Study on the Mechanical Properties and Failure Characteristics of Reinforced Segments Based on DIC

Abstract

Shield tunnel segments are prone to damage in practical use and require reinforcement. In order to test the reinforcement effect of internal adhesive steel plates on the segments, bending static tests were conducted on the standard block segments of shield tunnels. The effects of different burial depths (divided into mid buried segments and ultradeep buried segments) and different initial damage levels (initial loading values of 78% of the failure load of mid buried segments and 90% of the failure load of ultradeep buried segments) on reinforced shield tunnel segments strengthened by steel plates were studied. The changes in the main strain and displacement field of the reinforced shield tunnel standard block segments were measured using the digital image correlation (DIC) method, and the failure characteristics (including strain and crack development laws) of the reinforced shield tunnel were studied. The test results show that there is no significant change in the principal strain of the mid buried pipe segment in the early and middle stages of the bending static test after using internal adhesive steel plates for reinforcement. However, after using steel plates of the same size for reinforcement of the ultradeep buried pipe segment, many cracks and stress increases are evident in the early and middle stages of loading. In the later stage of loading, the strain of both types of reinforced segments at the end of the steel plate will suddenly increase, and the cracks will extend diagonally toward the midspan direction. When the final damage occurs, the steel plate falls off, and the end of the steel plate used to reinforce the pipe segment becomes a weak point. When the bending moment changes from 500 kN to final failure, the displacement field of the buried pipe segment under initial loading to 78% of the failure load changes significantly, with the maximum value being 1.4 times the change in the ultradeep buried pipe segment under initial loading to 90% of the failure load. An internal adhesive steel plate can effectively improve the stiffness of the pipe segment and significantly reduce the displacement in both the X and Y directions of the pipe segment.

Keywords

tunnel engineering / mechanical property / static bending test / shield tunnel segment / digital image correlation method

References

[1] Liu, X.; Zhang, J.; Jiang, Z.; Liu, Z.; Xu, P.; Li, F. Experimental Investigations of a Segmental Tunnel Ring Strengthened by Using UHPC. China Journal of Highway and Transport 2021, 34,181-190, doi:10.19721/j.cnki.1001-7372.2021.08.015.

[2] Li, J.; Lei, M.; Lin, Y.; Dai, X.; Liu, T. Causes Analysis and Safety Evaluation of Cracking Shield Segment. Journal of Railway Science and Engineering 2018, 15,1786-1792, doi:10.19713/j.cnki.43-1423/u.2018.07.021.

[3] Zhu, W.; Ju, S. Causes and Countermeasures for Segment Cracking in Shield- Driven Tunnel. Modern Tunnelling Technology 2003, 21-25, doi:10.13807/j.cnki.mtt.2003.01.005.

[4] Wu, B.; Luo, Y.; Zang, J. Experimental Study on Mechanical Performance of Tunnel Segment Joints Strengthened Using Concrete-Filled Steel Tubes. Journal of Building Structures 2019, 40,105-112, doi:10.14006/j.jzjgxb.2017.0775.

[5] Liu, X.; Jiang, Z.; Liu, S. Experiment of Deformed Shield Tunnels Strengthened by Steel Plate-concrete Composite Structure. China Journal of Highway and Transport 2020, 33,128-137, doi:10.19721/j.cnki.1001-7372.2020.01.013.

[6] Chen, R.; Lu, L.; Zhang, Y.; Wu, H. Reinforced Technology and Mechanical Properties of Shield Tunnel Lining with UHPC. Engineering Mechanics 2019, 36,41-49, doi:10.6052/j.issn.1000-4750.2018.11.0620.

[7] Piekarczyk, M.; Grec, R. Application of Adhesive Bonding in Steel and Aluminium Structures. Archives of Civil Engineering 2012, 58,309-329.

[8] Zhou, D. Calculation Method of CFRP Strengthened Highway Tunnel Lining Based on Reliability Theories. Master, Tongji University, Shanghai, 2008.

[9] Kiriyama, K.; Kakizaki, M.; Takabayashi, T.; Hirosawa, N.; Imafuku, K. Structure and Construction Examples of Tunnel Reinforcement Method Using Thin Steel Panels. Nippon Steel Technical Report 2005, 45-50.

[10] Liu, X.; Zhang, H.; Tang, M.; Lu, L.; Wang, X. Experimental Study of the Ultimate Bearing Capacity of a Shield Tunnel Reinforced by a Semi-Ring Steel Plate. Modern Tunnelling Technology 2014, 51,131-137, doi:10.13807/j.cnki.mtt.2014.03.021.

[11] Zhai, W.; Zhai, Y.; Zhang, D.; Wu, H.; Huang, H. Numerical Study on Shearing Performance of Steel Plate Strengthened Circumferential Joints of Segmental Tunnel Linings. Chinese Journal of Geotechnical Engineering 2019, 41,235-239, doi:10.11779/CJGE2019S2059.

[12] Liu, T.; Huang, H.; Xu, R.; Yang, X. Research on Load-bearing Capacity of Metro Shield Tunnel Lining Strengthened by Bonded Steel Plates. China Journal of Highway and Transport 2017, 30,91-99, doi:10.19721/j.cnki.1001-7372.2017.08.010.

[13] Liu, X.; Tang, M.; Lu, L.; Wang, X.; Zhu, Y. Experimental Study of Ultimate Bearing Capacity of Shield Tunnel Reinforced by Full-Ring Steel Plate. Chinese Journal of Rock Mechanics and Engineering 2013, 32,2300-2306.

[14] Bi, X.; Liu, X.; Wang, X.; Lu, L.; Zhu, Y. Experimental Study on the Ultimate Load-Bearing Capacity of Deformed Segmental Tunnel Linings Strengthened by Steel Plates. China Civil Engineering Journal 2014, 47,128-137, doi:10.15951/j.tmgcxb.2014.11.048.

[15] Dai, S.; Ma, S.; Pan, Y.; Dong, Z. Evaluation of Mode Ⅰ Stress Intensity Factor of Rock Utilizing Digital Speckle Correlation Method. Chinese Journal of Rock Mechanics and Engineering 2012, 31,2501-2507, doi:10.3969/j.issn.1000-6915.2012.12.014.

[16] Zhang, D. Digital Image Correlation: Theory and Applications. Journal of Medical Biomechanics 2009, 24,85-88+93.

[17] Chen, F.X.; Chen, X.; Xie, X.; Feng, X.; Yang, L.X. Full-Field 3D Measurement Using Multi-Camera Digital Image Correlation System. Opt Laser Eng 2013, 51,1044-1052, doi:10.1016/j.optlaseng.2013.03.001.

[18] Zhao, Y.; Xing, Y.; Huang, J.; Jiang, A. Study on the Fiber-Reinforced Concrete Pull-Out Test Using Digital Image Correlation Method. Engineering Mechanics 2010, 27,169-175.