摘要
受环境、设计、施工以及运营等方面的影响,盾构隧道壁后常存在难以探测的空洞缺陷,危及隧道结构安全。探地雷达是盾构隧道隐蔽缺陷探测的主要方法之一,但由于盾构隧道内部双层钢筋网的屏蔽效应,导致壁后空洞的电磁响应特征不明显。为探究不同类型壁后空洞特征,文章采用时域有限差分法,模拟探地雷达探测不同尺寸、形状的空气空洞/富水空洞,对仿真得到的特征图像进行分析,设计了模拟真实情况的盾构隧道壁后空洞模型进行实测实验,并验证仿真结论的准确性。结果表明:随着方形空洞尺寸的变化,正演模拟仿真图像中会对应呈现出双曲线、交叉状及碗状的反射特征,且其底部反射也呈现一定的变化规律;圆形空洞仿真图像均呈现曲率随空洞尺寸增大而增大的完整双层双曲线形。通过波场分析发现,钢筋会对雷达信号产生较强的干扰,电磁波在空洞内部产生多次反射,空气空洞与富水空洞中电磁波传播现象有较大差异。研究成果可为实际盾构隧道壁后空洞检测数据的解释提供参考。
Affected by the environment,design,construction,and operation,there are hidden defects behind a shield tunnel,which endanger the safety of the tunnel.Ground penetrating radar(GPR)has been widely applied to the detection of hidden defects behind a shield tunnel.However,due to the shielding effect of the double-layer rebar net inside the shield tunnel,the electromagnetic(EM)response characteristics of the void behind the concrete segment are not obvious.This paper applied finite difference time domain(FDTD)method to simulate the detection of the air-and water-filled voids behind the shield tunnel with different sizes using GPR.Then,a laboratory experiment was performed to verify the accuracy of the simulated results.The results mean that simulated cubical voids change with different sizes,the reflections of the defects show the characteristics of hyperbola,cross or bowl shape.The bottom reflections also vary with certain regularities.Through the wavefield analysis,it can be indicated that the radar echo will be interfered with by the rebars terribly.Moreover,multiple EM wave reflections propagate inside the voids,and the propagation of EM waves show a significant difference between the air-filled/water voids.In conclusion,the results of this paper can provide a reference for the data interpretation of the detection of hidden defects in shield tunnels.
作者
刘海
陈峻浩
孙竹妤
岳云鹏
赖思聪
孟旭
LIU Hai;CHEN Jun-hao;SUN Zhu-yu;YUE Yun-peng;LAI Si-cong;MENG Xu(School of Civil Engineering,Guangzhou University,Guangzhou 510006,China;Guangdong Engineering Research Center for Underground Infrastructural Protection in Coastal Clay Area,Guangzhou 510006,China)
出处
《广州大学学报（自然科学版）》
CAS
2023年第3期1-9,共9页
Journal of Guangzhou University:Natural Science Edition
基金
国家自然科学基金资助项目(41874120,5202010500)
广东省基础与应用基础研究基金资助项目(2021A1515010881,2021B1515130006)
广州市科技计划资助项目(202102020559)
广州大学大学生创新训练资助项目(xj202211078238)。
关键词
盾构隧道
空洞
探地雷达
无损检测
shield tunnel
voids
ground penetrating radar(GPR)
non-destructive testing(NDT)
