DESIGN ESTIMATION OF THE ULTIMATE LOAD-HOLDING CAPACITY OF GROUND ANCHORS

Following a brief description of the four major types of cement grout injection anchor used in current practice, empirical design methods for the estimation of the ultimate pull-out capacity of the grouted fixed anchor zone are presented. The design rules which have been created solely through systematic full scale testing and from general field experience are discussed in relation to rocks, cohesionless soils and cohesive soils. Topics for further investigation are highlighted such as load transfer mechanisms, grout pressure limits, fixed anchor load/displacement relationships and serviceability safety factors. The importance of construction technique and quality of workmanship are emphasised since they influence pull-out capacity and limit the designer's ability to make accurate predictions. (Author/TRRL)