Study on the deformation and failure characteristics and the evolution law of permeability characteristics of lattice limestone under triaxial loading conditions

Abstract

The automatic GDS triaxial seepage test system was used to carry out the stress-seepage coupling test of lattice limestone under seepage conditions. It is concluded that the peak stress and strain of lattice limestone increase with the increase of confining pressure, and the confining pressure effect is significant, and the weakening effect of saturated water has a great influence on the mechanical indexes of lattice limestone. Although the confining pressure increases, the failure mode transitions from X-shaped conjugate inclined shear failure to single-inclined shear failure, and finally presents a penetrating tensile failure form. Under different confining pressures, the permeability of lattice limestone corresponds well to the stress-strain curve. At the same time, the permeability loss rate(PSL) increases with the increase of confining pressure, and the permeability loss coefficient(EIP) is positive in the 1st to 4th stage loading, negative value after the 5th stage loading at low confining pressure, and negative value after the 6th and 7th levels of high confining pressure.

Keywords

trellis limestone / stress-seepage / rock destruction / permeability evolution