Stability of rectangular tunnel in Hoek–Brown rocks under steady-state groundwater flow

Abstract

This research study aims to determine the stability of a rectangular tunnel excavated in rock masses obeying Hoek–Brown yield criteria under steady-state groundwater flow using lower bound limit analysis. During tunnelling in the presence of groundwater table (GWT) seepage forces are generated, which causes a decrease in the stability of rock mass. The total head distribution due to seepage is obtained by using two-dimensional finite element software Optum G2. The stability has been presented by a non-dimensional number σci/γ′maxH obtained for various combinations of B/h, H/h, Hw/h, σci/γwh, mi, GSI and D where B and h are width and height of the tunnel, respectively, H is the depth of the tunnel from the ground surface and Hw is the height of GWT from the tunnel roof, respectively, σci and γ′ are uniaxial compressive strength and submerged unit weight of rock, respectively, γw is the unit weight of water and mi, GSI and D are the Hoek–Brown parameters.