Abstract Deformation of weak surrounding rock mainly occurs in front of the working face and the key point it is to control the deformation in front of the working face, i.e. pre-convergence. The pre-arch is characterized by good transverse continuity and rapid construction, and thus has positive effects on controlling the pre-convergence of weak surrounding rock. A 3D numerical model was set up by FLAC3D and the mechanism of the pre-arch to control deformation of weak surrounding rock was analyzed. Studies show that: (a) The pre-arch can effectively control the pre-convergence, convergence, and rock deformation above the tunnel. As rock conditions worsen, the effects of the pre-arch are more significant; (b) The pre-arch can effectively control the stress relief of the rock mass ahead of the working face and control the developing range of the collapsing arch above the tunnel, limit the distributing area of the collapsing arch at the tunnel crown, reduce the disturbance on surrounding rock, and restrict stress redistribution; and (c) Since stress relief is controlled, the rock load applied on the pre-arch is larger than that of conventional support.
Abstract：
Deformation of weak surrounding rock mainly occurs in front of the working face and the key point it is to control the deformation in front of the working face, i.e. pre-convergence. The pre-arch is characterized by good transverse continuity and rapid construction, and thus has positive effects on controlling the pre-convergence of weak surrounding rock. A 3D numerical model was set up by FLAC3D and the mechanism of the pre-arch to control deformation of weak surrounding rock was analyzed. Studies show that: (a) The pre-arch can effectively control the pre-convergence, convergence, and rock deformation above the tunnel. As rock conditions worsen, the effects of the pre-arch are more significant; (b) The pre-arch can effectively control the stress relief of the rock mass ahead of the working face and control the developing range of the collapsing arch above the tunnel, limit the distributing area of the collapsing arch at the tunnel crown, reduce the disturbance on surrounding rock, and restrict stress redistribution; and (c) Since stress relief is controlled, the rock load applied on the pre-arch is larger than that of conventional support.
DU Lin-Lin,
Wang-Xiu-Ying,
Liu-Wei-Ning
.On the Mechanism of Controlling Deformation of Weak Surrounding Rock with a Pre-Arch[J] MODERN TUNNELLING TECHNOLOGY, 2014,V51(1): 62-69
2014, Vol. 51 