【论文】地面塌陷分布式光纤感测模型试验研究

作者：韦超1，朱鸿鹄1,2，高宇新1，王静1，张巍1，施斌1

1南京大学地球科学与工程学院，江苏南京，210023
2南京大学(苏州〉高新技术研究院，江苏苏州，215123

来源：岩土力学, 2022, Vol. 43, Issue (9): 2443-2456.

doi: 10.16285/j.rsm.2021.1992

摘要：突发性地面塌陷对城市安全构成巨大威胁，掌握塌陷土体变形过程对地面塌陷事故的预测预报至关重要。基于分布式光频域反射（optical frequency domain reflectometry，简称 OFDR ）和粒子图像测速（particle image velocimetry，简称 PIV）技术，开展了地面塌陷模型试验，研究了塌陷过程中土体沉降的时空分布规律，并探究了不同应变感测光缆锚固方式对光纤监测结果的影响。结果表明：光纤应变监测曲线准确地反映了不同塌陷阶段上覆土体的变形状态，揭示了土体内部应变的演化机制；在光缆上设置圆片锚板，可以有效增强光缆与土体界面的耦合变形程度；在一定的埋置深度下，随着锚板尺寸的增大，光缆与土体间的变形协调性越好。研究结果显示，分布式应变传感技术在地面塌陷变形监测中具有较好的适用性，为该类地质灾害的早期识别提供了一种有力的工具。

关键词: 光纤传感器, 地面塌陷, 沉降监测, 界面效应, 模型试验

Abstract: Ground collapse accidents pose a large threat to the safety of cities due to their suddenness. It is very important to understand the development process of internal deformation of collapsed soil for prediction of ground collapse. In this study, based on the optical frequency domain reflectometry (OFDR) and particle image velocimetry (PIV) technologies, ground collapse model test was performed, and the tempo-spatial distributions of ground settlement in the collapsed area were investigated. The influence of anchoring methods of distributed strain sensing cables on the fiber optic monitoring results was explored. The results show that the fiber optic strain measurements reflect the deformation state of the overlying soil in different collapse stages and reveal the internal strain evolution mechanism of the ground soil. The coupling effect of the cable-soil interface is effectively enhanced by adding circular micro-anchor plates and is better with the increase of the diameter of the anchoring circulars at a certain burial depth. The research results show that the distributed strain sensing technology has good applicability in monitoring ground collapse and can provide a powerful tool for mitigating such geohazards.

Key words: fiber optic sensor, ground collapse, settlement monitoring, interface behavior, model test

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