the longer embedment lengths was by slippage the yield strength of the 34 swellex 34 bolt material was exceeded table 1______________________________________summary of laboratory tension testslong short peakembedment m embedment m load kn ______________________________________1 5 0 50 801 5 0 75 1001 5 1 00 1101 5 1 25 120______________________________________ a series of tests was designed to compare the performance of rock bolts according to the invention with the standard 34 swellex 34 in both axial tension and shear the results for axial tension tests are summarised in fig3 and the results obtained in the shear tests are summarised in fig4 these results show that the bolt of the invention can be arranged to achieve a range of axial load transfer and shear strengths this ability is consistent with the requirements of a variety of reinforcement applications for excavations in jointed rock this range of mechanical properties can be achieved whilst maintaining a consistent and quality assured reinforcement installation in practice reinforcement devices are subject to combined axial and shear loading caused by opening and shear of the discontinuities which they reinforce it is therefore particularly important that bolts of the invention have a high shear strength combined with adequate resistance to axial loading the preliminary tests have used a standard 34 swellex 34 bolt for inflation and outer split tubes made from steel this has dictated the range of sizes used for the bolts it will be appreciated however that the size of the bolt.