Study On The Stability Of Reservoir Bank Of Yalong River Forgnni Hydropower Station

The propsed Geni hydropower station is located in sichuan province ganzizhouGanZi county in yalong river upstream of the river.It is located in transition belt ofmountains and valleys of eastern margin of the Qinghai Tibetan Plateau cascade,theearth structure is located in the southwest margin of Sichuan Qinghai block, Thegeological structure background of complex,it is only4km about Ganzi--Yushufault.The survey found in large landslide and large oversize deformation development,the slope stability problems will become important after the impoundment of thereservoir, such as threatening the safety of dam and reservoir area residents along theriver highway, reservoir bank slope stability problems, therefore, research on thereservoir bank slope stability have important engineering practical value.According to the principle of Mechanical Analysis in Geological Processes andQuantitative Evaluation Technique, based on the structural type, deformation failuremode of the bank slope, also the characteristics and evolution of deformable body, theFuzzy Comprehensive Method was adopted to estimate multi index factors of thebank-slope stability. Besides, combining with the quantitative and the qualitativemethods, the typical bank slope and deformable body were evaluated emphatically inthis thesis. The major achievements were summed up as following.(1) There are three types of bank slope, layered rock slope、massive rock andslope slope and soil bank slope，the layered rock slope dominated，is classified intodipping downstream bank slope dipping reverse slope steep bank slope steep dip slopebank slope by the bank slope structure；bulk rock slope of granite slope；soil bankslope is classified into landslide slope, colluvial accumulation body slope, debris flowaccumulation body slope, alluvial talus slope.by origin of rock and soil.（2）there are generally have different degrees of bending deformation in layeredrock of longitudinal valley，particluar left bank，development toXie Bi Xia landsideand Xie Bi Xia、Kang Long1#、DaMa deformation，and so on; cross Valley andblock structure of bank slope is dominated by small scale collapse, landslide isdysplasia. The Bank of Geni is divided into3sections, Section I mainly by thelongitudinal valley, slope stability is poor; section II to cross Valley, slope stability isgood; section III block structure slope, slope stability is good. (3)After the reservoir comprehensive engineering geological investigation，studyon the basic characteristics of landslide and deformation, research law of deformationof bank slope, it concluded that landslide anddeformation developed in thelongitudinal valley river、metamorphic sandstone and slate interbedded steep reverseslope，deformation and failure modes for the bending ripping type, at last using theUDEC numerical simulation method to analyze the deformation and destructionmode.（4）Evaluation of bank slope stability by fuzzy comprehensive evaluationmethod. Left and right along the both sides of about64.8km, is divided into30sections of bank, which left19, right11.More stability of slope is12, with a totallength of about38.6km accounted for59.7%of the bank; basically stable slopesegment is11, with a total length of about15.4km, accounted for23.6%of the totallength of the reservoir bank；Poor stability of slope is4, with a total length of about10.0km, accounted for13.8%of the total length of reservoir bank；very poor stabilityof slope is3, with a total length of about0.8km, accounted for2.9%of the bank,which has poor stability and very poor stability segment length of about10.8km,accounted for16.7%of the total length of the reservoir bank, bank slope stabilityproblems.(5)Using engineering geological mapping and drilling methods,research the basiccharacteristics of Xie Bi Xia landslide that is near dam,the landslide volume of aboutfifty-four million cubic meters, is a bend rip the formation of the ancient landslide,two times larger collapse had occurred in the erosion of river water, but the recentdeformation is not obvious. Through the calculation of stability and numericalsimulation show, in natural condition, stable overall,1#,2#secondary landslide is instable state; in the3455m static water level condition, slope,1#,2#secondarylandslide is in stable state; in the storm conditions, in the basic steady state overall,1#,2#secondary landslide in less stable state; in seismic condition, the overall in theunstable state.(6) Analysis to deformable developing feature,choice Kang Long1#deformableas a typical case, study the stability calculation and numerical simulation, In naturalcondition, in steady state, the1#secondary landslide in less stable state; in the stormconditions, in the basic steady state overall,1#secondary landslide in less stable state;in the3455m static water level conditions, in the basic steady state overall,1#secondary landslide in less stable state in seismic condition; overall, in an unstablestate.