渭河隧道水文地质条件分析对“V”形坡设计方案的优化与施工建议

Design Scheme Optimization and Construction Measure Suggestion for V-shaped Slope of Weihe Tunnel Based on Hydrogeological Condition Analysis

在条件允许的情况下,地下水发育的特长隧道防排水一般优先采用"人"字坡设计。宝兰客运专线渭河特长隧道进口端,受不良工程地质和建筑物的控制,隧道采用"V"形坡形式下穿籍河河谷阶地区,下穿段及各斜井、竖井在施工中风险相对较大,存在涌水涌泥等风险,且隧道"V"形坡地下水需永久抽排。通过分析宝兰客运专线渭河隧道水文地质条件,研究隧道下穿籍河河谷段地表水、地下水及含水岩组的特征,进而对隧道涌水量进行预测,提出优化的下穿线路及辅助坑道方案并被采用,对通过富水地段的隧道和辅助坑道施工及运营安全提出具体建议。

Under suitable condition, the designers of super-long tunnels in rich groundwater regions usually give priority to a herringbone-shaped slope for the purpose of tunnel waterproofing and drainage. However in this paper, restrained by unfavorable geological conditions and by the existing structures at the tunnel entrance, the Weihe super-long tunnel on Baoji-Lanzhou passenger dedicated line would have to cross beneath the Jibe River valley terrace in the form of a V-shaped slope. Therefore, bigger risks might arise when constructing the beneath-crossing tunnel and constructing the inclined and vertical shafts, accompanied by other risks such as water inrush and mud gushing. Still more, the groundwater at the V-shaped slope of the tunnel would have to be permanently pumped and drained away. For this reason, this paper, after analyzing the hydrogeological conditions of this super-long tunnel, aiming at the Jihe River valley terrace where the tunnel would cross beneath, studied the characteristics of the surface water, groundwater and the aquifers. Further on, this paper forecasted the quantity of water inrush of the tunnel. As a result, an optimum route scheme for the tunnel crossing beneath the valley terrace and for its service galleries was put forward in this paper, subsequently being adopted in practice. Also, some suggestions were proposed in detail in this paper, concerning how to construct tunnel and its service galleries in water-rich region and how to ensure operation safety.