METHOD FOR CONCRETE LINING QUALITY EVALUATING ACCORDING TO CONCUSSION BLASTING EXCAVATION IN TUNNEL

摘要

A method for evaluating the quality of concrete lining by blast vibration at tunnel excavation is provided to secure the quality of concrete lining by measuring a strain rate and a crack growth phenomenon caused by blast vibration and evaluating the optimum level of the minimum safety distance for concrete lining construction. A method for evaluating the quality of concrete lining by blast vibration at tunnel excavation comprises the steps of: placing first model concrete lining(300) in a place within the safety distance(D) influenced by blast vibration in a tunnel, and second model concrete lining(400) in a place uninfluenced by blast vibration in a tunnel on the basis of a permissible level using a vibration equation deduced in a construction site if a tunnel(100) is excavated to the appointed length; installing many buried concrete strain gauges for measuring an effective strain rate exactly and artificial crack plates for measuring a crack growth phenomenon when placing the first model concrete lining and the second model concrete lining; blasting in a time zone when vibration has a sensitive influence on concrete strength after placing the first model concrete lining and the second model concrete lining; removing the artificial crack plates from the first model concrete lining and the second model concrete lining to form many artificial crack parts on internal walls of the first model concrete lining and the second model concrete lining; measuring a concrete lining strain rate and a crack growth phenomenon using the concrete strain gauges and the artificial crack plates installed to the first model concrete lining and the second model concrete lining; evaluating the optimum level of the minimum safety distance of concrete lining constructed at the rear of an excavated tunnel by analyzing the data on the measured concrete lining strain rate and the crack growth phenomenon; and performing blast excavation of a tunnel face and construction of concrete lining on the basis of the minimum safety distance simultaneously.