Abstract：
The effects of tunnel excavation on the deformation of a hollow cavity in a clay stratum was simulated by indoor model tests. The cavity deformation is divided into four modes of radial contraction deformation, oval deformation, vertical settlement deformation, horizontal lateral displacement and various combinations. The elastic solutions for the stress field around the cavern under complex displacement conditions were obtained by the Airy stress function method, and the scope of the plastic zone around the cavity was acquired based on shear yield conditions, with the effect of deformation patterns on plastic zone scope being studied. The results show that: 1) the radial contraction of the cavity makes the plastic zone at both sides develop into a closed ring and extend to the rock mass at a depth symmetrical with an angel of 45° around the tunnel; 2) oval deformation increases the extension of the plastic zone at the top and bottom of the cavity; 3) vertical settlement causes the transfer and extension of the yield scope further toward the top and bottom of the cavity; 4) horizontal lateral displacement makes the plastic zone gradually transfer to the other side of the cavity and develop to the rock mass at depth; and 5) the key point for construction of urban tunnels with cavities is to control the stability of the cavity structure. This research provides a reference for the accurate prediction of strata deformation and ground collapse.
2018, Vol. 55 