Research On Toppling Deformation Mechanism And Development Process Of Slope Under The Reservoir Water Uplifting

Recently,with the implementation of the western development strategy of China,A large number of resources major projects such as medium-sized reservoirs bring in construction in the western,it is used to ease the tension of our power,promoting economic and social development,And also changed the original geological conditions and load bearing environment,threatening people's lives and property safety in reservoir,bringing great harm to the country's development.Therefore,the study of slope stability problems have a great theoretical and practical significance for the people's life and property safety of the reservoir,and the smooth construction of hydropower projects,environmental protection and the operation of the reservoir area,and disaster prevention and reduction.In this paper,Taking the deformed rock mass of slope of a hydropower station in upstream of the Yellow River for the study,based on identifying its engineering geological conditions and deformation and failure,combiningthe slope deformation monitoring data,from engineering geological point of view,using a variety of numerical simulation tools for the development and evolution of deformation mechanism of slope toppling under the uplifting reservoir water,the specific content and the results are as follows:(1)The Reservoir Slope rockis composed mainly of granite,developmental four groups controlling structural surface.The effect factor of deformable body can be segmented into the geological factors and non geological factors.Non-geological factors in the reservoir water is the direct cause of uplifting deformable body produces,Yet the topography,strata combination form and the structural characteristics of slope in geological factors are the primary cause.(2)The elevation of reservoir waterweaken the most sensitive elevation 2400 m and 2700 m of the toe of slope 3 # Liang,resulting in a greater compressive deformation,thus increasing the deformation and failure of toppling cracking granite.in lateredge of active slope form a "tension crack-scattered" scarp,and at the top there are four developmental slope deformation controlled by the large-scale topping of "pull-collapse" band,respectively,controlling the slope of the deformation and failure.(3)Comparison displacement and deformation monitoring data of 2 #,3 # Liang of slope in the process of the water level lifting shows that 2 # Liang's large deformation displacement at the top of the slope turn,toe's deformation small;except the top of 3 # Liang,the bulge in the terrain 2600 m position also occurred near large deformation.Comparison the characteristics point of maximum displacement deformation of 2 # and 3 # Liang monitoring data,slope deformation is affected by the water level clearly,especially in the water uplifting moments,cumulative displacement and deformation rate of has a significant phenomenon increments after that,the water level raised to 2430 m cumulative displacement and deformation rates are relatively small.In addition,two typical profile monitoring data shows the large displacement occur at the surface of slope,and the small at the inner,with the signs of deformation coincided with site investigation,and further confirms the deformation pattern is bending and toppling.(4)Slope deformation and failure process under the reservoir water uplifting can be summarized as:(a)unloading rebound,granite slab cracking;(b)plate beam bending,toppling;(c)water level rise in the front of slope,weakening rock mass under the water line with water,tppling deformation increased;(d)further bending,breaking plate beam roots,fissures through the rock mass.With progressive deformation and failure of development,to the formation of the current slope form.(5)Based on engineering geological data to establish FLAC3 D model,The slope deformation characteristics were analyzed under the reservoir water uplifting,the water level of 2370 m and 2448 m the current water level water conditions were taken to analysis,it was found in the case of water level 2370 m,slope deformation and failure of the plastic zone are relatively small,while the relative slope deformation displacement is smaller,mainly in faults and fracture zones of the slope.In the 2448 m conditions,The deformation of 3# Liang is more significant,the main water line is located in the upper part fracture zone,the weakening of the mechanical strength parameters occur,thus increasing the range of deformation and failure,while the deformation displacement larger,2# Liang deformation relatively insignificant,so the water level upliftinghas a greatest impact on deformation of 3# Liang.Shear strain increment occurs mainly in parts of the site of fault or fracture zone,while rock mass boundary also appears larger shear strain zones,but not to be a through district of shear strain increment.(6)Combined the results on-site monitoring data with UDEC analysis data shows that: the process of reservoir water elevation,the deformation of 3# Liang is mostly serious,its part of thelargest deformation occurred in the convex area of the slope,due to the slope at the site construction structure of the surface crack formation and unloading "platecracking " rock plates bending deformation,and it is consistent with monitoring data.Using discrete element to analysis the slope deformation trends under the normal water level,the water uplifting effect on 2# Liang is little,3 # Liang has a sensitive reaction,mainly due to the lower of 3# Liang exists a certain thickness broken mass,The deformation process of slope development is reflected that with the reservoir water uplifting.Because of the deformation mechanism in the "chainamplification ",Recommended that the seriously deformation in upper slope and fracture zones are excavated,while local deformation violently parts setting support treatment.