基于模糊层次分析法的预应力锚索加固顺层边坡稳定性评价

An assessment model based on the hierarchical fuzzy analysis process for the bedding slope with the prestressed anchor cable frame reinforcement

预应力锚索框架结构是顺层边坡最常见的固坡方式之一,对于采用该类支护的边坡稳定性的评价,其影响因素众多且存在模糊不确定性。以贵州省公路顺层边坡为例,提出了一个基于模糊层次分析法的边坡稳定性评定模型。基于贵州省公路边坡的实际调研情况,建立了预应力锚索加固顺层边坡稳定性评价指标体系,包括5大类21个影响因素,即边坡几何特征、工程地质特征、预应力锚索框架梁工作状况参数、水文及截排水状况、其他参数。采用数值模拟方法分析了顺层边坡稳定性与边坡几何参数、结构面力学参数和锚索设计参数的关系。通过数值正交试验比较了边坡高度、边坡角度、坡后角和结构面强度对顺层边坡稳定性的影响,结果表明顺层边坡稳定性受结构面强度和坡后角影响显著。基于模糊层次分析法建立了预应力锚索加固顺层边坡稳定状况评价模型。模型基于数值计算结果并通过对影响因素的两两对比确定各评价参数的权重。将边坡稳定性划分为"非常稳定""稳定""较稳定""欠稳定""不稳定"5个等级。最后,使用该评价模型对贵(阳)遵(义)复线K86左幅边坡稳定状况进行评价,边坡稳定性模糊隶属度为(0.14,0.35,0.25,0.23,0),边坡稳定状态为"稳定,正常养护巡查"。评价结果与现场监测结果相符。

Focusing on the highway bedding slopes in Guizhou,the present paper has proposed a fuzzy analytic hierarchical process( AHP) based evaluation model for bedding slope stability. As is well known,the restressed anchor cable frame has been most widely adopted as the supports in the highway slope engineering projects. However, the stability assessment of such slopes with their reinforcement approaches remains a great challenge due to its complexity and fuzziness in the influential factors. The reason for the challenge can be said,first of all,based on the field investigation of highway bedding slopes in the context of Guizhou,which may involve an assessment indexcial factors of21. Such indexical factors can be grouped into 5 categories,namely,the geometric factors,the geotechnical factors,the design factors of cables and frames,the drainage factors and the environmental factors. And, secondly, numerical simulations have been conducted to investigate how to determine the bedding slope stability by the geometric factors,the mechanical factors of structural plane and the designing factors of the cables and frames. And,in such a situation,it would be mecessary to conduct an orthogonal numerical experiment to rank the factors of the slope height,slope angle,its back angle and structural plane strength in connection with the bedding slope stability. The results of our trying experiments show that bedding slope stability has been significantly influenced by the structural plane strength and the back angle. And,next,based on the results we have gained,we have established a fuzzy-AHP-based assessemnt model of the bedding slope stability. And,then,in the proposed model,factors weights have been dertemined by incorporating with the numerical results in a pair-wise comparison form among the affecting factors. And,last of all,the assessment model has been tranferred the slope stability into 5 categories,that is: very stable,stable, relatively stable, lower stable and unstable.And,then,a testing case of No. K86 slopes along Guiyang-Zunyi highway has been assessed to testify the efficiency of the proposed model. The fuzzy membership of the testing case has been found to be:( 0. 14,0. 35,0. 25,0. 23,0),whereas the testing slope has been assessed to be"stable though regular inspections are needed". And,therefore,the assessment results prove to be in a well-regualted agreement with the on-site monitoring data.