Study on the tensile-shear mechanical behavior of sandstone using a simple auxiliary apparatus

Abstract

Mixed failure of rock by tension and shear occurs frequently in underground openings, rock slopes, and transtension faults. In this study, a simple auxiliary device (which consists of an indenter and a hollowed base) is proposed to implement tension-shear tests of rock samples combined with a servo-controlled uniaxial compression machine. Experimental and numerical tension-shear tests are carried out on red sandstones using the proposed auxiliary device and particle flow code. The effects of sample height H and base hollow diameter D on the mechanical behaviors are analyzed in detail, including the peak load, fracture characteristics, and AE characteristics. The results show that peak load increases with the sample height while decreases with hollow diameter due to the change of inclination angle of the failure surface. The initial crack and dominant cracks changed from shear cracks to tensile cracks as D increase from 2 cm to 4 cm, which suggests the transition from shear failure to hybrid tension-shear failure.