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Water inrush during tunnel excavation severally threatens the mining safety as blind water-bearing structures may develop in front of the working face. The transient electromagnetic method (TEM) has been widely applied in the advanced detection of tunnel water-bearing structures. However, the metal interference of both supports and tools in the tunnel has become a bottleneck that reduces the forecast accuracy of this method. In this paper, we analyse the effect of metal interference on TEM data and propose a novel set of an observation and correction method under metal interference based on the ratio of anomalous and background apparent resistivity. Flume model experiments both with and without metal interference are carried out, showing that this interference can affect TEM measurements significantly and result in false anomalies, and that our proposed method can remove this ambient noise caused by metal interference appropriately. The practical application further proves that this method can effectively reduce low-resistivity interference introduced by the support and other metal tools inside the tunnel. By applying this correction method, the location of water-rich anomalies can be detected more precisely during the excavation process of the same tunnel, which is of high application value of reducing exploration difficulty and tunneling risk.

Characteristic information of FBG reflection spectra changes because of the existence of demodulation system error in the actual demodulation. The analysis of spectra for FBG under axial uniform force based on particle swarm optimization is given in this paper. Objective function is established and force experiments and numerical simulation of fiber Bragg grating have been made. The characteristic information of FBG reflection spectra under axial uniform force is extracted and theoretically reconstructed. The results show that, the improved particle swarm algorithm in fiber grating reflection spectra analysis is feasible. Also, the method has other characteristics such as high accuracy, good stability and fast convergence speed.

An accurate finite element model is a necessity for analyzing the bridge's health status. The uniform design combined with response surface finite element model updating method is proposed in this paper. The error of data obtained from updating model is less than 3% by contrasting static load test data in Shihe Bridge.The result shows that the updating model has a good fit with the actual bridge.

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