岩质边坡锚杆设计计算方法分析

Analysis of Design and Calculation Method for the Anchors in Rock Slope

结合岩质边坡工程实例,对岩质边坡支护设计中的锚杆轴向拉力设计方法进行了分析和评价。通过对比分析发现:采用极限平衡法、强度折减法、等效内摩擦角法、二维数值分析计算法等方法的设计计算结果偏大,三维数值分析计算法计算结果比较可靠,符合工程实际。侧向岩石压力计算方法与剩余下滑力法的计算结果与数值分析计算法基本一致。在侧向压力接近于零时,建筑边坡支护技术规范采用的侧向岩石压力计算方法计算结果存在安全隐患。在这种情况下,建议采用强度折减法进行锚杆拉力的设计计算。锚杆轴力并非均匀分布,对边坡顶部、底部锚杆应予以加强。在施工阶段稳定性较好的边坡,可按正作法施工,充分发挥边坡的自稳能力,以减小锚杆轴力,可优化设计。

Combined with rock slope engineering examples,the analysis of the calculation methods for anchors axial force in rock slope was carried out in different ways.The results show that the calculated values of bolt axial force by limit equilibrium method,the strength reduction method,equivalent internal friction angle method,2-D numerical analysis method are relatively large.The calculated values by 3-D numerical analysis method are reliable.It is consistent with the result from actual slope.The calculated values of anchors axial force by lateral rock pressure calculation method and unbalanced thrust method are almost the same with that by numerical analysis method.When the lateral pressure is close to zero,the calculation design method in technical code for building slope has potential safety problems.In this case,the strength reduction calculation method is proposed in this paper.Through a series of case studies,the applicability of the proposed method was clearly exhibited.Anchors axial force is not uniformly distributed,the anchors should be strengthened on the top and the bottom of the slope.The slope which has a good stability during the construction phase can be treated by direct construction method,because the stability of the slope has been fully used to reduce the anchors axial force,and also can optimize the designs.