瞬变电磁法及高密度电阻率法综合物探在长大隧道岩土工程勘察中的应用

Application of TEM and High-Density Resistivity Methods in the Geotechnical Investigation of Large Size and Long Tunnels

隧道跨越煤系地层分布区,准确探测隧道围岩影响范围内是否存在煤层采空区及其规模、位置是勘察的重大技术问题,直接影响隧道的投资规模、施工工期及选线。通过对满足工程区地球物理勘探前提的技术方法进行试验研究,最终采用瞬变电磁法及高密度电阻率综合物探探测,成功地在复杂地形地质条件下对隧道岩性构造进行了解译,特别是对隧址围岩影响范围内不存在采空区的探测论断,与开挖实际情况完全吻合,说明了物探技术在城市长大隧道探测中发挥的重要作用。

When a proposed tunnel is over a coal mining area,the accurate locating the underground mining voids within the surrounding rock mass of the tunnels is one of the critical issues in the geotechnical investigation.The coal mining voids might affect the capital investment,construction duration and even the re-alignment of a proposed tunnel.This paper briefly introduces all possible geophysical methods that could potentially be applied to the detection of void location and size.Then,a case history of interpreting the surrounding rock mass of a proposed tunnel by using the combination of Transient Electromagnetic Method（TEM） and High Density Resistivity Method.The results indicate that there are no mining voids within the tunnel influence zone.This conclusion was consistent with the findings after the tunnel excavation.This case history presents an application of geophysical methods in the geotechnical investigation of the large size and long tunnels in the urban area.