山西乡宁—吉县地区黄土高边坡可靠度研究  

Study on Reliability for Loess High Slopes in Xiangning-Jixian Area of Shanxi Province

作　　者：李萍[1] 赵纪飞[1] 李同录[1] 

机构地区：[1]长安大学地质工程与测绘学院,陕西西安710054

出　　处：《地球科学与环境学报》2012年第2期81-89,共9页Journal of Earth Sciences and Environment

基　　金：国家自然科学基金项目(40772181;40972182)

摘　　要：在山西乡宁—吉县地区实测了7个具有代表性的自然极限状态黄土高边坡断面,建立边坡地层结构模型;选取研究区合理的黄土物理力学参数,并分地层年代对10个典型工点的黄土强度参数内聚力和内摩擦角的变异性进行分析;选取6组典型的强度参数变异系数组合,基于Monte-Carlo法进行可靠度模拟,评价该区边坡稳定性;采用自然类比法进行边坡设计。结果表明:边坡失效概率随坡高的变化趋势一致,均是中等坡高(49.8m)的边坡失效概率较大,低坡和高坡的失效概率较低;当变异系数较小时,边坡失效概率对坡高和坡度的变化敏感,而当变异系数较大时,边坡失效概率对坡高和坡度的变化不敏感;当坡型一定、强度参数变异系数较小时,边坡的稳定系数基本不变,而当参数变异系数超过某一界限时,稳定系数随变异系数的增大而增大,二者存在非线性相关关系;研究区黄土边坡处于基本稳定状态,但其失效概率最大达69.3%,平均21.1%,介于20%～30%的比例为33.3%,大于30%的比例为14.3%,可靠度指标介于-0.5～8.5,其中小于2.7的比例为88.1%;对于坡高约为50m的黄土高边坡,若取30%作为可接受失效概率,边坡坡度需降至45°以下,如果期望可接受失效概率在10%以内,则坡度不宜超过34°。The sections of 7 representative natural limit state loess high slopes in Xiangning-Jixian Area of Shanxi Province were measured, and the strata structure models were built; the optimal physical and mechanical parameters of loess in the area were selected, and the variability of cohesions and internal frictional angle of loess in different strata ages from 10 typical sites was analyzed; 6 typical groups of coefficient of variation for strength parameters were selected, and the reliability was simulated by Monte-Carlo Method, and the stability of loess slopes was evaluated. The results showed that the variation of failure probability coincided with height of slope, the failure probability of slope with middle height （49.8 m） was high, but higher and lower slopes were low; the failure probability was sensitive to height and gradient of slope when the coefficient of variation was small, but it was insensitive when the coefficient was large; when the height and gradient of slope were constant and the coefficients of variation of strength parameters were small, stability coefficient was basically constant; but when the coefficients of variation exceeded a certain limit, stability coefficient increased with the coefficients of variation,and there was nonlinear correlativity between them; the loess slopes in the area were basically stable, but the maximum failure probability was 69. 3%, the average was 21. 1%, and the proportion of slopes with 20%-30% failure probability was 33. 3%, and the proportion with failure probability （〉30%） was 14.3%; reliability indexes were --0.5-8.5, and the proportion of slopes with the indexes （〈2.7） was 88.1%; for the loess high slope with about 50 m height, if 30% was taken as the acceptable failure probability, the gradient of slope would decrease to less than 45°, and if the acceptable failure probability was less than 10%, the gradient would be lower than 34°.

关 键 词：黄土 边坡 可靠度 MONTE-CARLO法 变异系数 失效概率 稳定系数 极限状态 

分 类 号：P642.131[天文地球—工程地质学] TU413.62[天文地球—地质矿产勘探]