Three-dimensional Connectivity And Stability Study Of The Left Abutment Of High Arch Dam In Baihetan Hydropower Station

Baihetan hydropower station is the double-curvature arch dam on Jinsha river , and it is another 10 million kilowatts of hydropower station after the Three Gorges, Xiluodu when the survey and design work would be carried out. Arch dam is 279m high, so dam abutment rock mass must have enough bearing capacity and the distortion stability for the support arch dam structure.It is important to verifies the dam abutment resisting force body's boundary condition in detail for the dam abutment anti-slippery stability analyses. More than a month's time,we had measured carefully fractures of rock mass in 29 square holes of The Left abutment of High Arch Dam in Baihetan Hydropower Station and collected some of the information on Geological Survey Obtained by the dam area of Huadong Institute.The dam area is the Hingham canyon landform, north higher than south, inclining to the east side; slope left bank of valley relatively is slow, but the right bank is high and precipitou,; the whole valley topographic is asymmetric "V" shape.Plans to construct the arch dam is a sec of Permian mass.It has good geological conditions for High Arch Dam in Baihetan Hydropower Station. The main body of rock mass structure is basalt lava layers, the layer structure of low angle fault zone, small-scale faults and steep dip of the tectonic fracture.Through research,the boundary mass structure (primarily sylvian surface and the sliding surface of left bank has been extracted and we have consolidated its geometric and mechanical characteristics.the sliding surface is relatively clear to Control dam stability. It is the abutment structure which tend to the valley , have flat or negative slide, is long, continuous or nearly continuous spatial distribution. Such structures are mainly surface layer, the layer faulted zone.Through analysis total of seven fault zone such as the LS331, LS3319, LS337, C3-1, C3, LS414, LS415 may constitute the sliding surface of left bank .Their shear mechanical parameters mainly reference from relevant experimental results of huadong Institute. The shear mechanical parameters of Uncertainty side surfaces are closely related to connectivity. Three-dimensional connectivity of rock mass is calculated by using a computer program which has been developed by Professor Chen Jianping , According to determining three-dimensional connectivity of rock mass discontinuity by projection .As the fracture surface is uneven development in the space, Three-dimensional connectivity of the left bank change from 0 to 38% .Thus, It is difficult to give an accurate value of connectivity.By the hole of the model range of connectivity, we calculate the average three-dimensional connectivity. It is calculated as follows: The three-dimensional connectivity tend to 300°is 6.73%; to 120°is 3.86%.From the fracture surface characteristics of the left bank abutment, it's connectivity of the left bank has good regularity ,the connectivity of upstream is more big than downstream. It appears higher connectivity in few situations.By connectivity, we can calculate he shear indexi of random side surfaces.Through the analysis of the structure surface, we received three deterministic sliding blocks and two uncertainty sliding blocks.According to rigid body limit equilibrium method Recommended by regulatory law ,we calculate the stability against sliding on the left bank abutment , The results show that the resistance body is safe abutment.