5.8 Bearing capacity from Cone Penetration Test (CPT) results
Various empirical methods have been proposed in the literature to estimate the bearing capacity of shallow foundations directly from in situ cone penetration tests. One of the more recent ones was proposed by Eslaamizaad and Robertson (1996), who recommend calculating the bearing capacity in terms of stress of footings on coarse-grained soils as:
(5.54) 
where qc,average is the average cone resistance below the footing foundation level along a depth z = B. The shape conversion factor Kφ (from cone resistance to footing bearing resistance) ranges between Kφ = 0.16 to 0.30 depending on the ratio B/Df , the shape of the footing and sand density and is given in Figure 5.50. However, given the uncertainties underlying this method it is recommended here to use Eq. 5.54 together with the lower bound value of the shape conversion factor Kφ = 0.16.
For fine-grained soils under undrained loading conditions, Eslaamizaad and Robertson (1996) proposed to calculate the bearing capacity in terms of stress as:
(5.55) 
where qc,average is again the average cone resistance over the influence depth defined above and KSu ranges between KSu = 0.30 to 0.60 depending on the ratio B/Df, the shape of the footing and OCR. It is proposed again to conservatively use Eq. 5.55 with the lower bound value KSu = 0.30.
