The regression equation for sandy soils is almost identical to

Equation 7.2 which included all the test data. The correlation for the

clayey soils is poor. This poor correlation tends to agree with obser-

vations of Jamiolkowski et al. (50) that qc cannot be correlated to any

drained soil modulus for cohesive deposits.

 The combined test data was also separated into above and below

water table categories for the purpose of assessing whether or not the

saturation state of the soils affected the ED-qc correlations. The

regression equation for above water table conditions,


 ED = 3.64 qc Eqn. 7.5


 (R2 = 0.926, N = 102)



 is similar to Equation 7.3 for sandy soils. The equation obtained for

 soils below water table,


 ED = 3.946 qc Eqn. 7.6


 (R2 = 0.778, N = 122)



 is almost the same as Equation 7.4 for cohesive soils. It is evident

 that the correlations were affected by the development of excess pore

 water pressures in the clayey soils during penetration. An attempt was

 made to measure pore water pressures using the piezocone. This was

 unsuccessful due to the clogging of the porous stone by fine sand

 particles.