CN-121328095-B - Method for constructing true triaxial shear dynamic model of anchor-rock assembly under water chemical corrosion

CN121328095BCN 121328095 BCN121328095 BCN 121328095BCN-121328095-B

Abstract

The invention relates to a method for constructing a true triaxial shear dynamic model of an anchor-rock combination body under water chemical corrosion, which comprises the steps of preprocessing an anchor rod in groups and constructing a corrosion parameter database, and quantifying mass loss rules of the anchor rod under different corrosion conditions; the method comprises the steps of firstly, obtaining mechanical response data of blank group samples and corrosion group samples through a true triaxial disturbance shear test, establishing an anchor rod damage variable function based on corrosion parameters, accurately representing a corrosion damage evolution mechanism, correcting the mechanical parameters of the corrosion group samples through the damage function to generate a post-corrosion strength predicted value, constructing an elastic-viscoplastic coupled fractional order constitutive model through combining the corrected parameters, and finally realizing dynamic verification through comparing model prediction with a test curve. The method solves the engineering problem of anchored rock corrosion-true triaxial stress-dynamic disturbance coupling characteristic theoretical characterization modeling, and provides a reliable theoretical tool for rock mass engineering support safety evaluation.

Inventors

ZHENG ZHI
WANG FENGYUN
WU PING
LI SHAOJUN
HUANG YONG
SHEN YUANYUAN
JIANG YIZHI
TAO HONGHUI
ZHANG QIANG
ZHANG XINGUI
PAN RUI

Assignees

广西大学
广西壮族自治区建筑工程质量检测中心有限公司

Dates

Publication Date: 20260512
Application Date: 20250929

Claims (8)

1. The method for constructing the true triaxial shear dynamic model of the anchor-rock assembly under the water chemical corrosion is characterized by comprising the following steps of: S1, immersing anchor rod samples in groups in constant temperature solutions with different pH values for corrosion for different durations, measuring the mass of all the anchor rod samples before and after corrosion, and generating a corrosion parameter database containing the pH values, the corrosion time and the mass loss; S2, assembling the pretreated anchor rod and the rock sample into an anchor-rock assembly sample, simultaneously performing the same assembly on blank control samples assembled by the anchor rod which are not subjected to corrosion pretreatment, applying preset normal stress and lateral stress to all the samples, loading shear stress according to a multistage incremental path, synchronously applying cyclic disturbance, recording stress-strain data, and generating a mechanical test database containing cracking stress, breaking stress and full-stage stress-strain curves of all the samples; S3, processing the corrosion parameter database, and establishing a preset function relation between the anchor rod damage variable and the pH value and corrosion time through data fitting according to the mass loss rate and the pH value and corrosion time, so as to generate a deterministic function for calculating the anchor rod damage variable under any corrosion condition; S4, carrying out proportional attenuation correction on the cracking stress and the destruction stress of the mechanical test database based on the deterministic function, and correcting an initial stress value according to a linear attenuation relation to generate actual shearing stress of the corroded anchor rod and cracking stress of a system after corrosion; S5, constructing a yield function based on the actual shearing stress of the corroded anchor rod and the cracking stress of the corroded system, and establishing an elastic-viscoplastic coupled differential equation set to generate a fractional order damage shearing constitutive model; s6, inputting a full-stage stress-strain curve of the corrosion group sample in the mechanical test database into the fractional order damage shearing constitutive model, fitting parameters by adopting a global optimization algorithm, and comparing test curves to generate a verified true triaxial shearing dynamic model; The method comprises the steps of carrying out proportional attenuation correction on the cracking stress and the destruction stress of the mechanical test data set based on the deterministic function, correcting an initial stress value according to a linear attenuation relation, generating actual shearing stress of the corroded anchor rod and cracking stress of a system after corrosion, and comprising the following steps: S41, performing blank group data extraction processing on the mechanical test database, and separating a cracking stress initial value and a breaking stress initial value of a control group sample to generate a reference stress data set; S42, performing damage value mapping treatment on the corrosion group sample of the corrosion parameter database based on the deterministic function, and calculating damage variable values corresponding to the corrosion group sample according to actual corrosion conditions to generate sample damage variable values; S43, carrying out proportional attenuation treatment on the reference stress data set based on the sample damage variable value, and calculating a post-corrosion stress value according to a preset attenuation relation to generate an actual shearing stress of the post-corrosion anchor rod and a post-corrosion system cracking stress; The method comprises the steps of constructing a yield function based on the actual shearing stress of the corroded anchor rod and the cracking stress of the corroded system, establishing a differential equation set of elastic-viscoplastic coupling, and generating a fractional order damaged shearing constitutive model, and comprises the following steps: s51, performing yield function construction treatment on the actual shear stress of the corroded anchor rod and the cracking stress of the corroded system, defining a critical threshold value of viscoplastic flow based on a predicted value of the cracking stress after corrosion, and generating a yield function representing the yield condition of the material; S52, performing constitutive equation derivation processing on the yield function, and establishing a differential equation set for describing the material deformation process according to the linear relation of stress-strain in the elastic deformation stage and the relation of strain rate and yield function in the viscoplastic flow stage; And S53, performing coupling modeling treatment on the differential equation set, and combining the rock constitutive relation and the anchor rod constitutive relation in parallel to generate a fractional order damage shear constitutive model representing the dynamic shear response of the anchor-rock combination.
2. The method according to claim 1, wherein S1 comprises: S11, grouping the anchor rod samples, namely dividing the anchor rods into blank groups and corrosion groups, soaking the corrosion groups in solutions with different pH values, standing for different periods of time at constant temperature, and generating a grouped anchor rod sample set; S12, quantifying mass loss of the grouped anchor rod sample sets, measuring mass before and after each group of anchor rods in the grouped anchor rod sample sets is corroded, and calculating mass loss percentage of each group of anchor rods; And S13, carrying out structural treatment on the mass loss percentage, and correlating the pH value, the corrosion time and the mass loss percentage of each group of anchor rods in the group anchor rod sample set to generate a corrosion parameter database.
3. The method according to claim 1, wherein S2 comprises: s21, assembling the pretreated anchor rods, assembling a blank group of anchor rods and rocks into a control group sample, and assembling an etching group anchor rod and rocks in the same batch into an etching group sample to generate an anchor-rock combination sample set; s22, carrying out stress field loading treatment on the anchor-rock combination body sample set, applying orthogonal direction fixed confining pressure, and stabilizing normal and lateral stress to preset values; S23, carrying out shear disturbance loading treatment on the anchor-rock assembly sample in a stress field state, increasing shear load stepwise according to an incremental path, and synchronously superposing cyclic fluctuation stress to generate dynamic shear response data containing a stress-strain relation; And S24, carrying out feature extraction processing on the dynamic shear response data, identifying stress-strain curve feature points of all samples, and generating a mechanical test database containing initial values of cracking stress, initial values of breaking stress and full-stage stress-strain curves.
4. The method according to claim 1, wherein S3 comprises: s31, constructing an input vector of the corrosion parameter database, extracting the pH value, the corrosion time and the mass loss percentage of each group of anchor rod samples, and forming a data matrix containing the association relation between the environmental parameters and the corrosion damage; S32, performing nonlinear function fitting on the data matrix, and adopting an exponential-time coupling equation to iteratively optimize material corrosion constant, pH decay coefficient and time nonlinear factor parameters to generate an initial damage variable function; And S33, performing physical verification on the initial damage variable function, calculating the deviation between the mass loss rate predicted by the function under different corrosion conditions and the actually measured mass loss rate, and generating a deterministic function for calculating the damage variable of the anchor rod under any corrosion condition.
5. The method of claim 4, wherein the expression of the initial injury variable function is: ; Wherein, the For the initial damage variable function, i.e. the anchor rod damage variable, Is the corrosion constant of the material properties, As a sensitivity factor of pH to corrosion rate, As a non-linear influencing factor for corrosion, Is the pH value of the solution, The corrosion time of the anchor rod sample.
6. The method of claim 1, wherein the yield function is expressed as: ; Wherein, the As a function of the yield point, To the shear stress to which the anchor-rock combination is subjected, As a result of the normal stress, To the internal friction angle of the rock-bolt system after corrosion, To the cohesive force of the rock-bolt system after corrosion, As a characteristic length parameter related to rock damage, Is the tensile strength of the rock and, Is the damage threshold value of the rock, Is the actual shear stress of the anchor rod after corrosion.
7. The method of claim 1, wherein the model expression of the fractional order lesion shearing constitutive model is: ; ; ; Wherein, the (T) is a model expression of fractional order damage shearing constitutive model, The shear stress applied to the anchor-rock combination is that G is the elastic shear modulus of the rock without damage, In order to stabilize the relevant mechanical function at the injury stage, In order to accelerate the relevant mechanical function of the injury phase, Is an initial damage variable of a rock mass in a water chemistry environment, For rock mass damage variable under shear stress loading, t is shear stress loading time, For the fractional order derivative order, As a function of the gamma-ray, Is the coefficient of the viscoelastic property of the material, For the fractional order derivative order, As the coefficient of the viscoelastic-plastic property, In order to damage the attenuation coefficient, As a parameter of the initial time of day, Is a characteristic parameter of the anchor rod material; Is the damage variable of the anchor rod in the water chemistry environment.
8. The method according to any one of claims 1-7, wherein S6 comprises: s61, carrying out characteristic segment interception treatment on a full-stage stress-strain curve of a corrosion group sample in the mechanical test database, separating characteristic data points of an elastic segment, a yield segment and a damage segment, and generating a model calibration data set; S62, carrying out parameter inversion processing on the model calibration data set and the fractional order damage shearing constitutive model, namely adopting a global optimization algorithm to fit material parameters of the fractional order damage shearing constitutive model, and realizing parameter optimization by minimizing deviation between a model prediction curve and a test curve to generate an optimized fractional order damage shearing constitutive model; and S63, carrying out dynamic response verification processing on the optimized fractional order damage shear constitutive model, namely verifying the coincidence degree of the model predicted strain rate and the actual strain rate based on test data under the cyclic disturbance loading condition, and generating a verified true triaxial shear dynamic model.

Description

Method for constructing true triaxial shear dynamic model of anchor-rock assembly under water chemical corrosion Technical Field The invention relates to the technical field of rock mechanical properties and engineering research, in particular to a method for constructing a true triaxial shear dynamic model of an anchor-rock assembly under water chemical corrosion. Background In the field of rock mass engineering support, an anchor-rock combination body formed by an anchor rod and surrounding rock is a core structure for guaranteeing long-term stability of a roadway. Because the underground environment commonly has acidic or alkaline underground water, the mechanical properties of the anchor rod can be gradually deteriorated along with the corrosion effect when the anchor rod is in a water chemical corrosion environment for a long time. In order to accurately predict the safety state of the support system in a corrosive environment, a dynamic model capable of quantifying the influence of the water chemical corrosion on the mechanical behavior of the anchor-rock combination needs to be established. The model needs to comprehensively consider the corrosion damage evolution, the true triaxial stress state and the coupling effect of dynamic disturbance load, so that a reliable theoretical basis is provided for the support design of the rock mass engineering. However, the existing anchor-rock combination mechanical model has the obvious defects that most models do not consider the damage mechanism of water chemistry corrosion to anchor rod materials, the attenuation rule of different corrosion conditions such as pH value, corrosion duration and the like to the anchor rod strength is difficult to quantify, and secondly, the existing method lacks accurate description of the coupling relation between corrosion damage and system strength attenuation in a simulated true triaxial stress state to cause larger deviation between a model prediction result and actual engineering, and in addition, in the existing model construction process, the calibration and dynamic verification links of corrosion damage parameters are disjointed, so that the engineering applicability of the model is reduced. Disclosure of Invention Based on the method, the invention aims to provide the method for constructing the true triaxial shear dynamic model of the anchor-rock combination body under the water chemistry corrosion, which can accurately quantify corrosion damage, construct the true triaxial dynamic shear response model and is verified by a system test. The invention adopts the following scheme: in a first aspect, the invention provides a method for constructing a true triaxial shear dynamic model of an anchor-rock assembly under water chemical corrosion, which comprises the following steps: S1, immersing anchor rod samples in groups in constant temperature solutions with different pH values for corrosion for different durations, measuring the mass of all the anchor rod samples before and after corrosion, and generating a corrosion parameter database containing the pH values, the corrosion time and the mass loss; S2, assembling the pretreated anchor rod and the rock sample into an anchor-rock assembly sample, simultaneously performing the same assembly on blank control samples assembled by the anchor rod which are not subjected to corrosion pretreatment, applying preset normal stress and lateral stress to all the samples, loading shear stress according to a multistage incremental path, synchronously applying cyclic disturbance, recording stress-strain data, and generating a mechanical test database containing cracking stress, breaking stress and full-stage stress-strain curves of all the samples; S3, processing the corrosion parameter database, and establishing a preset function relation between the anchor rod damage variable and the pH value and the corrosion time through data fitting according to the mass loss rate and the pH value and the corrosion time, so as to generate a deterministic function for calculating the anchor rod damage variable under any corrosion condition; s4, carrying out proportional attenuation correction on the cracking stress and the destruction stress of the mechanical test data set based on a deterministic function, and correcting an initial stress value according to a linear attenuation relation to generate actual shearing stress of the corroded anchor rod and cracking stress of the corroded system; S5, constructing a yield function based on the actual shearing stress of the corroded anchor rod and the cracking stress of the corroded system, and establishing an elastic-viscoplastic coupled differential equation set to generate a fractional order damage shearing constitutive model; and S6, inputting the full-stage stress-strain curve of the corrosion group sample in the mechanical test database into a fractional order damage shearing constitutive model, fitting parameters by adopting a global optimization algo