双线高密度电阻率法分析断层产状的原理和算法

发布时间：2018-07-07 22:23

本文选题：隧道工程 + 断层产状算法　；参考：《公路交通科技》2017年12期

【摘要】：断层产状计算是工程勘探中一个重要内容,一般利用地质罗盘和皮尺测量断层露头的方法进行计算,其运用范围受到了极大限制。利用高密度电法勘探可得到沿测线走向剖面上地下构造的电阻率剖面,结合已知的地层信息可以判断断层的存在和规模,但无法准确确定其产状。文中提出采用双线电法勘探的方法分析并准确计算断层产状,包括倾向、倾角和宽度指标。该方法假设断层同时切割两条测线,且在测线间断层结构面无较大褶曲,可简化为平面。计算过程中,首先根据单线电阻率剖面判断断层的范围和边界,采用最小二乘法确定其切割面参数,然后根据断层在两个剖面上的投影反算断层的倾向、倾角,最后根据断层和电阻率剖面的空间交互关系反推断层宽度。文中详细介绍了该方法的理论基础和推导过程,并对其运用条件进行了阐述。文中对该方法在厦门市某隧道勘探中断层产状计算成果进行了归纳、统计和分析,并选择断层出露地面位置的计算结果与采用传统地质罗盘测量结果进行了对比分析。结果表明根据文中计算分析方法得出的断层产状和宽度与实际测量结果相比有一定误差,倾向相差3°~5°,倾角相差2°~6°,宽度相差11%~16%,主要是因为断层延伸过程中受地质构造作用而发生几何性状变化引起的,但是在较小的勘探区域内仍然能够较为准确地反映实际情况。
[Abstract]:The calculation of fault occurrence is an important content in engineering exploration. The method of measuring outcrop of fault by geological compass and scale is generally used, and its application scope is greatly limited. The resistivity profiles of underground structures along the strike profile can be obtained by high-density electrical prospecting. The existence and scale of faults can be judged by combining the known formation information, but the occurrence of faults can not be determined accurately. In this paper, a method of double-wire electrical exploration is proposed to analyze and accurately calculate the occurrence of faults, including the indexes of inclination, inclination and width. This method assumes that the fault cuts two measuring lines at the same time, and there is no large fold on the discontinuous layer of the measuring line, which can be simplified as a plane. In the calculation process, the range and boundary of the fault are judged according to the single line resistivity profile, the parameters of the cutting surface are determined by the least square method, and then the inclination and inclination of the fault are inversely calculated according to the projection of the fault on the two sections. Finally, the width of fault is pushed back according to the spatial interaction between fault and resistivity profile. The theoretical basis and derivation process of this method are introduced in detail, and its application conditions are described. In this paper, the calculation results of fault occurrence in a tunnel exploration in Xiamen City are summarized, analyzed, and the calculated results of fault outcrop surface location are compared with those of traditional geological compass survey. The results show that the fault occurrence and width obtained by the calculation and analysis method in this paper have some errors compared with the actual measurement results. The tendency difference is 3 掳/ 5 掳, the dip angle is 2 掳/ 6 掳, and the width is 11 掳/ 16 掳, which is mainly caused by the change of geometric character in the process of fault extension by geological structure, but it can still reflect the actual situation more accurately in the smaller exploration area.
【作者单位】：广州市中心区交通项目领导小组办公室;
【分类号】：U452.11

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