某陡倾顺层岩质高边坡支护设计实践

Support Design Practice of a High Steep Inclined Bedding Rock Slope

岩质边坡的破坏模式与岩体的结构特征密切相关,边坡坡面倾向与岩层面或裂隙面等结构面倾向的夹角小于30°时形成顺层边坡,岩层结构面倾角越大,边坡产生顺层滑移破坏的风险越高。某工程直立高切坡临空面高度约20m,岩体为泥岩,岩层层面倾角为65°,边坡坡面倾向与岩层层面倾向夹角为12°,形成典型的陡倾顺层岩质高边坡。为兼顾边坡支护方案的安全性和经济性,分别对板肋式锚杆挡墙、锚拉式桩板挡墙和排桩式锚杆挡墙等3种支护方案进行综合分析评价。结果表明,排桩式锚杆挡墙能够有效规避板肋式锚杆挡墙逆作法施工期间的边坡失稳滑塌风险,其工程造价相比锚拉式桩板挡墙具有显著优势,可作为同类型陡倾顺层岩质高边坡支护设计的首选方案。

The failure mode of a rock slope is closely related to the structural characteristics of the rock mass.A bedding slope is formed when the angle between the inclination of slope surface and that of the structural planes such as the rock layer or the fracture plane is less than 30°,and the greater the dip angle of the rock structural plane,the higher the risk of a bedding slip failure of the slope.In the involved project,the excavated vertical slope is nearly 20m high,the rock mass is mudstone,the dip angle of the rock layer is 65°,and the angle between the inclination of the slope surface and that of the rock layer is 12°,forming a typical high steep inclined bedding rock slope.In order to give consideration to the safety and economy of the slope support design,three design schemes were comprehensively analyzed and evaluated,namely,the plate-ribbed anchor retaining wall,the anchored slab-pile retaining wall and the row-pile anchor retaining wall.The results showed that the row-pile anchor retaining wall can effectively avoid the risk of slope instability and collapse during the topdown construction of plate-ribbed anchor retaining walls;Meanwhile,compared with the anchored slab-pile retaining wall,it has a significant advantage in engineering cost.Thus,the row-pile anchor retaining wall can be used as the first choice for the support design of high steep inclined bedding rock slopes.