高密度电法和井间电磁波CT法在花岗岩球状风化体探测中的综合应用

The Application of the Combination of High-density Electrical Method and Electromagnetic CT to Detect Granite Spherical Weathering Body

花岗岩球状风化地段是地铁建设过程中几大难题之一。本文对高密度电法和井间电磁波CT法进行试验研究,总结归纳两种方法在探测花岗岩球状风化体中的有效性。高密度电法选择三种温纳排列装置,测量过程中存在接地条件差等因素,进行常规数据反演,与实际钻探结果误差较大。因此,测量中改进电极与地面耦合条件以及加大供电电压,采用比值法数据反演,根据高电阻率分布特征推断球状风化体的分布情况,其结果与钻探结果较为吻合,效果较好。同时,应用电磁波CT法,也取得了良好的效果。

Granite spherical weathering body area is one of the most difficult problems in the process of subway construction.The paper sums up the effectiveness of the two methods in looking for granite spherical weathering body by the experimental investigation on Highdensity Electrical Method and Electromagnetic CT techniques.Using three High-density Electrical Method Winner arrangements to carry out the inversion of conventional data,the condition of the sense contacting to the ground surface was poor.So it had substantial errors in the back analysis process.For this reason,the electrode with ground coupling con-ditions is improved in the measurement.The power supply voltage was also increased to improve the current penetration.Ratio method is adopted to improve the data inversion.According to the characteristic of high resistivity distribution to infer the spatial distribution of the granite spherical weathering body,the results coincide with the drilling results relatively.The results were successful.In addition,Electromagnetic CT techniques also achieved good results.