Abstract: By reflection of high freguency electromagnetic pulse,tcracks of buildings as well as voids or settlement underground could be detected by ground penetrating radar. Jacking pipe construction in dam foundation may cause settlement. Non-destructive testing by ground penetrating radar was carried out for tube wall and dam body on the jacking pipes during construction. The result showed that the heterogeneous structure existed in the scope of 5～10 m under the surface and void existed between the pipeline and upper soil. Combined with the geological conditions, it was found that the groundwater recession and the destruction of balanced force caused the settlement but not the underground cavity.

摘要： 探地雷达利用高频电磁脉冲波的反射原理，可用于建筑物裂缝、地层孔洞或沉陷的探测。在堤坝下方进行顶管施工会导致上部土层振动，产生引起堤坝沉陷的隐患。采用探地雷达法对顶管施工过程中的平湖市穿越白沙湾围垦大堤的污水处理排放管管壁和顶管上部堤坝均进行了无损检测，探测结果表明：地表到5～10 m 深度范围内存在不均匀结构；管道和原地层之间密实性不好，有一定的间隙存在。结合地质情况分析，下陷原因可能是施工过程中开挖面附近形成局部地下水位下降，力的平衡被暂时破坏，与地下空洞无重大关系。