南水北调西线一期工程区断层活动性及工程地质评价

南水北调西线一期工程位于青藏高原东部的边缘地带,海拔3 500 m以上,地质条件复杂,断层密集分布,褶皱强烈发育,构造活动频繁.通过ETM卫星影像和野外考察分析了工程引水隧洞线路区断层的空间分布及活动特征.工程区以桑日麻断裂、鲜水河断裂和甘德南断裂等对工程的影响最大,是潜在的发震断裂.深埋长引水隧洞在较高地应力作用下,软弱围岩及宽大断层带物质易产生大变形和长期流变.引水线路区褶皱、断层构造发育,有利于地下水富集、运移.在静、动水压力下,引水隧洞穿过断层及破碎带时易发生涌水、碎屑流和坍塌等地质灾害.

Main Engineering Geological Problems of Active Faults in the 1st Stage Project of Western Line for Transfering Water from Southern to Northern China

The first stage of the project, with an elevation of 3 500 m, which transfers water from the upper Yangtze River into the upper Yellow River, is located at the east edge of Qinghai-Tibet Plateau where the regional geological conditions are very complex, active faults are distributed over the project zone, strata are strongly folded and tectonic movements are frequently developed. Through ETM and exploring in site, analyze the distribution and the activity of active faults, evluate faults influences on the stability of deeply buried long tunnel. Sangrima Fault,Xianshuihe Fault and South Gande Fault have strong influence not only on the stability of tunnels but also on the regional tectonic stability of the project. Under high tectonic tress soft rock creep and big distortion are frequently developed. Water invasion, debris flow, collapse and paroxysmal dislocation of active faults are discussed in the paper.