Experimental and Numerical Study of the Dynamic Mechanical Behavior of Fully Grouted GFRP Rock Bolts

Due to good corrosion resistance and high tensile strength, glass fiber-reinforced plastic (GFRP) bolts are widely used in mining operations. However, GFRP bolts are susceptible to blast load damage, so it is important to understand their dynamic mechanical behavior. This experiment constructed a dynamic testing system to simulate the in situ rock bolt dynamic loading conditions. Using strain gauges, the axial load signals at different locations along the bolt were recorded and the corresponding axial stresses were analyzed. Moreover, a numerical model was established to analyze the axial stress distribution along the bolt under dynamic loading. The results showed that the maximum axial stress of GFRP bolt occurs at the bolt collar position and increases approximately linearly as the impact load increases. The axial stress decreased within a short distance from the bolt collar position following approximately an exponential function. In addition, the stronger the mechanical properties of the surrounding rock, the faster the axial stress decreases along the bolt and the greater the increasing rate of the maximum axial stress with an increase of the impact load. The location and increased characteristics of the maximum axial stress in metal and GFRP bolt were similar, but the dynamic load significantly affected the existence range and decreasing rate of axial stress in GFRP bolts than in metal bolts.