A prestressed concrete pile having a cross section 0.3 m by 0.3 m is driven 10 m into over consolidated clay. Soil properties determined by sampling and testing indicates that the soil unit weight is 17.5 kN/m3 and the shear strength cohesion, c, is 98 kPa. A load test is performed, and the load–settlement plot indicates the load to start a pile capacity failure (usually either when the maximum tolerable settlement is reached or when large settlements occur for small increases in loading) is 900 kN.

(This is a maximum safe load that should be assumed for the pile capacity; a design load capacity would be obtained by applying a factor of safety to that maximum safe load.) Perform a back analysis to obtain the alpha coefficient (α) that applies for the total stress method of analysis to determine capacity developed along the pile shaft. Use Equation 47 to determine the value of end bearing for the pile tip. (Compare computed value for α to values shown in Figure 33.)