地震作用下土质边坡稳定极限上限分析

Analysis of upper limit of stability of soil slopes under seismic loading

地震作用是影响边坡稳定性的重要因素之一。基于极限上限分析法,建立了地震作用下的三维土质边坡转动破环机制,采用拟静力法将地震作用简化为水平作用于三维土质边坡的荷载,给出了三维潜在滑动面搜索方法;并考虑内摩擦角、宽高比或坡角等因素,探究了地震作用对三维土质边坡稳定性的影响。分析表明:在地震作用下,内摩擦角较大的三维土质边坡的稳定性系数较大,而内摩擦角较小的边坡的稳定性系数较小;而在地震作用下,坡角较大的三维土质边坡的稳定性系数较小,而坡角较小的边坡的稳定性系数较大;地震作用对具有不同宽高比(三维效应强弱不同)的三维土质边坡的稳定性影响基本相同。因此,在工程设计与施工中一定要注意内摩擦角小和坡角大情况下地震作用对边坡稳定性的影响,研究结果对于地震作用下三维土质边坡的稳定性评估及工程设计具有一定参考价值。

Seismic load is one of the important factors affecting slope stability. Based on the upper limit analysis method,the rotational failure mechanism of three-dimensional soil slope under seismic load was established. The quasi-static method was used to reduce the seismic load to the horizontal load of the three-dimensional soil slope, and the search method of the three-dimensional potential sliding surface was given. Considering the internal friction angle, aspect ratio,or slope angle, the relationship between slope stability coefficient Ns and seismic acceleration factor kh obtained by the strength reduction method was established to explore the influence of each factor on the seismic stability of three-dimensional soil slope. The analysis shows that the stability coefficient of the three-dimensional soil slope with a larger internal friction angle is larger than that of the slope with a smaller internal friction angle under seismic load.Under seismic load, the stability coefficient of a three-dimensional soil slope with a larger slope angle is smaller, while the stability coefficient of a slope with a smaller slope angle is larger. The effect of seismic load on the stability of three-dimensional soil slopes with different width-height ratios(different strength of three-dimensional effect) is the same.Therefore, in engineering design and construction, attention must be paid to the influence of seismic load on slope stability under the condition of small internal friction angleangle and large slope angleangle. The research results have a certain reference value for the stability evaluation and engineering design of three-dimensional soil slope under the action of seismic load.