School of Electrical Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou 310018, China.
College of Mechanical and Electrical Engineering, China Jiliang University, Hangzhou, 310018, China.
Sensors (Basel). 2019 Mar 14;19(6):1297. doi: 10.3390/s19061297.
Surface and underground stretched deformation is one of the most important physical measurement quantities for geological-disaster monitoring. In this study, a parallel helical sensing cable (PHSC) based on the time⁻domain reflectometry (TDR) technique is proposed and used to monitor large ground stretched deformation. First, the PHSC structure and manufacturing process are introduced, and then, distributed capacitance, distributed inductance, and characteristic impedance were derived based on the proposed stretched-structure model. Next, the relationship between characteristic impedance and stretched deformation was found, and the principle of distributed deformation measurement based on the TDR technique and PHSC characteristic impedance was analyzed in detail. The function of the stretched deformation and characteristic impedance was obtained by curve fitting based on the theoretically calculated results. A laboratory calibration test was carried out by the designed tensile test platform. The results of multi-point positioning and the amount of stretched deformation are presented by the tensile test platform, multi-point positioning measurement absolute errors were less than 0.01 m, and the amount of stretched deformation measurement absolute errors were less than 3 mm, respectively. The measured results are in good agreement with the theoretically calculated results, which verify the correctness of theoretical derivation and show that a PHSC is very suitable for the distributed measurement of the ground stretched deformation.
地表与地下拉伸变形是地质灾害监测最重要的物理测量量之一。本研究提出了一种基于时域反射（TDR）技术的平行螺旋传感电缆（PHSC），用于监测大地拉伸变形。首先，介绍了 PHSC 的结构和制造工艺，然后基于所提出的拉伸结构模型推导出分布电容、分布电感和特性阻抗。接下来，找到了特性阻抗与拉伸变形之间的关系，并详细分析了基于 TDR 技术和 PHSC 特性阻抗的分布式变形测量原理。通过基于理论计算结果的曲线拟合得到了拉伸变形和特性阻抗的函数。通过设计的拉伸试验台进行了实验室校准测试。拉伸试验台给出了多点定位和拉伸变形量的结果，多点定位测量绝对误差小于 0.01 m，拉伸变形量测量绝对误差小于 3 mm。测量结果与理论计算结果吻合较好，验证了理论推导的正确性，表明 PHSC 非常适合大地拉伸变形的分布式测量。
