摘要
基于三峡库区实测降雨资料,研究了不同初始条件对不同土体边坡稳定性影响,建议了能够反映边坡含水状态的初始条件选取方法。在此基础上,采用非饱和渗流分析方法研究了前期降雨对不同土体边坡稳定性影响,以典型的砂土和黏土边坡为例初步探索了前期降雨对边坡稳定性影响规律。结果表明:初始条件对不同土体边坡稳定性影响不同;建议将多年平均降雨量对应的稳态渗流场作为初始条件进行非饱和渗流分析。边坡土体渗透系数越低,边坡稳定性受前期降雨的影响越大、影响时间也越长。砂土和黏土边坡稳定性分析时建议至少考虑15 d以上的前期降雨,对于砂土边坡还应根据这15 d前面5 d的降雨情况确定是否需要增加计算天数。短历时高强度前期降雨对砂土边坡稳定性影响更大,而长历时低强度前期降雨对黏土边坡稳定性影响更大。累积前期降雨量可以作为判断边坡最小安全系数出现时刻的依据。砂土边坡出现最小安全系数时刻与10 d累积前期降雨量最大的时刻较为吻合,而黏土边坡则与15 d累积前期降雨量最大的时刻较为吻合。
Based on the measured rainfall data in the Three Gorges reservoir area, this paper investigates the effect of different initial conditions on different types of soil slope stability. A method to reflect the real initial conditions of the water content in the slope is recommended. Unsaturated seepage analysis is adopted to study the effect of antecedent rainfall on different types of soil slope stability. The typical sand and clay slopes are taken as examples to investigate the effect of antecedent rainfall on slope stability. The results indicate that the effect of the initial conditions on different types of soil slope stability can differ considerably. It is recommended that the steady-state seepage field under average annual rainfall can be used as the initial conditions for transient seepage analysis. The lower soil permeability coefficient, the greater impact of antecedent rainfall can on slope stability, and the longer time affected by antecedent rainfall. It is recommended that more than 15 days antecedent rainfall should be considered for sand and clay slopes stability analysis. Furthermore, more computational effort for sand slopes will depend on the 5 days rainfall before these 15 days rainfall. The short term and high density antecedent rainfall has a significant effect on sand slope stability, whereas the long term and low density antecedent rainfall has a significant effect on clay slope. The cumulative antecedent rainfall can be taken as a criterion to determine the minimum factor of safety. For the sand slopes, the time corresponding to the minimum factor of safety matches well with the time corresponding to the maximum 10-day cumulative antecedent rainfall, whereas, for the clay slopes, it matches well with the time corresponding to the maximum 15-day cumulative antecedent rainfall.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2013年第11期3239-3248,共10页
Rock and Soil Mechanics
基金
国家重点基础研究发展计划973项目(No.2011CB013506)
国家自然科学基金项目(No.51225903
No.551329901
No.51079112)
关键词
边坡
稳定性
安全系数
前期降雨
非饱和渗流分析
slope
stability
safety factor
antecedent rainfall
unsaturated seepage analysis
