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| Numerical experimental study on dynamic pullout of rockbolt grouted structures under confining pressure |
| YU Shuisheng1,2, ZHANG Hongsen1, SUN Yuzhou2,3, ZHAO Yi1,2, LU Shucan1
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1. School of Intelligent Constructionand Civil Engineering, Zhongyuan University of Technology, Zhengzhou 451191, Henan, China;
2. Henan Engineering Research Center of Mechanics and Engineering Structures, Zhengzhou 451191, Henan, China;
3. Henan University of Urban Construction, Pingdingshan 467036, Henan, China |
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Abstract To investigate the dynamic mechanical response of rockbolt grouted structures under confining pressure, the load transfer characteristics and damage mechanisms were analyzed, and the influence of confining pressure on the dynamic bond strength enhancement effect of rockbolts was elucidated. Numerical and experimental studies on the pullout behavior of rockbolt grouted structures under various confining pressures and loading rates were conducted.The results showed that under confining pressure, the maximum pullout load of the rockbolt increased with the loading rate, and the bonding interface exhibited significant loading rate dependence and shear enhancement characteristics.At high loading rates, the local strain at the bond interface was increased during the softening phase, while the dynamic shear stress was found to fluctuate, with the fluctuating concave point shifting closer to the loading end due to the restraining effect of the confining pressure. The fluctuation amplitude was enhanced with increasing confining pressure, attributed to the improved bearing capacity of the grouted body.A positive correlation was identified between the relative bond strength and the logarithmic rate ratio, and the bond performance of the rockbolt was found to be more sensitive to the loading rate under higher confining pressure. After yielding, the slope of the relationship curve was increased by only 11.96% when the confining pressure was raised from 0.5 MPa to 1.0 MPa, indicating that the enhancement effect of confining pressure on the dynamic bond strength of the rockbolt tended toward saturation. The dynamic peak slip of the rockbolt initially increased and subsequently decreased as the confining pressure was elevated. Localized damage to the grouted body was progressively generated, and the failure zone was observed to extend toward the concrete surface.
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Published: 29 December 2025
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