海域花岗岩发育区地震反射精细地质构造调查  

Fine geological structure investigation in offshore granite distributed area by using seismic reflection exploration

作　　者：邓小虎 傅焰林 李青山 Deng Xiaohu;Fu Yanlin;Li Qingshan(Wuhan Institute of Earthquake Engineering Co.,Ltd.,Wuhan 430071,China;China Railway No.2 Engineering Group Co.,Ltd.,Chengdu 610031,China)

机构地区：[1]武汉地震工程研究院有限公司,武汉430071 [2]中铁二局集团有限公司,成都610031

出　　处：《工程勘察》2024年第6期72-78,共7页Geotechnical Investigation & Surveying

摘　　要：广东近海海域位于太平洋板块与大陆板块交界处,地质活动活跃,地质结构复杂。在花岗岩分布区,基岩不均匀风化形成风化基岩凹槽、隆起和孤石等,基岩面起伏较大。单一钻探方法难以反映隧道沿线地质结构的连续变化。本文采用高频小炮距水域地震反射方法,查明隧道沿线详细地质条件,总结各种地质体的地震反射特征,研究断裂走向及活动性。在小炮间距地震剖面中,基岩面表现为反射同相轴起伏变化,基岩隆起对应同相轴上隆,基岩凹槽对应同相轴下凹;断裂表现为同相轴缺失、突变、错断;抛石发育区与孤石(群)形成绕射波。本文利用多条地震反射剖面构建三维地质模型,全面展示隧道沿线复杂地质结构,划定强风化花岗岩区。对比研究发现地震反射解释结论与钻探揭示情况吻合较好,为隧道工程设计和施工提供了可靠的地质资料。The offshore of Guangdong Province is located at the junction of the Pacific plate and the continental plate,with active geological movements and complex geological structures.In granite distributed area,the uneven weathering of the granite forms the grooves,uplifts and solitary stones.The bedrock surface fluctuates greatly.It is difficult to disclose the continuous geological variation along the tunnel by drilling.In this paper,the reflective seismic exploration with high-frequency and small-distant sources is used,to identify the detailed geological conditions along the tunnel,to summarize the seismic characteristics of various geological bodies,and to study the strike and activity of fault.In the seismic profile,the bedrock surface is reflected as the fluctuation of seismic events,the uplift of the bedrock corresponds to the uplift of the events,the groove corresponds to the depression of the events.The fault is characterized by disappear,mutation and dislocation of the events.The ripraps and solitary rocks form diffraction waves.Multiple seismic profiles are used to construct a three-dimensional geological model,comprehensively displaying the complex geological structure along the tunnel,and delimiting strong weathered granite areas.It is found that the seismic interpretation results are in good agreement with the drilling results,which provides the reliable geological data for tunnel engineering design and construction.

关 键 词：水上地震反射 孤石 抛石 海洋地质勘察 风化凹槽 隆起 

分 类 号：P631.425[天文地球—地质矿产勘探]