Research On Wellbore Stability Of Deep Shaft Under High Stress Based On Modified D-P Constitutive

With the rapid development of economy,the demand for resources in various countries is increasing,and mining engineering is constantly developing to the deep.There are some problems such as serious deformation of surrounding rock and difficult support in deep roadway engineering under high ground stress.In this paper,the deep granite in a mine in Shandong Province is taken as the research object.Firstly,the true triaxial experiments of granite under high stress are carried out,and the deformation characteristics and strength characteristics of granite under high stress are studied.Then,based on the experimental results,a modified D-P constitutive model reflecting the softening characteristics of granite under high stress state is established,and the constitutive model is realized and verified by secondary development on Abaqus software platform.Finally,the research results are applied to the dynamic simulation of the shaft excavation and support process of the auxiliary shaft project in the mine in Shandong Province.The influence of shaft excavation disturbance,support structure strength and support time on the stability of surrounding rock and support structure under high ground stress is studied.The main research work carried out in this paper is as follows:（1）The representative deep granite in the auxiliary shaft project of a mine in Shandong Province was selected,and the true triaxial experiments of intermediate principal stress level from 10 MPa to 100 MPa were carried out.The influence of intermediate principal stress on the strength and deformation of granite was studied,and the softening characteristics and brittle failure characteristics of granite under high stress were explored.（2）Considering the softening characteristics of granite under high stress,based on the linear section of classical Drucker-Prager strength criterion,the parabola is used to characterize the nonlinear relationship between hydrostatic pressure p andJ₂ under high stress state,and a modified D-P constitutive model which can reflect the softening characteristics of granite under high stress state is established.（3）On the Abaqus software platform,based on the VUMAT constitutive model development interface.The modified D-P constitutive model is realized by secondary development.The indoor true triaxial experiment carried out in（1）is reproduced by numerical simulation.Based on the consistency of stress-strain curve and peak stress between numerical experiment and physical experiment,the validity and practicability of the modified D-P constitutive model are verified.（4）A three-dimensional finite element model of surrounding rock-excavation body-support structure of auxiliary shaft project in a mine in Shandong Province was established.The modified D-P constitutive model was used to reflect the softening characteristics of granite under high stress.The dynamic simulation of shaft excavation and support process is carried out,and the influence of deep shaft excavation disturbance on the stability of surrounding rock and support structure is studied.Engineering suggestions are put forward for excavation mode,support time and support structure selection.