Studies On Causes And Control Conditions And Stability On The Right Abutment Of The 2# Deformation Body Of Huangdeng Hydropower Station On The Lancang River

The dam area of Huangdeng Hydropower Station is located in Yingpan Town of Lanping County of Yunnan Province which is belonged to deep valley in the middle-high mountains of the upper reaches of the Lancang River. And the construction area is located in western Lanping-Simao Depression which is the second geologic unit of Thangla-Lanping-Simao geosynclinal fold belt. The rock mass of the right bank slope in dam area generally are metamorphosed volcanic breccia with metamorphic tuff (T3xd) and slate (J2h) which consisted the geological structure of transverse wide-angle inclined slope. The 2~# toppling deformation body developed in the local anti-toppling structure slope which is in the lower reaches of the 7~# gully of right abutment. And this position toppling deformation is very strongly in rock mass which developed some shear fault zones, faults and steep outside-slope toppling fractures. So it is high sensitivity of the project.Be different from the other toppling deformation bodies at the Lancang River, the 2~# toppling deformation body is belonged to be a very unique problem on toppling deformation. Particularities mainly in the following areas:(1)The strata strike and the development direction of valley in dam area are wide-angle intersection. Generally it to be a typical transverse valley structure and it usually does not has the terrain - geological conditions to generated toppling deformation. And the development of the 2~# toppling deformation body is obviously contradicted with overhead terrain conditions that occurred toppling deformation. According to site geological survey and in-depth study on rock mechanics, the particularities of formation controlling conditions lies in:â‘ The extension terrain direction of the lower reaches of 7~# gully is nearly parallel with the strata strike, and the strata steep inclined inside-slope.â‘¡The F12 fault which developed along with the bottom of 7~# gully, that provided an indispensable lateral segmentation-slip controlling boundary for emergence and development of toppling deformation. And it has special significance of rock mechanics.(2)The 2~# toppling deformation body is merely developed in the midst-upper hill, because this is controlled by the special segmentation mode of terrain condition and the F12 fault that developed on the bottom of the 7~# gully.(3)The 2~# toppling deformation body presents complicated characteristics on toppling deformation. The medial boundary of rock mass happened lateral low-angle shear-slip, and the bottom and deep and tail boundary happened"toppling-fracture"deformation (local bending), and internal are more consistent happened toppling-creep. We called this deformation mode is the"lateral slip-toppling fracture"mode which types of toppling deformation have shear-slip, toppling-fracture and toppling-creep.(4)The toppling deformation body is only developed Class A extremely strong toppling deformation and Class B toppling deformation, and weak toppling deformation is generally not well developed. And this is related to rock boundary conditions and characteristics on relatively harder lithological combination.As this toppling deformation type of failure slope is controlled by local terrain and lateral segmentation fault, and in the current study has not yet been seen in reports. Therefore, study on stability and this particular formation mechanism of the toppling deformation body. And it is not only offered engineering scientific basis for prediction and stability on failure of anti-toppling rock slope, but also makes significant progress in researches on problems of toppling deformation in large-scale hills which are formation controlling conditions and mechanism of deformation mode, and so on. This is the main innovation of my research paper.Through analysis on characteristics on stress-strain distribution and limit equilibrium stability of the right abutment slope of the 2~# toppling deformation body, the stress is generally low-value distribution and near the bottom boundary presents stress concentration. The vertical displacement is greater than the horizontal displacement above midst-upper of the toppling deformation body, that means rock deformation is mainly toppling deformation. According to stability analysis on three instability modes of right abutment slope, the results show that slope is stable under natural condition, but it is lower safety reserve, and it is less stable-unstable under most unfavorable condition of water-earthquake condition.The project effect on 2~# toppling deformation body mainly in the following areas:â‘ Affect the rock stability of right abutment slope.â‘¡Affect the choice of dam line position and dam type.â‘¢Affect the determination of abutment foundation surface.â‘£Affect the determination of rock reinforcement programs.