The Analysis Of Left Bank Dam Abutment Slope Stability Of Dagu Hydropower Station

The Tibet Dagu Hydropower Station is associated with a 126 m high dam and 660 MW installed capacity. Dam site area has high and steep slope, subjected to internal and external forcing in different periods, different scale, rock mass structure is complex, the dam slope problem is more prominent.Especially large dam site on the Dagu left abutment slope, relatively dense joints, fault development, the influence to the stability of slope, the need for a comprehensive evaluation system of the slope stability of dam abutment analysis, provide the necessary geological basis for the design and construction, to ensure the slope in the hydropower station dam abutment stability safety during construction and operation.This paper by Tibet Brahmaputra waters Dagu hydropower station dam site area slope stability research project as the backing, in the full understanding of rock slope stability on the basis of the research status quo, through to the dam site area surface, adit of field survey, collect related data of the slope stability, through the statistical analysis, the slope rock mass structure characteristics, rock mass quality, weathering and unloading characteristics, the types of slope failure and boundary condition is studied, through geological macroscopic qualitative combined with quantitative analysis and calculation, focus on the natural slope stability and after excavation engineering system of slope stability analysis and evaluation, for the design, construction and operation of the hydropower project construction to provide geological basis.Specific research contents and results are as follows:(1) Geological environmental conditions of the study area.The natural environment conditions, regional geological survey in the studied area are studied.Including the meteorological, hydrological conditions;Regional landforms and formation lithology;The main fracture and its activity;The new tectonic movement characteristics and its division;Earthquake influence on the stability of field research, etc.(2) On the left bank abutment slope engineering geology research.Including slope landform, stratum lithology, geological structure, weathering & unloading, hydrogeological conditions, etc.(3) Rock mass structure characteristic research: research different genetic structure of the distribution, density, surface characteristics, characteristics of continuous development and the space combination form of them.Structural planes include native building structural plane, reconstruction of tectonic structural planes and supergene structural plane.Investigation method window line method and the test method is used in the ground, the structure of the tunnel surface outcrop.Through the systematic study of rock mass structure, for the dam site area rock mass quality classification and provide evidence for the selection of rock mechanics parameters.(4) Left bank slope rock mass quality classification and dam abutment rock mass mechanics parameters selection: a comparative analysis of different types of slope rock mass quality classification method applicability, select correct CSMR rock mass quality classification method for dam site on the left bank slope rock mass quality classification, it is concluded that the slope rock mass quality classification in dam abutment Ⅲ, Ⅳ rock mass is given priority to, Ⅴ typically in shallow slope rock mass of a small scale distribution;On the basis of slope rock mass quality classification, refer to mechanical parameters of rock mass quality classification in the specification, combining with field test and laboratory test data of rock mass mechanics parameters.By connecting rate in quantitative calculation of stability under the influence of the comprehensive strength parameters.(5) Dam site on the left bank slope belongs to block the overall structure, the table of slope deformation failure mode depends on the joint and fracture.Structural plane cutting by the different direction, forming many block, individual development becomes perilous rock.Deep deformation mainly depends on ct, grew up weak zone and fracture combination.Dip slope in the structural plane control, the slope deformation failure mode is mainly for the slip cracking damage, the surface deformation and failure characteristics mainly for sliding cracking after the formation of the cavity.(6) Abutment slope stability analysis and evaluation: through the site, find out the state of the distribution on the surface of the structure and characteristics of the slope, looking for potential control of slope sliding block boundary conditions, analysis of the possible combinations of block boundary condition model, get the geological prototype, and then generalized the geological prototype, a generalized geological model is set up, according to a generalized geological model of slope stability calculation model, the stability calculation and analysis, and carries on the comprehensive evaluation of the slope stability of dam abutment.