FACTORS INFLUENCING THE EFFECTIVENESS OF SPLIT SET FRICTION STABILIZER BOLTS

Many underground mining operations use Split Set fiction stabilizer bo lts for rock support Currently, however, little has been done to quant ify the effects of various rock mechanics and operational parameters o n the capacity of frictional supper? systems. The strength of Split Se ts is usually measured by means of a pull test wherein a jacking force is applied to the boil and a slip load is obtained. In order to evolv e a rational design procedure for this type support, an extensive data base of over 900 pull test results from more than 50 mines through-out North America has been assembled and analyzed. Associated relevant ra ck mechanics parameters (rock type and quality) and operational detail s (drilling method, bit size, drive lime, lime to pull test) were also obtained as completely as possible, for each lest. Analysis of the in formation has yielded several charts that relate pull-out strength to relevant parameters and simple statistical analyses were conducted whe re necessary. Quantified distributions for pull-out strength were also produced for several operating conditions. The factors that most sign ificantly affect boil strength have been identified and specific appli cations to design are discussed. The information presented will assist mining engineers in designing safer and more economic support using S plit Sets.