(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. Southwest Research Institute，China Railway Engineering Group Co.，Ltd.， Chengdu，Sichuan 610031，China)
Spherically weathered granite(commonly known as the“boulder”)is the remnant of a granite body which has been unevenly weathered.Their existence poses a serious operational risk to the subway shield tunnel construction efficientand accurate detection of boulder has been a difficult problem in geotechnical investigation for subway shield tunnel. Using self-determined sparker and geology expert analysismethod，sonic wave is created and received in the drills around the detection region. By the difference of longitudinal wave¢ speed in the boulder and other geological body，first arrival time is recorded and explained，and a 3D velocity field of sonic waveis produced by an inversion algorithm，which can describe the geological structure of the detection region. Taking the boulders survey of a certainsubway as an example，validity and reliability of this method is verified. The results demonstrate that the cross-hole sonic computer tomography is a very effective technique for“boulder”detection and mapping. Thus，sonic computer tomography can successfully detect similar geological investigation problems and provide scientific basis for the follow-up construction.
冯 涛. 武广客运专线韶花段球状风化花岗岩工程特性研究[博士学位论文][D]. 成都：西南交通大学，2007.(FENG Tao. Research on engineering properties of spheroidal weathering granite in Shaoguan- Huadu section of the Wuhan-Guangzhou high-speed railway[Ph. D. Thesis][D]. Chengdu：Southwest Jiaotong University，2007.(in Chinese))
[2]
杨雄飞，袁 鸿. 广州地铁3号线孤石地层的探测及处理[J]. 建筑机械化，2011，32(6)：73-76. (YANG Xiongfei，YUAN Hong. The detecting and measure of the boulder layer at the site of Guangzhou metro line 3[J]. Construction Mechanization，2011，32(6)：73-76.(in Chinese))
[3]
谢 壮. 花岗岩球状风化体地段地铁盾构施工风险分析与控制[硕士学位论文][D]. 长沙：中南大学，2010.(XIE Zhuang. Risk analysis and control of metro shield construction in spherical weathering granite[M. S. Thesis][D]. Changsha：Central South University，2010.(in Chinese))
[4]
杨书江. 厦门地铁复杂地质条件下盾构法施工技术探讨[J]. 隧道建设，2014，34(8)：765-770.(YANG Shujiang. Shield tunneling technologies for Xiamen metro under complex geological conditions[J]. Tunnel Construction，2014，34(8)：765-770.(in Chinese))
[5]
李建强，冯 涛，何 平. 花岗岩球状风化综合勘察技术研究[J]. 铁道建筑，2008，(10)：73-75.(LI Jianqiang，FENG Tao，HE Ping. Study on integrated investigation techniques of spherically weathered granite[J]. Railway Engineering，2008，(10)：73-75.(in Chinese))
[6]
刘宏岳. 地震反射波CDP叠加技术在海域花岗岩孤石探测中的应用[J]. 工程地球物理学报，2010，7(6)：714-718.(LIU Hongyue. Marine seismic reflection for the detection of the weathering residues in the granite[J]. Chinese Journal of Engineering Geophysics，2010，7(6)：714-718.(in Chinese))
[7]
徐佩芬，侍 文，凌苏群，等. 二维微动剖面探测“孤石”：以深圳地铁7号线为例[J]. 地球物理学报，2012，55(6)：2 120-2 128. (XU Peifen，SHI Wen，LING Suqun，et al. Mapping spherically weathered“boulders”using 2D microtremor profiling method：a case study along subway line 7 in Shenzhen[J]. Chinese Journal of Geophysics，2012，55(6)：2 120-2 128.(in Chinese))
[8]
桑松龄. 地质雷达检测在无锡地铁不良地质段的应用[J]. 铁道建筑技术，2015，(4)：78-80.(SANG Songling. Application of GPR in unfavorable geological section of Wuxi Metro[J]. Railway Construction Technology，2015，(4)：78-80.(in Chinese))
[9]
李建强. 武广客运专线韶关至花都段球状风化花岗岩综合勘查方法及勘探技术研究[硕士学位论文][D]. 成都：西南交通大学，2006.(LI Jianqiang. Research on compositive reconnaissance means and technology about spherical weathering granite in Shaoguan-Huadu section of the Wuhan-Guangzhou special passenger transport railway. [M. S. Thesis][D]. Chengdu：Southwest Jiaotong University，2006.(in Chinese))
张 亮，王 蔚，汤洪志，等. 高密度电法和井间电磁波CT法在花岗岩球状风化体探测中的综合应用[J]. 工程地球物理学报，2015，12(1)：40-44.(ZHANG Liang，WANG Wei，TANG Hongzhi，et al. The application of the combination of high-density electrical method and electromagnetic CT to detect granite spherical weathering body[J]. Chinese Journal of Engineering Geophysics，2015，12(1)：40-44.(in Chinese))
[12]
李红立，张 华，汪传斌. 跨孔超高密度电阻率法在花岗岩球状风化体勘探中的试验研究[J]. 工程勘察，2010，38(8)：88-92.(LI Hongli，ZHANG Hua，WANG Chuanbin. Experimental study on the cross-hole ultra-density resistivity method used in the exploration for the spherical lightly-weathered granite[J]. Geotechnical Investigation and Surveying，2010，38(8)：88-92.(in Chinese))
[13]
王千年，车爱兰，郭 强，等. 孔内声波CT技术在软土地区地下溶洞调查中的应用[J]. 西北地震学报，2011，33(增1)：335-339. (WANG Qiannian，CHE Ailan，GUO Qiang，et al. Technology of borehole sonic computer tomography and its application survey of underground cave[J]. Northwestern Seismological Journal，2011，33(Supp.1)：335-339.(in Chinese))
[14]
程学丰，刘盛东，刘登宪. 煤层采后围岩破坏规律的声波CT探测[J]. 煤炭学报，2001，26(2)：153-155.(CHENG Xuefeng，LIU Shengdong，LIU Dengxian. Sound-wave CT detection for failure patterns of surrounding rock after mining[J]. Journal of China Coal Society，2001，26(2)：153-155.(in Chinese))
[15]
陈宗刚，李平宏，张建成，等. 声波层析成像在特大涌水地质区域探测中的应用[J]. 物探与化探，2013，37(1)：180-185.(CHEN Zonggang，LI Pinghong，ZHANG Jiancheng，et al. The application of sound wave computerized tomography to the geological regional detection in an extra large water gushing channel[J]. Geophysical and Geochemical Exploration，2013，37(1)：180-185.(in Chinese))
2017, Vol. 36 
