ANALYSIS OF DISEASE CAUSES AND TREATMENT MEASURES OF HIGHWAY TUNNEL IN LOESS

After having been operated for several years, a highway tunnel produces the diseases of lining cracks and tunnel settlement in loess area. Analysis of the development process of the diseases indicates that the main causes are loess characteristics, surface water and the depth of loess tunnel. In response to the diseases, a finite element analysis is conducted for four different conditions of the reinforcement measures. The numerical results show that the local structural reinforcement, surface water treatment, and the soil-structure interaction can reduce stress concentration and improve the tunnel stress distribution. The reinforcement at the bottom corners of tunnel arch structures can strengthen the overall stress distribution more reasonable and enhance the tunnel ability to undertake external loading. Hence, the tunnel lining cracks should be repaired and strengthened. At the same time, the arch foot foundation should be reinforced with root pile and rammed-pedestal pile. These measures would improve the safety of the tunnel capacity.