Influence of a Rock Bridge on the Shearing Behavior of Nonpersistent Rough Joints: An Experimental Study.

The interaction between the joints and the rock bridge beforehand is very complex, which is mainly reflected in the sequence of mobilization and stress distribution between them. To better understand the influence of the rock bridge, direct shear tests were carried out through a newly proposed method on rock specimens which contain two parallel incipient joints. As an innovative study, a method of preparing specimens using 3D printing technology is presented and the localized deformation in rock bridge and joint area is of interest. Test results showed that the failure process of nonpersistent closed rough joints can be divided into seven stages. The seven stages have been successfully verified using PFC2D (Particle Flow Code 2D). The joint surface roughness influences the mobilization pattern by altering the failure process, while rock bridges can weaken the transmission of shear stress, causing the mobilization displacements of the joints on either side of the rock bridge to be out of sync. The roughness of the joint surface after shearing increases with increasing initial JRC. The rock bridge reduces the peak displacement of the joint surface by altering the degree of wear of the joint surface; and the peak displacement of the rock bridge increases due to the unsynchronised mobilization of the joint surface on either side of the rock bridge, thus altering the failure behavior of the rock joints. Highlights: By analyzing the localized deformation of a rock bridge and joint surfaces, the interaction between them and the shear failure characteristics of the whole joint plane were investigated. Rock bridge in nonpersistent joints weakens the transmission of shear stress, causing the mobilization displacements of the joints on either side of the rock bridge to be out of sync. The peak displacement of the rock bridge increases due to the unsynchronized mobilization of the joint surface on either side of the rock bridge, thus altering the failure behavior. [ABSTRACT FROM AUTHOR]