等值反磁通瞬变电磁法在地铁盾构孤石探测中的应用  

Application of Opposing Coils Transient Electromagnetic Method in Metro Shielding Boulder Detection

作　　者：赵东东 陈基炜 宗全兵 张宝松[1] 邸兵叶[1] 朱红兵[1] 王佳龙 Zhao Dongdong;Chen Jiwei;Zong Quanbing;Zhang Baosong;Di Bingye;Zhu Hongbing;Wang Jialong(Nanjing Center,China Geological Survey,Nanjing Jiangsu 210016, China;Fuzhou Metro Group Co.Ltd,Fuzhou Fujian 350000, China)

机构地区：[1]中国地质调查局南京地质调查中心,江苏南京210016 [2]福州地铁集团有限公司,福建福州350000

出　　处：《工程地球物理学报》2021年第4期495-502,共8页Chinese Journal of Engineering Geophysics

基　　金：自然资源部中国地质调查局项目(编号:DD20190301)。

摘　　要：孤石是花岗岩不均匀风化所残留的风化核,具有空间分布不规律、埋藏深度不定、粒径不均等主要特征,给地铁盾构施工带来了重大安全风险。在地铁工程建设中,孤石精准探测一直都是城市地铁盾构施工面临的重要难题之一。等值反磁通瞬变电磁法采用双线圈源建立一次场零磁通接收平面来消除一次场对接收线圈的影响,实现纯二次场聚焦观测,增强了涡流聚集,降低了体积效应,具有探测精度高、抗干扰能力强和工作效率高等诸多优良特性。为了研究等值反磁通瞬变电磁法对孤石探测的有效性和适用性,将其应用于福州地铁F1线孤石探测方法优选试验中,通过与钻孔验证表明,该方法能有效圈定孤石体的位置、大小和空间分布,尤其适用于干扰严重、交通繁忙和建筑密集的城市复杂环境。Boulder is the weathered core left by the uneven weathering of granite,and it has the main characteristics of irregular spatial distribution,uncertain burial depth and uneven particle size,which brings great safety risks to the construction of subway shield.In subway construction,the accurate detection of isolated stone has always been one of the important problems in shield construction of urban subway.The opposing Ccoils transient electromagnetic method(OCTEM)has such excellent characteristics as high detection precision,strong anti-interference ability and high working efficiency.By way ofdouble-coil source this method establishes zero-flux receiving plane of primary field to eliminate the influence of primary field on receiving coil,realize pure secondary field focusing observation,enhance eddy current aggregation and reduce volume effect.Through the detection experiment and application of OCTEM in Fuzhou subway line F1 boulder precision,the mutual authentication with drilling and other geophysical methods this paper shows that this method can effectively identify areas of the boulder body position,size and spatial distribution.It is especially applicable to the serious interference with a dense,heavy traffic,and construction of urban complex environment.

关 键 词：等值反磁通瞬变电磁法 地铁盾构 孤石探测 

分 类 号：P631.3[天文地球—地质矿产勘探]