ABSTRACT
As per Fig. 15.10, the value of Le/d is about 25 for </J equal to 45° and it decreases with a decrease in the angle of friction </J. Normally, the magnitude of Lb/d for piles is greater than 0.5 (Le/d) so that maximum values'of Neand Nq may apply for the calculation of qb' the unit bearing pressure of the pile. Meyerhof prescribes a limiting value for qb' based on his findings on static cone penetration resistance. The expression for the limiting value, qbl' is
for dense sand: qbl = 50 Nq tan </J kN/m2
for loose sand: qbl = 25 Nq tan </J kN/m2 (15.19a) (15.19b)
where </J is the angle of shearing resistance of the bearing stratum. The limiting qbl values given by Eqs (15.9a and b) remain practically independent of the effective overburden pressure and groundwater conditions beyond the critical depth.
