Study On Genetic Mechanism And Storage Stability Of The Down Deformation Of The Leef Bank Of A Hydropower Station In The Upper Langcang River

In hydropower construction project,the dumping of deformation is a very common and important engineering geological problem,and occur in the bedding rock slope is steep dip dump deformation is relatively complex,depth and scope of the development,general by the special environmental conditions and their control the mechanical properties of rock mass,unique.Dump deformation slope stability generally good,natural condition and the late power station reservoir,rock mass affected by water softening,mud,and its physical and mechanical properties decreased,while the penetration increased,the generation of pore water pressure and time effect influence its stability will produce a certain degree of reduced.Lancang River upstream of a hydropower station left bank of the development of large area in the front of the dam has fallen in the front of the dam deformation,in this paper,on the basis of engineering practice,specific to the engineering geological conditions and analysis of dump deformation characteristics as the foundation,further study of the dump deformation deformation development distribution,damage characteristics,genetic mechanism and so on.On the basis of the "geological process mechanism analysis" method,and combined with a variety of numerical simulation methods,through the dumping of two-dimensional discrete element analysis causes deformation mechanism,using three dimensional finite element and its stability analysis and evaluation,the rigid body limit equilibrium theory for engineering construction smoothly and the normal operation of the completed,it is very necessary.The main research content and results are as follows:(1)the dumping of dam deformation distance of about 310 m,vertical distribution range of 2150 m~2500 m elevation,slope surface is 28°~42°,less vegetation.According to the geological survey,the two flat stage development height is 2150 m and 2300 m,and the height is 2150 m and the base rock is visible from the river.The transverse width of the toppling deformation body is about 300 m to 1070 m,showing a fan-shaped distribution with a narrower upper part and wider lower part.The horizontal development depth is about 90.7m to 111.2m,and the total volume is about 700 * 104m3.(2)The problem of dumping deformation is very similar to that of the previous Lancang River valley.The mechanical boundary of the deviated rock mass is mainly controlled by two aspects: rock structure and valley topography.(3)The tandem deformation zone is characterized by strong uplift,the Lancang River valley is cut quickly,rock mass unloading rebound,rock formation bending-dumping deformation.There are two critical faults in the middle and middle lower part of the dumping deformation,and the tapering deformation occurs along the fault,and the shear deformation is affected by the fault during the historical evolution.Where the dumping deformation of the body is more special,the dumping deformation pattern from top to bottom can be roughly divided into two areas: upper pouring bending,breaking zone,middle and lower pouring bending shear zone.(4)Two-dimensional discrete element software(UDEC)is used to simulate the deformation and failure characteristics of the dumped slope during the process of cutting down the valley.it is concluded that steep dip bedded rock mass experience:(1)micro(not)dump deformation stage(2)the dumping-bending creep stage(3)bending strongly,crack nearly completed stage(4)stage of sliding instability.(5)Based on the Mohr-Coulomb criterion,the FLAC-3D software is used to simulate and analyze the stress-strain characteristics of the dumped deformed slope reservoir before and after the impoundment.The conclusion is that the reservoir is not impounded and the deformed deformed body is relatively stable The stability of the deformed deformation of the dam before the reservoir is reduced by the increase of the pore water pressure and the decrease of the strength of the rock and soil,and the possibility of destabilizing the deformation of the deformed body under the adverse load such as earthquakes.The overall stability of the strongly deformed deformable body after reservoir impoundment is good,and the overall stability of the highly deformed deformable body is relatively poor.(6)Based on the understanding of the engineering geological conditions,the characteristics of dumping deformation and the mechanism of the dumping body slope,the failure pattern classification of the dumping deformation body is carried out,and the stability of the dumped deformation body is evaluated based on the rigid body equilibrium equilibrium theory.The following basic conclusions are as follows: The safe reserve of the rock after the impoundment of the reservoir is relatively low.After the impoundment of the reservoir,the deformation of the deformed body under various conditions(rainstorm and earthquake)is possible.While the strong dumping deformation before and after the impurity,the stability has been reduced,but its safe reserves are high,in a stable state.(7)Damage to the deformation of the deformed body Based on the results of the slope stability calculation and analysis,we mainly consider the main two kinds of slip and failure modes which may occur under the strong dumping.According to the energy method and the Schenderger method the results show that the mean velocity of the two methods is 6.15 m / s and 12.67 m / s respectively.According to the method of sliding speed and instability,the velocity of the method is 6.15 m / s and 12.67 m / s respectively:(6.01 m,12.59m);(4.93m;10.32m);(2.48m;4.37m),respectively.The highest surge can be predicted at the dam site.