Experimental study on liquid-solid coupling of rocks

The effect of stress on hydro-geological conditions or permeability of water-bearing media should follow some laws or principles.Deformed and crashed rocks induced by change of geo-stress fields provide space for groundwater storage and flow.Groundwater adjusts water-bearing space and dilatates fractures by flowing and press transferring.This is one way of coupling of liquid and solid under large deformation or rock failure.Tests show that rock permeability attains the maximum value before and after rock failure,relations of permeability and strain follow logarithmic function for brittle rocks or the quadratic parabola function for soft rocks.On the other hand,stress changing causes only small deformation and can not make rock failure in most cases.This is another way of coupling of liquid and solid.Variety of permeability with effective stresses has relation with pore shape which includes tri-porosity media,fractured rocks,porous rocks and capillary rocks.Investigations indicate that porosity and permeability loss in fractured rocks are greater than that in porous rocks or capillary rocks,permeabil-ity changes are always larger than porosity changes.Porosity or permeability changing rules of porous rocks with variation of effective stresses can be described as the index function,the model of power exponent functions is suitable for those of fractured rocks,and the model of the quadratic parabola is suitable for capillary rocks.