跨孔地震CT在地铁岩溶勘察中的应用

Application of Cross Hole Seismic CT in Karst Survey of Metro

无锡地铁4号线3号标段的四院站-河埒口站在初勘阶段有岩溶揭露,且该地段地处市区,交通流量较大,建筑物密集,地下管线多,地质条件较为复杂,为后期的工程建设埋下了安全隐患。为查明该区段岩溶发育情况,结合前期的钻孔勘探,采用跨孔地震CT技术对岩溶地段进行现场数据采集,利用Matlab程序对数据进行分析解译,并据此画出剖面波速等值线云图,基于波速层析成像原理,通过分析弹性波在空间结构的传播速度来推断地质异常体的空间分布情况。结果表明整个场地岩溶比较发育,并分布有多处岩层破碎带,发育溶洞、裂隙的剖面共20余条。结合前期钻探资料及地质分析可知,跨孔地震CT在地铁岩溶地质勘察中可靠性较高,能弥补传统勘察资料的不足,实现对孔间岩溶发育的高精度预报。

There is the karst exposure in the primary survey stage of Siyuan Station-Hekiekou Station in the Bid No.3 of Wuxi Metro Line 4, and this section is located in the city area with the larger traffic flow, dense buildings, many underground pipelines and complex geological conditions, which has laid a hidden danger for the later engineering construction. In order to find out the karst development of this section and combined with the previous drilling exploration, the cross hole seismic CT technology is used to carry out the site data collection of the karst section, the Matlab program is used to analyze the data, and accordingly the profile wave velocity contour map is drawn. Based on the wave velocity tomography principle, the spatial distribution situation of geological anomalous body is deduced by the analysis on the propagation velocity of elastic wave in the spatial structure. The result shows that the karst in the whole site is relatively developed, and there are many rock stratum broken zones, and more than 20 developed karst caves and fissures. Combined with the prophase drilling data and geological analysis, the cross-hole seismic CT is higher reliable in the karst geological survey of metro, can makes up the shortage of the traditional data and realize the high precision prediction of karst development among the caves.