Failure mode analysis of jointed rock masses around underground opening under excavation unloading

摘要

The failure modes and loosened mechanism for jointed rock masses around an undergroundnopening under excavation unloading are studied using the discontinuous deformation analysisn(DDA) method. A sequential excavation algorithm for jointed rock masses is proposed andnimplemented into the original DDA program. Different combinations of joint dip angle are used tonstudy their effects on the failure modes and deformation behaviour of jointed rock masses. Thenresults of both DDA and physical model show that the failure modes of jointed rock massesnaround the underground opening are mainly dependent on disadvantage combination of freenexcavating surface and discontinuities surfaces. The different joint orientations result in differentnfailure modes and collapse areas of surrounding rocks. Opening and sliding failure in the left andnright sidewalls of the underground opening occur for the orthogonal joint set with dip angles ofn306120u, while toppling failure was observed in the right sidewall for the joint set with dip anglesnof 456135u.