谱激电法判别岩溶管道充填物性质实验研究

Experimental Study on Judging the Nature of Karst Pipe Fillings by SIP Method

频谱激电法中的谱激电参数含有岩层内部孔隙结构的信息,不同的充填物往往具有不同的频谱特性,本文利用频谱特性差异来研究岩溶管道充填物的性质。通过大量的物理模型实验,研究了溶洞充水、充土、充泥、充盐水、无洞和空洞时的谱激电响应,得出:模拟溶洞充填物性质不同时相位谱有或大或小的差异;充水、充泥时和空洞、无洞时相比电阻率振幅谱、相位谱和虚电阻率谱有明显差异;充水、充盐水、充泥和充土时的时间常数比无洞和空洞时明显要大;充泥时的时间常数τ最大,充土其次,充自来水再次,充盐水最小。仔细分析原始数据图件和反演获得的频谱激电参数的大小变化及其分布情况,同时结合其他资料,定性地对岩溶充填物属性的判断是可行的。

Spectral induced polarization（SIP）parameters contain the information of internal pore structure in rocks,and different fillings lead to different frequency spectrum characteristic,which is used by this paper to judge the property of fillings.Enormous experiments have been conducted to study SIP response characteristics when different fillings are tested such as soil,water,brine,mud.Induced polarization parameters of SIP method（polarizability,relaxation time constant,frequency correlation coefficient,etc）are calculated and the following conclusion is obtained：a）Compared with empty caves,caves filling with wa-ter,mud has significantly difference in amplitude spectrums,phase spectrums and imaginary resistivity spectrums,the first peak of phase in phase spectrums arrivals in a lower frequency;b）With different properties of fillings in analog cave,the imaginary resistivity spectrum has clear discrepancy;c）Compared with empty caves,caves filling with water,brine,mud have much larger relaxation time constant;d）When filling is with different fillings,the relaxation time constant arranged in the following order,from higher to lower is water,mud,brine.Two field experiments conducted in Gui Zhou with different Karst pipeline fillings are performed V8multi-function electromagnetic system.Based on the comparison with two experiment results,the following characteristics are given in the water-rich region：a）Compared with background value,the value of relaxation time constant（τ）increased obviously（typically two orders of magnitude,size：n^10＊n）;the value of polarizability（m）is to be 0.05around;and the value of frequency correlation coefficient（c）is small（0.01to 0.04）.b）.When Karst pipeline filling is water,the abnormal value ofτwould not be isolated but associated with other points,because of good permeability of water.The value of c is small,and the value of m is 0.05around.These characteristics are important and helpful in finding water in in Karst region of Guizhou,China.Synthesizing geological information,the spectral induced polarization method is feasible in distinguishing properties of fillings in Karst pipeline.