Study on the Major Factors causing Road Slope strong Deformation of the Shuiluo River Transmission Project in Sichuan

摘要

The access road slope of Shuiluo River 500KV transmission project has a loose earth-rock structure which is in a continuous state of slight creep deformation in natural conditions. Road construction period was coincided with the rainy season. On August 18, 2011, after several days of continuous rain, dramatic deformation of engineering slope occurred in the road K0+305～K0+345 segment. Gradually a sliding deformation body was formed that vertical length is about 80m, horizontal width is 30～50m, the front and back edge height difference is 50m, the total volume is about 6.0 million m~3. Finite element numerical simulation and limit equilibrium calculation show that the overall deformation and local landslide collapse of the engineering slope was caused by two factors: paring slope and concentrated rainfall. On the one hand, the position of engineering slope was mainly in the anti-sliding section of the potential sliding body, slope excavation reduced the effective stabilizing force; On the other hand, construction was coincided with the period of concentrated rainfall, groundwater level raised significantly due to excess supply of rainfall (120mm/d), the state of slip soil changed from unsaturated to saturated. Slip soil strength decreased due to softening of water, and effective stress of sliding surface lowered due to the raise of pore water pressure, so slope stability was leaded to a sharp decrease.