Abstract: Quasi-static uniaxial and triaxial compressive tests for the limestone from Fankou Zinc-lead Mine are carried out through MTS Testing System,and the stress-strain curves of limestone samples before and after the peak value under different confining pressures are obtained.According to the testing results,the loading-displacement behaviors of rock samples,and the characteristics between elastic moduli,peak-strength and confining pressures before peak value of the rocks are analyzed.The quantitative relationships between peak strength and peak strain,confining pressure and stress are proposed respectively.Then the further studies on strain-softening and residual strength of rock samples after peak strength are carried out,and the quantitative relationships between residual strength,initiating residual strain and confining pressures are established.An important strain-softening property of "elastic-fragile drop" is obtained for most of the rock samples under the quasi-loading conditions.It offers the basis for theoretical study on constitutive model of deep rock of the mine in engineering application.

Key words: Limestone, Residual strength, Strain-softening