Abstract:

In order to study the influencing sequence of karst geoenvironmental factors on safety of tunnel construction, the indoor model test on typical highway tunnels in Hunan and Guangdong karst areas, which considers the layout of karst caves, joint inclination, diameter of karst caves and the distance between karst caves and tunnels, is carried out. Some conclusions are drown as follows: (1） The pore water pressure on lining surface is mainly affected by the inclination of joint surface and the layout of the karst caves; and the effect of the joint inclination is stronger than that of the karst caves; the pore water pressure of vertical orthogonal layout of karst caves is about 10 times that of the oblique layout of karst caves; and the pore pressure variation at 0° of lining is about 10 times that at 180 ° of lining. (2） The influencing sequence of soil pressure on lining surface is the layout of karst cave, and then the joint inclination and cave diameter followed by the distance between cave and tunnel. (3） The increase of the joint inclination and cave diameter leads to the decrease of soil pressure; when the distance between cave and tunnel （l） and the inclination （θ） show a relationship of l<-0.4θ+30, there is a clear trend of pressure increasing at the top of lining. The results can provide reference for the study of tunnel disaster in karst area.

Key words: karst tunnel, indoor test, water gushing, tunnel safety, influencing sequence