CN-122021107-A - Three-dimensional ground stress field inversion method based on fitting function boundary

CN122021107ACN 122021107 ACN122021107 ACN 122021107ACN-122021107-A

Abstract

The invention provides a three-dimensional ground stress field inversion method based on a fitting function boundary, which belongs to the technical field of geotechnical engineering and comprises the steps of establishing a three-dimensional finite element model, extracting lateral boundary coordinates and performing polynomial fitting to obtain a boundary elevation fitting function; the method comprises the steps of calculating lateral pressure values of boundary points according to the fitting function, applying six independent working condition loads on a model, carrying out finite element calculation to obtain stress components of each measuring point, carrying out multiple linear regression analysis on the stress components by taking measured stress as a target value to obtain working condition coefficients, and carrying out weighted superposition on the stress fields of each working condition to obtain an inverted initial ground stress field. According to the invention, by accurately fitting the lateral boundary topography, the problem of inaccurate boundary condition application in the traditional method is solved, and the accuracy and reliability of ground stress inversion under the complex topography condition are remarkably improved.

Inventors

YANG LI
LU ZHENGPAN
PENG JUNYU
YANG MINGLI
YU JIYUAN
REN XUHUA
YU PING
LIU XINBO
TAN BIN
ZHANG JIXUN
ZHANG HUI

Assignees

华能澜沧江水电股份有限公司
中国电建集团中南勘测设计研究院有限公司
河海大学

Dates

Publication Date: 20260512
Application Date: 20251218

Claims (10)

1. The three-dimensional ground stress field inversion method based on the fitted function boundary is characterized by comprising the following steps of: S1, obtaining geological data of an engineering area of an underground cavity, wherein the geological data comprise topographic information, geological structure information, rock mass mechanical parameters and actually measured ground stress data; s2, establishing a three-dimensional finite element model according to the topographic information and the geological structure information, wherein the three-dimensional finite element model comprises a grotto group geometric structure, and setting the measuring point position of the actually measured ground stress data as a node of the three-dimensional finite element model; s3, applying six working condition loads to the three-dimensional finite element model, wherein the six working condition loads comprise dead weight load and first working condition load Directional boundary load, second Directional boundary load, first Directional boundary load, second Directional boundary load Directional boundary loads, wherein the first Directional boundary load, the second Directional boundary load, the first Directional boundary load and said second The directional boundary load determines side pressure distribution through a fitting function obtained by fitting the side boundary topography corresponding to the three-dimensional finite element model; s4, performing finite element calculation on the three-dimensional finite element model after the six working condition loads are applied, and obtaining calculated stress values of each measuring point under the six working condition loads; S5, calculating regression coefficients corresponding to the six working condition loads by adopting a multiple linear regression method according to the calculated stress values of the measuring points under the six working condition loads and the actually measured ground stress data; And S6, according to the regression coefficient and the stress value of any point in the three-dimensional finite element model under the six working condition loads, obtaining inversion stress of the any point through weighted superposition calculation, and thus obtaining an inversion ground stress field of the underground cavity engineering region.
2. The method of inversion of three-dimensional ground stress field based on fitted function boundary according to claim 1, wherein said geological data in step S1 further comprises fault construction data, formation distribution data and ground stress measuring point coordinate information.
3. The method for three-dimensional ground stress field inversion based on fitted function boundary according to claim 1, wherein said step S2 of establishing said three-dimensional finite element model comprises establishing a three-dimensional geometric model containing said geological structure information, meshing with hexahedral cells, and establishing a coordinate system, wherein The shaft is in a vertical direction, The axis is vertical to the river direction, The axis is along the river direction, and the measuring point position is set as a unit node.
4. The method of inversion of three-dimensional ground stress field based on fitted function boundary according to claim 1, wherein in step S3, the first step is that Directional boundary loads are applied to the three-dimensional finite element model Side boundaries of maximum coordinates, the second Directional boundary loads are applied to the three-dimensional finite element model A side boundary of a minimum value of coordinates, the first Directional boundary loads are applied to the three-dimensional finite element model A side boundary of the minimum value of the coordinates, the second Directional boundary loads are applied to the three-dimensional finite element model Side boundaries of the maximum of coordinates.
5. The method of three-dimensional ground stress field inversion based on fitted function boundary according to claim 1, wherein in said step S3, said fitted function is obtained by fitting a third order polynomial to the ground elevation of said side boundary, for a direction perpendicular to The side boundaries of the axis, the fitting function is expressed as: ; In the middle of Is the height of the ground surface, the height of the ground surface is the height of the ground surface, As a point on the side boundary The coordinates of the two points of the coordinate system, 、、 And Fitting coefficients for a first set of coefficients perpendicular to The side boundaries of the axis, the fitting function is expressed as: ; In the formula, As a point on the side boundary The coordinates of the two points of the coordinate system, 、、 And Fitting coefficients for a second set.
6. The method of inversion of three-dimensional ground stress field based on fitted function boundary according to claim 5, wherein in step S3, the side pressure distribution is calculated by the following two equations: For being perpendicular to Side pressure at points on the side boundary of the shaft: ; For being perpendicular to Side pressure at points on the side boundary of the shaft: ; In the formula, For the side pressure to be the pressure of the fluid, As a coefficient of the side pressure, Is the weight of the rock-soil body, Is the elevation coordinate of the point on the side boundary.
7. The method for three-dimensional ground stress field inversion based on fitted function boundary according to claim 1, wherein in step S5, the regression coefficient is calculated by the following formula: ; In the formula, Is the first First measuring point of each measuring point Regression values of the individual stress components, Is the first The regression coefficient corresponding to the load of the seed working condition, Is the first First measuring point of each measuring point Stress component at the first Calculated stress value under load of seed working condition by making Obtaining the regression coefficient by means of error minimization and solution of the measured ground stress data 。
8. The method for inversion of the three-dimensional ground stress field based on the boundary of the fitting function according to claim 7, wherein in the step S6, the inversion stress of the arbitrary point is calculated by the following formula: ; In the formula, Is the first The first point of any point Inversion values of the individual stress components, Is the first The first point of any point Stress component at the first The stress value under the load of the working condition, For the first step obtained in the step S5 Regression coefficients corresponding to the working condition load.
9. The method according to claim 1, wherein in the step S4, the finite element calculation uses an elastic constitutive model, the rock mechanical parameters include elastic modulus, poisson ratio and gravity, and the finite element calculation outputs the positive stress component and the shear stress component of each measuring point.
10. The method for inverting the three-dimensional ground stress field based on the fitted function boundary according to claim 1, wherein in the step S3, a fixed constraint is applied to the bottom of the three-dimensional finite element model before the six working condition loads are applied, so as to limit the vertical and horizontal displacement of the bottom.

Description

Three-dimensional ground stress field inversion method based on fitting function boundary Technical Field The invention relates to the technical field of geotechnical engineering, in particular to a three-dimensional ground stress field inversion method based on a fitting function boundary. Background In the engineering construction of underground cavern group, the accurate grasping of the distribution state of the ground stress field is a primary and key foundation for the determination of excavation design, stability analysis and supporting scheme. The ground stress field is an inherent stress field in a rock-soil body, is jointly influenced by various factors such as geological structure, topography, dead load and the like, and has complexity. At present, the ground stress field inversion based on the finite element or boundary element method is a common method in engineering. However, in the prior art, in order to simplify calculation and apply boundary conditions, the model lateral boundary is often set to an ideal vertical plane or horizontal plane, and a simplified uniform load or lateral pressure calculated from an empirical formula is applied. In areas of flat terrain, this simplification is generally acceptable, but in areas of engineering with complex undulating surfaces, such as western regions or mountainous regions of our country, the lateral boundaries of the model are actually changing with terrain elevation. If simplified boundary conditions are still adopted, the application of lateral pressure load is inconsistent with the actual terrain elevation difference, particularly when the surface fluctuation is severe, the boundary error generated by the application is obviously transmitted into the model, so that the initial ground stress field of the inversion is greatly deviated from the actual situation, the accuracy and the reliability of the inversion result are reduced, accurate basic data cannot be provided for subsequent engineering analysis, and the method is a technical problem to be solved in the prior art. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a three-dimensional ground stress field inversion method based on a fitting function boundary, which is used for accurately determining lateral pressure load by extracting lateral boundary topographic coordinates and performing polynomial fitting, applying six independent working condition loads in a finite element model and finally inverting an initial ground stress field efficiently and accurately by utilizing multiple linear regression and weighted superposition. In order to solve the technical problems, the technical scheme adopted by the invention is that the three-dimensional ground stress field inversion method based on the fitted function boundary comprises the following steps: S1, obtaining geological data of an engineering area of an underground cavity, wherein the geological data comprise topographic information, geological structure information, rock mass mechanical parameters and actually measured ground stress data; s2, establishing a three-dimensional finite element model according to the topographic information and the geological structure information, wherein the three-dimensional finite element model comprises a grotto group geometric structure, and setting the measuring point position of the actually measured ground stress data as a node of the three-dimensional finite element model; s3, applying six working condition loads to the three-dimensional finite element model, wherein the six working condition loads comprise dead weight load and first working condition load Directional boundary load, secondDirectional boundary load, firstDirectional boundary load, secondDirectional boundary loadDirectional boundary loads, wherein the firstDirectional boundary load, the secondDirectional boundary load, the firstDirectional boundary load and said secondThe directional boundary load determines side pressure distribution through a fitting function obtained by fitting the side boundary topography corresponding to the three-dimensional finite element model; s4, performing finite element calculation on the three-dimensional finite element model after the six working condition loads are applied, and obtaining calculated stress values of each measuring point under the six working condition loads; S5, calculating regression coefficients corresponding to the six working condition loads by adopting a multiple linear regression method according to the calculated stress values of the measuring points under the six working condition loads and the actually measured ground stress data; And S6, according to the regression coefficient and the stress value of any point in the three-dimensional finite element model under the six working condition loads, obtaining inversion stress of the any point through weighted superposition calculation, and thus obtaining an inversion ground stress field of the undergr