Abstract：Research purposes: The grade division of carbonate rock is often confused with the insoluble rock and its grade division is often relatively low． The new orientation and evaluation of rock grade and stability of carbonate rock are made by doing the polarizing appraisal and mechanics test of the rock sampled in the fault zone and influence scope along with using the engineering geological survey data for tunnel construction．
Research conclusions: As the carbonate rock is affected by the fracture structure，its strength is related to the fracture distance． Although the rock strength is much reduced，the rock integrity is still good due to the cementation of calcite． So the grade division of the surrounding rock of karst tunnel may be higher than that of the insoluble rock． As the karst geological disaster area and carbonate rock of karst tunnel are abrupt，the special design should be made for streng thening them．
Staff Room of Geology and Hydrogeology Engineering Tongji University． Structural Geology and Geomechanics ［M］． Beijing: China Architecture ＆ Building Press， 1982．
Wu Zhisheng， Fu Bosen． The Relationship between Krast，Surface Subsidence and Geological Structure in Xialianxi Nanling Tunnel ［J ］． Hydrogeology ＆ Engineering Geology，1986( 1) : 31．
Fourth Survey＆Design Institute of MOR． The Research between Krast，Railway Engineering and Environmental Geology［J］． Wuhan: Fourth Survey＆Design Institute of MOR， 2004．
Qing River Geological Unit Yangtze Water Resources Committee． Qing River Valley Planning Report ( Geological Engineering) ［R］． Wuhan: Qing River Geological Unit Yangtze Water Resources Committee， 1993．
China Railway Siyuan Survey and Design Group Co． Ltd． Construction geological informationof Nanling Tunnel ［R］ ． Wuhan: China Railway Siyuan Survey and Design Group Co． Ltd，1985．
［8］ TB 10012—2007，铁路工程地质勘察规范［S］．
TB 10012—2007，Code for Geology Investigation of Railway Engineering［S］．
2012, Vol. 29 
版权所有 © 2014 《铁道工程学报》编辑部