为解决地铁地下车站装配式结构质量与尺寸大、施工工况多，极易导致结构的变形和应力集中造成的损伤问题，基于高精度、高空间分辨率分布式OFDR技术，对地下装配式结构侧墙内部连续空间的应变进行监测，探索侧墙、顶板、相邻块的拼装，以及车站顶部回填土在多种施工工况下对侧墙内部变形特征的影响；量化分析不同施工工况对侧墙应变场与弯矩分布特征的影响规律，探究多种施工工况对侧墙结构中部与端部弯矩的贡献度，总结地铁地下车站装配式结构高风险点对应的施工工况。研究结果表明： 1）侧墙在拼装与顶部回填土阶段呈现较明显的压弯效应，顶部回填土施工阶段为装配式侧墙结构的最不利工况。2）支撑倒换与侧壁回填工序会增大侧墙结构的弯矩，平均增幅分别为42.8%与19.3%； 顶部土体回填期间，B1、B2侧墙最大弯矩分别较前一阶段增长510%、252%。3）侧墙两端与中部弯矩随拼装与回填土工况的进行而不断增大，产生明显弯曲效应。顶部回填土阶段对中部、顶部、底部的弯矩平均贡献度分别为70.4%、69.4%、55.1%；
由于上部回填土对侧墙弯矩贡献度最大，回填土施工阶段需要关注上部回填土压力对拼装车站侧墙结构受力的影响。
The massive weight and size
of prefabricated structures in underground metro stations, combined with
multiple construction conditions, can lead to structural deformation, stress
reconcentration, and ultimately, structural damage. To address these challenges,
high-precision and high-spatial-resolution distributed optical
frequency domain reflectometry technology is utilized to monitor the strain
distribution within the sidewalls of underground prefabricated structures. The
authors investigate the effects of various construction conditions, including
sidewall assembly, roof slab installation, adjacent block assembly, and topsoil
backfilling, on the deformation characteristics of the sidewalls. In addition,
the effects of varying construction conditions on the strain field and bending
moment distribution in the sidewalls are quantitatively analyzed. The
contributions of each construction condition to the bending moments in the
middle and end positions of the sidewall structures are also investigated. The
results reveal the following: (1) Distributed fiber-optic
strain monitoring indicates an obvious compression bending effect on the
sidewalls during the assembly and topsoil backfilling stages. Among all
construction stages, the topsoil backfilling process emerges as the most
unfavorable for the stability of sidewall structures. (2) The support
replacement and sidewall backfilling processes cause notable increases in the
bending moment of the sidewall structure, with average increases of 42.8% and
19.3%, respectively. During the topsoil backfilling stage, bending moments in
the B1 and B2 sidewalls increase by 510% and 252%, respectively, compared to
the previous stage. (3) Bending moments at the ends and middle of the sidewalls
continuously increase with the assembly and backfilling conditions, causing
significant bending effects. The average contributions of the topsoil
backfilling stage to the bending moments in the middle, top, and bottom of the
sidewall are 70.4%, 69.4%, and 55.1%, respectively. The topsoil backfilling
contributes the most to the sidewall bending moments. Significant attention
should be paid to the influence of the top overburden soil pressure on the
structural behavior of the sidewalls of the prefabricated metro station.
