Non-destructive testing of rock bolt fastening as an element of monitoring the state of mine workings
S. Skipochka1, O. Krukovskyi1, S. Serhiienko1, I. Krasovskyi1
1Institute of Geotechnical Mechanics named after M.S. Polyakov of the National Academy of Sciences of Ukraine, Dnipro, Ukraine
Min. miner. depos. 2019, 13(1):16-23
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Purpose. To substantiate the informative parameter, to develop the method and equipment for non-destructive testing (NDT) of rock bolt fastening, as an element of geomechanical monitoring of the mine workings state.
Methods. Analytical and bench experimental testing of shock-wave processes in the “rock bolt – bonding layer – rock massif” system.
Findings. It has been established, that the non-destructive shock-wave method is the most satisfying for monitoring the geomechanical state of the “rock bolt – bonding layer – rock massif” system. This method is based on the registration and analysis of rock bolt oscillations, caused by non-normalized hit to the rock bolt end. It has been confirmed, that the most informative parameter is the relaxation time, that is the time over which the amplitude of oscillations decreases by “e” times. It has been shown, that clamping of the resin-grouted rock bolt in massif and its tensioning affects the relaxation time of damped oscillations. Furthermore, the relaxation time is inversely proportional to the degree of the rock bolt clamping, and is linked linearly with an increase in the rock bolt tensioning. The spectral composition of wedge shaped rock bolts self-oscillations, which are caused by impact excitation, depends both on the nature of clamping and on the rock bolt length, and makes it possible to identify the rock bolts by their length.
Originality.The existence of a special type of damped longitudinal oscillations of the rock bolt in viscoelastic medium of the bonding layer has been established. The relaxation time of the specified type of oscillations was chosen as an informative parameter. An analytical link has been established between the informative parameter of shock-wave method of monitoring and the main indicators of rock bolt fastening quality: the degree of adhesion with massif and tension value.
Practical implications. The method has been improved and equipment has been developed for non-destructive testing of rock bolt fastening, which makes it possible to control in-situ the rock bolt fastening quality, including the geomechanical state monitoring of mine workings.
Keywords: mine working, monitoring of state, rock bolt, non-destructive testing, method, equipment and methods of control
Bastami, M., Shahriar, K., & Ghadimi, M. (2017). Verification of the analytical model for fully grouted rock bolts based on pull-out test (case study: Tabas coal mine). Procedia Engineering, (191), 1068-1074.
Blanco-Martín, L., Tijani, M., Hadj-Hassen, F., & Noiret, A. (2013). Assessment of the bolt-grout interface behaviour of fully grouted rockbolts from laboratory experiments under axial loads. International Journal of Rock Mechanics and Mining Sciences, (63), 50-61.
Forbes, B., Vlachopoulos, N., Hyett, A.J., & Diederichs, M.S. (2017). A new optical sensing technique for monitoring shear of rock bolts. Tunnelling and Underground Space Technology, (66), 34-46.
He, C., Van Velsor, J.K., Lee, C.M., & Rose, J.L. (2006). Health monitoring of rock bolts using ultrasonic guided waves. AIP Conference Proceedings, 820(1), 195-201.
Ivanovic, A., & Neilson, R.D. (2013). Non-destructive testing of rock bolts for estimating total bolt length. International Journal of Rock Mechanics and Mining Sciences, (64), 36-43.
Kang, H., Yang, J., & Meng, X. (2015) Tests and analysis of mechanical behaviors of rock bolt components for China's coal mine roadways. Journal of Rock Mechanics and Geotechnical Engineering, 7(1), 14-26.
Li, C.C. (2017). Rockbolting: principles and applications. London, England: Butterworth-Heinemann.
Li, C.C., Kristjansson, G., & Høien, A.H. (2016). Critical embedment length and bond strength of fully encapsulated rebar rockbolts. Tunnelling and Underground Space Technology, (59), 16-23.
Liu, X., Wang, J., Huang, J., & Jiang, H. (2017). Full-scale pullout tests and analyses of ground anchors in rocks under ultimate load conditions. Engineering Geology, (228), 1-10.
Moridi, M.A., Sharifzadeh, M., Kawamura, Y., & Jang, H.D. (2018). Development of wireless sensor networks for underground communication and monitoring systems (the cases of underground mine environments). Tunnelling and Underground Space Technology, (73), 127-138.
Shi, Z.M., Liu, L., Peng, M., Liu, C.C., Tao, F.J., & Liu, C.S. (2018). Non-destructive testing of full-length bonded rock bolts based on HHT signal analysis. Journal of Applied Geophysics, (151), 47-65.
Skipochka, S.I., Serhiienko, V.N., & Krasovskyi, I.S. (2017). Rationale of mounting quality control parameters for anchors in rocks by vibroacoustic method. Metallurgical and Mining Industry, 304(1), 106-110.
Skipochka, S.I., Sergienko, V.N., & Krasovskiy, I.S. (2018). Rationale of improved method of anchorage impact-wave control. Up-to-Date Resource- and Energy-Saving Technologies in Mining Industry, 21(1), 47-55.
Tamrakar, S.B., Asaue, H., Shiotani, T., Chang, K.C., & Fujiwara, Y. (2018). In situ ultrasonic method for estimating residual tension of wedge fix type anchors. Construction and Building Materials, 189(20), 1184-1190.
Thenevin, I., Blanco-Martín, L., Hadj-Hassen, F., Schleifer, J., Lubosik, Z., & Wranab, A. (2017). Laboratory pull-out tests on fully grouted rock bolts and cable bolts: results and lessons learned. Journal of Rock Mechanics and Geotechnical Engineering, 9(5), 843-855.
Voznesenskiy, A.S., Koryakin, V.V., & Voznesenskiy, E.A. (2016). Physico-technical evaluation of shock response spectrum method for strata bolting control. Gornyi Zhurnal, 2224(3), 17-20.
Wang, S., Hagan, P., & Cao, C. (2016). Advances in rock-support and geotechnical engineering. London, England: Butterworth-Heinemann.
Zhao, Y., & Yang, M. (2011). Pull-out behavior of an imperfectly bonded anchor system. International Journal of Rock Mechanics and Mining Sciences, 48(3), 469-475.
Zou, D.H., & Cui, Y. (2011). A new approach for field instrumentation in grouted rock bolt monitoring using guided ultrasonic waves. Journal of Applied Geophysics, 75(3), 506-512.