REINFORCEMENT MECHANISMS OF ROCK BOLT: A LABORATORY INVESTIGATION

Abstract

The use of rock bolts as rock reinforcement is becoming more popular in Malaysia.
However, its effectiveness depends on a number of factors particularly with regards to the
technique of installing the bolt. Its reinforcement mechanism also restricts its application for
certain modes of instability and types of rock. This paper highlights a laboratory investigation on
the reinforcement mechanisms of rock bolts, specifically on bolt inclination, anchorage type and
level of pre-tension. The investigation was conducted using a physical model of a rock bolt
intersecting a joint plane. Results obtained show that a better reinforcement can be obtained if bolt
is inclined at an angle to the joint plane so that it elongates upon joint displacement. Full-bonded
bolt is more superior in terms of mobilising the anchorage capacity and consequently, this allows
for immediate utilisation of the reinforcing element. Pre-tensioning of bolt induces clamping effect
on joint surface consequently, helps to reduce joint dilatation and increases the inherent shear
strength of the joint.