Abstract:
This research is focused on finding the correlation of unconfined
compressive strength (UCS) with Point load Index (PU) of gneissic rocks, and to
propose proper correlating value, based on a study carried out for Sri Lankan
Gneissic rocks. There has been an increasing use of the PU as a measure of :rock
strength since its introduction in 1972. The small size and the simplicity of the point
load tester have led to its use on site in many projects. The rock samples were
obtained from three rock quarries in the Western Province. Using the results of
laboratory testing of gneissic rocks under point loading as well as in Uniaxial
Compression, and statistical analysis, different conversion factors relating UCS and
PU are determined for each quarry. The sample preparation and testing arc
conducted according to the ASTM code. Exactly 206 individual test results, from 3:1
distinct rock units were used. The conversion factor between UCS and PLI of the
study is found to be between 9 and 14. The results of the study are useful to find the
strength of rocks conveniently through point load testing
