The inverse finite element method (iFEM) is a mechanics-based algorithm for dynamic tracking of full-field structural displacements. Accurate deformed structural-shape can be attained without any material properties and loading information, even when some discrete locations lack in-situ strain measurements. The structure is discretized by inverse finite elements, enabling superior predictive capability for complex structural deformations. These exclusive advantages make iFEM suitable for geotechnical deformation monitoring, but very few researches and applications are present in the existing literature. With this in mind, a novel inclinometer that employs iFEM methodology as its underlying design theory is developed in this paper. The inclinometer is fabricated by lowering the fiber optic shape sensor into the conventional inclinometer casing leveraging on sliding fixtures. Distributed strain measures are captured using self-developed fiber Bragg grating sensors and then input into the iFEM model to regenerate the internal displacement of soil structures. The present inclinometer serves to both increase the survival rate of the sensors while at the same time achieving the sensing element reuse. A series of indoor and field validation tests have been performed and demonstrated the high accuracy, robustness, and practical usefulness of the iFEM-based inclinometer.

逆有限元法 (iFEM) 是一种基于力学的算法，用于动态跟踪全场结构位移。无需任何材料特性和载荷信息即可获得准确的变形结构形状，即使某些离散位置缺乏原位应变测量。该结构通过逆有限元进行离散化，对复杂的结构变形具有卓越的预测能力。这些独有的优势使 iFEM 适用于岩土变形监测，但现有文献中很少有研究和应用。考虑到这一点，本文开发了一种采用 iFEM 方法作为其基本设计理论的新型倾角仪。倾角仪是通过利用滑动夹具将光纤形状传感器降低到传统的倾角仪外壳中来制造的。使用自主开发的光纤布拉格光栅传感器捕获分布式应变测量，然后输入 iFEM 模型以重新生成土壤结构的内部位移。本倾角仪既能提高传感器的存活率，又能实现传感元件的重复使用。已经执行了一系列室内和现场验证测试，并证明了基于 iFEM 的倾角计的高精度、稳健性和实用性。