A Geologic Investigation And Study On Bank Collapse Forecasting Of Chongqing Segment In Three Gorges Reservoir

Bank collapse of reservoir between 135m and 175m a.s.l will happen after Three Gorges Reservoir impounds, so the department concerning order to carry out special reaserch about bank collapse geological investigation, bank collapse prognosticate and bank collapse prevention.Chongqing segment is taken as an example.In order to forecast bank collapse zone, investigation of geology and analysis in room are adoped, the geology about Chongqing 7 districts,Yubei district,Banan district and Jiangjin city all of 55 reservoir banks are investigated systematically, it is generalized:(1)It is summed up that Chongqing has three main bank-collapsing types: wash and abrasion type, soil collapse (rock sliding) type, slide type, and the length of wash and abrasion type mainly occupies 54%, soil collapse (rock sliding) type mainly occupies 42%, and slide type is only 4%.(2)Analysis of investigation statistics shows: with worst stability of bank slope accounts for 7.3%, worse stability of bank slope accounts for 33.9%, more good stability of bank slope accounts for 41.2%, good stability of bank slope accounts for 17.6%. About 80% banks collapse are distributed in soil bank slope, About 15% banks collapse are distributed combination bank slope of soil and rock, only few banks collapse are distributed rock bank slopes.(3)Based on investigation, in view of different bank-collapsing types and different riverbank structures, corresponding bank-collapse forecasting method and parameters are adopted. The forecasting result shows that total length of bank-collapsing zone is less than 20m is about 67%, and zone of bank-collapsing zone more than 20m is about...