INSTRUMENTED FULL-SCALE RE-USABLE LABORATORY APPARATUS FOR ROCK ANCHORAGE TESTING

Whilst data acquired in the field are invaluable to the understanding of anchorage behaviour in a rock mass, a full-scale re-usable instrumented laboratory model offers a controlled and reproducible tool for investigating in greater detail the load transfer mechanisms of the tendon bond length within the fixed anchor during stressing. The broad objectives of gunbarrel testing are (i) to study load transfer and failure mechanisms of modelled fixed anchors within a rock mass, (ii) to determine grout/steel bond values for different tendon configurations, and (iii) to establish a data base for future physical modelling for comparative purposes and to assist in the validation of theoretical models. The purpose of this paper is to introduce the key elements of a re-usable gunbarrel apparatus. To illustrate the output of instrumented gunbarrel testing, data and typical analyses are presented for 4No 15,2mm diameter parallel strands (Tult = 1200kN) bonded over a 3m length in a 76mm diameter borehole in simulated "weak mudstone". (A) For the covering abstract see IRRD 898458.