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浅议高密度电阻率法在地震地质探测中的应用

2014-08-22宫传梅

中华建设科技 2014年7期
关键词:特征测量

【摘 要】随着现代科技的高速发展,物探方法在工程地质领域得到广泛应用,高密度电法在解决相应工程地质问题中发挥着越来越大的作用,高密度电法是电测深和电剖面两种方法的组合,在装置和排列上一次可以完成纵横二维的勘探过程,既能揭示地下某一深度水平岩性的变化又能提供岩性纵向的变化情况。该方法在地震地质领域的应用虽然有着一定的优势,由于在对勘测资料的解释方面,主要是根据地质体的电性变化特征为依据,所以我们必须对探测区探测对象进行调查分析,掌握隐伏断层的地质表现形式及电性特征;在工作时尽量避免各种影响因素,才能使探测结果趋于真实合理。本文以温纳装置为例,介绍高密度电法在地震地质勘探中的应用。

【关键词】高密度电阻率法;探测;视电阻率;等值线;断层;地质表现形式;电性特征

【Abstract】With the rapid development of modern technology, the field of geophysical methods in geological engineering are widely used, high density electrical method plays an increasingly important role in solving the corresponding engineering geological problems, the high-density electrical method is electrical sounding and electrical profiling two combination of methods, and on the device and can be arranged in a two-dimensional aspect to complete the exploration process, both to reveal the changes in the level of underground rock of a certain depth and can provide longitudinal changes in lithology. The method used in the field of earthquake geology, although there is a certain advantage, since the interpretation of the survey data, mainly based on changes in electrical characteristics based on geological body, so we must be investigated to detect object detection zone analysis, master concealed geological characteristics and electrical manifestations fault; while working to avoid a variety of factors in order to make more reasonable real detection results. In this paper, Wenner device as an example, the application of high-density electrical method in seismic and geologic exploration.

【Key words】High density resistivity method;Detection;Apparent resistivity;Contour; fault;Geological manifestations;Electrical characteristics

1. 高密度电法探测原理

(1)高密度电法的物理前提是地下介质的导电性差异。它通过A﹑B电极向地下供电流I,然后在M﹑N极间测量电位差ΔV,从而求得该记录点的视电阻率值ρs=KΔV/I,根据实测的视电阻率剖面进行计算、处理、分析,便可获得地层中电阻率的分布情况,从而可以划分地层、圈闭异常。对于固定断面扫描测量,适用方法是α-排列(温纳装置),示意图如图1。

(2)测试前先将电极打入地下,再布设测线,测量时,AM=MN=NB,为一个电极间距,A、B、M、N逐点同时向右移动,得到第一条剖面线,接着AM、MN、NB增大一个电极间距,A、B、M、N逐点同时向右移动,得到另一条剖面线,这样不断测量扫描下去,得到倒梯形断面。……

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