Research On Bank Slope Stability Of Typical Bridges In Gorge Area In Yichang-Wanzhou Railway

This thesis puts forward a systemic method to analyze stability of bridge bank slope in gorge area. It includes elementary field geological evaluation, calculation of stable angle of bank slope with empirical formula, simulation of slope stress state with FEM and rockmass strength judgement. Then rational laying position of bridge piers can be confirmed. And the author applies this systemic method to make stability evaluation of bank slopes of the four bridges across Qingjiang river, Yeshanhe river, Mashuihe river and Hunshuihe river in Yichang-Wanzhou railway.Although the empirical formula ? = yh[14.7(rwRlogD) + \3] has been applied successfully to some engineerings, but it is a general formula, not one specially for rocky bank slope in gorge area. So the author constructs a statistical formula SMR . The engineering applying results indicate this formula is feasible. However, the finite number of samples influences its precision. Therefore, it is necessary to improve this formula.By the way of stress analysis of bank slope, the positions of different laying depths are found ,where the stress state is close to that of semi-infinite plane. Then the shape of stress slack zone can be confirmed to acquire the safe rule of laying foundation for bridge design. And the engineering applications prove its correctness.Furthermore, to make the stress analysis of bank slope easier and more intuitionistic, the author develops a special post-processing software for FEM to visualize the calculating results of FEM. The engineering applications show that the software is banausic.Researches indicate:(1) For Qingjiang river bridge, the stable angel of Yichang and Wanzhou bank slopes should both be 62? and the depth of piers on Yichang and Wanzhou banks should both be 10m and the piers shouldbe at least 16m and 30m respectively away from the slope edge.(2) For Yeshanhe river bridge, the stable angel of Yichang and Wanzhou bank slopes should be 60?and 78?respectively; and the depth of piers on Yichang and Wanzhou banks should both be 10m and the piers should be at least 25m and 24m respectively away from the slope edge.(3) For Mashuihe river bridge, the stable angel of Yichang and Wanzhou bank slopes should be 61? and 62? respectively; and the depth of piers on Yichang and Wanzhou banks should be 39m and 49m respectively and the piers should be at least 30m and 16m correspondingly away from the slope edge.(4) For Hunshuihe river bridge, the stable angel of Yichang and Wanzhou bank slopes should be 62? and 50?respectively ; and the depth of piers on Yichang and Wanzhou banks should both be 21.5m and the piers should both be at least 20m away from the slope edge.