地下三维体上电测深曲线规律

以均匀半空间中等轴状三维地质体为例,利用边界积分方程法对对称四极和温纳尔2种装置的电测深进行数值计算,并与相应解析表达式的计算结果进行对比;用数值模拟方法研究了均匀半空间中板状体的对称四极、温纳尔等装置电测深拟断面图"看得见但看不穿”的规律.研究结果表明温纳尔、偶极等测深装置不仅能"看到”而且能"看穿”地下三维体,而对称四极装置及交流电法中采用平面波场的CSAMT,AMT等观测方式通常只能"看到”但不能"看穿”三维异常体;在对称四极测深装置中心剖面上,根据水平板状体的规模及埋深等因素,可分别将其视为一维层状体或均匀半空间处理,这对野外实际工作具有指导意义.

Rules of resistivity sounding curves for underground 3-D bodies

Using boundary integral equation method, the authors calculate the results of symmetric four pole sounding and Wenner array sounding for an equiaxial 3 D body in homogeneous half space, and proves that the results are correct by comparing the results with calculating results of relevant analytic equation. Based on it, the authors, using the pseudosection map of symmetric four pole sounding and Wenner array sounding in homogeneous half space, further study some rules of "can see the 3 D body but cannot penetrate it" and conclude that Wenner array sounding, double pole sounding and others can not only see the 3 D body but also penetrate it, but symmetric four pole sounding and CSAMT, AMT, and other observation manners, which use plane wave,among alternating current methods can only see the 3 D body but cannot penetrate it. Level flat underground can be treated as 1 D stratum body or homogeneous half space when we observe on center profile using symmetric four pole sounding according to the magnitude, burying depth of level flat et al . The above rules are important for our field work.