chapter  12
Estimation of the static vertical subgrade reaction modulus ks from CPT
ByN. Barounis, J. Philpot
Pages 6

A methodology for the estimation of the static vertical subgrade reaction modulus (ks ) for cohesionless soils from the Cone Penetration Test (CPT) has been introduced in 2013 (Barounis et al.) and 2015 (Barounis and McMahon) and has recently been integrated (Barounis and Philpot, 2017). In this paper, the conclusions from the early two papers are utilized for developing an integrated methodology based on the correlation between qc and N60 (Robertson, 2012). The fundamental concepts and the theory of the proposed methodology are presented with a step-by-step procedure in this paper. The methodology returns one value termed KF, which is the equivalent spring stiffness for any foundation depth and shape under consideration. The methodology produces values that are as conservative as the traditional SPT approach proposed by Scott (Scott, 1981). The methodology is applied on numerous sandy sites in New Zealand for different foundation typologies.