Analysis Of Development Law And Genetic Mechanism Of The Landsides In Kala Area, Yalong River

Yalong River is the key areas of hydropower exploitation in China, where there are 12 large scale constructed, constructing and planning hydropower stations. Building reservoirs can change the geo-environment conditions of the slopes, and may cause the slopes instability or the old(ancient) landsides resurrection, which is a serious threat to the people’s lives and property, road traffic, hydropower stations and other projects. So carrying out the research of development law and formation of the landsides in Kala area has a vast importance to landsides prevention and theoretical research.This paper is founded on the investigation of geologic hazards of Kala scale 1:50000. We combined with previous research and finished this paper with a lot of methods. The methods includes remote sensing interpreting, surveying on large scale, engineering geology drilling, ESR dating, soil-rock physical and mechanical test, statistical analysis using SPSS, numerical simulation and so on. We obtained the following results and conclusions:(1)Kala area is located in the Qinghai Tibet Plateau to Sichuan Basin transitional area and belongs to the eastern edge of Qinghai Tibet Plateau eroded mountain area strong- strong cutting of mountain area. There are 13 large—super-large landsides in Kala area. These landsides include Yijiang landside, Zhoujia landside, Luoguai landside, Batong1# landside, Batong2# landside, Shangtianzhenbei landside, Xiatianzhen landside, Tiansan landside, Gangjian landside, Yanggou landside, Kala landside, Xiamajidian landside and Caoping landside. The volume of all the landsides is over 6.19×108m3.(2) The plane law of the landsides is the linear distribution along the river the fault, and the number of the landside in trunk stream is more than in tributary, and on the right bank of Yalong River is more than on the left bank. The law in the section of the valley is that the altitude of the landsides distribution is 2500 m, and the altitude is the slope turning of canyon to wide-valley of Yalong River.(3)There are 3 landsides developing before 0~11700 years(the Holocene), 8 landsides developing before 11700~40000 years(terminal late Pleistocene) and 2 landsides developing before 4000~126000 years(metaphase-early Pleistocene). We can deduce that new tectonic movement in the area is strongly, climate changes violently and geological hazards Occur frequently.(4)According to relationship between sliding surface and rock stratum, there are 9 bedding landsides and 4 Cutting-layer landslides. According to thickness of the main body, there are 3 medium thickness landsides, 5 deep level landslides and 5 super-deep level landslides. According to volume of main body, there are 1 big landsides and 12 super-big landslides. According to the time of landsides occurs, there are 3 old landsides and 10 ancient landslides.(5)The formation and evolution of the typical landside(Tiansan landsides) is simulated by FEM and DDA, Which recreates the whole process of the formation mechanism of Tiansan landside, and the simulation results and the field geological survey and geological analysis are in good agreement.(6)We summarized the controlling formation factors and the typical models of formation mechanism of the landsides. The landslides are formed under the action of properties of rock mass and rock combination, Slope geological structure, the geological structures and the new tectonic movement, and underground water. Four geological and mechanics typical models of formation mechanism of the landslides are bedding slip- bending- shearing type, bedding sliding tension type, bending and breaking and sliding tension type,ladder sliding tension type.