Research on Formation Mechanism of Deep Cracks in Left Bank Slope of Jinping First Stage Hydropower Station Based on DDA Method

Abstract

Deep crack of high slope in the deep-cutting canyon region is a special geological phenomenon which exists in hydropower engineering in the west of China. High steep rock slopes are usually chosen as action sites of dam abutment. However, many deep cracks are often discovered in the depth of these high slopes. And irrefutably deep cracks greatly influence the stability of the engineering. By taking the deep cracks of left bank in Jinping I hydropower station as an example, formation mechanism of deep crack in high slope is partially revealed in this paper. Deep cracks were result of release of high geo-stress including body stress and tectonic stress when external environmental condition changed (such as river valley deep-cutting). Geometry and mechanics characteristics of discontinuous are internal factors result in the formation of deep cracks; deep cracks maybe have stepped-up process when combination of discontinuous is unfavorable; and intense release of high geo-stress caused by valley deep-cutting is external factor. In this paper, different combination of discontinuous was analyzed, and the formation process of deep cracks was simulated by DDA method. It concludes that the formation of deep cracks go through a series of complex process including river valley stress concentration caused by intense unloading - the high slope tension crack caused by horizontal stress release- part of the tension crack rock mass generates shear-tension crack downward along the slope under gravity”, etc. Research on this subject is a theory support for excavation and reinforcement of high slope where deep cracks exist.