Ground Fault Effect on Utility Tunnel in Loess Stratum

Utility tunnel is important for modern cities to transport water, heat, and gas to city core. Its safety is influenced heavily by stratum conditions, extremely by ground fault in Xi’an featured with loess stratum in geology. In this paper, the stress and deformation of utility tunnel are analyzed under the different intersecting angles between ground fault and utility tunnel by means of numerical method. The results show that vertical, horizontal, and bending deformations occur in utility tunnel with ground fault movement, and the deformations are inversely proportional to intersection angle. The deformations concentrate along utility tunnel on both sides of ground fault with a range of 20 m roughly. The top plate of utility tunnel is subjected to compressive stress; the bottom plate is subjected to tensile stress in the hanging wall of ground fault, reversely in foot wall. The maximum stress in utility tunnel decreases with the increasing of the intersection angle. Disconnecting phenomenon takes place between bottom plate and loess stratum, and the disconnecting area is independent to intersection angle. It is recommended to avoid small-angle intersection in the designing and constructing of utility tunnel in loess stratum.