基于随机有限元的黄土边坡可靠度研究
发布时间：2018-08-15 15:02
【摘要】：黄土边坡稳定性的评价一直以来是岩土工程界研究的热点课题，但由于黄土强度参数变异性大，取值较为困难，致使边坡稳定性评价的确定性方法难以获得可靠的结果。本文利用黄土空间变异性与相关性的特点，研究了其垂向自相关距离，采用Monte-Carlo模拟的随机有限元法，对甘泉地区的黄土高边坡稳定系数和失效概率进行了系统研究，详细分析了自相关距离对失效概率和稳定系数的影响。取得的研究成果如下： （1）分析了甘泉地区的工程地质条件，收集了黄陵-延安高速公路工程报告中黄土实验数据，对物理力学指标做了统计，并对该区强度参数概型分布进行了分析，结果表明该区所有地层的c、值都接受对数正态分布。以静探实验结果为基础数据，分别利用递推空间法、空间均值法和空间趋势法计算了该区的黄土参数的自相关距离，发现空间均值法和递推空间法侧摩阻力计算所得结果基本是锥尖阻力计算结果的2倍左右。以锥尖阻力数据用以上三种方法求得的相关距离范围为0.76—2.85m，以侧摩擦阻力数据求得的相关距离范围为0.64—6.32m。 （2）通过研究岩土参数自相关距离对可靠度分析结果的影响，认为当边坡失效概率小于38.0%时，随着自相关距离的增大，失效概率增大，意味着土坡越均匀，会增加边坡不稳定性，而强度随深度变化剧烈的土坡，能一定程度提高边坡稳定性。反之，当边坡失效概率大于38.0%时，随着自相关距离的增大，失效概率减小，意味着强度随深度变化剧烈的土坡，会增加边坡不稳定性，均匀土坡则一定程度上提高边坡稳定性。工程中采用均质土坡或分成2-3个大层将不均匀的黄土高边坡地层简化进行稳定性评估，对稳定性差的边坡，将高估边坡的稳定性，获得冒险的结果。而对于较稳定的边坡，，则会低估边坡的稳定性，获得保守的结果。
[Abstract]:The evaluation of loess slope stability has always been a hot topic in geotechnical engineering. However, because of the large variability of loess strength parameters, it is difficult to obtain reliable results by the deterministic method of slope stability evaluation. Based on the characteristics of spatial variability and correlation of loess, the vertical autocorrelation distance of loess is studied in this paper. The stability coefficient and failure probability of high loess slope in Ganquan area are studied systematically by using the stochastic finite element method simulated by Monte-Carlo. The influence of autocorrelation distance on failure probability and stability coefficient is analyzed in detail. The research results are as follows: (1) the engineering geological conditions in Ganquan area are analyzed, the loess experimental data of Huangling-Yan'an expressway engineering report are collected, and the physical and mechanical indexes are counted. The results show that the values of c and C of all strata in this area accept logarithmic normal distribution. The autocorrelation distance of loess parameters in this area is calculated by using recursive space method, spatial mean method and spatial trend method based on the results of static exploration experiments. It is found that the results obtained by the spatial mean method and the recursive space method are about 2 times of the calculated results of the cone tip resistance. The range of correlation distance is 0.76-2.85musing the data of cone tip resistance and 0.64-6.32m. (2) the reliability of autocorrelation distance of geotechnical parameters is studied by studying the autocorrelation distance of geotechnical parameters. The impact of the analysis, It is considered that when the slope failure probability is less than 38.0, the failure probability increases with the increase of autocorrelation distance, which means that the more uniform the soil slope is, the more unstable the slope will be, and the soil slope whose strength varies sharply with the depth. It can improve slope stability to some extent. On the contrary, when the slope failure probability is greater than 38.0, with the increase of autocorrelation distance, the failure probability decreases, which means that the soil slope whose strength varies sharply with the depth will increase the slope instability, and the even soil slope will improve the slope stability to some extent. In engineering, homogeneous soil slope or 2-3 layers are used to simplify the formation of uneven loess high slope for stability evaluation. The slope with poor stability will overestimate the stability of slope and obtain risky results. For a more stable slope, the stability of the slope is underestimated and conservative results are obtained.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU444;TU43
本文编号：2184565
[Abstract]:The evaluation of loess slope stability has always been a hot topic in geotechnical engineering. However, because of the large variability of loess strength parameters, it is difficult to obtain reliable results by the deterministic method of slope stability evaluation. Based on the characteristics of spatial variability and correlation of loess, the vertical autocorrelation distance of loess is studied in this paper. The stability coefficient and failure probability of high loess slope in Ganquan area are studied systematically by using the stochastic finite element method simulated by Monte-Carlo. The influence of autocorrelation distance on failure probability and stability coefficient is analyzed in detail. The research results are as follows: (1) the engineering geological conditions in Ganquan area are analyzed, the loess experimental data of Huangling-Yan'an expressway engineering report are collected, and the physical and mechanical indexes are counted. The results show that the values of c and C of all strata in this area accept logarithmic normal distribution. The autocorrelation distance of loess parameters in this area is calculated by using recursive space method, spatial mean method and spatial trend method based on the results of static exploration experiments. It is found that the results obtained by the spatial mean method and the recursive space method are about 2 times of the calculated results of the cone tip resistance. The range of correlation distance is 0.76-2.85musing the data of cone tip resistance and 0.64-6.32m. (2) the reliability of autocorrelation distance of geotechnical parameters is studied by studying the autocorrelation distance of geotechnical parameters. The impact of the analysis, It is considered that when the slope failure probability is less than 38.0, the failure probability increases with the increase of autocorrelation distance, which means that the more uniform the soil slope is, the more unstable the slope will be, and the soil slope whose strength varies sharply with the depth. It can improve slope stability to some extent. On the contrary, when the slope failure probability is greater than 38.0, with the increase of autocorrelation distance, the failure probability decreases, which means that the soil slope whose strength varies sharply with the depth will increase the slope instability, and the even soil slope will improve the slope stability to some extent. In engineering, homogeneous soil slope or 2-3 layers are used to simplify the formation of uneven loess high slope for stability evaluation. The slope with poor stability will overestimate the stability of slope and obtain risky results. For a more stable slope, the stability of the slope is underestimated and conservative results are obtained.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU444;TU43
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