国道306线经棚隧道穿越风积砂地层的综合施工技术探讨

Research on Construction Techniques passing through Wind-blown Sand Stratum of Jingpeng Tunnel

经棚隧道位于内蒙古自治区赤峰市克什克腾旗经棚东侧,是国道306线控制工程,也是呼海大通道进入经棚的要道。隧道地处中低山区,地形起伏较大。隧道通过地区上层为第四系上更新统(Q3)地层,下部为燕山中期花岗岩。隧道进口段洞身处在风积砂丘中,最大埋深约34 m。由于砂质隧道施工技术和方法还不完善,还没有成型的系统的可供运用的施工模式。本文详细介绍了在经棚隧道风积砂软弱围岩地质施工中采用的加强超前支护、进洞挂网喷浆预加固、大管棚先行注浆、双侧壁导坑钢插板支护、缩小开挖断面、短挖短支、全断面格栅喷射混凝土初期支护等项技术。经棚隧道风积砂地层施工技术的成功实践为同类型工程提供了技术参考和借鉴。

Jingpeng Tunnel, located at the east side of Keshiketeng Banner in Chifeng City of Nei Mongolia Autonomous Region, is the control engineering of 306 national road, and the strategic pass to enter into Jingpeng in Huhai big passage. The runnel lies in the low mountainous area, and the hypsographic relief is big. The stratum of the tunnel through is the upper Pleistocene epoch（Q3） in Quatemary period, and lower part is the granite in Yanshan intermediate stage. The inlet of the tunnel places in the wind-blown sand, and the greatest burying depth is approximately 34 m. Because of the construction technique and method for a sandy tunnel are imperfect, there is no the formative and systematic construction pattern to be utilized. The paper introduces the construction techniques for the long-span tunnel in the wind-blown sand,including to strengthen the advanced support, to gunite for pre-reinforcement, to grout with the big tube awning advancedly, to support with the two-sided wall guiding hole and embedded steel plate, to reduce the excavated section, to support with the sprayed concrete in the whole section and son on, which offer the beneficial references for the similar works.