摘要
岩土工程勘察规范统一使用95%保证率单侧置信下限值作为土体强度指标标准值,用于补偿小样本抽样带来的安全风险,但在变异性较大时可能造成过盈估计。基于均值相同的小、中、大变异水平强度参数总体,采用固定容量的小样本多批次随机抽样方法,构建不同保证率的c和φ标准值分布空间,分析与之映射的均质土坡安全系数结果空间的分布特征,讨论等安全系数原则下参数保证率与土体变异水平的内在关系。研究结果表明:安全系数的离散程度与土体变异性和参数置信水平均呈正相关,采用95%置信水平统一值将导致对变异性较大土体的边坡安全程度估计过低;以安全系数结果空间的分位值相等为控制条件,提出土体变异性增大可相应降低参数置信水平的建议。
Code for investigation of geotechnical engineering uniformly adopts 95% assurance unilateral confidence lower limit value as indicators of soil strength standard values, which can compensate the security risks of small sample sampling. But it may cause interference estimation when larger variability. Based on the small, medium and large variation of the overall strength parameters with respect to the same level of mean, and adopting multi-batches small sample random sampling method with fixed capacity, the distribution space of standard c and ^ corresponding to different reliability was constructed. The distribution characteristic of mapping soil slope safety factor results was analyzed, and the internal relations of the variability level and assurance rate under the principle of equal safety factor were discussed. Study shows that the dispersion degree of safety factor are positively correlated with the variability level and assurance rate, and the parameters of the unified 95% confidence level will lead to low estimated safety to larger variability of soil slope; With control condition of same safety factor, the advice for reducing the confidence level for larger variability of soil is proposed.
出处
《铁道科学与工程学报》
CAS
CSCD
北大核心
2017年第4期697-704,共8页
Journal of Railway Science and Engineering
基金
国家重点基础研究发展规划(973计划)项目(2013CB036204)
关键词
岩土参数
小样本
置信水平
变异性
边坡稳定
geotechnical parameters
small sample
confidence level
variability
stability of slope
