Assessment of the activity intensity of Caijiapo engineering landslide on the north bank of Weihe River in Baoji City

For the purpose of studing the activity intensity of landslides in the disturbed area of large projects, the authors summarized the evaluation methods for the activity intensity of landslides with the slope zone in Caijiapo that the Weihe River diversion hydro-project passes through as an example, and then studied the possible deformation pattern and intensity of each slope unit along Caijiapo section and evaluated the sliding speed and distance of new single landslide mass by using two calculation methods, namely geomorphological process analysis and dynamic value simulation. The study was based on geological survey and prospecting, collection of historical data on landslide deformation, large-scale topographic survey and mechanical test on the slippery strata. Some conclusions have been reached: ①The ancient landslide mass is most sensitive to engineering disturbance, followed by landslide masses after the disturbance of the northern slope zone by the project. The renewal of ancient landslides in Nanshetou becomes an extreme landslide event after the completion of the project, and the acceleration of exchange of leaked ground water from Weihe River diversion has affected the boosting of the creep deformation of landslides in No. 9 Shaanxi Textile Factory and Caijiapo; ②The high activity areas in Caijiapo section are concentrated in the old landslide in No. 9 Shaanxi Textile Factory, new landslide in Caijiapo and front edge of old landslide in agricultural products company, while the geomorphic scarps on the periphery of large sliding masses form the middle activity areas which will be influenced by shallow failure and soil flow induced by rainfall; ③The slope deformation activity of new landslide in Caijiapo is transmitted from the rear edge to the slope toe, causing the subsidence of the rear edge and the uplifting of the front edge. In the process of creeping, the speed in X direction reaches the maximum of about 1.0m/s, while that in Y direction reaches the maximum of about 1.5m/s. In the sliding process of masses, the maximum sliding distance is 130m approximately; therefore, the maximum speed in X direction is about 4.5m/s, while that in Y direction is about 4.0m/s.