确定岩质边坡地震安全系数的新方法

地震作用下岩质边坡安全系数是一个随时间变化的函数,如何依据岩质边坡安全系数时程给出边坡在地震作用下的稳定性评价指标,这是一个尚未很好解决的工程难题.基于显式波动有限元方法,给出了岩质边坡动力安全系数时程的计算方法,并引入可靠度的概念,提出了新的边坡动力稳定性评价指标-可靠度动力安全系数,给出了相应的计算方法,即边坡的可靠度动力安全系数等于边坡安全系数时程的平均值减去边坡安全系数时程的标准差与工程可接受的可靠度的乘积,使边坡的动力稳定性评价与工程可接受的风险紧密结合起来.将其应用于某岩质边坡,并与拟静力法的结果进行了比较.结果表明,所提出的边坡动力稳定性评价指标能够较好地考虑工程风险,其计算方法是可靠的,可直接应用实际工程.

New method for determining the seismic safety factor of a rock slope

The safety factor for a rock slope experiencing seismic activity is a function that changes with time. Assessments of the potential instability of a rock slope under seismic stress have been based on a time history of a rock slope's safety factor. This is a difficult engineering problem that remains unresolved. Based on the explicit finite element method, a new method of calculating the dynamic safety factor was proposed. To enhance reliability theory,a new concept, a dynamic stability evaluation index, more accurately called a dynamic safety factor of reliability,was proposed, and a method for calculating it was developed. The proposed dynamic safety factor of reliability of rock slope equals to the difference that the mean value of time history of dynamic safety factor of rock slope subtracts the product of standard error of time history of safety factor and risk level accepted by engineering. This compactly integrates stability evaluation of slope with an evaluation of acceptable levels of risk. The proposed method was used to calculate the safety factor for a rock slope, and the result was compared to that derived using the pseudo-static method. The comparison indicates that the proposed method is reliable, and can be used directly in engineering.