REAL TIME MONITORING AND ANALYSIS FOR SAFE CONSTRUCTION OF DOUBLE-ARCH HIGHWAY TUNNEL IN SOFT AND WEAK SURROUNDING ROCK MASS

Considering the characteristics of Hujiaba double-arch highway tunnel constructed with three pilot tunnels excavated in advance and its large excavation width and shallow buried depth,safety construction measures were put forward such as the grouting from the ground surface,excavating by manpower in the upper bench and blasting in lower bench,blasting with small detonation dose,timely installation of the inverts,and so on.The field monitoring works focused on the following three items:(1) the displacement of surrounding rock;such as crown settlement,displacement of the ground,displacement of inner surrounding rock;(2) the stress and stain of support structure;(3) the internal force in the mid-partition wall.During construction,monitoring data was analyzed in time.Structural material parameters were analyzed backward and modified in response to the monitoring data in order to guarantee safety construction.The engineering practice has proved the applicability and feasibility of the safety monitoring and informationization construction methods.