Study on seismic safety of Poshitougou flood intercepting dam

Abstract

Poshitougou dam is located in Xichang City, Sichuan Province. The purpose of the dam is to divert the river section passing through the open-pit mining site to ensure the safe operation of the mining site. The dam is a concrete gravity dam with a length of 148.61m and a height of 34.0m, built on deep alluvium foundation with a depth of 160m. The nearest distance between the dam and the Anninghe fault is 10km, and the fault may have a magnitude 7.5 earthquake in the future, so the seismic safety of the dam is very important. In this paper, the finite element dynamic method is used to analyse the seismic response and dam safety under the design earthquake. According to the calculation results, there are serious potential safety hazards in the dam under strong earthquake, including: collision between adjacent dam sections may occur during the earthquake, causing local damage to the concrete near the joint; joint deformation may tear the water stop, leading to dam leakage; breakage of dam foundation curtain grouting may occur during the earthquake. This paper also discusses the possibility of constructing hardfill dam on deep alluvium foundation in strong earthquake area. The calculation results show that the seismic displacement of the hardfill dam is obviously reduced, the seismic amplification effect of the dam is significantly reduced, the dynamic stress of the dam is smaller and its seismic performance is good.