N-S-TRENDING ACTIVE STRUCTURES ALONG THE QINGHAI TIBET RAILWAY AND THEIR INFLUENCES ON RAILWAY BED ENGINEERING

A nearly N-S-trending active tectonic belt is attested to exist along the Qinghai-Tibet Railway under construction according to surface geological route survey,active tectonic mapping at different scales and geophysical exploration of different depths.The N-S-trending tectonic belt along the railway exhibits evidently active faulting,crustal deformation,Quaternary down-faulted basins,earthquake activity,linear distribution of hot springs and distinct geophysical anomalies and different formations distributed on both sides of it.The N-S-trending tectonic belt also shows relatively strong tectonic activity at present and a trend of enhancing of the tectonic activity in the future and can induce many kinds of geological hazards and jeopardize the railway bed,highway bed and permant engineering works to different degrees.