Presentation of Empirical Equations for Estimating Internal Friction Angle of SP and SC Soils in Mashhad, Iran Using Standard Penetration and Direct Shear Tests and Comparison with Previous Equations. 10 [Internet]. 2015 May 30 [cited 2026 Aug. 12];4(5):89-95. Available from: https://archive.conscientiabeam.com/index.php/10/article/view/1938