We propose a combined migration velocity analysis and imaging method based on Kirchhoff integral migration and reverse time migration,using the residual curvature analysis and layer stripping strategy to build the velocity model.This method improves the image resolution of Kirchhoff integral migration and reduces the computations of the reverse time migration.It combines the advantages of efficiency and accuracy of the two migration methods.Its application in tunnel seismic prediction shows good results.Numerical experiments show that the imaging results of reverse time migration are better than the imaging results of Kirchhoff integral migration in many aspects of tunnel prediction.Field data show that this method has efficient computations and can establish a reasonable velocity model and a high quality imaging section.Combination with geological information can make an accurate prediction of the front of the tunnel geological structure.
Multi-electrodes Resistivity Imaging Survey(MRIS)is an array method of electrical survey.In practice how to choose a reasonable array is the key to get reliable survey results.Based on four methods of MRIS such as Wenner,Schlumberger,Pole-pole and Dipole-dipole the authors established the model,by studying the result of the forward numerical simulation modeling and inverse modeling,and analyzed the differences among the different forms of detection devices.
The ultrasonic computed tomography （USCT） method is derived from the basic principles of X-ray section scanning. This method records the arriving times of ultrasonic wave between the probes and the sources to ealculate the elastic wave velocity values in the section using the arrival times. Through analyzed the distribution Of elastic wave velocity in aim area, the information of the strength and the homogeneity of the investigated zone could be got indirectly. The authors introduced the operational principle of USCT and a practical case of using this method to detect the interior defects in large scale concrete structural member. Compared with other exploration methods, this method is more efficient and accurate.
Xiaopei ZHANGJianhui QIUJianjun NIULizhi DUXuege WANG
TSD is one of the classical methods of tunnel seismic prediction based on higher accuracy multi-wave multi-component seismology.The working principle of the TSD and an application example of the TSD on tunnel prediction in Chongqing are introduced in this paper.This system has two ports for speed signal and acceleration signal,and the equipment is more portable and easy to use.According to the application results we can conclude that the TSD prediction system is accurate and it has the wide application prospect in tunnel seismic detection.
