地质构造对成昆铁路峨边至德昌段泥石流发育规律的控制作用

Control Action of Geological Structure on Development Law of Debris Flow at Ebian-Dechang Section of Chengdu-Kunming Railway

地质构造对成昆铁路沿线泥石流的发育规律有明显的控制作用。通过成昆铁路峨边—德昌段35条泥石流沟的详细调查,采用构造纲要图、工程地质分区图和泥石流分布图叠置分析的方法,研究了该区构造体系对泥石流发育规律的控制作用,取得以下认识:①沿线跨越三大次级构造单元,其中位于凉山拗褶区和安宁河隆起区结合带附近的下普雄—泸沽分水岭段泥石流最为发育;②泥石流在该区所处区域大地构造线控制作用下,呈明显的带状分布规律;③泥石流在该区新构造运动的影响下呈垂直分布规律,在差异性升降运动强烈的地区,泥石流沟集中发育,活动频繁;④泥石流多沿本区的地震构造带展布,本区处于川滇经向构造带的南段,几个强震震中距离铁路很近,如冕宁、西昌等,是泥石流发育集中、活跃的地带。

Geological structure significantly controls the development law of debris flow along Chengdu- Kunming Railway. By means of the specific survey on 35 debris flow gullies at Ebian-Dechang Section of the Railway and overlay analysis on the maps of structural outline, engineering geological zoning and debris flow distribution, the control action of the reginal structural system on development law of debris flow is studied, through which the following understandings are obtained： ① the railway line steps cross three sub-tectonic units, wherein the debris flow located at Xiapuxiong-Lugu Divide near the junction zone of the folded downwarping region in Liangshan and the raised area of Anning River is developed mostly; ② the debris flow presents obvious zonal distribution law under the control action of tectonic line thereof; ③ the debris flow presents vertical distribution law under the effect of neotectonic movement in the region, and the debris flow gully is developed intensively with frequent activities in such area where strong differential uplifting-subsidence movement is strong; ④ the debris flow mostly spreads along the seismotectonic zone in the region which locates in the south of Sichuan Yunnan Meridional Structural Zone, in which several epicenters of strong earthquake near the railway, such as Mianning, Xichang, are the zone having intensive and active development of debris flow.