Stability Analysis of Underground Cavity by Numerical Modeling

Abstract

Sinkhole subsidence is a significant global concern. This thesis examines the stability of areas above and around an assumed underground cavity in cohesive soil and limestone utilizing numerical modeling with Examine 2D and RS2. Stability was assessed by the strength factor (S.F.), with areas considered unstable if the value is below 1. Two scenarios were evaluated: 'Fixed bottom' and 'Fixed dimension', focusing on the impact of different overburden thicknesses and cavity dimensions under dry and fully saturated conditions. For cohesive soil, higher cohesion is necessary for ground surface stability, particularly under fully saturated conditions. The minimum required overburden thickness for ground stability decreases as cohesion increases. Similar trends were observed in limestone, where higher Geological Strength Index (GSI) values enhance stability. Weaker materials and saturated conditions result in larger unstable zones around the cavity, potentially leading to sinkhole formation.