近场震源的高精度定位在工程建设与军事应用等方面意义重大且应用广泛,如炮弹落点定位或车辆追踪等.定位过程面临速度结构未知、高分辨率要求等问题,传统的震源定位方法有一定的局限性.本文将超声波检测中的时差分布图(Delta T Mapping,简称DTM)方法首次成功引入近场震源定位问题中.DTM定位法首先建立一个测区的到时差模型,然后基于此模型对新的震源进行定位.有两种建立模型的方法,(1)网格搜索法:对原有模型进行线性插值,得到更高分辨率的到时差分布模型;(2)统计定位法:利用高斯过程回归建立到时差数据与位置坐标之问的映射关系.本文在北京某郊区进行了炸点定位实验,在140 m× 90 m的测试区域内,定位误差为0.5～5.1 m结果表明,DTM方法是一种可靠、高精度、具有近实时性的近场震源定位方法.进一步利用接收点、源点互换,在获得高精度DTM同时,可大幅降低标定与数据分析成本.结合震源扫描法具有解决多目标定位问题的潜力.%Near-field seismic localization has important significance and wide applications in the real world,for instance,locating explosions or tracking traffic movements.Those traditional methods designed for far-field scenarios are limited here due to the unknown velocity structures and high accuracy demands.This paper,for the first time,applied the Delta T Mapping (DTM) technique from acoustic emission detection in near-field seismic localization.DTM first needs to construct a mapping of the difference of first arrivals on which the following locating is based.There are two approaches for establishing such model:(1) grid search method:using linear scattered point interpolation to obtain new DTM of higher resolution;(2) statistical locating method:using Gaussian Process Regression to build the mapping from Delta T to positions.The experiment was conducted in an area of 140 m × 90 m in a suburb in Beijing.The locating error was 0.5～5.1 m.The results showed that DTM is reliable,highly accurate and suitable for real-time use for near-field seismic localization.The cost of learning DTM and analyzing data could be further decreased while obtaining high accurate DTM by switching the sources and receivers.Furthermore,combining source-scan algorithm has certain potential to locate multi-sources.
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