The Nonlinear Creep Characteristics And Anchoring Mechanism Of Soft Rock

Creep is an important mechanics characteristics of rock material, many geotechnical problems have close relationship with the creep properties of the rock, the effects of rock creep phenomenon to actual engineering has aroused wide attention of scholars both at home and abroad. Underground engineering of soft rock creep characteristics and anchoring mechanism is a hotspot of research question, in this paper, through the experimental research, the research methods of combining theoretical analysis and numerical simulation, the basic mechanical properties of mudstone, creep property, nonlinear creep model, parameter identification and bolt anchoring interface bond-slip relationship conducted in-depth research, and is applied to research Gao Guliang coal mine soft rock tunnel supporting structure analysis, the thesis mainly work as follows:(1) Conventional uniaxial compression test of mudstone are performed, and studied the strength and deformation characteristics, and obtained the basic mechanics characteristic parameters. According to the mudstone creep test compressive strength was determined in hierarchical load level and strength. Mudstone respectively to make use of rock triaxial test apparatus for staging of uniaxial and triaxial loading creep test, the different loading paths including confining pressure is constant, grading increase axial compression; Constant axial compression, grading increase under confining pressure mudstone creep characteristic has carried on the system research, obtained under different loading paths and different stress level the deformation characteristics of mudstone creep process and the changing rule of the creep rate;(2) Regarding the rock creep process as a superposition of linear and nonlinear creep process, based on the modeling method of component model, the viscous coefficient containing fractional order calculus FC components instead of Newton stick pot with Kelvin, spring components in series, at the same time introduced considering the effect of load level and time damage variables, a five element nonlinear creep damage model is put forward, and a better simulation of mudstone creep process, especially the mudstone accelerated creep stage, and deduce the constitutive equation and creep equation of the model;(3) Because the parameters are more in the creep model, this paper adopts the genetic crossover factor of the improved particle swarm optimization (pso) algorithm and least square method of joint inversion method, according to the mudstone creep test data, for five elements in this paper, nonlinear creep damage model parameters for the identification, it is concluded that the reasonable numerical parameters;(4) In order to study the anchoring mechanism,the paper carry out the anchor center drawing experiment. Using the configuration analysis of five kinds of cement mortar reinforced and compressive strength of cement mortar interface, get the optimal mixing proportion. According to the results of laboratory test, based on the load transfer method is deduced from the anchor-mortar interface through the elastic state, the plastic softening and cracking and sliding the mathematical model of three phases;(5) By containing the fractional order of the five elements of nonlinear creep damage constitutive equation of the model, stylized implementation based on FLAC3D constitutive model secondary development. And combined with the port anchor-mortar interface is derived in the elastic state, the plastic softening and cracking slip, the mathematical model of three phase, numerical simulation was carried out on the Gao Guliang coal mine soft rock supporting structure analysis. By FLAC3D and the displacement field and stress field before and after the roadway support calculation and analysis, compare the results of numerical calculation and field monitoring data analysis, tests the joint support of soft rock roadways deformation control effect.