ABSTRACT
The stability of dual elliptical tunnels in soft clay has been investigated by using lower bound finite element limit analysis with second-order conic programming (SOCP). A uniform compressive normal pressure (σi) is required to apply at the tunnel periphery with the help of lining or anchorage system to maintain the stability. The magnitude of compressive pressure (σi) is determined in the form of normalised pressure (σi/cu0) for different combinations of D/B, H/B, S/B, γB/cu0 and m, where H refers to soil cover depth, B and D refer to width and height of an elliptical tunnel, respectively, γ is unit weight of soil, cu0 is the undrained shear strength at the ground surface and m is the normalised rate at which the undrained shear strength of the soil increases linearly with depth. The results are presented in the form of dimensionless charts expressing the effect of S/B on the magnitude of σi/cu0 for different values of D/B, H/B, γB/cu0 and m.
Disclosure statement
No potential conflict of interest was reported by the authors.