跨孔超高密度电法CT在岩溶勘察中的应用
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摘要
常用电阻率法的空间效应和视电阻率拟断面记录点对应深度方面的不确定性,以及对场地的要求随深度增加而增加,而分辨率却下降等等制约因素,使其工程应用受到限制,尤其是在解决孔与孔之间的电阻率情况更是一筹莫展。本文所推荐的跨孔超高密度电法是根据电场的基本理论和地震CT勘探的原理,提出了利用在平行钻孔中布设电极、然后利用一孔的两个电极供电、其余的电极同时测量的一种电法测量方式;它不仅比较准确地解决了孔与孔之间的电阻率问题,对场地无太大要求且施工较方便;本文通过对清远伦洲大桥18#、19#桥墩内岩溶发育情况进行电阻率的测试,充分证明该技术在解决此类问题的有效性和准确性。
There are many shortcomings about common resistivity methods,such as steric effect and uncertainty in the corresponding depth of measuring points for apparent resistivity pseudo sections.Moreover,the prospecting resolution reduces with deeper investigation depth,so their applications come under limitation,especially on resistivity measurement among parallel holes.According to the fundamental principles of the electric field and the theory of seismic CT technology,the prospecting technology of cross-hole direct-current resistivity method CT has been brought forward,which is called CT method of cross-hole super-high density resistivity.It sets many electrodes in two parallel boreholes,and then uses one current electrode that is in one borehole to perform power supply,and all electrodes in another borehole conduct synchronous prospecting.The method not only solves the problem of resistivity measurement among parallel holes,but also requires smaller work area.In the paper,the method has been adopted to investigate the karst development for bridge pier of Lunzhou Bridge in Qingyuan.The results also proved the feasibility and accuracy of the technology.
There are many shortcomings about common resistivity methods,such as steric effect and uncertainty in the corresponding depth of measuring points for apparent resistivity pseudo sections.Moreover,the prospecting resolution reduces with deeper investigation depth,so their applications come under limitation,especially on resistivity measurement among parallel holes.According to the fundamental principles of the electric field and the theory of seismic CT technology,the prospecting technology of cross-hole direct-current resistivity method CT has been brought forward,which is called CT method of cross-hole super-high density resistivity.It sets many electrodes in two parallel boreholes,and then uses one current electrode that is in one borehole to perform power supply,and all electrodes in another borehole conduct synchronous prospecting.The method not only solves the problem of resistivity measurement among parallel holes,but also requires smaller work area.In the paper,the method has been adopted to investigate the karst development for bridge pier of Lunzhou Bridge in Qingyuan.The results also proved the feasibility and accuracy of the technology.
引文
[1]傅良魁.应用地球物理教程电法放射性地热[M].北京:地质出版社,1991.
[2]王桦,纪洪广.跨孔直流电阻率法CT勘探技术研究[J].地球物理学进展,2010,25(5):1833～1840.
[3]林达明,尚彦军,王松,等.等位线追踪法在井间电阻率成像中的应用初探[J].地球物理学进展,2010,25(5):1841～1847.
[4]底青云,王妙月.电流线追踪电位电阻率层析成像方法初探[J].地球物理学进展,1997,12(4):27～35.
[5]朱涛,冯锐,徐中信.垂直线电流源的三维电阻率成像[J].CT理论与应用研究,2004,13(2):1～5.
[6]邱庆程,李伟和.跨孔地震CT层析成像在岩溶勘察中的应用[J].物探与化探,2001,25(3):236～240.
[2]王桦,纪洪广.跨孔直流电阻率法CT勘探技术研究[J].地球物理学进展,2010,25(5):1833～1840.
[3]林达明,尚彦军,王松,等.等位线追踪法在井间电阻率成像中的应用初探[J].地球物理学进展,2010,25(5):1841～1847.
[4]底青云,王妙月.电流线追踪电位电阻率层析成像方法初探[J].地球物理学进展,1997,12(4):27～35.
[5]朱涛,冯锐,徐中信.垂直线电流源的三维电阻率成像[J].CT理论与应用研究,2004,13(2):1～5.
[6]邱庆程,李伟和.跨孔地震CT层析成像在岩溶勘察中的应用[J].物探与化探,2001,25(3):236～240.
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