跨孔超高密度电阻率法在花岗岩球状风化体勘探中的试验研究

Experimental study on the cross-hole ultra-density resistivity method used in the exploration for the spheric lightly-weathered granite

跨孔超高密度电阻率法是一种全新的电法勘探理念,在两钻孔中一次布极,采集任意组合电极间的电位信息,1h内能采集数万条数据,在城市中采用跨孔观测能避开近地表干扰,提高数据信噪比,数据预处理后利用2.5维反演技术计算断面真电阻率数值。本文就一揭露的孤石进行跨孔超高密度电阻率试验,试验结果表明该法对孤石发育位置勘探结果理想,能满足地质超前预报需要,勘探精度随孔深和孔间距的比例系数增大而提高,结合试验过程总结该方法应用中应注意事项和发展方向。

The method with cross-hole ultra-density resistivity is a new concept of resistivity prospecting. It distributes electrodes in two boreholes at a time, collecting the potential information of any electrode combinations, and can collect about sixty thousand data during one hour. It could avoid the near-surface disturbance and improve the data SNR when adopting cross-hole observation method in a city. After the data preprocess, it could be inversed into the true resistivity values of the cross-section by using 2.5D inverse technology. The tests with cross-hole ultra-density resistivity for an exposure isolated stone are carried out. The test resu｜ts indicate that this method is ideal for exploring the isolated stones, which could meet the need of geological forecast. The exploration accuracy would be improved with the increase of the ratio between the depth of the boreholes and the distance between the boreholes. Based on the tests, the matters needing attention and the development direction in the application of the method are summarized.