3294 Behaviour of paddled energy-absorbing rockbolts under complex loading laboratory conditions
DOI:
https://doi.org/10.17159/Abstract
Since their introduction in 2010 paddled energy-absorbing rockbolts have been widely used in seismically active hard rock mines. This paper provides new data and reviews previous work to quantify the performance of paddled energy-absorbing rockbolts under controlled laboratory conditions. Of significance is the realisation that the typical split location in impact tests, at the centre between two paddle anchor points at best can provide an upper limit value. This inherent variability in performance under different testing configurations should be acknowledged and taken into consideration in the design of ground support in seismic conditions.
This paper discusses the reduction in capacity of paddled rockbolts as a function of loading angle from a maximum value during axial tests (0° loading angle) to the lowest value during pure shear (loading angle of 90°). A significant reduction in displacement capacity is observed as the loading angle changes between axial (0°) and 40°. Beyond a 40° loading angle up to shear (90°) loading the reduction in displacement capacity is less significant.
Due to the variances in the capacity observed through the variance of the testing configuration: loading mechanism, direction of loading, location / presence of a discontinuity, it must be recognised that results from laboratory-based testing is not independent of the testing configuration. This should be acknowledged when extrapolating anticipated performance in the field.
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