Stability of the rock block system involved in the Jiweishan landslide in China

The objective of the paper is to investigate the initiation of the Jiweishan landslide by simulating the field geological conditions around and inside a selected critical rock block and then to study its stability through 3-D discontinuum stress analysis. The study led to the following main conclusions: (i) The mining excavations that occurred underneath the investigated block at the landslide site, the friction angle of T2 discontinuities and sliding plane, and the dip angle of the sliding plane seem to be the most important factors with respect to the instability of the investigated block, (ii) It seems that the inction angle of T2 discontinuities and sliding plane need to drop to a value between 5° and 10° for the investigated block to be unstable. This means that rainfall and karstification have played important roles in reducing the said friction angle and contributed to the failure of the investigated block, (iii) The northern part of the investigated block (key block) had moved out first from the top of the mountain in a direction parallel to the strike of the north boundary discontinuity plane (T2) and had undergone shear failure on the T2 surface as well as on a weak shale layer (the sliding plane) and the remaining part of the investigated block (driving block) had moved in a NNE direction and had undergone shear failure on the sliding plane and separation from southern and western boundary discontinuity planes (TO and Tl) to fill the empty space created by the key block to initiate the Jiweishan landslide.