识别隐伏岩溶的魏格纳-威尔分布改进方法  

Hidden karst identification with modified Wigner-Ville distribution method

作　　者：魏栋华[1] 许多[2] 曹云勇[1] WEI Dong-hua;XU Duo;CAO Yun-yong(China Railway Eryuan Engineering Group Company Limited,Chengdu 610031,China;The Exploration and Production Institute of South-West Branch,Sinopec,Chengdu 610041,China)

机构地区：[1]中铁二院工程集团有限责任公司,成都610031 [2]中国石化西南油气分公司勘探开发研究院,成都610041

出　　处：《地球物理学进展》2020年第6期2397-2401,共5页Progress in Geophysics

摘　　要：碳酸盐岩分布广泛,隐伏岩溶洞穴对各类建筑工程构成威胁,工程勘探岩溶识别方法中的主要物探方法之一是地震映像数据时频分析技术.然而,由于地震时频分析的精度原因该技术在岩溶识别中的效果有限.为此,本文提出一种高精度的岩溶识别方法.首先,对地震映像数据进行预处理得到能量均衡、无明显噪声的地震映像剖面;然后,利用魏格纳-威尔分布改进算法,对地震数据道进行时频分解获得各地震道高精度的时频谱;通过求取时频谱的一阶矩来获得各时间采样点的高精度瞬时频率;利用高精度瞬时频率的低频异常直接进行岩溶识别.选取某高速铁路岩溶隧道隧底段进行岩溶识别测试,获得了与实钻吻合的岩溶分布结果,表明该方法是工程勘探中识别岩溶的一种有效方法.Carbonate rocks are widely distributed in the world, and hidden karst caves are harmful to all kinds of construction works. The time-frequency analysis of seismic image data is one of geophysical methods for karst identification in engineering survey. However, the karst identification effect cannot satisfy the practical requirements due to the problem of inaccuracy of time-frequency analysis. Therefore, this paper proposes a high-precision karst identification method:(1) preprocessing raw data to obtain a seismic image profile with balanced energy and no obvious noise;(2) producing an accurate time-frequency spectrum for each trace, using the modified WVD algorithm;(3) estimating the high-precision instantaneous frequency at each time sampling by calculating the first moment of the spectrum;(4) identifying karst by low-frequency anomalies of the instantaneous frequency. We carry out karst identification at the bottom of a segment of high-speed railway crossing the karst channel. The distribution of subsurface karsts is highly coincident with the actual drill. The result demonstrates that this method is an effective method for karst identification in the engineering survey.

关 键 词：岩溶识别 改进魏格纳-威尔分布 瞬时频率 一阶矩 地震时频谱 

分 类 号：P631[天文地球—地质矿产勘探]