软土盾构隧道施工沉陷的探地雷达检测

Detecting ground settlement of shield tunneling in soft soil by ground penetrating radar

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。文章采用探地雷达法对上海地铁2号线延长线川沙东—航殷路软土段盾构隧道和隧道上部地表进行了无损检测和评价,探测结果表明：552-576 m区段盾构隧道衬砌周围土层出现松动状况,由于盾构施工,隧道衬砌上部土体之间存在间隙,导致地表不均匀沉降;684-720 m区段隧道上部覆盖层土体较为松散,隧道左轴线处可能存在孔隙区,因而导致沉降和灌浆激增。

With the reflection of high frequency electromagnetic pulse, cracks of building as well as voids or settlement underground can be detected by ground penetrating radar. This paper deals with non-destructive testing and evaluation of the shield tunnel and upper ground of the second subway line from Chuanshadong to Hangyinlu in Shanghai. The testing results show that in the section from 552 m to 576 m, the soil around the pipeline is loose, and voids exist between the upper soil and the shield, leading to uneven surface subsidence; and in the section from 684 m to 720 m, the upper layer is loose and void areas may exist in the soil layer along the left axis, which leads to the settlement and surge of grouting.