微动测深法探测厚覆盖层结构——以北京城市副中心为例  

Exploring thick overburden structure by microtremor survey: a case study in the subsidiary administrative center

作　　者：李巧灵 雷晓东[1] 李晨[1] 冉伟彦[2] 杨全合 何祎[1] LI Qiao-ling;LEI Xiao-dong;LI Chen;RAN Wei-yan;YANG Quan-he;HE Yi(Beijing Institute of Geo-exploration Technology,Beijing 100120,China;Beijing Institute of Geological Survey,Beijing 100195,China)

机构地区：[1]北京市地质勘察技术院,北京100120 [2]北京市地质矿产勘查开发局,北京100195

出　　处：《地球物理学进展》2019年第4期1635-1643,共9页Progress in Geophysics

基　　金：通州城市副中心地区重大地质问题调查与评价项目(PXM2016_158203_000008);通州某建设新区深部地热资源勘查与示范项目(PXM2016_158307_000013);北京市平原区1:5万工程地质调查(12120114033901)联合资助

摘　　要：微动测深法通过提取表征介质物性差异的频散曲线,反演S波速度结构,为厚覆盖层结构划分提供地球物理依据.本文以北京城市副中心为例,在通州北部布设45个微动测深点,采用扩展空间自相关法(ESPAC)从预处理后的微动信号垂向分量中提取Rayleigh波相速度频散曲线,基于遗传搜索算法模型反演,获得各测点S波速度结构特征.沿北西向近似垂直地质构造走向切剖面AA’,利用剖面附近各测点反演结果,勾画主要地层结构.研究表明,微动测深可以有效探测新生界覆盖层厚度和结构,探明研究区新生界覆盖层厚度约为200~700 m,东南部甘棠凹陷沉积中心新生界覆盖层厚度约为700 m,凹陷发育受控于燕郊断裂和张家湾断裂.新生界覆盖层厚度和结构变化特征与区内搜集到的钻孔资料吻合.研究成果为北京副中心地区地质灾害防控和地热资源利用提供了科学依据.In order to study the thickness and structural characteristics of overburden layer in the northern area of Beijing subsidiary administrative center,microtremor survey were carried out and analyzed in this area.Based on 45 measurement data,phase velocity dispersion curve of Rayleigh wave was derived from vertical components of preprocessed microtremor signal by Extended Spatial Autocorrelation(ESPAC)method,S wave velocity was obtained at measurement locations through model inversion by genetic searching algorithm,and then 3D S wave velocity model was built using Kriging interpolation method,the thickness and 3D distribution of overburden were interpreted in the study area.Vertical geological structure along the AA'section in direction NW,which is approximately perpendicular with the formation strike in the study area,are obtained using the inversion results of microtremor survey points near the section.The results are in good agreement with the measurement values acquired by other geological and geophysical techniques.Research shows that microtremor survey can effectively detect the thickness and formation of covering layer.In this study,the thickness of the overburden is about 200~700 m,while the thickness of the depositional center of Gantang depression in the southeast of the research area is about 700 m,and the depression is controlled by Yanjiao fault and Zhangjiawan fault.The results are consistent with drilling hole information collected in the study region.This research results provide scientific basis for the prevention of geological disasters and the utilization of geothermal resources for Tongzhou which is the subsidiary administrative center.

关 键 词：微动测深 扩展空间自相关 频散曲线 S波速度 城市副中心 通州 

分 类 号：P315[天文地球—地震学] P631[天文地球—固体地球物理学]