%0 Journal Article %T Presentation of Empirical Equations for Estimating Internal Friction Angle of GW and GC Soils in Mashhad, Iran Using Standard Penetration and Direct Shear Tests and Comparison with Previous Equations %A Salari, Pouya %A Lashkaripour, Gholam Reza %A Ghafoori, Mohammad %J Open Journal of Geology %@ 2161-7570 %D 2015