大地电磁测深法在深埋隧洞勘察中的应用

发布时间：2018-04-05 15:32

本文选题：大地电磁法　切入点：深埋隧洞　出处：《水利水电技术》2017年10期

【摘要】：针对大深埋超长越岭隧洞埋深大、地质与水文地质条件复杂、地面自然条件复杂严苛等问题,为了在隧洞建设中现场勘察隧洞沿线的工程地质条件和水文地质特征,选择对地形适应性较强、探测深度大、具有一定探测精度的大地电磁测深法,结合部分隧洞工程勘察实例分析了不同岩性、断裂构造特征、岩体富水性和围岩类别的电磁特性,并利用施工开挖和钻探等方法对勘察精度和可靠性进行比较。据此,总结提出了判别标准,同时也分析了该方法的适用条件和局限。结果表明:电阻率很低的软岩岩体富水性一般较强,硬岩地下水活动强烈的岩体电阻率主要受地下水性质控制,岩石强度和完整性的影响微弱。随着埋深加大地应力会逐渐提高,岩体压密导致电阻率逐渐提高,不宜采用浅部的电阻率指标判断深部岩体的富水性。软岩Ⅲ类、Ⅳ类、Ⅴ类围岩按电阻率分类标准分别为200Ω·m、50~200Ω·m、50Ω·m;硬岩优于Ⅱ类、Ⅲ类、Ⅳ类、Ⅴ类围岩按电阻率分类标准分别为5 000Ω·m、1 000~5 000Ω·m、100~1 000Ω·m、100Ω·m。大地电磁测深法是深埋地下工程较为有效的勘察手段,可供类似隧洞工程参考借鉴。
[Abstract]:In order to investigate the engineering geological conditions and hydrogeological characteristics along the tunnel in the construction of the tunnel, the geological and hydrogeological conditions are complex, and the natural conditions of the ground surface are complex and severe, in order to investigate the engineering geological conditions and the hydrogeological characteristics along the tunnel in order to investigate the engineering geological conditions and the hydrogeological characteristics along the tunnel during the tunnel construction.The magnetotelluric sounding method, which has strong adaptability to topography, great exploration depth and certain detection precision, is selected. Combined with some examples of tunnel engineering survey, the electromagnetic characteristics of different lithology, fracture structure, water-rich rock mass and surrounding rock type are analyzed.The precision and reliability of exploration are compared by excavation and drilling.On the basis of this, the discriminant criteria are summarized, and the applicable conditions and limitations of the method are also analyzed.The results show that the soft rock mass with very low resistivity is generally strong in water content, and the rock resistivity of hard rock with strong groundwater activity is mainly controlled by the nature of groundwater, and the strength and integrity of rock is weak.With the increasing of the buried depth and the increasing of the in-situ stress, the resistivity of the deep rock mass is gradually increased, and the resistivity index of the shallow part should not be used to judge the rich water content of the deep rock mass.Magnetotelluric sounding method is an effective method for deep buried underground engineering and can be used for reference in similar tunnel projects.
【作者单位】：中水北方勘测设计研究有限责任公司;宁夏水务投资集团有限公司;
【基金】：国家重点研发计划项目(2016YFC0401801)
【分类号】：TV221

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