Answer Happy

Question Barton's empirical equation for the shear strength, tp of a rough joint is given by JCS Tp = ₁ tan + JRC Log10 , tanto On Where On is the effective normal stress þú is the basic friction angle of a smooth joint surface JRC is the Joint Roughness Coefficient in the range 0 to 20 JCS is the uniaxial compressive strength of the joint wall material (a) A shear test on a smooth joint surface of sandstone at an effective normal stress of 0.8 MPa gave a shear strength of 0.47 MPa. Calculate the basic friction angle of this ro material. (10 marks) (b) A shear test on a fresh rough joint surface in the same sandstone at an effective normal stress of 0.8 MPa gave a shear strength of 0.75 MPa. Tests on the joint wall material gave a uniaxial compressive strength of 35 MPa. Calculate the Joint Roughne Coefficient for this joint. What are the units of JRC? (15 marks) (c) By graphical or other means, calculate the Coulomb shear strength parameters cohesion and angle of friction that are equivalent to the Barton shear strength model for this fresh rough joint surface over the effective normal stress range 1.5 to 2 MPa. (25 marks)