海底盾构隧道瞬变电磁岩溶识别探测技术研究

Study on Transient Electromagnetic Method for Karst Identification and Detection in Subsea Shield Tunnel

海域瞬变电磁法具有对水底低阻地质体(包括岩溶、破碎带等)反映敏感、分辨率及施工效率较高的优点,是海底岩溶探测中常用的物探手段之一。为进一步查明大连地铁5号线工程跨海段岩溶发育规律,采用瞬变电磁岩溶识别探测技术进行岩溶探测,并采用钻探进行验证。结果表明:瞬变电磁物探法推测隧址区主要存在36处岩溶发育区,58处岩体破碎带,4条断裂破碎带,推测的岩溶发育区、岩体破碎带与前期详勘钻探资料吻合性较好,经钻孔验证该方法基本可满足岩溶勘察技术要求,通过该方法得到的岩溶勘察结果可靠性较高,能为隧址区岩溶处理提供基础支撑,本次成功应用可为类似工程岩溶探测提供借鉴与参考。

Transient electromagnetic method(TEM)is one of the commonly used geophysical methods in subsea karst exploration because it is sensitive to low resistivity of geological bodies(including karst and fracture zone)and has the advantages of high resolution and high construction efficiency.In order to further find out the law of karst development in the sea-crossing section of Dalian Metro Line 5 project,the transient electromagnetic method(TEM)is used to detect karst and furthermore the drilling is used to verify the detection result.The results show that there are 36 karst development zones,58 fracture zones and 4 fault fracture zones in the tunnel site.The predicted karst development areas and fracture zones are consistent with the preliminary detailed survey data.The method can basically meet the technical requirements of karst exploration through drilling verification,and the karst exploration results obtained by this method have high reliability,which can provide basic support for karst treatment in tunnel site.This successful application can provide a reference for karst detection in similar projects.