论东格高速公路小江断裂带内工程地质选线

东格高速公路由于地形、经济、规划条件限制，须在小江断裂带内展布，是首条全部线路位于小江断裂带内的高速公路。小江断裂是区域性全新世活动断裂，沿线地质条件非常复杂。小江断裂带的工程地质特征及其对路基、桥梁、隧道等工程类型的不同影响，是东格高速公路工程地质选线的首要控制因素。在收集小江断裂既有研究成果的基础上、采用详细工程地质测绘、钻探、物探、遥感等综合手段后，准确分析和评价了小江断裂带内沿线几个线路比选方案的工程地质条件，初步确定了小江东西支断裂的交接位置，从而确定了合理的线路方案，并总结出全新世活动断裂带内山区高速公路工程几条选线原则：工程敷设方式应以路基、短隧、低桥为主，尽量少采用长隧、高桥等发生震害时不易修复的工程类型；隧道工程应尽量避开断层破碎带中心位置或地表破裂带，尽量短距离穿越断层破碎带，在多个断裂交接位置应尽量避免设置隧道；线路走向应尽量绕避断裂带内成因复杂的混合堆积台地或阶地。

THE RESEARCH OF ENGINEERING GEOLOGICAL ROUTE SELECTION IN XIAOJIANG FAULT ZONE OF DONGGE EXPRESSWAY

Due to the limitation of topography, economy and planning conditions, Dongge Expressway must be spread in Xiaojiang fault zone. It is the first expressway with all lines located in Xiaojiang fault zone. Xiaojiang fault is a regional Holocene active fault with complex geological conditions along it. The engineering geological characteristics of Xiaojiang fault zone and its different effects on cutting, bridges and tunnels are the primary controlling factors for engineering geological route selection of Dongge Expressway. On the basis of collecting the existing research results of Xiaojiang fault and adopting comprehensive means such as detailed engineering geological mapping, drilling, geophysical prospecting and remote sensing, the engineering geological conditions of several alternative schemes along the Xiaojiang fault zone are accurately analyzed and evaluated, and the junction position of the eastern and Western branches of Xiaojiang fault is preliminarily determined, thus the reasonable route scheme is determined. Several principles for route selection of Expressway Engineering in mountainous areas within Holocene active fault zone are summarized as follows:the main laying methods of the project should be subgrade, short tunnel and low bridge, and the engineering types which are difficult to repair when earthquake damage occurs, such as long tunnel and high bridge, should be used as little as possible; the tunnel engineering should avoid the central position of fault fracture zone or surface fracture zone as far as possible, cross fault fracture zone as short distance as possible, and avoid multiple fault junction positions as possible. Tunnels should be set up and the strike of the line should avoid the mixed accumulation platform or terrace with complex origin in the fault zone as far as possible.