【论文】基于光纤神经系统的城市开发区地下多物理场监测

城市发展的快速扩张导致了民用基础设施的广泛建设。然而，这些新兴的城市开发区往往隐藏着地质灾害的隐患。这在很大程度上是因为详尽的现场勘查以及对地下地质状况持续监测的缺失。掌握地下多场信息的时空变化对于确保工程安全建设和实现城市地下空间高效利用至关重要。在中国四川省天府新区，本研究通过光纤神经系统（FONS）获取了全面的地下多物理信息，涵盖了地层变形、温度和地表水文数据。该系统整合了三种尖端的光纤传感技术：光纤布拉格光栅（FBG）、布里渊光时域反射（BOTDR）和拉曼光时域反射（ROTDR）。我们在9个监测钻孔中安装了全分布式和准分布式的应变/温度传感电缆，这些钻孔覆盖了平原、阶地以及活动断层带等多种地质特征区域。现场监测数据充分证实了在城市开发区应用光纤神经系统进行地质勘探和监测的可行性，为这一经济高效的技术在未来地质灾害防治领域的应用提供了宝贵的参考依据。

 
图 1.在城市开发区部署 FONS 进行现场监测

图 2.用于应变和温度传感的 DFOS 技术原理


图 3.研究区的位置和监测孔


图 4.六个监测孔的地层剖面

图 6.监测站施工照片：（a） 光缆安装的准备工作;（b） 将光缆放入钻孔中;（c） 回填钻孔;（d） 使用光纤解调仪进行数据采集

图 7.阶地区域不同光缆测得的应变曲线：（a） 定点式应变感测光缆;（b） 内定点应变感测光缆;及 （c） 金属基索状应变光缆

图 9.监测孔和水文钻孔中的地层温度分布对比

图 10.阶地区域表面的水分分布：（a） 温度特性值;（b） 表层土壤层的水分分布。

图 11.三个不同深度的含水量变化和相应的降雨数据。


图 12.龙泉山断裂带东坡不同光缆测得的应变曲线：（a） 定点式应变感测光缆;（b） 内定点应变感测光缆;及 （c） 金属基索状应变光缆

图 14.不同光缆的应变传递系数比较

本研究针对四川省天府新区特殊的地质条件，探讨了 FONS 在中国四川省天府新区的适用性。两年多来，不同地区的 9 个监测孔采用了三类光纤传感技术来监测地层变形、温度和地表水文数据。从这项研究中得出以下结论：

  • (1) 现场监测结果证实了使用 FONS 在地质灾害易发地区进行地质调查的可行性。该技术可以有效地捕捉地下变形、温度、水文地质特征以及地质过程和灾害的时空演变。这种方法在地质环境监测和地质灾害防治方面具有巨大潜力。
  • (2) 不同类型的光缆表现出不同的地层变形表现。为了监测地层结构的变形，选择合适的光缆以准确捕获岩土变形至关重要。建议在钻孔中使用各种应变传感电缆来估计测量误差。
  • (3) 钻孔回填工艺对于确保监测数据的质量至关重要。在钻孔回填之后，扰动效应逐渐减弱，FO 电缆与周围回填和地层之间的耦合慢慢稳定，达到新的平衡状态。

将光纤神经系统（FONS）与云计算、大数据等尖端技术相结合，为其未来应用开辟了广阔的前景。这种技术融合极大地扩展了FONS的功能，使其从一个基础的数据收集工具转变为一个多功能的平台。人工智能和机器学习技术的融入，标志着地质监测领域的一次飞跃。这种集成不仅提高了数据处理和管理的效率，而且促进了实时信息的检索和分析。在这些技术的加持下，FONS能够执行一系列超越基础数据检索的高级功能。利用边缘计算，FONS能够在实时处理数据的同时，全面、连续地监控地质资源和地质环境条件。它能够捕捉到可能预示潜在风险的微妙变化，如滑坡、沉降或结构失稳，并提供关于地基承载状态的早期预警。这种预警机制对于预防和减轻潜在地质灾害至关重要。FONS在辅助防灾减灾决策过程和提供应急响应措施方面的能力尤为突出，这意味着它在应急响应策略和制定城市规划与建设的明智决策中扮演着关键角色，特别是在地质灾害多发区域。

FONS 的部署为在主要经济发展区（包括中国的长江三角洲和珠江三角洲）建立城市规模的监测网络提供了巨大潜力。这种扩展对于构建智慧城市和推动社会可持续发展具有重要意义。此外，FONS在促进地下空间开发和有效利用方面的潜力也将进一步被探索，这对于人口密集地区的城市发展是一个至关重要的议题。 

上述成果近日以“Subsurface multi-physical monitoring of urban development zone using a fiber optic nerve system”为题，发表于工程地质领域顶级期刊《Journal of Rock Mechanics and Geotechnical Engineering》, 南京大学博士研究生王静为论文第一作者，朱鸿鹄教授和谭道远副教授为共同通讯作者，合作者包括成都地调中心王东辉、郭子奇，以及南京大学颜杜民。该工作得到了国家杰出青年科学基金项目和国家自然科学基金面上项目的资助。

原文链接：https://doi.org/10.1016/j.jrmge.2024.11.032

Subsurface multi-physical monitoring of urban development zone using a fiber optic nerve system

Jing Wanga, Donghui Wangb, Hong-Hu Zhua,c,⁎, Ziqi Guob, Dumin Yana,d, Dao-Yuan Tana,⁎⁎

a School of Earth Sciences and Engineering, Nanjing University, Nanjing, 210023, China
b Chengdu Geological Survey Center, China Geological Survey, Chengdu, 610081, China
c Engineering Research Center for Earth Sensing and Disaster Control of Jiangsu Province, Nanjing, 210023, China
d China Railway Construction Corporation Limited, Beijing, 100855, China

Abstract: The rapid expansion of urban development has led to the extensive construction of civil infrastructures. However, these urban development zones frequently face potential geohazards, primarily due to the lack of detailed site investigations and long-term monitoring of subsurface geological conditions. Understanding the temporal and spatial distributions of underground multi-field information is vital for successful engineering construction and effective utilization of urban underground space. In this study, a fiber optic nerve system (FONS) was utilized in the Tianfu New Area, Sichuan Province, China, to obtain comprehensive subsurface multi-physical information, including geological deformation, temperature, and surface hydrological data. The FONS incorporates three advanced fiber optic sensing techniques, i.e. fiber Bragg grating (FBG), Brillouin optical time domain reflectometry (BOTDR), and Raman optical time domain reflectometry (ROTDR). Fully- and quasi-distributed strain/temperature sensing cables have been installed in nine monitoring boreholes, covering various geological features such as plains, terraces, and areas within active fault zones. The field monitoring results confirm the feasibility of employing FONS for geological investigations within urban development zones, offering a valuable reference for future applications of this cost-effective technology in geohazard mitigation.

Keywords: Urban development zone, Geotechnical monitoring, Multi-physical evolution, Fiber optic sensor

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