某超大断面隧道结构设计关键技术

Key Technology for Structural Design of an Oversized Section Tunnel

超大断面隧道的关键点在于其结构设计。以杨柳井隧道为例,从内轮廓确定、衬砌结构设计、施工工法、超浅埋段及岩溶段处置方案等方面出发,探讨了超大断面隧道结构设计的关键技术,得出如下结论:(1)结合工程类比及工程经济性合理确定内轮廓扁平率;(2)采用加强型复合式衬砌结构可替代三次衬砌结构;(3)对于超大断面,可采用划大为小的双侧壁导坑法施工;(4)对于超浅埋段,可采取加强衬砌支护及取消拱部锚杆、超前管棚与超前小导管相结合、喷锚支护加强掌子面稳定等措施;(5)对于岩溶段,可采取喷锚支护稳固溶腔、设置缓冲层、加强防排水措施等方案。

The key point of oversized sectional tunnel lies in its structure design. Taking Yangliujing Tunnel as an example, this paper discusses the key technologies for the structural design of oversized sectional tunnel from the determination of internal contour, design of lining structure, method of construction, and treatment schemes of ultra-shallow buried section and karst section. The following conclusions are that(1) the inner contour flattening rate is determined reasonably by engineering analogy and engineering economy,(2) the three-time lining structure can be replaced by using the reinforced composite lining structure,(3) for the oversized section, the construction can be carried out with the method of double-sided pit method with large dividing into small dividing,(4) for the ultra-shallow buried section, the measures of strengthening the lining support combined with removing the arch bolt, the leading pipe shed and the leading small pipe, and strengthening the face stability with the combined bolting and shotcrete are taken,(5) for karst section, the measures of combined bolting and shotcrete to stabilize the cavity, buffer layer to set up, and waterproof and drainage to strengthen are taken.