Geological origin and stability analysis of the Suoduoxi accumulation body in the upper reaches of the Jinsha River

摘要

The accumulation body is a aggregate of accumulations. It can be seen everywhere along the upper reaches of the Jinsha River. Exploratory pits and boring were used to study the accumulation. On its geological origin and stability, the four recognitions below are obtained. (1) Most of the accumulation is composed of big rock blocks and gravel-bearing soil, dominated by big rock blocks. So there is a rock block arching in the accumulation. But domain 2 has obvious different structure from other domains. (2) Domain 2 is composed of gravel-bearing soil and rock blocks, dominated by gravel-bearing soil. Furthermore, there is a grading feature from up to down. This is a typical character of debris-flow. So, domain 2 came from anti-shore. (3) The stability of the accumulation is largely good. But collapse will probably happen at domain 2. So some control measures should be adopted to domain 2 before the construction of the hydropower station. (4) The product period of domain 1 is earlier than that of the other domains. But river blocking did not happen during the production period of domain 1. The production of domain 1 made just the river diverting. The true river blocking happened after production of domain 2, domain 3 and domain 4.