富水软弱V级、VI级围岩隧道施工技术探索

Exploring Construction Technique of Water-rich Weak V and VI Completely Weathered Granite Tunnel

以江门隧道施工为实例,具体介绍了Ⅴ级、Ⅵ级浅埋富水全风化花岗岩隧道的施工工艺和施工方法,采用洞内降水和洞内外土体改良及加固方法。实践证明,针对隧道下穿玉龙湖泄洪道段隧道洞身超浅埋、强-弱风花岗岩软弱围岩、裂隙发育、地表水发育等特点采用的脚手架网格配合防水板铺底、水平选喷桩超前支护以及在进行水平选喷的前提下采用三台阶加临时仰拱的开挖方法等技术方案在提高隧道围岩强度、防止地表水渗流至洞内、降低地表沉降和变形方面是成功的,确保了隧道的开挖安全,顺利通过泄洪通道。针对浅埋富水软弱围岩段隧道下穿过程中围岩软弱、下穿道路过程中沉降控制严格的特点,在施工过程中从加强超前支护强度、全断面注浆等技术、保证隧道开挖安全;对隧道开挖地表段采用了旋喷桩和搅拌桩组合加固措施进行地表加固,控制隧道开挖过程中地下水的流动。通过采用以上技术措施,实现了隧道下穿过程中安全施工,保证了地面城市道路和周围建筑物的安全。

Taking Jiangmen tunnel construction for an example, the paper was introduced construction technology and con-struction methods of V ＆amp; VI completely weathered granite tunnel, using precipitation in tunnel and improvement and strengthening methods inside and outside. Practice has proved that technical solutions of bottoming with scaffold grid and wa-terproof board, advance support of horizontal jet grouting piles and excavation method of three-step ＆amp; temporary inverted arch has insured safety of excavation and successfully go through floodway aiming at shallow buried of going through Yu-long Lake spillway, soft surrounding rock of strong-wake weathered granite, growth of fissure and surface water, including improving strength of wall rock, preventing surface water transfusion in tunnel, reducing surface subsidence and deformation. Aiming at features of weak surrounding rock in process of shallow buried ＆amp; water-rich section of tunnel in weak rock, and strict subsidence control, ensuring safety from strengthening strength of advance support and whole section grouting; surface section of tunnel excavation was taken reinforcement measure of jet grouting piles and mixing pile composite and control of groundwater flow in the process of tunnel excavation, which realized safety construction in the process of the tunnel excava-tion, ensured safety of city road and the surrounding buildings above ground, and also provided references for similar engi-neering construction.