防汛墙下砂土管涌隐患的地质雷达探测

GPR Detection of Hidden Danger of Sand Boil under Flood Wall

针对长江下游某港口长江港池新建防汛墙在高潮位时发生直径1．5-2．0 m的管涌事故,运用美国Sir-2型地质雷达设备,对整个防汛墙底板下土层的密实程度和管涌等病害情况进行了无损探测。结果表明:新建防汛墙底板以上的陆域侧回填土以及防汛墙底板以下的粉质粘土中局部存在孔隙较大的松散介质,为部分细颗粒流失或潜在渗漏通道区域。探测还发现粉细砂层中局部夹杂有粘土层。最后,根据事故发生的原因,提出了处理建议。

Based on the occurrence of sand boils with diameters from 1.5 m to 2.0 m under a new flood wall for a port at the lower reach of the Changjiang River during a high tide, GPR equipment of SIR-2 was used to carry out a nondestructive investigation of the density of the foundation soil and sand boils below the whole length of the flood wall. The results of the investigation showed that loose materials with large porosity were found in the backfill above the base plates behind the flood wall and in the silty clay below the base plates, which are deduced to be the areas for the running-off of fine particles or areas of potential sand boiling. During the GPR investigation, it was also discovered that the silty fine sand stratum contains clayey soil in some areas. Finally, measures to tackle such occurrences are proposed on the basis of the causes of the sand boils under the flood wall.