微动探测方法研究进展与展望

Review and prospect prediction for microtremor survey method

微动探测方法是在背景噪声成像理论的基础上发展起来的一种新型地球物理探测手段,其根据获取野外数据的观测台站方式分为微动阵列方法和微动单台方法.本文综述了前人对微动探测方法的研究进展,并对目前该方法存在的问题及研究的发展趋势进行了展望.微动阵列方法采用频率波数法或空间自相关法从微动信号中提取频散曲线,进而反演获得地下横波速度结构.微动单台方法即H/V谱比法以三分量台站为观测基础,对水平分量信号与垂直分量信号进行傅里叶谱比,以此估算沉积层厚度、获得共振频率以及场地放大因子等.目前微动探测发展还有诸多问题需要进行深入研究,例如瑞雷波与勒夫波浅层探测理论方法、同时考虑基阶和高阶面波的影响进行多阶面波反演方法研究以及H/V谱比曲线与频散曲线联合反演方法研究等,从而提高微动探测方法浅层探测精度以满足城市地下空间精细探测的需求,加深探测深度为透明地壳、地下第三空间的精细探测提供一种新型地球物理手段.

Microtremor survey method is one kind of new geophysical methods based on the theory of ambient noise. It includes microtremor array method and microtremor single station method, which are distinguished by the means of collecting the field data. In this paper, it reviews the progress of the microtremor survey method and proposes the development trend. Microtremor array method adopts the F-K method or SPAC method to extract the dispersion curve from microtremor signal and obtain the S-wave structure of the underground by inversion. Microtremor single station method(H/V spectral ratio method) based on the observation of three component stations. It is the signal fourier ratio of the horizontal to the vertical, which help to estimate the thickness of sediments, obtain the resonance frequency and field amplification factor. However, there are many problems for the development of microtremor survey method which need to be further researched, such as the theory of Rayleigh and Love wave to probe the shallow structure, the muti-mode surface wave inversion method allowing for the fundamental and higher mode surface wave, the joint inversion of H/V spectral ratio curve and dispersion curve. As a result, it will satisfy the requirement of the fine exploration of urban underground space by improving the shallow detection accuracy of microtremor survey method. At the same time, it will play as an important alternative new geophysical method for the plan of transparent crust and the fine survey of the third space of the underground.