考虑渗流和地震时的砂土边坡稳定性计算

基于极限平衡理论,以砂土边坡为研究对象,推导了渗流和地震存在时拟静力法和拟动力法边坡安全系数的计算表达式。通过程序求解,与已有算例对比表明,计算结果基本一致,验证了2种方法解析式的合理性。参数分析表明,水位越高,边坡失稳越严重,水力梯度与安全系数基本为线性关系。渗流方向向下时,稳定性随水力梯度的增加而增大;渗流方向向上时,变化规律相反。水平地震加速度系数对稳定性的影响剧烈,竖向地震加速度系数对稳定性影响较小,简化计算可以忽略不计。最终得出拟静力法的解析式,简单、实用,而拟动力法则可以更为全面地考察砂土边坡稳定性随时间变化的特点。

Calculation of sand slope stability with considering seepage and earthquake

On the basis of the limit equilibrium theory, we took a sand slope as research object and deduced the expressions of the slope safety factor with quasi-static method and pseudo-dynamic method when steady seepage and earthquake were present. The results of computer programs agree well with those of exiting methods, which verifies the validity of the two analytic methods. Parameter analysis shows that there is a linear relationship between hydraulic gradient and safety factor, and the higher the water level, the easier the slope is to lose stability. When the seepage direction is downward, the slope stability increases with the increase of hydraulic gradient, and when the seepage direction is upward, the change rule is opposite. The slope stability increases significantly with the increase of horizontal seismic acceleration factor, and the effect of vertical seismic acceleration factor on the slope stability is relatively small, which can be ignored in simplified calculation. Generally, the analytic formula of pseudo-static method is simple and practical, and the formula of the pseudo-dynamic method can more comprehensively investigate the characteristics of the slope stability changing with time.