Research On Damage Evolution Rules And Permeability Characteristics Of Coal Rocks Under Fluid-structure Coupling

As a natural heterogeneous material,coal rock contains a large number of internal defects,such as fissures,pores and joint cracks.These defects provide a place for the storage and migration of groundwater.The coupling of the seepage field and the stress field makes the coal rock failure mechanism very complicated,which makes the study of the seepage-stress coupling problem more general theoretical significance and practical value.In order to analyze the damage and failure evolution mechanism and seepage characteristics of coal rock under the coupling of seepage and stress.In this paper,theoretical analysis,laboratory tests and programming simulations are used synthetically to study the evolution of coal rock damage and permeability characteristics under the condition of seepage-stress coupling.The main tasks are as follows:1)Uniaxial compression tests and seepage-stress coupling experiments for coal rock,based on the experimental results and related theories,the strain-permeability relationship equation is established,which provides a theoretical basis for constructing the constitutive equations and numerical models for the elastic-brittle coal rock damage under the coupling of seepage-stress.2)Improved boundary particle processing in the SPH(smooth particle hydrodynamics)method,solve the problem of stress imbalance under heterogeneous conditions,combining elastic mechanics,mesoscopic statistical damage mechanics and classical seepage theory.Based on the SPH method and the Visual Studio programming platform,improved the seepage-stress coupling numerical simulation program for brittle brittle coal.3)Numerical simulation based on a coupled program,systematically study the seepage failure of coal rock specimens under different confining pressure,pore water pressure,and homogeneity.At the same time,the law of permeability changes under different stress states and the evolution of coal rock damage under the effect of seepage stress are studied,which initially revealed the seepage-stress interaction mechanism.