The Research Of Landslide Deformation Mechanism Induced By Reservoir Water Changes And Criterion Of Early Warning

The landslide is a geological disasters in Three Gorges Reservoir area of the most number, about3884disaster. Since the impoundment of the Three Gorges R eservoir area, many of the old landslide revival and deformation, but also produce s some new landslides. Cyclic fluctuation of reservoir and reservoir water level pe riod is one of the main inducement or resurrection in new and old landslide. Acc ording to the statistic analysis, the Three Gorges reservoir large wading landslide of5000000party below accounted for61%,10000000the following accounts for84%,1000-5000million accounted for13%, more than50000000accounted for3%. In the hilly and mountainous areas in the reservoir, because of water caused by the operation of reservoir landslide generated and resurrection of the phenomen on is very common, and the failure consequences are very serious, sometimes eve n catastrophic. At present, the Three Gorges Reservoir area water level of reservoi r operation in the range of145-175m lifting, the stability of reservoir water landsl ide will produce different effect. The purpose of this paper is to study the mecha nism of reservoir water level fluctuation induced landslide deformation, is applied to the landslide early warning and forecast model and criterion based on monitorin g and numerical analysis of deformation, early warning and forecasting used in res ervoir water slide, also has a definite reference value to other area of china. Since the Three Gorges reservoir, carried out a large number of landslide research and monitoring and early warning, the collection of relevant information on the geologi cal conditions, reservoir landslide formed a certain foundation for understanding th e characteristics of the development, obtained the following results and conclusion through a series of analysis and research:(1) On the basis of the analysis of Three Gorges reservoir water level fl uctuation induced landslide development and basic types of analysis, combined with the effects of interaction of water and rock soil and deformation monitori ng, from the aspects of structure, material composition, mechanical properties,1 andslide inducing factors, the Shuping landslide, landslide, white dragon pond v illage landslide as the object of study, the study area by reservoir water fluctu ation mechanism and characteristics of different types of deformation mechanis m of landslide induced. Reservoir water induced landslide deformation mechani sm is divided into:①forming, osmotic pressure head difference between groun dwater level and water seepage in rock and soil, the excess pore water pressur e is produced, the landslide sliding force, affecting the stability of landslide. W ater drops, stability was the worst. Shuping landslide for the type, the characte ristics of soil bedding landslide, front below the reservoir water145m, surface morphology is linear, the reservoir water fluctuation range mainly affected the landslide gliding, plus the permeability of ordinary, seepage lag.②float weigh t function:the effect of water on slope stability for the hydrostatic pressure, to soak in the sliding body produce buoyancy in the water column, decrease soil severe, acting on the anti sliding section, change the sliding resistance force, i nfluence the stability of landslide. Water rises, the landslide stability is the wor st. Fish ponds landslide for this type of landslide, which usually is a soil bedd ing landslide, front just below the water surface175m, a more gentle, shape o f arc type, reservoir water fluctuation range mainly affects the anti slide, slide body good permeability.③erosion:in repeated lifting process of reservoir water, slope toe erosion scour. The resistance reducing period of anti sliding landslid e, causing the lower slide, and then gradually decline caused by traction upper, landslide deformation instability. Yunyang Bailong village for the type, occurri ng in the landslide erosion collapse phenomenon. This type of landslide, landsli de permeability is low, rainfall and groundwater infiltration were difficult to. T he sliding body structure loose, low intensity, front steep, susceptible to water erosion.(2) The use of Geo-slople simulation example, the landslide seepage fiel d changes in the whole process of lifting water slide in the landslide deformati on, and overall stability calculation of landslide. Study on Landslide in lifting water and different rate conditions, changes of the slide body seepage and stab ility.Osmotic pressure type:with the change of reservoir water level of undergr ound water and change, but has a certain lag, rise to be a concave shape, dro p a convex. The reservoir water fluctuation rate becomes faster, hysteresis is g reater, the more obvious concave and convex. The landslide stability increases with water, and decreases with the decrease of reservoir water.Uplift reduction heavy:with the change of groundwater level and the chan ge of reservoir water, underground water level consistent with the reservoir wat er saturation curve, straight, no obvious lag. To speed up the rate of reservoir water, a certain lag. The landslide stability decreased with the water rise, rise with the drawdown.(3) through the landslide impact factor deformation response and deformati on monitoring data, to determine the relationship between landslide deformation and reservoir water level fluctuation. The main control factor in the water lev el variation in the landslide, the deformation mechanism theory combined with the history of deformation and numerical analysis of deformation prediction of landslide deformation, tendency of the landslide. The calculated minimum lands lide stability in different reservoir water level fluctuation rate value,function re lation with reservoir water rate and the lowest stability value of landslide as a link, launched the landslide stability value warning classification corresponding to the water level variation rate, as the landslide deformation failure criterion of reservoir water rate.(4) the early warning model and the criterion is applied to the case of Ian dslide.Shuping landslide belongs to the reverse slope deposit landslide, slope stra ight, smooth front flat, the steep, permeability medium. Water loss is the main factor inducing landslide deformation, and the reservoir water fluctuation range and sliding section in landslide, change water main osmotic pressure generated effects, build rate criterion water drop:blue, yellow, orange, red alert2.8, res pectively4.7,6.7,8.6m/d water drop rate.Fish ponds landslide belongs to the slope accumulation type landslide, slop e straight line shape, the front elevation, surface smooth in front, part of steep, good permeability. Reservoir water rise is mainly induced landslide deformatio n, and the reservoir water fluctuation range anti sliding section in the landslide, reservoir water float weight effect on the sliding body, build rate criterion bas e water rising:blue, yellow, orange, red alert0.35,0.23,0.18respectively, the0.11m/d Library under water drop rate. White dragon village landslide belongs to the slope accumulation type Ian dslide, slope straight line shape, smooth lines, the overall relatively flat, perme ability medium. From the analysis of monitoring data, the deformation of the1andslide has no significant correlation with water, reservoir water mainly produ ces erosion effect on the prediction of landslide, the reservoir water repeatedly washed under, front may collapse phenomenon, caused by the front part of th e sliding body decline, even traction landslide deformation instability.