The stability of a rock dam site under seismic conditions

This paper takes the Daliushu Dam Site in Yellow River as an example, which is located near the active fault zone with high seismic intensity. It studies the seepage of dam abutment rock mass in meizoseismal area and the stability under earthquake condition. The assessments on the key engineering problems of this project are based upon a large number of investigations, in-situ and laboratory tests, etc., which are carried out in the field by the author. We know that the "5. 12" Wenchuan Earthquake in 2008 triggered strong ruptures and damages of massif, and destructed the concrete facing of the Zipinpu rock-fill dam in Minjiang River, which is very close to the earthquake source and sufferd a 0.56g' seismic acceleration. For this reason, this paper analyzes the possible damage on the Daliushu Dam site rock mass under the grouting in the future earthquake, returning to the present poor quality condition of rock mass, while this dam shares the seismic intensity, seismic acceleration, dam type and dam height similar to the Zipinpu Project. This paper puts forward a new research thought, which is the longtime -lasting strong earthquake,first causes the rupture of rock mass and the decrease of rock mass mechani cal parameters, and the lasting earthquake will then worsen the rock mass structure mechanics parameters, and even cause the large-scale massif damage. From this viewpoint, this paper, analyzes the stability of the dam foundation and abutment rock mass especially the stability of the thin massif of the right dam abutment by the numerical analysis. The analysis show that under the normal and the earthquake conditions (excluding the rock mass damage and mechanical parameters decrese resulted from the lasting earthquake), The Daliushu Dam Site and the right dam abutment are still stable when the safety factor is assumed to be 0.802 under the lasting earthquake. In addition, the calculation results show that the stability is not enough.