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Study On The Stability Of The Ancient Landslide Of Ergu Groove-Wanbo Groove Of Meigu Pingtou Hydropower Station

Posted on:2010-06-27Degree:MasterType:Thesis
Country:ChinaCandidate:Z T HuFull Text:PDF
GTID:2120360278960631Subject:Geotechnical engineering
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The ancient landslide of Ergu groove– Wanbo groove,which is located on the banks of site areaⅢdistrict at Meigu Pingtou hydropower station , is a deep oblique bedding rock slide. The elevation of leading edge of landslide is 610m and trailing edge is about 1200m. The maximum depth of slip surface is 282m, the size is around 8500×10~4m~3 . It is an ultra-large deep-seated landslides. The upper part of the surface appeared relatively flat, central extrude, the leading edge variable steep , which are terrain characteristics typical of landslide. Landslide's deformation and failure is obvious,Ⅰ#,Ⅱ# of the two deep rupture zones at the central and posterior marginal of landslide are nearly the same strike to the slope. It is created by tectonic stress, the vertical dimension of the "X" joints, parallel to the steep banks dump unloading cracks and bedding portfolio development, formed a similar special-shaped slide groove borders. It has clear three-dimensional effect. At the same time, there is desertification phenomenon in the structure of various types of cracks. Underground priming tunnel through the Landslide and post-operational safety of the projects will be under threat. It is particularly critical that how to understand the formation mechanism and failure mode of landslides, and the correct evaluation of its stability.(1) Based on the Geological Survey in the field, indoor and outdoor tests, we identify the engineering geological conditions of landslide areas of and landslide boundary, material composition and structure of deformation and failure, then lan??des in the sliding plane is divided into zones (Ⅲ1+Ⅲ2) and rupture zone (Ⅲ3).(2) Through engineering geological conditions of the landslide area and the basic characteristics of landslide , combined with the evolution of regional river valley, characteristics of rebuilding and dating date of the superficial surface of slope rock, the author analysises the formation conditions of landslide and the inducement of deformation and failure conditions. And then the pattern of the deformation and failure of landslide is explored through the causes of law of the geological history , mechanisms supported by physical simulation.(3) The results of landslide stability geological analysis and a simple two-dimensional limit equilibrium calculation show that the current structure is conducive to landslide slope stability, landslides is stable integrally. At the same time, the results of two-dimensional quantitative analysis shows that it will be presented the plug-style landslide characteristics when landslide is instability under heavy rain.(4) We calculate the three-dimensional stability of landslide under natural conditions, heavy rain condition and natural + earthquake conditions factors with three-dimensional transfer coefficient method (MJ model expansion) and FLAC3D strength reduction and analysis the impact factors of landslides. The results showed that:①In this paper, three-dimensional model expansion applied to calculate the stability of the landslide is appropriate and feasible;②The results show that landslide is in the steady-state landslide under natural conditions and natural + seismic conditions; Under heavy rain conditions, when water-filled crack with a high degree is equal to theⅠ# fracturing 0.65 times, the former Department ofⅢ1-a district will be taken place to start,Ⅲ1-b will be silded because of after appropriate hydraulic appropriate conditions. However, due to the existing of g??natural drainage gully channels, the upstream and downstream, the critical buckling water-filled height is difficult to achieve, so that the slide in the rain is still stable at this stage;③landslide stability is very sensitive to the water-filled height of rupture zones, sliding friction angle has a great influence on the stability of landslides .(5) According to the stability of the geological analysis and the results calculated by three-dimensional method, it is evaluated comprehensively that the landslide is stability or not. Based on the deformation characteristics and current situation of the landslides, we proposed construction attention and strengthen the monitoring of landslides.
Keywords/Search Tags:Pingtou hydropower station, Plug-type landslide triggered by torrential rainfall, Three-dimensional transfer coefficient method, FLAC3D strength reduction method, Comprehensive evaluation of the stability
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