Monitoring the damage evolution of reinforced concrete during tunnel boring machine hoisting by acoustic emission

Abstract

Due to its high sensitivity to concrete damage signals and the real-time dynamic monitoring feature, acoustic emission (AE) technology has been successfully applied to the health monitoring of reinforced concrete (RC) structures. In this paper, a wide-band-low-frequency sensor tailored for monitoring the health of the concrete structure at the maximumstress position of the tunnel portal during the hoisting of the tunnel boring machine (TBM) was developed. Based on the customized sensor, the hoisting process of the cutter head centralstructure and some parts of the TBM were monitored by AE technology. Distinct AE signatures were recorded during various phases of loading, and AE analysis using established methods indicates that the energy and counts as two important characteristic parameters were very sensitive to the damage evolution of RC structure and could be employed to effectively monitor the damage evolution of RC structure in real-time during the hoisting process of the TBM. The damage evolution and crack mode analysis were also carried out to evaluate the damage degree and the dominant cracking mode of RC structures at the tunnel portal, which provided information about cracking conditions and evaluated the remaining life of the structure. This work practiced the application of AE technology in the TBM hoisting and proved the effectiveness of its field implementation.