Rock and Soil Mechanics ›› 2022, Vol. 43 ›› Issue (3): 808-818.doi: 10.16285/j.rsm.2021.5426

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Static characteristics and engineering applications of micro negative Poisson’s ratio bolt

TAO Zhi-gang1, 2, GUO Ai-peng1, 2, HE Man-chao1, 2, ZHANG Jin3, XIA Min4, WANG Ding1, 2, LI Meng-nan1, 2, ZHU Zhen1, 5   

  1. 1. School of Mechanics and Civil Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China 2. State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China 3. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing, Jiangsu 210098, China 4. College of Civil Engineering, Tongji University, Shanghai 200092, China; 5. School of Civil Engineering, Qingdao University of Technology, Qingdao, Shandong 266033, China
  • Online:2022-03-17 Published:2022-05-17
  • Contact: GUO Ai-peng, male, born in 1993, PhD candidate, focusing on support of tunnels and underground. E-mail: guoaipeng0422@163com
  • About author:TAO Zhi-gang, male, born 1981, PhD, Associate Professor, Doctoral supervisor, mainly engaged in theoretical research and teaching of rock mechanics and engineering disaster control.
  • Supported by:
    the National Natural Science Foundation of China (NSFC)(41941018), the Second Tibetan Plateau Scientific Expedition and Research (2019QZKK0708), and the Open Foundation of State Key Laboratory for Geomechanics and Deep Underground Engineering (SKLGDUEK2024).

Abstract: Compared with traditional small deformation bolt materials, the negative Poisson’s ratio (NPR) bolt/cable material has excellent mechanical properties such as large elongation, high strength, high toughness, high constant resistance, and energy absorption. Based on the research and application of macro-NPR bolts/cables, He Manchao developed a new type of micro-NPR steel material and a new type of micro-NPR bolt. At present, there are few studies on the static characteristics of the micro-NPR steel, and the applicability of the micro-NPR anchor in urban underground tunnel engineering needs to be verified by field tests. The mechanical properties of the micro-NPR steel were studied by the static tensile test in laboratory. The results show that the average elongation ratio of this batch of micro-NPR steel is 34.68%, and the constant resistance range is 203.9?240.7 kN. The tensile deformation is uniform in the whole process, and there is no yielding platform and no obvious necking when breaking. Through theoretical derivation, the elastoplastic incremental constitutive model of the micro-NPR bolt under micro-static tensile condition was established. Taking the air duct section of a subway station as the engineering background, this paper introduced the construction technology of the micro-NPR bolt, and tested the ultimate pull-out force, elongation ratio, and axial force on site. The results show that the micro-NPR bolt has the advantages of high constant resistance and large elongation. The application test of the bolt supporting was carried out in the tunnel with the large-deformation surrounding rock, and the large deformation control effects of the surrounding rock were verified.

Key words: micro-NPR bolt, static characteristics, constitutive model, field test