Determination of strength variation in jointed anisotropic rocks behavior using UCS and Brazilian Tensile test

Abstract

Abstract The objective of this study is to determine the variations of strength on anisotropic rock using Uniaxial Compressive Strength (UCS) and Brazilian Tensile Strength (BTS) tests. The variability and distribution of UCS and BTS values were statistically estimated using measured strength of rock. The strength obtained was later to correlate with the quality of rock mass zones. The location of study is at the Ulu Jelai Hydroelectric Dam project, Cameroon Highland, the NW corner of Pahang on the upper reaches of the Sg. Bertam downstream of the existing Sultan Abu Bakar Dam and east of the township of Ringlet. The study is essentially required due to the exposure of sheared bedrock in the mylonite zones beneath the proposed dam. Six (6) boreholes were drilled at different depths along the dam foundation and 23 cores were collected and tested using the UCS and BTS tests. Simple regression analysis was conducted and a wide range of data on uniaxial compression strength and tensile strength of the rock were tabulated. The correlation between UCS and BTS obtained in this experiment is moderately correlated with R2 = 0.8066. Based on the UCS and BTS results, the overall range of UCS was in between 0.9 and 96.0 MPa and tensile strength range is between 0.5 and 14.31 MPa. For further correlation, UCS and Young’s Modulus were studied to shows good reliability (R2 = 0.818). The distribution of UCS data of each borehole is affected by the anisotropic rock behaviour that controls the quality of rock mass zoning.