河道清淤对岸坡稳定性影响分析

莆田市涵江区宫口河两侧岸坡直立，临河建筑物密集，清淤施工易造成塌岸，影响周围道路及附近建筑物稳定，采用极限平衡方法与有限差分理论研究其发生塌岸的破坏机理。结果表明，排水后的岸坡安全系数1．20，岸坡稳定。开挖至坡脚时，安全系数降至1．06，岸坡失稳。开挖后岸坡高度增加，坡率增大，坡脚土体压脚作用消失，致使岸坡坡脚沿水平方向位移19．6ｍｍ，坡顶沉降13．5ｍｍ，岸坡出现潜在滑移面，造成塌岸。采用坡脚1∶5放坡逐级清淤30ｃｍ处理措施后，坡面最大水平位移减小至5．7ｍｍ，坡顶竖向位移降至5．0ｍｍ，放坡开挖在清淤的同时，显著提高岸坡稳定性。

Analysis of Influence of River Desilting on Bank Slope Stability--A Case as Gongkou River in Putian City

The bank slopes on both sides of the Gongkou River in Hanjiang District,Putian City have deep slope,and there are dense buildings near the river.Therefore,the dredging construction is easy to cause bank collapse and affect the stability of surrounding roads and nearby buildings.Limit equilibrium method and finite difference theory are used to analyze the bank collapse mechanism.The results are as follows.The safety factor of the bank slope after drainage is 1.20,and the bank slope is stable.When the excavation reaches the foot of the slope,the safety factor drops to 1.06 and the bank slope eventually becomes unstable.After excavation,the height of the bank slope increases,the slope rate also increases,and the effects of the pressure foot of the slope foot disappears,which causes the bank slope toe move 19.6 mm in the horizontal direction,the slope top settles 13.5 mm,and the bank slope appears a potential slip surface,causing collapse shore.After adopting the slope foot 1∶5 grading dredging 30 cm treatment measures,the maximum horizontal displacement of the slope surface is reduced to 5.7 mm,and the vertical displacement of the slope top is reduced to 5.0 mm.The grading excavation has been significantly improved while dredging the silt.