A different mechanics behaviour and a different failure process are observed of the large porous sanstone with diffrent confining pressures and diffrent saturating fluids(e.g.oil and water). Laboratory tests under complex loading paths demonstrate that a critical value of confining pressure is proved to exist

when the confining pressure increases

the main pressure-shear failure is changed into slough failure. In this paper

two failure throries are used to explain failure processes of large porous sandstone with water saturation and oil saturation respectively through an analysis of the results of laboratory tests. A constitutive model of the saturating sandstone with different fluids of oil and water is established by using the typical plasticity

and 3-dimensional nonlinear FEM is used to check the elastoplastic model based on the laboratory tests. The numerical results show that the laboratory tests are good in agreement with the mumerical simulation results by using the model of the paper

and the several failure mechanisms under complex loading paths and the additional subsidence of large porous saturating sandstone from oil exploration by hydraulic grouting are also simulated well.