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The paper discusses the basic principles of blind source separation and modal identification of structures, analyses the feasibility that using blind source separation techniques for modal parameter identification. According to the noisy features of the measured data in experiments, a second-order blind identification algorithm based on moving average method is proposed. By moving average method the noises are efficiently eliminated. It greatly improves the separation performance of this algorithm. The cantilever experiments verify the stability and the applicability of the algorithm.

The paper discusses the basic principle of blind source separation algorithm applying in structural modal identification. By improving the signal-whitening method, a robust second-order blind identification (RSOBI) algorithm is established on the basis of second-order statistics. The modal responses and mode shapes can be obtained using the RSOBI algorithm from the observed data of structures in time domain. Frequency and damping are estimated from the modal responses by traditional single degree of freedom methods. The simulation results show that the RSOBI algorithm has good performance in modal identification of structures.

Yuan yanghui tunnel as the engineering background of this study, the layout of USTB micro-seismic monitoring system is introduced. The positioning accuracy of the system has been adjusted according to artificial fixed blasting tests. Combining with the relationship between activity rate and time of micro-seismic events, different types of micro-seismic events have been distinguished, which explain the emergence of those events. The results show that the design and implementation of micro-seismic monitoring system can meet the global monitoring of rock mass deformation during the construction of the tunnel. Imported with location condition, combining micro-seismic monitoring with conventional monitoring technique can find the concentration zone of rock failure more exactly and orientate the position of potential instable face, which has considerable engineering guiding significance and economic benefit.