A numerical estimation on Dynamic Direct Tensile Strength (DDTS) of rock by introducing centrifugal field

Abstract

The tensile strength of rock is a crucial parameter for establishing constitutive equation of rock mechanics and stability assessment of rock engineering, which is typically determined by an indirect or direct tension test. While the direct tension test receives less attention, because the loading system may produce undesirable failure modes caused by stress concentrations and slight misalignments. Compared with the indirect tension test, the direct tension test is an ideal method to obtain tensile strength and characterize the tensile properties of rock better under static or dynamic condition. Centrifugal testing is widely used in geotechnical engineering but rarely applied to measure the tensile strength of rocks. In this work, a novel testing method was proposed to determine dynamic direct tensile strength (DDTS) by introducing centrifugal field in four-dimensional lattice spring model (4D-LSM). The effect of loading rate and fixture density in the centrifugal field on DDTS and critical angular velocity of specimen failure was studied. Moreover, based on the same testing fixtures, the DDTS was determined and compared with static direct tensile strength (SDTS). The results showed that the DDTS estimated by numerical simulation was rate dependent, and different from that under static condition. While the failure mode of rock specimen under dynamic centrifugal test was basically consistent with that under static load.