The Isolated Engineering Rock Mass Stress-Deformation Characteristic Research Of MiaoWei Hydraulic Key Project Area On Lancang River

MiaoWei hydraulic key project Station dam site of the Lancang River is located in the city of Dali in Yunnan Province Yunlong County, Miao Mei Estate, about 1 km downstream, Left Bank more complex terrain, deep valleys and isolated mountain landscape based, relatively poor integrity of terrain. Key Project is located in the space of three facing isolated mountain, the axis direction of spillway is N73°W , four underground seepage tunnels are arranged parallel in horizon which axis direction is N59°W and the axle wires intersect with syncline axis obtusely, and roughly parallel to rock formation. Complex underground tunnels are formed under such formidable conditions, a number of internal development interlaminar shear fault zone, fault and the joints, resulting in dumping slope deformation. Complex geological environment and concentrated arrangement of underground seepage tunnels in the project show great threaten to the safety of construction and operation.Take aim of stress - deformation characteristics analysis of the spillway and underground seepage tunnels in the left bank of MiaoWei hydraulic key project Station of Lancang River,the paper bases study on engineering geology environmental conditions in dam area,through the site measure and statistic of rock mass structure in the spot explores adit , a systematical analysis is presented of the structure characteristic of engineering rock mass and geological properties,and then makes an analysis aimed at the classification of rockmass joints,classification of violent degree of dumpling deformation and rock mass structure classification, Accordingly it has been reached a geologic model in accordance with the geological condition . On this basis,a reasonable geomechanics models is founded,two-dim FEM and DEM numerical analogue analysis method is used on deepening simulation study and comparison analysis of stress and deformation fields on the natrual and engineer excavation conditions, a study on the adjacent of displacement and stress Field at the stage of derivation tunnel excavation, and then the appraisal an the forecast of the distortion trend of development and the latent destruction condition has been carried on.The findings indicated that natural slopes of the isolated mountain are at the steady state, after the spillway and derivation tunnel excavates, the left and right side slope of the spillway only in falls nearby the zone of fracture , excavation of the key project could not effect the slopes to be at the steady state, but because of the influence of the fault F₁₄₄ and the fall break belts, the roof and the left of tunnel wall in 1#, 3# derivation tunnel has the micro distortion, and along with the time lapse, the distortion tends to be stable; after 2# derivation tunnel excavates, rock mass at the place of the roof and the left of tunnel wall which distortion sustained growth, has the possibility to present the large-scale slipping the situation; after 4# derivation tunnel excavates, the vertical displacement of the roof rock mass accelerate to grow, its latent destruction way is landslide destruction .We should emphatically carries on the supports and protections at the place of roof and the left of tunnel wall in 2# and 4# derivation tunnel.The research results has the very important project practice significance that it can optimize design plan, guarantee construction quality and the security, avoid the latent harm and control engineering investment and so on.