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Abstract By physical model test，the response of end-anchored rockbolt close to working face is studied under blasting loading in mass charge. The dynamic strain measured from strain gauges mounted on rockbolts are obtained considering gauge?s locations on rockbolts and distances from working face. And then，the measured data are analyzed. The results show that：(1) Rockbolts vibration approximately ceases after duration of 5 ms. And the initial wave is either tensile wave or compressive wave. (2) After blasting，the residual deformations exist on the rockbolts. The maximum residual strain appears on the free segment of rockbolts? tail，while the maximum dynamic tensile strain appears on the anchoring segment of rockbolts? middle. When the total strain is divided into axial strain and bending strain，it is found that：(1) The main deformation of rockbolt close to working face under blasting load is bending deformation；and the axial deformation is small relatively. (2) The rockbolts are bending after blasting. And the frequency and magnitude of bending strain wave apparently decrease with the increase of distance. Based on wavelet packet theory，vibration frequency distribution of rockbolt caused by blasting is analyzed. The analysis also proves the attenuation law of vibration frequency of rockbolt. Comparison with previous field test results indicates that the strain waves measured in model test reflect the dynamic response of engineering rockbolts on the whole
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Received: 31 December 2010
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2011, Vol. 30 
