京九铁路江淮段降水型路基坍塌的地质、降水条件分析

京九铁路是新开辟的连接北京和香港九龙的南北大动脉，1996年9月正式通车。其中江淮段指淮河与长江之间的 306.1 km区段，自河南淮滨站至湖北蕲春站。由于沿线地形复杂，降水强度大，路基坍塌成为安全运行的主要危害。据统计，1997－2007年间，发生各种坍塌灾害455次，毁坏路段总长约53 000 m。运用京九铁路江淮段地质资料、1997－2007年 11 a间所发生的路基坍塌资料和铁路沿线10个气象站雨量实况资料，对京九铁路江淮段地质地岩状况进行了分类，分级处理了不同地质条件下路基坍塌的发生频次和强度，详细分析了路基坍塌发生前24～72 h雨量，得到诱发京九铁路江淮段路基坍塌灾害的地质条件和降水阀值，并对各种不同地质条件下发生路基坍塌的降水阀值及其超过阀值后灾害次数上升情况进行评述，绘制出京九铁路江淮段路基坍塌易发程度等级分区图，提出了相应的处治方法和系统图。可见不利地质条件与强降水共同作用是导致某些路段路基集中坍塌的根本原因。

Analysis of geological disasters caused by heavy rainfall along Jianghuai Section of Beijing-Kowloon Railway

Beijing-Kowloon Railway is a new main artery linking Beijing with Kowloon of Hongkong that has been finished and opened to traffic in June 1996. The Jianghuai Section is an interval of 306.1 km from the Huaihe River to the Yangtze River or from Huaibin railway station of Henan Province to Qichun railway station of Hubei Province. Because of complicated topography and heavy raining, collapsed disasters of the roadbeds have become the main damages. According to the statistics, 455 sites of collapsed disasters with 53 000 m of road damages are recorded from 1997 to 2007 along the Jianghuai Section. Basing on the geological background, all cases of collapsed disasters of the roadbeds and meteorological data of 10 meteorological stations from 1997 to 2007 along the Jianghuai Section of Beijing-Kowloon Railway, the rock situations are classified; the occurrence frequency and intensity of collapsed disasters of the roadbeds are graded; and the rainfall in 24-72 h preceding every case are analyzed in detail. Then the conditions of geological backgrounds and precipitation conditions in favor of the happening of collapsed disasters of the roadbeds are obtained and graded; the requirement for the conditions of precipitation especially heavy rain under different geological conditions are commented on; a map with the grades of the happening of collapsed disasters of the roadbeds around the Jianghuai Section of Beijing- Kowloon Railway are drawn out; and some countermeasure methods and a routing map of how to prevent and control collapsed disasters are given. It is clear that the combined action of the weak geological conditions with strong rainfall is the root causes of collapsed disasters of the some roadbeds.