34 d 34 of the pile 10 should be sufficient however given the inherent uncertainty of these theoretical studies the laboratory and field tests were conducted to verify the results type of granular material 20 various sand and small gravels were tested sand and gravel placement was carried out in both wet and dry environments for the dry samples the sand was placed primarily by raining through a tube fitted with a sieve the sieve enhanced the placement technique causing the sand to pack in a denser and more homogenous manner in the wet environment the sand was fluviated through a column of water and was allowed to seek equilibrium independent of any external influences the results from these tests indicated that the 34 lock up 34 behavior did occur for example pressures up to 1 000 000 psf were supported by sand columns about 1 6 feet long or about 6 5 times the diameter of the model pile further the load applied was fully carried by shear transfer from the granular material to the pile walls as no cap or other obstruction was placed on top of the sand or gravel the same parameters used in the laboratory experiments were varied in the field tests the sand or gravel was.