复杂条件下长大隧道涌水预测及其对环境影响评价

PREDICTION OF GROUNDWATER INFLOW IN LONG TUNNEL AND ITS INFLUENCE ON ENVIRONMENT UNDER COMPLEX CONDITIONS

隧道涌水不但影响施工进度、施工费用、稳定和安全,也会引起地下水位的下降。由于环保意识的增强,对隧道涌水控制已成为隧道设计、施工和建设的重要部分。考虑降雨补给、真实三维地形、隧道埋深及时空开挖对隧道涌水的影响,利用地理信息系统(GIS)和FLAC3D对日本九州地区新干线筑紫隧道涌水及其对地下水位的影响进行分析。首先利用GIS中的水理分析将所研究的筑紫隧道周围区域划分为若干个小的流域,对每一个小流域利用tank模型进行降雨渗透分析;然后利用数值三维模型对隧道开挖阶段和使用后的涌水及其对地下水位的影响进行时空预测和分析。

The groundwater inflow into a tunnel affects not only the construction schedule, cost, stability and safety, but also the groundwater level. Because of the increasing public concern regarding the impact of tunneling on surrounding environments, the control of groundwater has become an essential part of the planning, design and construction of a tunneling project. The impact on groundwater table due to groundwater inflow into Shinkansen （high speed trains） Chikushi Tunnel in Japan is analyzed by coupling geographic information systems（GIS） and FLAC3D. Firstly, the area around Shinkansen Chikushi Tunnel is drawn into watersheds using the hydrologicanalysis of ArcGIS; and tank model, which is a method for hydrologic balance analysis of precipitation, evaporation, water flow and infiltration, is used for calculating the rainfall infiltration. All the data, such as the geological data, three-dimensional terrain and rainfall, are processed using GIS. Then, a three-dimensional groundwater flow numerical model is used to predict the groundwater inflow into tunnel and the drop of groundwater level around the tunnel. Based on the 3D numerical model, considering the rainfall infiltration and the tunnel excavation sequences, a time-spatial simulation of the groundwater inflow and its influence on the groundwater level of Shinkansen Chikushi Tunnel are presented.