大断面公路隧道洞口段穿越堆积体设计

湄渝高速公路中仙至坂面段的珠峰隧道洞口地段需下穿堆积体,施工过程中存在较大风险,针对该隧道开挖断面大(163m2)、洞口埋深浅、围岩条件差、地下水较为发育的特点以及存在的问题,提出地表注浆、超前管棚支护、接长明洞、加强洞内支护,双侧壁导坑法短进尺开挖等多项综合处理措施,并利用数值模拟验证了设计方案的可行性。验算结果表明,设计方案能够满足边坡及隧道的安全性要求,对控制土体变形,减小沉降具有明显的效果,可达到预期的设计目的。

The Design of Large Section Highway Tunnel Entrance Passing Through Colluvial Deposits

The Mei-Yu highway Zhufeng tunnel,located between Zhongxian and Banmian,has to pass through a wide range of colluvial deposits,which may face some risks during construction. Because of the difficult construction conditions such as large excavation cross section( 163 m2),shallow burial,poor rock condition and rich underground water,corresponding measures as strata grouting,advance shed supporting,extended open-cut tunnel and reinforced internal support,and double-side-wall pilot hole are proposed to pass through colluvial deposits. The design schedule is verified with numerical simulation and proved to meet the requirements for the safety of the slope and the tunnel,and effective to control soil deformation and reduce settlement.