Applicability of powder-based 3D printing technology in shear behavior analysis of rock mass containing non-persistent joints

Abstract

To evaluate the shear strength of rock mass containing non-persistent joints, a comprehensive knowledge of the shear mechanism of both joint and rock bridge is required. In this study, different joint configurations were initially designed, then the 3D printed and plaster specimens were made applying 3D printing technology and casting process, respectively. A novel procedure was applied to build plaster specimens embedding finite (closed/open) joints surrounded by intact material from all sides. Subsequently, joint persistence (rock bridge ratio) and joint dispersion effects of both single joint and coplanar intermittent joints on the shear strength of the specimens were experimentally examined by conducting several direct shear tests under constant normal load (CNL) condition. The experimental results obtained from the plaster and 3D printed specimens were compared to assess the applicability of powder-based 3D printing technology to shear behavior analysis of weakness planes containing non-persistent joints. Moreover, the joint friction contribution to the shear strength of the plaster specimens containing a single non-persistent joint was investigated thanks to the proposed casting procedure. It was found that the embedded joints of the specimens with greater rock bridge ratios have less contribution to the shear strength.