In previous researches, to avert the aggravation of pile penetration
during embankment filling, end-bearing piles such as CFG piles were not recommended to reinforce the soils with low shear strength.
Feng and Deschamps  used the finite difference program, FLAC, to simulate the pile-hammer-soil system in which several variables including soil strength, pile-soil interface friction angle, lateral earth pressure coefficient, hammer operating frequency, bias weight, hammer centrifugal force, and pile embedment were examined to assess their relative importance in pile penetration rate.
Stopwatches with the precision of 0.01 s are used to record penetration time, and the time per half one meter of pile penetration is recorded; besides, a camera is fixed to record the pile sinking process for checking in later.
Their study focused on small scale laboratory tests where the horizontal and vertical chamber pressure, the number of hammer blows, pile penetration
depth ratio, and mean normal stress of the soil were set as inputs of the network model while the ultimate bearing capacity was selected as the model output.
The pile penetration
depth under the maximum tensile force was also computed by the Japanese bridge construction standard (2002), API recommended practice 2A-WSD, AASHTO, and Broms' analysis method.
--layer 1, thickness 10.0 m, pile penetration
in this layer is 5.0 m (to bottom of pile);