CN-115906262-B - Surrounding rock plastic damage area analysis and prediction method based on stress balance

CN115906262BCN 115906262 BCN115906262 BCN 115906262BCN-115906262-B

Abstract

The invention discloses a surrounding rock plastic damage area analysis prediction method based on stress balance, which belongs to the technical field of tunnel engineering and comprises the following steps of obtaining an initial plastic area boundary, obtaining the sum of elastic loads of a part lower than yield stress before surrounding rock stress adjustment and the sum of elastic loads born by an elastic area after stress adjustment when the radius tends to infinity based on a plastic area correction model and elastic stress distribution of a part lower than plastic stress, obtaining the radius of a surrounding rock plastic area based on a stress balance principle, and obtaining the range and shape distribution characteristics of the surrounding rock plastic area of a tunnel based on the radius and polar coordinate drawing of the surrounding rock plastic area.

Inventors

REN LI
Zheng Liangjuan
ZHANG RU
LUO ZIWEN
ZHANG ZHILONG
ZHANG ZETIAN
XIE JING
ZHANG GUANGZE
WANG DONG
ZHANG LANBIN

Assignees

四川大学

Dates

Publication Date: 20260508
Application Date: 20221222

Claims (7)

1. The analysis and prediction method for the plastic damage area of the surrounding rock based on stress balance is characterized by comprising the following steps of: s1, obtaining an initial plastic region boundary ; The step S1 includes the steps of: S11, based on a Moire-coulomb criterion, obtaining a Moire-coulomb criterion model of the elastic boundary surrounding rock: Wherein, the Representing the maximum principal stress of the boundary surrounding rock of the elastic zone, Representing the minimum principal stress of the boundary surrounding rock of the elastic zone, Represents the coefficient of friction angle in the rock mass, Indicating the cohesive force of the rock mass, Representing the internal friction angle of the rock mass; S12, based on a Moire-coulomb criterion model and surrounding rock shear stress in a non-uniform stress field, obtaining a main stress model: Wherein, the Representing the radial stress of the surrounding rock, Represents the tangential stress of the surrounding rock, Representing the shear stress of surrounding rock; S13, bringing a yield criterion into the main stress model to obtain a yield model expressed by stress components: ; S14, obtaining a plastic region boundary model based on the yield model and the elastic region stress model: Wherein, the Representing the boundary of the plastic region, 、、、 And All are the constant coefficients of the two-dimensional space, The square ratio of the radius is represented, The radius of the tunnel is indicated and, The radius is indicated as such, Represents the coefficient of the side pressure, Indicating the supporting reaction force of the wall of the hole, Representing the initial ground stress in the vertical direction, The angle is indicated as such, Representing a moire-coulomb based radius coefficient; s15, obtaining the radius r and the angle based on the plastic region boundary model Implicit equations of (2); s16, calculating to obtain the boundary of the initial plastic region based on the implicit equation and the actual engineering conditions ; S2, expanding the boundary of the initial plastic region based on static balance conditions to obtain a plastic region area correction model; S3, based on the plastic area correction model and the elastic stress distribution of the part lower than the plastic stress, obtaining the sum of elastic loads of the part lower than the yield stress before surrounding rock stress adjustment Sum of elastic load born by elastic region after stress adjustment Equal when radius r goes to infinity; s4, based on the sum of elastic loads of the parts lower than the yield stress before surrounding rock stress adjustment Sum of elastic load born by elastic region after stress adjustment The elastic load sum of the parts which are higher than the yield stress before the stress adjustment of the surrounding rock is obtained when the radius r approaches infinity Sum of load bearing in plastic region after stress adjustment Equal; S5, based on the sum of elastic loads of parts, which are higher than yield stress, before surrounding rock stress adjustment Sum of load bearing in plastic region after stress adjustment Equal and stress balance principle, and obtaining the radius of the plastic region of the surrounding rock ; S6, based on radius of surrounding rock plastic region And polar coordinate drawing to obtain the plastic region range and morphological distribution characteristics of the tunnel surrounding rock.
2. The method for analyzing and predicting the plastic damage area of the surrounding rock based on stress balance according to claim 1, wherein the calculation expression of the plastic area correction model in the step S2 is as follows: Wherein, the Representing the sum of the elastic loads of the parts of the surrounding rock which are higher than the yield stress before stress adjustment, Representing the sum of the elastic loads of the portions of the surrounding rock below the yield stress prior to stress adjustment, Representing the sum of the load carried by the plastic region after stress adjustment, Representing the sum of the elastic loads borne by the elastic region after stress adjustment.
3. The method for predicting the plastic failure zone of surrounding rock based on stress balance according to claim 2, wherein the step S5 comprises the steps of: S51, setting stress distribution in a surrounding rock plastic region to be linear, and calculating based on radius r to obtain the sum of elastic loads of the parts, which are higher than yield stress, of the surrounding rock before stress adjustment ; S52, calculating and obtaining tangential stress of boundary of plastic region based on point criterion ; S53, calculating based on radius r to obtain sum of load bearing of stress-adjusted plastic region ; S54, based on the sum of load borne by the plastic region after stress adjustment Obtaining the radius of the plastic region of the surrounding rock 。
4. The method for analyzing and predicting the plastic failure zone of surrounding rock based on stress balance according to claim 3, wherein the step S51 is characterized by the sum of elastic loads The calculated expression of (2) is as follows: 。
5. the method for analyzing and predicting plastic failure zone of surrounding rock based on stress balance according to claim 4, wherein the tangential stress of the boundary of the plastic zone in step S52 The calculated expression of (2) is as follows: 。
6. The method for analyzing and predicting the plastic failure zone of surrounding rock based on stress balance according to claim 5, wherein the step S53 is characterized in that the sum of loads born by the plastic zone after stress adjustment The calculated expression of (2) is as follows: 。
7. the method for analyzing and predicting the plastic failure zone of the surrounding rock based on stress balance according to claim 6, wherein the radius of the plastic failure zone of the surrounding rock in the step S54 The calculated expression of (2) is as follows: 。

Description

Surrounding rock plastic damage area analysis and prediction method based on stress balance Technical Field The invention belongs to the technical field of tunnel engineering, and particularly relates to a surrounding rock plastic damage area analysis and prediction method based on stress balance. Background The surrounding rock plastic region is an important basis for evaluating the stability of the surrounding rock of the tunnel and a theoretical basis for the design of the tunnel support. In actual engineering, the original rock environment is most in a nonuniform stress field, especially in a construction active region with strong construction stress. Because of the stress asymmetry of the non-uniform stress field, elastoplastic analysis is more complex and difficult than that of the uniform stress field, and is usually carried out by adopting a plurality of approximate algorithms or by means of a mathematical analysis method through proper assumption, the prior art I refers to the existing elastic stress solution and the uniform stress field plastic solution of the surrounding rock of the non-uniform stress field, constructs a surrounding rock stress component expression and obtains an approximate solution of a plastic region boundary, the prior art II refers to the mechanical model of the surrounding rock plastic region of a circular cavity of the non-uniform stress field to be equivalent to an axisymmetric plane strain problem, and then combines with the classical elastic Bass solution to obtain the elastoplastic boundary of the surrounding rock approximately, and in recent years, research is carried out to deduce the boundary analysis of the surrounding rock plastic region of the non-uniform stress field through a method of constructing stress, and the classical analysis method is summarized as a stress construction method. The stress construction method has simple solving process, and the obtained result has certain precision, but has the following defects: (1) The radial stress on the elastic-plastic boundary line is zero; (2) Using the equilibrium differential equation in the case of axisymmetry; (3) Considering that the maximum and minimum main stresses of the surrounding rock in the plastic area are theoretical defects such as tangential stress sigma θ and radial force sigma r respectively; The approximate implicit method is one of the main flow methods for analyzing the plastic region of the surrounding rock of the circular tunnel with the non-uniform stress field, after the method is proposed in 1971, a large number of students develop analysis theoretical researches on the plastic region of the surrounding rock with the non-uniform stress field by using the approximate implicit method, firstly analyze the range of the plastic region based on different strength criteria, and sequentially consider the influence of intermediate main stress, rock shear expansion characteristics and seepage in the rock mass occurrence environment on the range of the plastic region. Besides a stress construction method and an approximately implicit method, the prior art introduces a mathematical analysis method into analysis research of a plastic region of the surrounding rock of the non-uniform stress field, explores analysis methods such as a complex function method, a perturbation method, a logarithmic transformation method and the like, provides ideas for analysis of the plastic region of the surrounding rock of the non-circular chamber, enriches the elastoplastic analysis theory of the surrounding rock of the non-uniform stress field, but has relatively complex theoretical analysis based on the analysis and limited engineering application degree. Disclosure of Invention Aiming at the defects in the prior art, the analysis and prediction method for the surrounding rock plastic damage area based on stress balance provided by the invention is based on an approximate implicit method, and attempts are made to correct the range of the surrounding rock plastic area of the nonuniform stress field obtained by a traditional point criterion method based on a stress balance principle, so that the problem of insufficient solving accuracy of the tunnel engineering surrounding rock plastic area of the stress salient area is solved. In order to achieve the aim of the invention, the invention adopts the following technical scheme: the invention provides a stress balance-based surrounding rock plastic damage area analysis and prediction method, which comprises the following steps: s1, acquiring an initial plastic region boundary R p; S2, expanding the boundary of the initial plastic region based on static balance conditions to obtain a plastic region area correction model; S3, based on a plastic area correction model and the elastic stress distribution of a part lower than plastic stress, obtaining that the elastic load sum S 2 of the part lower than yield stress before surrounding rock stress adjustment is equal to the elasti