汶九高速A5标泥石流灾害特征及地质选线研究

Research on the Characteristic of Debris Flow Disaster and Geological Alignment for the 5th Section of Wunchuan- Jiuzhaigou Expressway

研究目的:拟建高速公路汶川至川主寺段处于汶川"5.12"地震中心影响区,因其复杂的地形地貌、地层岩性及地质构造等影响,沿线沟槽及其两侧泥石流物源十分丰富,强降雨条件下易引发大量的泥石流等次生地质灾害。本文通过资料收集、遥感解译及现场地质勘测等工作和手段,查明沿线泥石流的分布规律及危害特征,进行高速公路工程地质选线。研究结论:(1)沿线泥石流数量多、危害面广,具有规模大小不一、危害程度差异性大及泥石流活动频繁、重复成灾的特性;(2)沿线泥石流对拟建高速公路段的危害方式主要体现为淤埋及冲毁危害,次为堵河阻水危害;(3)峡谷区河段选线应在查明泥石流活动痕迹的基础上判定泥石流规模后再确定线路的位置和高程,在处于形成期、发展期及淤积严重的泥石流沟处线路选线宜采用绕避原则,峡谷区线路选线严禁穿越泥石流堆积区,宜在泥石流沟通顺段落的流通区以高墩大跨设桥的形式通过;(4)本研究结论对汶川地区公路、铁路等工程地质选线具有指导意义。

Research purposes： The proposed Wenchuan - Chuanzhusi expressway, which is the part of proposed Wenchuan-Jiuzhaigou expressway, is located in the area of Wenehuan ＂5.12＂ earthquake affected. The groove and the two sides of proposed expressway have rich debris flow matters because of its complicated influence factor of topography, lithology and geological structure, which easily triggers debris flow disaster under the storm condition. Based on the measures of data collection, remote sensing interpretation and field geological surveys, this paper found out the distribution and damage characteristic of debris flow of the expressway area, and guided the engineering geological alignment of the expressway. Research conclusions： （ 1 ） Within the area of expressway, the debris flow has the characteristics of breaking out with numbers, large area, high frequency and high truculency. （2）Debris flow distributed along the proposed expressway has the damage modes of buried hazards, destroyed hazards and blocking fiver hazards. （ 3 ） In the area of valley, the engineering geological alignment of the proposed expressway should be done before ascertaining the traces of debris flow activity and its scale, and then determined the position and elevation of the expressway; The alignment of the proposed expressway should avoid the debris flow which is in the period of formation and development, or is afflicted by serious silting ; In the valley area the alignment of the expressway should be prohibited passing through the position of debris flow deposit, but allowed to cross the flowing area of debris flow by the form of high - span bridge. （4） The research conclusions can be widely applied in the geological alignment for expressway, railway engineering in Wenchuan area.