Hong Chengyu, Xu Chengkai, Chen Weibin, Liu Jianwei, Tan Junkun
China Railway Seventh Group Co., Ltd., Zhengzhou 450016, China.
College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China.
Sensors (Basel). 2025 Jan 4;25(1):254. doi: 10.3390/s25010254.
This paper investigates the use of the BOTDA (Brillouin Optical Time-Domain Analysis) technology to monitor a large-scale bored pile wall in the field. Distributed fiber optic sensors (DFOSs) were deployed to measure internal temperature and strain changes during cement grouting, hardening, and excavation-induced deformation of a secant pile wall. The study details the geological conditions and DFOS installation process. During grouting, the temperature increased by approximately 69 °C due to cement hydration 30 min post-grouting, while the strain decreased by 0.5% on average due to cement slurry shrinkage. During excavation, the temperature changes were minimal, but the excavation depth significantly influenced the strain distribution, with continuous compressive deformation observed in two monitored boreholes. Two analytical methods, the numerical integration method (NIM) and the finite difference method (FDM), were used to calculate the lateral pile displacement based on the monitored strain data. The results were compared with previous monitoring data, showing that the lateral displacement of the pile was minimal after excavation and was attributed to the high stiffness of the secant pile wall. This study demonstrates the effectiveness of DFOSs and BOTDA technology for monitoring complex pile wall behaviors during construction.
本文研究了利用布里渊光时域分析（BOTDA）技术对现场大规模钻孔灌注桩墙进行监测。部署了分布式光纤传感器（DFOS）来测量在水泥灌浆、硬化以及咬合桩墙开挖引起变形过程中的内部温度和应变变化。该研究详细介绍了地质条件和DFOS安装过程。在灌浆过程中，由于水泥水化作用，灌浆后30分钟温度升高约69℃，而由于水泥浆体收缩，应变平均降低0.5%。在开挖过程中，温度变化极小，但开挖深度对应变分布有显著影响，在两个监测钻孔中观察到持续的压缩变形。采用数值积分法（NIM）和有限差分法（FDM）两种分析方法，根据监测到的应变数据计算桩的横向位移。将结果与之前的监测数据进行比较，结果表明开挖后桩的横向位移极小，这归因于咬合桩墙的高刚度。本研究证明了DFOS和BOTDA技术在监测施工过程中复杂桩墙行为方面的有效性。
