Effect of Finished Ground
If the original terrain, from which the CPT tests were carried out, is excavated before piles performing, the measured values of cone resistance qc are reduced due to a decrease of the geostatic stress at all test points as follows:
Where: | qc,i,red | - | reduced cone resistance in the ith layer |
qc,i | - | original cone resistance in the ith layer | |
χi | - | reduction coefficient in the ith layer |
Reduction coefficient χi is determined as follows:
Where: | σz,i | - | original geostatic stress in the ith layer |
σd | - | original geostatic stress in the place of finished ground (in the depth d) | |
σCPT | - | original geostatic stress in the place of first point of CPT test |
Cone resistance reduction due to effect of finished ground
In case, that CPT test were carried out on the finished ground, cone resistance values are not reduced.