Research methods: Through making the analyses haled on the geological conditions at the eastern portal of Huaying Mountain Tunnel，it is concluded there is possibility of karst stratum at the eastern portal of Huaying Mountain Tunnel. Therefore，the treatment ways are presented for the prevention of the appearance of disaster in the course of karst tunnel construction.
Research conclusions: The process of geological forecast in advance taken to karst tunnel is as follows; long distance geological survey-medium distance geological survey- -short distance geological survey. The survey in advance and location are done for the karst within the range of 50 m in front of the working face of Karst development area by adopting geological radar and other physical survey means. Based on the result of long distance survey, the precision location is done for drilling hales in advance to suspected places within the range of 25 m in front of the working face in order to make clear of watery and mud situations of karst in front of the working face. The karst condition is made clear through drilling holes and geological sketch of the working face. The preventive measures of drainage or block should be taken in advance according to the situation of surveyed karst.
2007, Vol. 24 
