三峡库区长江水位变化条件下滑坡稳定性二元指标体系研究

STUDY ON SLOPE STABILITY BY DUAL INDEX SYSTEM UNDER CHANGING OF WATER LEVEL OF YANGTZE RIVER IN THREE GORGES RESERVOIR AREAS

安全系数是边坡稳定性评价中的常用方法,在长期的工程实践中积累了丰富的经验,其最大的缺点是不能考虑边坡岩土体中实际存在的不确定性。可靠性理论可有效地考虑边坡系统内实际存在的不确定性和相关性,但是缺乏丰富的工程实践经验,因此,将工程实践经验丰富的安全系数与先进的可靠性理论相结合,建立安全系数与可靠性相耦合的二元评价体系具有重要的理论意义和应用价值。以巴东县东壤口镇宋家屋场滑坡为实例,计算了长江水位从135 m至175 m变化过程中的平均安全系数(最大可能安全系数)和相应的可靠性。将最大可能安全系数与边坡可靠性相乘,对最大可能安全系数进行折减,得到边坡可靠的安全系数。设折减后安全系数的临界值为1．05,由此计算出不同最大可能安全系数的临界变异系数和临界破坏概率。根据不同的最大可能安全系数及它的临界破坏概率,绘制出边坡稳定性分区图。用均值安全系数和可靠性二元指标对宋家屋场滑坡的稳定性进行了评价,结果是可靠的安全系数为1．068,略大于临界值,处于基本稳定状态。文中论述了边坡稳定性二元指标体系的建立方法。

The traditional method of slope stability analysis is safety factor, and its applications have long time, broad prospects and abundant experience; However, the weakness of safety factor cannot consider uncertainty of parameters and models. Reliability theory can effectively solve uncertain and correlative problems in slope system; However, Reliability theory is complicated and short of abundant experience. Therefore it is necessity to build dual index system of slope stability coupling safety factor and reliability. As an example, under changing of water level of Yangtze River from 135m to 175m, average safety factor （most likely safety factor） and corressponding reliability of Songjiawu landslide in Dongxiangkou town of Badong county were calculated. Multiplied most likely safety factor by corresponding reliability and reduced most likely safety factor, reliability safety factor of slope was obtained. Suppose that critical value of reduced safety factor is 1.05, critical failure probability and variation coefficient corressponding different most likely safety factors can be calculated. According to different most likely safety factors and their failure probabilities, divisional chart of slope stability was drawn. By dual index system of slope stability coupling safety factor and reliability, stability of Songjiawu landslide was assesssed; research result shows that reliability safety factor of this landslide is I. 068, slightly great than 1.05, and this landslide is low stability. In this paper, building method of dual index system of slope stability coupling safety factor and reliability was presented.