After-peak Characteristics And Constitutive Modeling Of Non-penetrating Crack Rock-like Specimen

The 21 st century is the century of underground engineering,with the building of underground project,people find that the bearing capacity is not completely lost under confining pressure,which is important to engineering.Therefore,it is necessary to study the after-peak strength of crack rock mass.Using cement mortar to make rock specimen,by embedding sheet metal to simulate fracture in rock mass,thus obtain the rock-like specimen with different non-penetrating crack.Obtain the stress-strain curve of the non-penetrating crack specimen under uniaxial compression test and triaxial compression test,analysis the influence of confining pressure and crack angle to the peak strength and after-peak strength;introduce the concept of after-peak elastic modulus and rate strength to quantify the plastic characteristics of specimen;Compare and analyze the changes of c and f values in the peak and after-peak stages of rock-like specimen;Meanwhile,on the basis of failure mode,the failure modes of rock-like specimens are divided into two situations: failure along the precast crack surface and failure not along the precast crack surface,using element model to simulate constitutive relation whose failure mode of the specimen is along the precast crack surface damage,using relevant knowledge to simulate constitutive relation whose failure mode of the specimen is not along the precast crack damage,show that:Compare with peak strength,after-peak strength is more sensitivity to the confining pressure,and the sensitivity of after-peak strength to confining pressure changes over the confining pressure.The after-peak strength of the non-penetrating crack specimen decreases first and then increases with the increase of the crack angle.The crack angle affects the plastic characteristics of the after-peak section of non-penetrating crack specimen,to a certain extent.When the angle of crack is 90°,the crack increase plastic characteristics of the specimen,,while the angle of crack is75°,the crack reduce the plastic characteristics of the specimens.The failure mode of the specimen is mainly related to the confining pressure.,the damage mode of specimen is fracturing damage under low confining pressure;with the increase of confining pressure,the damage mode of specimen is shear damage;the specimen present certain plastic flow failure mode under highconfining pressure...