Research purposes:In November 17,2013,Engineering Management Center of China Railway Corporation issued "the notice on carrying out karst exploration work of railway tunnel and subgrade under construction",which required carrying out the geophysical exploration in constructing railway tunnel and subgrade in karst area.In the past 3 years,we have carried out a large number of geophysical exploration work in the construction of Guiyang-Guangzhou railway line and other lines under construction,and made some effect,but there are also many problems,for example the geophysical results cannot meet the design requirement of karst disease treatment.This paper studies the existing problems,which will provide basis for correcdy positioning the geophysical work and improving detection scheme of karst tunnel and subgrade in the future.Research conclusions:(1) Because the site is difficult to have the prerequisite of geophysical exploration,the limitations of the selected geophysical methods and using geophysical exploration can not directly detect underground fissure water and other reasons,geophysical exploration of the railway tunnel and subgrade base under construction in karst area can only solve part of karst detection problems of the tunnel bottom and subgrade base.(2) The geophysical exploration belongs to the indirect exploration means,and in order to exclude multiple solutions of the geophysical exploration results,we should adopt comprehensive exploration methods in karst area,namely 30％ geophysical anomaly excavation revealed or confirmatory drilling.(3) When validation data show that the karst is very developing,we should choose the cross-hole electromagnetic wave (seismic wave) tomography method to fine detection of karst,which provides reliable basic information for the subsequent design of tunnel and subgrade karst.(4) The research conclusion is applied on karst exploration in the railway tunnel and subgrade.%研究目的:2013年11月17日中国铁路总公司工管中心下发《关于开展在建铁路隧道、路基基底岩溶探测工作的通知》,要求对在建铁路的隧道和路基基底岩溶开展物探.近3年来在贵广等线的在建铁路上通过开展大量的物探工作,在取得一些效果的同时也发现诸多问题,如物探成果资料难以满足岩溶病害整治设计的需要等,因此本文研究探讨所存在的问题,从而为物探工作正确定位和改进今后隧道和路基的岩溶探测方案提供依据.研究结论:(1)对于在建铁路隧道和路基基底岩溶物探,由于现场难以具备地球物理勘探前提条件、所选物探方法的局限性以及采用物探不能直接探测地下裂隙水等原因,只能部分解决隧底和路基基底的岩溶探测问题;(2)物探属于间接性勘探手段,并且为排除物探结果的多解性,应采用综合岩溶勘探手段,即选择30％的物探异常进行开挖揭示或验证性钻探;(3)当验证钻探资料表明岩溶特别发育时,应选择跨孔电磁波(地震波)层析成像法对岩溶进行比较精细的探测,为后续隧道和路基岩溶整治设计提供可靠的基础资料;(4)本研究成果可用于铁路隧道和路基的岩溶探测领域.
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