高频大地电磁法在宜万铁路隧道岩溶的应用
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摘要
宜万铁路沿线二叠和三叠及寒武的碳酸盐岩广泛分布,地表岩溶类型齐全、形态各异,地下岩溶洞穴、暗河特别发育,并由断层连通地面、地下水系,其地形和地质的复杂程度堪称铁路建筑之最。为此,采用了观测频率为0.001~100 kHz的天然场源的高频大地电磁测深法,对宜万铁路深埋岩溶隧道进行了岩溶勘察。根据勘察的视电阻率异常区和反演结果,圈定了隐伏的深大岩溶,并设计了钻探井位。根据目前已开挖的资料统计,所揭露的较大型溶洞暗河,都位于大地电磁测深的低阻异常范围内。本文通过对三个隧道的高频大地电磁的勘探结果,说明高频大地电磁法是一种勘探深度大、勘探效果好的铁路岩溶勘探方法,其结果对施工过程中地质灾害的预防和处理起着很大的指导作用。
The carbonate rocks of Permian,Triassic and Cambrian are widely distributed along Yiwan Railroad.Because the erosional processes associated with cavern and karst development usually take place due to the movement of water along the faults,the construction conditions of Yiwan railroad is one of the most difficult due to the complex limestone caves.In order to avoid the disaster in the tunnels along the Yiwan railroad we adopted the high frequency magnetotelluric method(HMT) at frequencies range from 0.001 to 100 kHz by using the natural electromagnetic sources.According to apparent resistivity abnormals and inversion results of HMT the position and size of karst caves were deployed.It showed that all the large-scale kast caves and underground rivers were in the area which represented low resistivity abnormal.In this paper three cases of the application of HMT to tunnel exploration is discussed and it shows that HMT can be used in the deep large-scale karst exploration and that it is applicable to the prevention and management of geological disaster in the engineering process.
The carbonate rocks of Permian,Triassic and Cambrian are widely distributed along Yiwan Railroad.Because the erosional processes associated with cavern and karst development usually take place due to the movement of water along the faults,the construction conditions of Yiwan railroad is one of the most difficult due to the complex limestone caves.In order to avoid the disaster in the tunnels along the Yiwan railroad we adopted the high frequency magnetotelluric method(HMT) at frequencies range from 0.001 to 100 kHz by using the natural electromagnetic sources.According to apparent resistivity abnormals and inversion results of HMT the position and size of karst caves were deployed.It showed that all the large-scale kast caves and underground rivers were in the area which represented low resistivity abnormal.In this paper three cases of the application of HMT to tunnel exploration is discussed and it shows that HMT can be used in the deep large-scale karst exploration and that it is applicable to the prevention and management of geological disaster in the engineering process.
引文
[1]曹哲明.音频大地电磁法在宜万铁路隧道勘察中的应用效果[J].铁道勘察,2004,(1):53—55.
[2]王烨,曹哲明,汤井田,等.铁路隧道工程勘察中高频大地电磁测深应用效果研究[J].工程地质学报,2005,13(3):424—428.
[3]傅良魁.应用地球物理学教程电法勘探[M].北京:地质出版社,1990.
[4]石应骏,刘国栋,吴广耀,等.大地电磁测深法教程[M].北京:地震出版社,1985.
[2]王烨,曹哲明,汤井田,等.铁路隧道工程勘察中高频大地电磁测深应用效果研究[J].工程地质学报,2005,13(3):424—428.
[3]傅良魁.应用地球物理学教程电法勘探[M].北京:地质出版社,1990.
[4]石应骏,刘国栋,吴广耀,等.大地电磁测深法教程[M].北京:地震出版社,1985.
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