Cite this paper
Salari, P. , Lashkaripour, G. and Ghafoori, M. (2015) 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. Open Journal of Geology
, 231-238. doi: 10.4236/ojg.2015.55021
 McGregor, J. and Duncan, J.M. (1998) Performance and Use of the Standard Penetration Test in Geotechnical Engineering Practice. Report of CGPR, Virginia Polytechnic Institute, Blacksburg.
 Shioi, Y. and Fukui, J. (1982) Application of N-Value to Design of Foundation in Japan. 2nd ESOPT, Vol. 1, 40-93.
 Silva, S.D., Wightman, E.N.R. and Kamruzzaman, M. (2010) Geotechnical Ground Investigation for the Padmamain Bridge. In: Amin, Okui, Bhuiyan, Eds., IABCE-JSCE Joint Conference on Advances in Bridge Engineering-II, Dhaka, Bangladesh, 8-10 August 2010, 427-436.
 Hettiarachchi, H. and Brown, T. (2009) Use of SPT Blow Counts to Estimate Shear Strength Properties of Soils: Energy Balance Approach, Journal of Geotechnical and Geoenvironmental Engineering, 135, 25-32.
 Jianguo, C. (2012) Correlation Analysis of SPT N Values and Cohesion and Internal Angle of a Clay. Soil Engineering and Foundation, 26, 91-93.
 Kaliniski, M. (2011) Soil Mechanics Lab Manual. 2nd Edition, John Wiley & Sons, Inc., Hoboken.
 Mohammad, M. (2013) Reliability of Standard Penetration Test (SPT) in Predicting Properties of Silty Clay with Sand Soil. International Journal of Civil and Structural Engineering, 3, 85-94.
 Bowles, J.E. (1988) Foundation Analysis and Design. 4th Edition, McGraw Hill.
 Budhu, M. (2011) Soil Mechanics and Foundation. 3rd Edition, John Wiley & Sons, Inc., Hoboken.
 FHWAO-IF-03-17 (2003) Geotechnical Engineering Circular, No.3, Soil Nail Walls.
 Aggour, M.S. and Radding, W.R. (2001) Standard Penetration Test (SPT) Correction. Research Report, Civil and Environmental Engineering Department, University of Maryland College Park, Maryland, 20742.
 Soil and Structure Consulting Engineers Company (2014) Geotechnical Reports of Vakilabad Region Projects.
 Rad, M. (2008) Engineering Statistics and Probabilities. Publications of Hafiz and Tafresh University, Tafresh.
 Isotalo, J. (2001) Basics of Statistics. University of Tampere, Tampere.