Unload Pull-out Test of Full-length Grouted Bolts in Slope Reconstruction and Expansion


  • Jiang Guan
  • Feng Zhongju Highway School, Chang’an University, Xi’an 710064, China
  • Ruixin Zhao Highway School, Chang’an University, Xi’an 710064, China
  • Zhangzhengxu Zhangzhengxu Shandong Hi-speed Group, Jinan 250014, China
  • Junqiang Wen Highway School, Chang’an University, Xi’an 710064, China




The Unloading Pull-out Test Method (UPTM) is proposed to evaluate the residual stress of existing anchorage systems and explore the actual stable state of the slope before excavation. A series of destructive pull-out tests are applied to detect the working state of the existing rock bolts. The working load and ultimate load of the existing bolts are determined by field test measurement of the P-S curve. The experimental result showed that a displacement increment of the bolts was present in the elastic stage, the elastoplastic stage, the slip stage, and the debonding stage. The working load and the ultimate load were in the elastoplastic stage and the debonding stage respectively. The working load of the bolts is closely related to the sliding deformation. The ultimate load of the bolts, however, is only related to the design parameters, slope lithology and other factors. After 20 years of natural forces acting on the bolts in the slope, their ultimate bearing capacity had a stress loss of 24.0% ~ 32.0%.


Yu, H., Wang, Y. & Zou, C., Study on Subgrade Settlement Characteristics After Widening Project of Highway Built on Weak Foundation, Arabian Journal for Science & Engineering, 42(1), pp. 1-10, 2017.

Liu, C.H. & Li, Y.Z., Research Progress in Bolting Mechanism and Theories of Fully Grouted Bolts in Jointed Rock Masses, Chinese Journal of Rock Mechanics and Engineering, 37(8), pp. 1856-1872, 2018.

Zhong-ju, F., Yanmin, Z. & Xuechi, G., Safety Evaluation Model of Excavating Rock Slope Based on Entropy-Grey Correlation Method, Journal of Traffic and Transportation Engineering, 20(02), pp. 55-65, 2020.

Carter, T., De Graf, P. & Booth, P., Innovative Design for A Challenging Highway Widening Project in Hong Kong, Better Highways Through Applied Geology Highway Geology Symposium. San Luis Obispo, California 2002.

Bao, X.K., Liu, H.H. & Liang, L.J., Development States and Existing Problems Research of Nondestructive Testing of Bolt, Applied Mechanics and Materials, 580-583, pp. 1223-1226, 2014.

Suh, D.M. & Kim, W.W., A New Ultrasonic Technique for Detection and Sizing of Small Cracks in Studs and Bolts, Journal of Nondestructive Evaluation, 14(4), pp. 201-206, 1995.

Ito, F., Nakahara, F. & Kawano, R., Visualization of Failure in A Pull-Out Test of Cable Bolts Using X-ray CT, Construction and Building Materials, 15(5), pp. 263-270, 2001.

Martin, L.B., Tijani, M. & Hadj-Hassen, F., A New Analytical Solution to the Mechanical Behaviour of Fully Grouted Rockbolts Subjected to Pull-Out Tests, Construction and Building Materials, 25(2), pp. 749-755, 2011

Xu, J.M. & Gu, L.Y., Testing Study on the Peak Shear Strength Between Grout and Bore Wall in the Interior Bond Section of Prestressed Anchorage Cable, Chinese Journal of Rock Mechanics and Engineering, 23(22), pp. 3765-3769, 2004.

He, R.L., Zhang, P. & Li, N., Working Mechanism of Fully Grouted Bolt in Pull-out Working State, J. Cent. South Univ. (Science and Technologic), 37(2), pp. 401-407, 2006.

You, C.A., Zhan, Y.B. & Liu, Q.Y., Shear Lag-Debonding Model for Anchorage Section of Prestressed Anchor Cable, Chinese Journal of Rock Mechanics and Engineering, 32(4), pp. 800-806, 2013.

Zhou, D., Analysis of Mechanical Effects of Bonding Anchors in Layered Stratum, Geotechnical Engineering Technique, 26(1), pp. 28-30, 2012.

Kaiser, P.K., Yazici, S. & Nosé, J., Effect of Stress Change on the Bond Strength of Fully Grouted Cables, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 29(3), pp. 293-306, 1992.

Hyett, A.J. & Bawden, The Effect of Rock Mass Confinement on the Bond Strength of Fully Grouted Cable Bolts, International Journal of Rock Mechanics & Mining Sciences & Geomechanics Abstracts, 29(5), pp. 503-524, 1992.

Sano, H., Shono, T., Sonoda, H., Takatsu, T., Ciucchi, B., Carvalho, R. & Pashley, D. H., Relationship Between Surface Area for Adhesion and Tensile Bond Strength - Evaluation of a Micro-Tensile Bond Test, Dental Materials, 10(4), pp. 236-240, 1994.

Laura, B.M., Michel, T. & Faouzi, H.H., Assessment of the Bolt-Grout Interface Behavior of Fully Grouted Rock Bolts from Laboratory Experiments Under Axial Loads], International Journal of Rock Mechanics & Mining Sciences, 63, pp. 50-61, 2013.

He, S.M. & Li, XP., Study on Mechanism of Prestressed Anchor Bolt, Chinese Journal of Rock Mechanics and Engineering, 25(9), pp. 1876-1880, 2006.

Duan, J., Yan, Z.X. & Guo, R.J., Failure Analysis of Soil Anchors Induced by Loose Interface Under Pullout Load, Chinese Journal of Geotechnical Engineering, 34(5), pp. 936-941, 2012.

Guo, R.J., Chen, W.W. & Duan, J., Pullout Mechanical Analysis of Soil Anchor Based on Softening Behavior of Interface], Journal of Central South University (Science and Technology), 43(10), pp. 4003-4009, 2012.

Zhang, K., Yang, Q. & Jiang, J.C., Numerical Simulation of Fully-grouted Rock Bolt Under Pull-out Load, Journal of Dalian University of Technology, 53(5), pp. 710-714, 2013.

Kihc, A., Yasar, E. & Celik, A.G., Effect of Grout Properties on the Pull-Out Load Capacity of Fully Grouted Rock Bolt, Tunnelling and Underground Space Technology, 17(4), pp. 355-362, 2002.

Kilic, A., Yasar, E. & Atis, C.D., Effect of Bar Shape on the Pull-out Capacity of Fully-Grouted Rockbolts, Tunnelling and Underground Space Technology, 18(1), pp. 1-6, 2003.

Singh, D.R., Mishra, A.K. & Agrawal, H., Performance Evaluation of Fully Grouted Rock Bolt in an Indian Hard Rock Underground Mine, Indorock, 2016.

Na, C.A., Hwa, B., & Mjb, C., DEM Investigation of Rock/bolt Mechanical Behaviour in Pull-out Tests, Particuology, 52, pp. 10-27, 2020.

Jiang, M., Jiang, T. & Crosta, G.B., Modeling Failure of Jointed Rock Slope with Two Main Joint Sets Using a Novel DEM Bond Contact Model, Engineering Geology, 193, pp. 79-96, 2015.

Jiang, M., Sun, C. & Rodriguez-Dono, A., Influence of Time-Dependence on Failure of Echelon Rock Joints Through a Novel DEM Model, Revue Française de Génie Civil, 19(sup l), pp. 108-s118, 2015.