall stability and dynamic response laws are reflected in the coupled calculations of the hypergravity test model and the elastoplastic effective stress numerical analysis model. Hypergravity experiments can reproduce the overall dynamic response of slopes under strong earthquakes, improving the authenticity and engineering applicability of the analysis results. It combines the advantages of both experimental and numerical calculations, avoiding the drawbacks of long cycles and high costs associated with purely physical experiments, and overcoming the limitations of numerical simulations that rely on empirical parameters and have limited accuracy. This significantly improves the accuracy and reliability of slope stability analysis under dynamic loading. Through safety factor time history calculations and post-earthquake deformation predictions, it can provide a scientific basis for seismic safety evaluation of major projects such as hydraulic slopes, transportation slopes, and mining slopes. Attached Figure Description

[0014] Figure 1 This is a flowchart of the present invention.

[0015] Figure 2 This is a schematic diagram of the slope physical model of the present invention placed inside a supergravity centrifuge.

[0016] Figure 3 This is a schematic diagram of the slope physical model of the present invention.

[0017] Figure labels: 01-Slope physical model, 02-Vibration table, 03-Supergravity centrifuge, 04-Counterweight, 11-Model box, 12-Soil, 13-Bedrock, 14-Displacement sensor, 15-Earth pressure sensor, 16-Acceleration sensor, 17-Pore water pressure sensor. Detailed Implementation

[0018] 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] See Figure 1 The slope stability analysis method based on the coupling of unit cell and hypergravity test model includes the following steps: (1) The stress-strain relationship and pore water pressure evolution characteristics of the slope soil under different loading conditions were tested by unit cell tests, thereby calibrating the unit cell mechanical parameters of the slope soil. The unit cell mechanical parameters include effective cohesion. Effective internal friction angle Dynamic shear modulus Dynamic damping ratio ; (2) See Figure 2 The slope physical model 01 is placed on the shaking table 02, and then the shaking table 02 together with the slope physical model 01 is placed in one of the baskets inside the hypergravity centrifuge 03. The other basket inside the hypergravity centrifuge is equipped with a counterweight 04, thus constructing a hypergravity test model. External force loads are applied through the shaking table 02 and the hypergravity centrifuge 03. At the same time, the pore water pressure, displacement and displacement acceleration of the slope physical model under the action of external force loads are obtained through the sensors in the slope physical model 01. See Figure 3 The slope physical model 01 includes a model box 11, slope soil (composed of soil 12 and bedrock 13) set inside the model box 11, multiple sensor groups set inside the slope soil (soil 12 and bedrock 13), displacement sensors 14 set inside the model box 11 facing the slope surface of soil 12, and a data acquisition module. Multiple displacement sensors 14 are arranged from top to bottom along the slope surface of the slope soil. Multiple sensor groups are distributed at different horizontal heights in the slope soil. Each sensor group includes an earth pressure sensor 15, an acceleration sensor 16, and a pore water pressure sensor 17. Multiple sensor groups and displacement sensors 14 are connected to the data acquisition module. The data acquisition module is connected to an external computer via fiber optic cable or shielded cable. The computer uses Kriging interpolation to obtain the data distribution of the slope physical model based on the data collected by multiple sensors. (3) Construct a numerical analysis model of elastoplastic effective stress. The numerical analysis model of elastoplastic effective stress is a numerical model, which specifically includes the effective stress equation, the mass conservation equation of water-soil mixture and the displacement-external force load relationship equation. The effective stress equation is shown in equation (1), the mass conservation equation of water-soil mixture is shown in equation (2), and the displacement-external force load relationship equation is shown in equation (3). (1); In equation (1), This represents the effective stress at time t; The total stress at time t is collected by an earth pressure sensor. This represents the pore water pressure at time t; (2); In equation (2), The water storage coefficient is used to describe the amount of water that can be stored in a unit volume of soil. This represents the Biot coefficient, which describes the coupling effect between the slope soil and pore water. Divergence is used to describe the divergence or convergence of a vector field in space. The first derivative represents the displacement of the slope soil, and the displacement velocity of the soil is also represented. The permeability coefficient of the slope soil; Represents the viscosity of water; Represents the gradient; Represents pore water pressure; The term "source" represents the input, output, or change in water source caused by external factors. (3); In equation (3), The mass matrix representing the slope soil. Represents the damping matrix. Represents the elastic-plastic stiffness matrix. The spatial distribution of slope soil displacement, i.e., the displacement field. The first derivative represents the displacement of the slope soil, and the displacement velocity of the soil is also represented. The second derivative represents the displacement of the slope soil, and the displacement acceleration of the soil is also represented. This represents the external force load applied by the shaking table and the centrifuge. The pore water pressure and displacement are iteratively calculated based on the constructed elastoplastic effective stress numerical analysis model. At the same time, the pore water pressure, displacement and displacement acceleration of the slope physical model under seismic load obtained from the hypergravity test model are iteratively converged and optimized to obtain a trained elastoplastic effective stress numerical analysis model. The elastoplastic effective stress numerical analysis model iteratively calculates the pore water pressure and displacement at each time step and determines whether it converges. When the following equation (4) is satisfied, it is determined that the iteration has converged. (4); In equation (4), The convergence tolerance represents the pore water pressure; The convergence tolerance represents the displacement; This represents the empirical harmonic parameter, with a value range of 0.85 to 1.32. represent The pore water pressure at that time represent The pore water pressure at that time represent Displacement at time t, represent Displacement at time t, Representational norm; (4) The potential sliding surface of the slope is determined by the limit equilibrium method (using the Bishop method or the MP method. The limit equilibrium method assumes that the slope is in a critical stable state, that is, the most dangerous sliding surface of the slope is the beginning of soil failure. In this state, the total shear stress of the slope is equal to the sum of the shear strength. The calculated slope stability safety factor represents the stability of the slope under a specific load). The potential sliding surface is divided into several soil elements. Each soil element is predicted using a trained elastoplastic effective stress numerical analysis model. The pore water pressure of each soil element is predicted. Time history, displacement acceleration Time history, displacement Time history and effective stress The time history is obtained by calculating the slope stability safety factor using the limit equilibrium method and the mechanical parameters of the unit body. Based on the calculated slope stability safety factor, a slope stability assessment is performed to obtain the stability evaluation results under strong earthquake conditions. The specific steps include: S41. Update the effective stress of each soil element at different times based on the trained elastoplastic effective stress numerical analysis model. ; S42. Under the Mohr-Coulomb criterion, calculate the shear strength of the soil according to the following formula (5): (5); In equation (5), Represents the shear strength at time t; Represents effective cohesion; Represents the effective internal friction angle; Represents the dynamic damping ratio; Represents the dynamic shear modulus; Represents shear strain, indicating the degree of shear deformation of the slope soil; S43. Calculate the shear strength of the slope soil according to the following formula (6): (6); In equation (6), This represents the shear force of the i-th soil element at time t. Shear strength of the i-th soil element at time t Represents the length of the sliding surface of the i-th soil element; S44. Calculate the driving force of each soil element according to the following formula (7). : (7); In equation (7), The self-weight of each soil element is calculated by the following formula (9); The pore water pressure at time t for each soil element is calculated by the following formula (10); The seismic load borne by each soil element represents the inertial force caused by the earthquake, which varies with the seismic wave and is calculated by the following formula (11); (9); In equation (9), Represents the mass of each soil element. Represents gravitational acceleration; (10); In equation (10), The average pore water pressure represents the unit length. Represents the length of the sliding surface of the i-th soil element; (11); In equation (11), Represents the mass of each soil element. Represents the seismic acceleration at time t; S45. For each time step, calculate the time history of the slope stability safety factor using the limit equilibrium method. The specific calculation is shown in the following formula (8): (8); S46. Set the critical value of the safety factor. When the calculated slope stability safety factor The value remained below the set safety factor threshold for multiple time steps. This indicates that the slope is in an unstable state; when Below in a short period of time However, it recovered and remained above [a certain level] after a short period of time. The value indicates that the slope has experienced short-term fluctuations; when the slope stability safety factor is calculated over multiple time steps... The maximum value in is lower than This indicates that the slope is in a dangerous state of instability, and the stability of the slope has been threatened, especially when... When the maximum value approaches 1, an alarm will be triggered quickly.

[0020] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A slope stability analysis method based on coupling of a unit body and a supergravity test model, characterized in that: Specifically comprising the following steps: (1) The stress-strain relationship and the pore water pressure evolution characteristics of the slope soil under different loading conditions are tested through unit test, so as to calibrate the unit mechanical parameters of the slope soil; (2) The slope physical model is placed on the shaking table, and then the shaking table together with the slope physical model is placed in the basket in the supergravity centrifuge, so as to construct a supergravity test model; external force load is applied through the shaking table and the supergravity centrifuge, and the pore water pressure, displacement and displacement acceleration of the slope physical model under the action of the external force load are obtained through the sensors in the slope physical model; (3) An elastoplastic effective stress numerical analysis model is constructed, and the elastoplastic effective stress numerical analysis model is iteratively trained according to the pore water pressure, displacement and displacement acceleration of the slope physical model under the action of the external force load obtained by the supergravity test model, so as to obtain the trained elastoplastic effective stress numerical analysis model; (4) The potential sliding surface of the slope is determined by using the limit equilibrium method, and the potential sliding surface is divided into a plurality of soil units; the trained elastoplastic effective stress numerical analysis model is used to predict the pore water pressure time history, acceleration time history, displacement time history and effective stress time history of each soil unit; then the limit equilibrium method is used to calculate the time history of the safety factor of the slope stability according to the unit mechanical parameters, and the slope stability is evaluated according to the calculated safety factor of the slope stability, so as to obtain the stability evaluation result under the strong earthquake working condition.

2. The method according to claim 1, wherein the method is characterized by: The unit mechanical parameters include effective cohesion, effective internal friction angle, dynamic shear modulus and dynamic damping ratio.

3. The method according to claim 2, wherein the method is characterized by: The slope physical model comprises a model box, a slope soil arranged in the model box, a plurality of sensor groups arranged in the slope soil, a plurality of displacement sensors arranged in the model box and facing the slope surface of the slope soil, and a data acquisition module; the plurality of displacement sensors are arranged along the slope surface of the slope soil from top to bottom; each sensor group comprises a soil pressure sensor, an acceleration sensor and a pore water pressure sensor; the plurality of sensor groups and the displacement sensors are connected with the data acquisition module; and the data acquisition module is wirelessly connected with an external computer.

4. The method according to claim 3, wherein the method is characterized by: The elastoplastic effective stress numerical analysis model is a numerical model, specifically comprising an effective stress equation, a water-soil mixture mass conservation equation and a displacement-external force load relationship equation; the effective stress equation is shown in formula (1) below, the water-soil mixture mass conservation equation is shown in formula (2) below, and the displacement-external force load relationship equation is shown in formula (3) below; （1）； In formula (1), represents the effective stress at time t; represents the total stress at time t, which is acquired by the soil pressure sensor; represents the pore water pressure at time t; （2）； In formula (2), represents the water storage coefficient, which describes the amount of water that can be stored in a unit volume of soil; represents the Biot coefficient, which describes the coupling effect between the slope soil and the pore water; represents the divergence, which describes the divergence or convergence of a vector field in space; represents the first derivative of the displacement of the slope soil, indicating the displacement velocity of the soil; represents the permeability coefficient of the slope soil; represents the viscosity of water; represents the gradient; represents the pore water pressure; represents the source term, indicating the input, drainage or water source change of water flow caused by external factors; （3）； In formula (3), a mass matrix representing the soil body of the slope, a damping matrix, an elastic-plastic stiffness matrix, a spatial distribution of displacement of the soil body of the slope, i.e., a displacement field, a first-order derivative of displacement of the soil body of the slope, indicating the displacement velocity of the soil body; a second-order derivative of displacement of the soil body of the slope, indicating the displacement acceleration of the soil body; external force loads applied by the shaking table and the supergravity centrifuge; The pore water pressure and displacement are iteratively calculated according to the constructed elastoplastic effective stress numerical analysis model, and the elastoplastic effective stress numerical analysis model is iteratively converged and optimally updated according to the pore water pressure, displacement acceleration and displacement of the slope physical model under the action of the external force load obtained by the supergravity test model, so as to obtain the trained elastoplastic effective stress numerical analysis model.

5. The method according to claim 4, wherein the method is characterized by: The elastic-plastic effective stress numerical analysis model iteratively calculates the pore water pressure and displacement of each time step, and determines whether to converge, and when the following formula (4) is satisfied, it is determined that the iteration is completed. （4）； In formula (4), convergence tolerance representing pore water pressure; convergence tolerance representing displacement; representing empirical harmonic parameter, the value range is 0.85~1.32; representing pore water pressure at time t, representing pore water pressure at time t, representing displacement at time t, representing displacement at time t, representing norm.

6. The method according to claim 4, wherein the method is characterized by: The potential sliding surface of the slope is determined by using the limit equilibrium method, and the potential sliding surface is divided into a plurality of soil units, each soil unit is predicted by using the trained elastic-plastic effective stress numerical analysis model, the pore water pressure time history, the displacement acceleration time history, the displacement time history and the effective stress time history of each soil unit are obtained, and then the time history of the safety factor of the slope stability is calculated by using the limit equilibrium method and according to the unit mechanical parameters, and specifically includes the following steps: S41, updating the effective stress of each soil unit at different time according to the trained elastic-plastic effective stress numerical analysis model ; S42, calculate the shear strength of the soil according to the following formula (5): （5）； In formula (5), represents the shear strength at time t; represents the effective cohesion; represents the effective internal friction angle; represents the dynamic damping ratio; represents the dynamic shear modulus; represents the shear strain, indicating the degree of shear deformation of the slope soil body; S43, calculate the shear strength of the slope soil according to the following formula (6): （6）； In formula (6), represents the shear resistance of the i-th soil element at time t, represents the shear resistance of the i-th soil element at time t, represents the length of the sliding surface of the i-th soil element; S44, calculate the driving force of each soil element according to the following formula (7) : （7）； In formula (7), represents the self-weight of each soil element; represents the pore water pressure of each soil element at time t; represents the seismic load borne by each soil element, indicating the inertial force caused by the earthquake, which varies with the seismic wave; S45、For each time step, the time history of the safety factor of slope stability is calculated by the limit equilibrium method, the safety factor The calculation of the safety factor is specifically shown in the following formula (8): （8）。 7. The method according to claim 4, wherein the method is characterized by: The specific method for evaluating the slope stability according to the calculated slope stability safety factor is: first, setting a safety factor critical value When the calculated slope stability safety factor is lower than the set safety factor critical value , it indicates that the slope is in an unstable state.

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