Investigation on Uniaxial Compression and Fracture Damage Mode of Prefabricated Parallel Double-Jointed Red Sandstone

Abstract

Abstract In order to study the strength characteristics and damage characteristics of parallel double jointed red sandstone, physical uniaxial compression tests were carried out on parallel double jointed red sandstone filled with cement mortar under different geometric parameters. A method for calculating stress intensity factor of parallel double-jointed fractures was proposed. The results show that the larger the connectivity rate of collinear joints, the smaller the peak stress and strain. When the length of rock bridge decreases, the peak stress changes greatly. When the collinear joint is close to connectivity, the axial peak strain changes greatly, and the increase of connectivity rate will affect the change rate of transverse strain in the center of rock bridge. When the length and dip angle of the rock bridge remain unchanged, the closer the dip angle of the joint is, the lower the peak stress is and the shorter the failure time is. The failure mode of joint tip penetration affects the lateral displacement of the center of the rock bridge, and the displacement is always close to the first failure part. The closer the joint tip is to the load, the easier the end-face penetrating cracks occur.