Research On S Velocity Structure Of Shallow Stratum Inferred Array Records Of Microtremors

In recent years, as a new geological prospecting method, inversion of the S-wave velocity structure of shallow stratum using array records of microtremors is one research focus and current trends of promotion. Some scientists and engineers in Europe , United States, Japan and China effort to get S-wave velocity structures of sites using this method.The specific content of this article are follows:(1) To introduce comprehensively the theory of stationary stochastic waves. The result of derivation and perspective shows the characteristics of stochastic waves are stationary in time and space.(2) The methodologies to study S-wave velocity structure of shallow stratum using array records of microtremors was discussed, they are extraction phase velocity using long-period and short-period of microtremors, beamforming which removed accidental vibration; inversion of S-wave velocity structure from dispersion curves for different array; the stripping inversion, joint inversion of microtremor dispersion curve and horizontal-to-vertical (H/V)spectrum to get S-velocity of bedrock..;(3) Depending on the situation of site, we propose construction program of this research, and design nested triangle and concentric circles array, and apply stripping method to inverse S-wave velocity structure in different aperture of array.(4)We carry on a observation of microtremor at Jurong, Jiangsu Province, provide example of that the phase velocities of surface wave were determined by spatial autocorrelation(SPAC) from array records of microtremors using the method of designed construction program, get the S-wave velocity structure of shallow stratum using stripping. The good result after comparison with the actual drilling data present that the S-wave inversion from microtremors is a practical method in engineering..