The Distribution Characteristics of Lateral Earth Loads on Complex Underground Spatial Structure

Abstract

Complex spatial underground structures, formed by shaft with intersectional tunnels, divided the surrounding earth, which in turn has great influence on the distribution of earth load acting on the underground structures. The traditional load calculating model of earth pressure is not applicable to this kind of spatial structure since it is basically based on the assumption of plane strain. Using three dimensional (3D) finite element methods (FEM), this work analyzed the earth pressure on spatial underground structures. We found that the lateral earth loads on shaft near the tunnel has different pattern from the case that without tunnels. Beneath the tunnel, the lateral load on the shaft is smaller comparing to the earth loads at rest for the bearing ability of the tunnel. On the position near the apex of the tunnel, the earth loads on the shaft is about equal to the rest earth pressure for the deformation of this part is almost zero. The distribution of lateral loads on the tunnel showed significant arching effect and the arching effect of soil was reduced with distance between the adjacent shafts and tunnels became smaller.