Experimental Study And Numerical Analysis Of The Coupling Between Seepage Field And Stress Field Of Rock Mass With Unloading

At present, the study on the coupling between seepage field and stress field of rock mass is a advanced problem of Geotechnical Engineering. Distribution and coupling condition of seepage field and stress field are important influencing factors for the stability of rock mass engineering. Based theoretical analysis, experimental study and numerical calculation, the unloading effects on rock mass permeability at low stress have been depicted. The main conclusions are as follows:(1) Based the depiction of geometrical and mechanical characteristic of the crack of fractured rock mass, and the depiction of models for the coupling between seepage field and stress field of fractured rock mass, and on the basic of the cubic law, a relation between permeability and the unloading stresses is suggested.(2) Based the least square method, the equation parameters of the relation between permeability and stresses have been optimized by using'Matlab'soft.(3) On the basic of P-M model of hysteretic phenomena in the stress-strain curve, the P-M model of hysteretic phenomena in the stress-permeability curve of fractured rock mass is suggested.(4) The test shows that the relationship between the permeability and the effective normal stress is highly nonlinear when the unloading normal stress reaches 60%~80% of its initial value.(5) Observation on intact and cracked rock samples have been done by using CT technique. A single nearly axial fracture has been found in most cases, which lead to a quick increase of seepage.(6) Numerical calculation on the test model has been done by using finite element method, which shows that the radial distribution of stress of coupling is more truer than uncoupling.(7) By applying the cubic law and to a nonparallel smooth wedge-shape walled fracture, the distribution of pore pressure along the walls is derived and compared with the result of numerical calculation.(8) A study on the effect which is the result of bank slopes when the reservoir water level fluctuates has been done.