Engineering Transactions, 64, 1, pp. 89–103, 2016

Anchoring Principles of a New Energy-Absorbing Expandable Rock Bolt

Zhijie WEN
Research Center of Geotechnical and Structural Engineering, Shandong University, Jinan, Shandong 250061, P R China; State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, Shandong 266590, P R China.
China

Yujing JIANG
State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, Shandong 266590, P R China.
China

Zuozhen HAN

China

Sitong YANG
State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, Shandong 266590, P R China
China

Xiao WANG
State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, Shandong 266590, P R China
China

The greater the mine, the harder stability control will be. And the conventional rock bolts do not adapt well to the severe rock stress conditions. An ideal bolt having a high resistance and large deformation should be developed. Based on the test results and theoretical study, this paper proposes an energy-absorbing expandable rock bolt, which consists of the bar, sleeve, bolt plate, nut, and bolt end. The anchoring mechanism and its efficiency were systematically analysed in the laboratory and in practice: the anchoring mechanism and supporting density, especially the quantitative relationship, were deduced under the Energy Balance Theory, that is, $E_B=\frac{1}{2} n \cdot F_0\cdot(u_0+2\Delta u)$. As compared with the conventional bolt and large deformation bolts, the new type of bolt could provide a larger constant resistance, even in the soft rock roadway with large squeezing deformation, the pulling force can be achieved by $F=A \cdot \sigma \cdot f_2$, it mainly being generated by a normal stress acting on the pore surface. These characteristics are helpful in making the supported roadway safe. The amount of released energy during the large deforming process of the surrounding rock is expressed through conservation of energy, which can provide reference to the quantitative calculation of the bolt supporting system
Keywords: rock bolt; energy-absorbing; large deformation; constant resistance; action mechanism
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