基于机器学习与可靠度算法的围岩动态分级方法及其工程应用

Dynamic classification method of surrounding rock and its engineering application based on machine learning and reliability algorithm

为了实现公路隧道建设过程中掌子面前方围岩质量的准确、快速评价,在传统岩体分级BQ方法基础上,基于机器学习与可靠度算法提出了一种隧道施工过程中围岩动态分级方法。机器学习工具选取为最小二乘支持向量机(LSSVM),并通过细菌觅食算法(BFOA)对其参数进行优化选取,以此构建分级指标组与围岩级别之间的非线性映射关系,其中分级指标组是由地质超前预报结果、掌子面强度回弹值等易于在施工过程中获取的参数形成。而且对于某些分级指标获取过程中可能存在的随机性问题,引入可靠度理论加以修正,通过机器学习结果构建可靠度计算的功能函数,最终得出具有概率意义的围岩分级结果。将所述方法应用于甄峰岭隧道现场,根据计算结果对部分区段进行了设计变更,通过自动化监测数据证明了变更方案的适用性。结果表明,所述分级方法可有效实现施工过程中围岩动态分级计算,为隧道建设的动态设计过程提供了一种新思路。

In order to realize the accurate and quick evaluation on the surrounding rock mass in front of tunnel face during the construction process,in this paper,a dynamic classification method for tunnel surrounding rock,which is based on traditonal BQ classification method,is proposed depending on machine learning and reliability algorithm.The machine learning tool is selected as the least squares support vector machine(LSSVM),and its parameters are optimized by the bacterial foraging algorithm(BFOA)to construct a nonlinear mapping relationship between the hierarchical index group and the surrounding rock level.The grading index group is made up of parameters include geological advance prediction results and the strength rebound value of the face surface,which are easy to be acquired during the construction process.Furthermore,the reliability theory is applied to verify the randomness problems that may exist in the results of some grading indicators.By constructing the functional function of reliability calculation through machine learning results,the surrounding rock classification with probability meaning are realized.To verify its feasibility in some sections based on calculation results,the new dynamic grading method is applied in Zhenfengling tunnel and its applicability is proved by automated monitoring data.The results show that the classification method can effectively realize the dynamic grading calculation of surrounding rock during construction,which provides a new idea for the dynamic design process of tunnel construction.