Stability of rectangular tunnel in cohesionless soils

Abstract

Stability of rectangular tunnel in cohesionless soils has been investigated by using lower-bound finite-element limit analysis with second-order conic programming (SOCP). The rectangular tunnel of width B and height D is placed at a depth of H from the ground surface. A uniform compressive pressure is applied at the tunnel periphery with the help of a lining or anchorage system to support it. The lining pressure (σt) is optimized subjected to a set of equality and inequality constraints by using the SOCP optimization technique. The variation of normalized compressive pressure (σt/γD) is presented for combinations of B/D, H/D and ϕ where ϕ is the internal friction angle for both smooth and rough tunnel surface.