在某城区顶管隧道始发井和接收井开挖施工过程中均发现基坑中存在未知的建筑残留桩基。因时间久远，施工区域内残留桩基的位置和范围均无法获知。为保证顶管隧道顺利施工，需在施工前调查清楚其影响范围内是否存在残留桩基。由于顶管隧道横穿繁忙交通道路，地表没有大范围钻孔勘查的条件，只能采用地球物理方法进行探测。经比选，采用探地雷达和磁法探测相结合的方法可满足探测要求。根据探测结果，在异常区域进行钻探验证，并采取针对性的处理措施，保证了顶管隧道的安全施工。

Some unknown residual pile foundations are encountered during the construction of launching shaft and receiving shaft of pipejacking tunnel in urban area. The location and scope of residual pile foundation in the construction area are not clear. As a result, it is necessary to find out whether there is any residual pile foundation in the tunnel area before carrying out construction. Only the geophysical method can be adopted for there is no condition for extensive drilling exploration. The method of residual pile foundation detecting by ground penetrating radar and magnetic method, which can meet the detection requirements, are selected. According to the detection results, the drilling verification in abnormal area is carried out and the countermeasures are taken to guarantee safe construction of pipejacking tunnel.