Stability Evaluation And Treatment Engineering Design Of H₁Landslide In Yushu Xihang Hydropower Station

An Ms7.1earthquake occurred on Apr.14,2010, in Yushu, Qinghai Province, the depth offocus is14km, and the epicenter is16km away from the county in the northwest. Influenced bythe Yushu earthquake, the Xihang hydropower station slope in Jiegu town generated a mass ofcambered tensile cracks and crags, the largest crack is about0.5m width, with obvious verticaldislocation. The height of the slope here is about300m, because the rock mass is loose after theearthquake, the landslides is of high possibility to take place. It is a great threat to the Xihanghydropower station, the emergency fuel power plant, south circular road, the houses andbuildings in the planning area along the south circular road, the municipal project, thecommercial group and people’s life safety, so it is urgent in need of eliminating the hazard.In this paper, the Xihang hydropower station slope H1was chosen as the study object, baseon the cause of formation and influence factor of the slope H1, The stability of the landslide wasevaluated with transfer coefficient method, and demonstrated the landslide treatment scheme,and then carried out Landslide prevention project. The results of this research were stated asfollows:1) The slope H1is mainly an old landslide, with chair-like shape, the trailing edgecharacteristics is obvious. Influenced by the Yushu earthquake, the trailing edge and the lateralmargin of the old landslide have varying degrees of cracking and deformation, the crack in thetrailing edge is about3-8cm width, the front edge is in free space by excavation, it is a negativefactor of the landslide stability and may bring about the slide.2) The superficial layer part of the Xihang slope H1is under met stable state, in thecondition of earthquakes and rainstorms, it is under unstable state, the deep layer of the slope H1is under stable state in natural and rainstorm condition, but still lower than the Ⅱ level controlengineering safety coefficient, therefore, project prevention is necessary. The evaluation result isin accordance with the qualitative judgment of the crack in the slope.(3) By the principles of economic, rational and secure, the optimal scheme of the landslideH1prevention is slide-resistant pile backfill and the pressure slope surface drainage.