POINT LOAD LUMP TESTS ON ROCKS

Abstract

In order to get uniaxial compressive strength of rock material quickly in the field, the point load test on irregular rock lumps is a quick and simple test. In this work comprehensive point load lump testing was carried out on nine rock types and point load lump strength index ( %50=P/(`,^ID )0'75 ~"5 ) for all rock types were computed. Point load tests on rock cores were also carried out with penetration measurement and point load strength (Is(50)) for cores were computed. Uniaxial compressive strength tests with deformation measurement were carried out on cylindrical rock core specimens by using universal compression testing machine of capacity 200 Tonnes. With these test-data, uniaxial compre- ssive strength (q0) and secant modulus of elasticity (E50) for various rocks were found out. For determining the dynamic elastic constants of rock, ultrasonic test was conducted. With these comprehensive test data, correlation between qc and IV 50), and between qc and Is(50) were developed. The correlation between L50 and (P50/350D) for cores, and E50 and (P50/50 for lumps L were also developed. This would help in finding out elastic constant of rocks; indirectly through point load testing with penetration measurement on rock cores or lumps. It is felt that the standard size(D) of rock lumps should be 5 cm as per ISRM Standard and thickness (D) of the sample should be less than 1.5 W. ~