Dd. Tannant et al., ROCKBOLT BEHAVIOR UNDER DYNAMIC LOADING - FIELD-TESTS AND MODELING, International journal of rock mechanics and mining sciences & geomechanics abstracts, 32(6), 1995, pp. 537-550
Citations number
15
Categorie Soggetti
Geosciences, Interdisciplinary","Mining & Mineral Processing
Knowledge of rockbolt response under dynamic loading conditions is imp
ortant when rockbolts are used to support ground subjected loads from
blasts, earthquakes or rockbursts. Dynamic strain measurements from st
rain gauges mounted on end-anchored rockbolts and velocity measurement
s from geophones mounted on the rock surface were recorded during two
different blasts. These blasts caused peak particle velocities in the
rock exceeding 1 m/sec but maximum dynamic stresses in the bolts were
well below the yield point of the steel. The measurements were analyse
d by analytical methods and a numerical model which was developed to e
xplain the measured rockbolt variations resulting from the dynamic loa
ding caused by the blasts. The numerical model developed for this stud
y is a one-dimensional finite difference representation of a mechanica
l system involving the following components: the wave source, the rock
mass, the mechanical rockbolt, and the anchor and head connections. Th
e measured strains on the rockbolts and the dynamic movement of the ro
ck surface were closely simulated by the numerical model. Both axial a
nd lateral free vibrations were excited in the rockbolts by the dynami
c loading and the vibrations persisted much longer than the ground mot
ions. Damping al the connections between the rockbolt and the rockmass
at the anchor and the plate influence the transfer of the stress wave
from the rock to the bolt and the resulting frequency of vibrations i
n the rockbolt.