Cause discussion and Stability Evaluation of the Accumulation body near the Dam of a hydropower station

Between the upper dam site and the middle dam site of the planned a hydropower station, there is a large near-dam accumulation body. Whether the hydropower station can be approved by the state depends on whether the accumulation body is stable. Through field surveys and on-site geological exploration and other means, the development characteristics and material composition of the deposits near the dam of a hydropower station were revealed and it is estimated that the volume of the accumulation body is about $7200 \times 10^{4} {\mathrm {m}}^{3}$. It is judged that it is a large accumulation body composed of Quaternary collapse deposits and multi-periodic glacier (water) terminal or lateral moraine deposits. Because the accumulation body is located between the upper dam site and the middle dam site of the planned hydropower station, the stability of the accumulation body has attracted much attention. The stability of the accumulation was evaluated by a combination of qualitative and quantitative methods, and It was concluded that although there are blocks with poor local stability in the front edge of the accumulation body, due to the support and anti-slip effect of the bedrock pedestal under the accumulation body, the overall stability of the accumulation body is relatively good, After the water storage, the possibility of overall instability of the accumulation body is unlikely, and it has little impact on the planned hydropower station. The research results can provide references for the origin and stability evaluation of the corresponding accumulation body in southeastern Tibet.