基于强度反演的破碎泥质粉砂岩边坡稳定分析

Stability analysis of broken argillaceous siltstone slope based on strength inversion

当强风化泥质粉砂岩极为破碎,部分夹中风化碎岩块时,边坡勘察钻孔取样的岩体完整程度低,试验给出的抗剪强度与天然状态土体不符。为了得到合理的强度参数,针对不同时期的开挖边坡,结合改进的试验数据,构建有限元分析模型,利用理论分析方法对岩土材料的强度参数进行反演计算,以研究确定泥质粉砂岩的强度特性,进行可靠的高边坡防护设计。研究结果表明:对于开挖4年后未出现滑动的稳定边坡,首次勘察得出的强风化泥质粉砂岩抗剪强度参数及计算得到的边坡稳定性系数偏低;补勘时采用“双管双动+半开管”可最大限度地采取原状岩样,平均岩芯采取率达到91%,得出的抗剪强度参数更为真实;结合室内试验,建立模型进行反演得到的强风化泥质粉砂岩抗剪强度参数c=36 kPa、φ=31°较为合理;实践表明,根据数值计算、场地地质条件等进行边坡支护结构设计经济可靠,效果良好。

When highly weathered argillaceous siltstone is extremely fragmented and partially sandwiched with weathered fragments,the integrity of the rock mass sampled from the slope survey borehole is low,and the shear strength given by the test does not match the natural state of the soil.In order to obtain reasonable strength parameters,a finite element analysis model is constructed based on improved experimental data for excavation slopes in different periods.Theoretical analysis methods are used to calculate the strength parameters of geotechnical materials inversely,in order to study and determine the strength characteristics of muddy siltstone and conduct reliable high slope protection design.The research result has shown that for stable slopes that have not experienced sliding after 4 years of excavation,the shear strength parameters of strongly weathered argillaceous siltstone obtained from the first survey and the calculated slope stability coefficient are relatively low.The use of"double tube double action+semi open tube"during supplementary exploration can maximize the collection of undisturbed rock samples,with an average core recovery rate of 91%,resulting in more realistic shear strength parameters.Based on indoor experiment,a model is established for inversion to obtain the shear strength parameter c=36 kPa of strongly weathered argillaceous siltstoneφ=31°is more reasonable.The practice has shown that the design of slope support structures based on numerical calculation,site geological condition,etc.is economical,reliable,and effective.