| 冷铸锚头性能光纤监测 |
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| 引用本文： | 吴俊,周世良,舒岳阶,曹师宝,周远航.冷铸锚头性能光纤监测[J].交通运输工程学报,2019,19(6):37-44. |
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| 作者姓名： | 吴俊 周世良 舒岳阶 曹师宝 周远航 |
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| 作者单位： | 重庆交通大学 重庆西南水运工程科学研究所, 重庆 400016 |
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| 基金项目： | 国家自然科学基金项目51508059重庆市基础研究与前沿探索项目cstc2018jcyjAX0345重庆市教育委员会科学技术研究项目KJQN201800739宁波市交通运输科技项目201704内河航道整治技术交通行业重点实验室开放基金项目NHHD-201502 |
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| 摘 要： | 为监测冷铸锚头性能, 分析了其结构受力特点, 建立了锚头内钢丝与改性环氧填料微元体静载平衡模型, 分析了钢丝与环氧填料间黏接应力对钢丝应力分布特性的影响, 将锚头的失效表征为黏接应力的奇异变化, 提出了通过测量钢丝轴向多点应力分布实现对锚头性能状态无损监测的新方法; 针对LMLPES-7-211型锚头, 利用有限元方法分析了锚头内钢丝的轴向应力分布特性; 根据冷铸锚头内非均匀应变特性与恶劣环境要求, 提出了毛细管封装的应变均化拉丝塔光栅(DTG)测量方案, 开发了冷铸锚头植入式专用分布式应变传感器; 进行了缆索锚头性能状态监测模拟试验, 分别将2个分布式DTG应变传感器植入锚头1(性能正常)与锚头2(性能异常)内, 对锚头标准受力状态下钢丝分布式应变进行监测。分析结果表明: 锚头1、2内钢丝分布式应变呈现较大的差异性, 锚头1内应变衰减趋势较为平滑, 与有限元仿真结果比较误差小于5%, 锚头2应变衰减趋势平滑性不足, 且与有限元结果比较最大误差超过40%;性能衰退会导致近锚固始端区段的黏接应力大幅下降, 最大达到-2.55 MPa, 靠近分丝底板锚固区段的黏接应力大幅增加, 增加量达到3.25倍。通过设置黏接应力合理偏离阈值, 就可实现对锚头结构性能状态的在线监测与预警。
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| 关 键 词： | 桥梁工程 性能监测 光纤分布式传感 冷铸锚头 黏接应力 应变均化拉丝塔光栅 |
| 收稿时间： | 2019-05-19 |
Fiber monitoring of cold-casting anchor's performance |
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| WU Jun,ZHOU Shi-liang,SHU Yue-jie,CAO Shi-bao,ZHOU Yuan-hang.Fiber monitoring of cold-casting anchor's performance[J].Journal of Traffic and Transportation Engineering,2019,19(6):37-44. |
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| Authors: | WU Jun ZHOU Shi-liang SHU Yue-jie CAO Shi-bao ZHOU Yuan-hang |
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| Affiliation: | Chongqing Southwestern Research Institute of Water Engineering, Chongqing Jiaotong University, Chongqing 400016, China |
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| Abstract: | To monitor the performance of cold-casting anchor, the structural stress characteristics were analyzed, and the micro unit static balancing model of steel wire in the anchor and modified epoxy filler was established. The impact of bond stress between steel wire and epoxy filler on the steel wire stress distribution characteristics was analyzed, and the failure of anchor was characterized as a singular change of bond stress. A non-destructive monitoring method of anchor's performance status by measuring the axial multi-point stress distributions of steel wires was proposed. For the LMLPES-7-211 anchor, the axial stress distribution characteristics of steel wires in the anchor were analyzed by using the finite element method. According to the non-uniform strain characteristics and harsh environment requirements, a strain-equalized DTG measurement scheme using the capillary encapsulation was proposed, and a special implantable distributed strain sensor for cold-casting anchor was developed. The simulation tests of cable anchor's performance state monitoring were carried out, two DTG distributed strain sensors were implanted into anchor 1 with normal performance and anchor 2 with abnormal performance, respectively, and then the distributed strains of steel wires under the standard stress state of anchor were monitored. Analysis result shows that the distributed strains of steel wire in the anchors 1 and 2 present a big difference. The strain attenuation trend in the anchor 1 is smoother, and the error is less than 5% compared with the finite element simulation result. The smoothness of strain attenuation trend in anchor 2 is insufficient, and the maximum error is more than 40% compared with the finite element simulation result. The performance degradation causes the bond stress of near the anchoring section to drop sharply, reaching a maximum of-2.55 MPa, and the bond stress near the anchoring section of tapping base plate increases greatly, and the increment reaches 3.25 times. Therefore, by setting the reasonable threshold of bond stress, the online monitoring and early warning of anchor's performance state can be realized. |
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