旱涝急转下河道堤防抗滑稳定性研究

Study on Stability against Sliding of Embankment under Rapid Change of Flood and Drought

针对南方地区尤其是长江中下游地区旱涝急转现象发生频繁导致河道水位或库水位骤变,从而时有发生溃堤或垮坝事故的现象,基于非稳定-非饱和渗流理论,采用GEO Studio的SEEP/W模块分析了长江中下游地区某河道堤防在旱涝急转期堤防典型断面渗流场变化,并根据渗流计算分析结果,采用Bishop刚体极限平衡法分析了各典型时段下游坡稳定。计算表明,旱涝急转期堤防断面孔隙水压力上升,孔隙水压力等值线曲率增大,随着降雨的持续,堤防滑动面位置变化不大,但由于滑动体内孔隙水压力增大,边坡抗滑稳定安全系数呈逐步减小的趋势。

In the southern region,especially in the middle and lower reaches of Yangtze River,rapid changes of flood and drought frequently lead to sudden changes of river or reservoir water level,and sometimes embankment break or dam collapse occurs.Based on the unstable-unsaturated seepage theory,the SEEP/W module of GEO Studio is used to analyze the seepage field change of a typical section of a river embankment in the middle and lower reaches of the Yangtze River during the period of draught and flood.According to the results of seepage calculation and analysis,the stability of downstream slope in each typical period is analyzed by Bishop rigid body limit equilibrium method.The results show that the pore water pressure of embankment section increases and the curvature of the pore water pressure isopleth increases during the rapid transition period of drought and flood.With the continuous rainfall,the position of the sliding surface of the embankment does not change much.However,due to the increase of pore water pressure in the sliding body,the safety factor of slope stability against sliding gradually decreases.