三轴循环荷载下珊瑚砾块灰岩力学特性试验OA北大核心

In order to explore the mechanical properties of coral boulder limestone under cyclic loading,this pa-per uses the electro-hydraulic servo triaxial test system(MTS 815.03)to conduct triaxial compressive strength test and triaxial constant cyclic load test on coral boulder limestone under different confining pressures.The stress-strain curves of coral boulder limestone samples are analyzed from the aspects of morphology,strength characteris-tics and failure mode.The test results show that the stress-strain curves of coral boulder limestone samples show obvious hysteretic effect during triaxial cyclic loading test.The triaxial peak strength of reef limestone under cyclic loading is higher than that of triaxial compressive strength,and the peak strength of coral boulder limestone in-creases obviously with the increase of confining pressure and loading frequency.Coral boulder limestone keeps high residual strength after failure under triaxial and cyclic loading.The strength of coral boulder limestone con-forms to Mohr-Coulomb strength criterion.Under cyclic loading,coral boulder limestone presents a complex split-shear failure mode.With the increase of confining pressure and loading frequency,the failure mode of coral boul-der limestone gradually changes from split-shear failure mode to single-inclined shear failure mode,and most of the failure cracks occur along the parts with poor biological component cementation and more through pores.The results are helpful to improve the understanding of mechanical properties and damage characteristics of coral boul-der limestone,and provide important reference for strength design and construction of coral reef engineering.