跨孔超高密度电阻率法在球状风化花岗岩体探测中的应用
APPLICATION OF CROSS-HOLE ULTRA-DENSITY RESISTIVITY METHOD TO DETECTION OF SPHERICALLY WEATHERED GRANITE
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摘要: 花岗岩发育地区球状风化体(俗称孤石)的分布直接影响城市轨道交通工程的建设,准确探明花岗岩孤石的空间分布具有重要的现实意义。为了探明地铁建设过程中花岗岩孤石的分布情况,结合深圳地铁11号线某区间孤石探测试验,采用跨孔超高密度电阻率法研究两孔间孤石分布情况,试验数据能较好反映出土层间电阻异常。试验分析结果与现场验证钻孔的对比表明:该物探方法能在一定程度上揭示孤石的空间分布,为进一步针对地铁工程勘察提供了指导,丰富了花岗岩孤石的探测手段。Abstract: Distribution of the spherically weathered granite(commonly known as the boulder)has a direct impact on the construction of urban rail transit project. It has important practical significance to detect spatial distribution of boulder accurately. This paper explores the distribution of granite boulders during subway construction. It combines with an instance of geophysical testing for detecting the distribution of granite boulders at the site of Shenzhen Metro Line 11.The distribution of granite boulders between two wells was studied with cross-hole ultra-density resistivity imaging. Test results can distinguish the difference of resistance between boulder and surrounding soil. Test results and field-proven drilling show that the geophysical method is satisfactory in detecting the spatial distribution of granite boulders in a certain degree, which provides guidance for further targeted investigation of the subway project and rich detection means of granite boulders.