场地钻井台阵观测中斜入射P波和SV波的近似剥离方法

通常认为，成层介质中P波和SV波互相转化、耦合交织而不可以解耦得到单独的P和SV波入射场.针对钻井台阵的两处三分量加速度记录，根据反向方位角将两水平分量分解为径向水平分量和横向水平分量，假设横向水平分量由SH波系组成，竖向分量和径向分水平量由P-SV波系组成.本文提出在频域内解联立方程组的方法，并结合遗传算法-单纯形法混合优化策略，对P-SV耦合场包括SH波系进行了联合剥离反演，最终得到了基岩斜入射P、SV和SH波.最后，通过场地条件差别较大的另一附近钻井台站的联合反演结果，初步验证了其合理性.该项研究对于断层特征和震相特性研究、近地表“软”基岩或土层介质参数研究、场地效应的细致评价具有一定意义.

Approximate decomposition method of oblique incidence P, SV wave fields in observation of site borehole array

Usually we believe that the P wave and the SV wave transform and couple mutually in the stratified medium, independent incidence field of P and SV wave may not be obtained. Firstly, radial horizontal component and transverse horizontal component are derived from tri-channel seismic data at the surface and the bedrock in borehole array by back-azimuth decomposition method, and the histories of radial and vertical components are divided into two parts by S_8 wave arrived time. Moreover, it is supposed that transverse horizontal components are made up of SH wave, while vertical component and radial horizontal component are constituted by P-SV wave system. Secondly, the methods of solving simultaneous equations in frequency domain are brought forward, this method combined a global-local optimization algorithm, which is genetic algorithm (GA) - Simplex Method, P, SV wave fields including SH wave are gained. At last, the preliminary rationality of this method is proved by the result coherence of another nearby borehole array at quite different site condition. This work has certain significance for study on fault characteristic, seismic phase, parameters of "soft" outcrop bedrock or soil-layer medium and detailed evaluation of site effect.