地震荷载作用下岩石边坡的抗倾覆稳定性分析及可靠度研究

STABILITY ANALYSIS AND RELIABILITY STUDY OF ANTI-OVERTURNING STABILITY OF ROCK SLOPE UNDER SEISMIC LOAD

在地震多发地区,地震荷载对岩石边坡的稳定性影响显著。因此,在边坡抗震设计中,准确有效地评估其稳定性显得非常重要。安全系数法未考虑地震荷载等影响因素的不确定性,因此具有一定的局限性。本文在考虑到破坏面出流缝未堵塞和被堵塞两种情况下,利用拟动力方法计算了岩石边坡抗倾覆稳定性安全系数。在此基础上,考虑到地震荷载、坡顶超载及张裂缝内水位深度的变异性,对岩石边坡的抗倾覆稳定性进行了可靠度分析。研究发现,当破坏面出流缝被堵塞时,岩石边坡的抗倾覆稳定性急剧降低。此外,地震荷载等因素的变异性对岩石边坡的抗倾覆稳定性有着显著的影响。因此,同时利用安全系数及可靠度指标来评估岩石边坡的稳定性,且适当地考虑岩体放大系数,有利于岩石边坡抗震设计的安全性。

In earthquake-prone areas, seismic load can significantly influence the stability of rock slope.Therefore,accurately and effectively estimate the stability is very important in seismic design of rock slope. Safety coefficient method has its limitation as this method ignores the uncertainties of seismic load and other influential factors. Under the condition that the smooth flow gap is uncongested and congested,this paper calculated the antioverturning safety factor of rock slope by pseudo-dynamic method,and analyzed the influence of the seismic load,surcharge and depths of water in the tensile crack on anti-overturning safety factors of rock slope. Based on the deterministic calculation model of anti-overturning stability and in consideration of the variability of seismic load,surcharge and the depth of water in tension crack,the reliability analysis of anti-overturing stability of rock slope isdeveloped. The mean values and coefficients of variation of seismic load,surcharge and depths of water in the tensile crack on anti-overturning reliability index were analyzed. Based on the study of this paper,it can be found that the anti-overturning safety factor of rock slope decreased rapidly when the smooth flow gap is congested.Besides,the variability of seismic load and other influential factors can significantly influence the stability of rock slope. Therefore,safety factor and reliability index are combined to estimate the anti-overturning stability is benefical to the safety of seismic design of rock slope by appropriately considering the amplification factor.