|Table of Contents|

Fiber monitoring of cold-casting anchor's performance(PDF)

《交通运输工程学报》[ISSN:1671-1637/CN:61-1369/U]

Issue:
2019年06期
Page:
37-44
Research Field:
道路与铁道工程
Publishing date:

Info

Title:
Fiber monitoring of cold-casting anchor's performance
Author(s):
WU Jun;  ZHOU Shi-liang;  SHU Yue-jie;  CAO Shi-bao;  ZHOU Yuan-hang
(Chongqing Southwestern Research Institute of Water Engineering, Chongqing Jiaotong University, Chongqing 400016, China)
Keywords:
bridge engineering;  performance monitoring;  fiber distributed sensing;  cold-casting anchor;  bond stress;  strain-equalized DTG
PACS:
U446
DOI:
10.19818/j.cnki.1671-1637.2019.06.004
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. 4 tabs, 13 figs, 28 refs.

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Last Update: 2020-01-13