基于岩体质量指标BQ的岩质边坡工程岩体分级方法

ENGINEERING ROCK MASS CLASSIFICATION METHOD BASED ON ROCK MASS QUALITY INDEX BQ FOR ROCK SLOPE

对于线路工程上具有普遍性的岩质边坡,因数量多,范围广,工程勘察深度相对较浅。依据规范的测试和试验,建立一种基础性岩体质量评价方法,实现边坡工程岩体分级,并根据行业要求与经验提出支护措施,对提高岩质边坡工程设计与施工的科学性无疑具有重要的意义。针对现有的《工程岩体分级标准》(GB50218—94)没有涉及边坡工程岩体分级,在深入研究和系统消化边坡工程岩体分级成果基础上,提出基于岩体质量指标BQ的岩质边坡工程岩体分级方法(简称BQ-RSlope方法)。该方法在岩体基本质量指标基础上,考虑控制边坡稳定性的主要结构面类型与延伸性、结构面产状与坡面间关系以及边坡内地下水发育程度等影响因素,对岩体基本质量指标进行修正,由此确定边坡工程岩体级别,并给出各级别边坡工程岩体自稳能力的评价。结合4个边坡工程10个坡段的应用性验证,表明依据文中方法获得的各边坡坡段的岩体质量分级以及该基于质量指标对边坡稳定性的评价结果与工程实际总体相符,提出的依据BQ的岩质边坡工程岩体分级方法是合适的。

The engineering classification in rock slopes is not included in the current standard of engineering classification of rock masses（GB50218--94）. This paper presents the engineering classification method for rock slopes（BQ-R Slope） based on the quality index of rock mass BQ. In this method, several modified factors are employed as to correct rock mass basic quality, and the engineering rock mass classifications for rock slopes are determined by the modified rock mass quality, and the evaluation for stand-up time of rock slope in correspondence with each class of rock mass is further proposed. The employed factors consist of the type and the persistence of major structural planes, the relationship between orientations of structural planes in rock mass and rock slope surface and the groundwater conditions in rock slope. The presented method is verified through applications to four rock slope projects and ten slope sections in total. It is found that the engineering classification and the corresponding evaluation results of each slope section with the method proposed are generally in good agreement with the practical situation. This indicates that the presented method for engineering rock massclassification of rock slopes based on BQ index is appropriate.