一、既有铁路增设棚洞面临的问题棚洞一般适用于有小量坍塌落石的半路堑,其内侧基岩为中等强度(Ⅲ类)以上的围岩。我国现有的多数棚洞是在铁路交付运营后修建的,其主要原因是修建时为了早日通车,在依山傍河地段设计了高路堑并采用了扬弃爆破施工,使堑坡岩层及山坡上岩石松动,通车后又由于雨水冲刷、冻胀、风化、树根挤压等原因,就不断产生落石,在一些严重落石地段,虽采取了支挡、嵌补等 First, the problems existing in adding railways to existing railways Shed holes are generally suitable for half-graben with a small amount of falling rockfalls, and the inner bedrock is surrounded by medium-strength (Class Ⅲ) rock. Most of the existing sheds in our country were built after the railway was delivered and operated. The main reason for this is that for the purpose of early opening to traffic, a high-speed cut was designed in the hillside riverside and a subgrade blasting construction was adopted so that the cutting slope rock and hillside Rock loose, after opening due to rain erosion, frost heave, weathering, root compression and other reasons, continue to produce rockfall, in some serious rockfall lots, although the support block, such as embedded