地震CT与折射波法在第四系覆盖层厚度勘察中的应用  

Application of seismic CT and refraction wave method to detect the thickness of Quaternary overburden

作　　者：李小伟 纪银刚 邱松 孙涛 Li Xiaowei;Ji Yingang;Qiu Song;Sun Tao(Sino Shaanxi Nuclear Industry Group Geological Survey Co. , Ltd. , Xi＇an 710100, China)

机构地区：[1]中陕核工业集团地质调查院有限公司,西安710100

出　　处：《工程勘察》2018年第5期73-78,共6页Geotechnical Investigation & Surveying

摘　　要：浅层地震折射波法野外施工简单,成本低,效率高,初至波易于拾取,资料解释较为容易,是解决覆盖层厚度探测等类似地质勘查问题可靠有效的方法,以其能够确定折射界面的速度而广泛用于工程地质勘察。本文通过对关中盆地某采石场进行折射波法勘探,利用常规折射波法计算结果作为初始模型,采用射线层析成像方法,获得丰富的浅层地层的变化信息。通过CT速度反演,由速度值的不同变化可以划分出区内黄土地层的分层及厚度变化,再通过合理布置小折射点,与CT速度成像结果和钻孔资料相结合,查明了地下100m以内第四系覆盖层厚度,得出的资料解释与实际情况相符,可信度较高,为后续采石施工提供了可靠的物探勘查信息。Shallow refraction seismic is widely used in engineering geology investigation for easy to operate,efficient and low cost. The preliminary wave is easy to collect and data interpretation is relatively simple. It is a reliable and effective method to measure the thickness of the overburden layers and measure the velocity of the refraction surface. A shallow seismic refraction for a quarry exploration in Guanzhong Basin was performed. Plentiful shallow strata information is obtained with the calculated result of the conventional refraction method as the initial model,and the ray tomography method. Through CT velocity inversion,the distribution and thickness of loess layer can be distinguished from the speed changes. The thickness of the Quaternary layer up to 100 meters underground could be measured through reasonable arrangement of the refraction points, combined with the CT velocity imaging results and drilling information. The results consist with the actual finding which could provide reliable geophysical prospecting information for the subsequent quarrying construction.

关 键 词：浅层地震折射 CT速度反演 小折射 覆盖层厚度 

分 类 号：P631[天文地球—地质矿产勘探]