Prefabricated concrete piling (reinforced) and pre stressed concrete piling pipe (driven) affected by the ground water conditions.
Advantages:
1.Do not corrode or rot.
2.Are easy to splice. Relatively inexpensive.
3.The quality of the concrete can be checked before driving.
4.Stable in squeezing ground, for example, soft clays, silts and peats pile material can be inspected before piling.
5.Can be re driven if affected by ground heave. Construction procedure unaffected by ground water.
6.Can be driven in long lengths. Can be carried above ground level, for example, through water for marine structures.
Disadvantages:
1.Relatively difficult to cut.
2.Displacement, heave, and disturbance of the soil during driving.
3.Can be damaged during driving. Replacement piles may be required.
4.Sometimes problems with noise and vibration.
5.Cannot be driven with very large diameters or in condition of limited headroom.
Driven and cast-in-place concrete piling
Advantages:
1.Can be inspected before casting can easily be cut or extended to the desired length.
2.Relatively inexpensive.
3.Low noise level.
4.The piles can be cast before excavation.
5.Piling lengths are readily adjustable.
6.An enlarged base can be formed which can increase the relative density of a granular founding stratum leading to much higher end bearing capacity.
Disadvantages:
1.Heave of neighbouring ground surface, which could lead to re consolidation and the development of negative skin friction forces on piles.
2.Displacement of nearby retaining walls. Lifting of previously driven piles, where the penetration at the toe have been sufficient to resist upward movements.
3.Tensile damage to unreinforced piles or piles consisting of green concrete, where forces at the toe have been sufficient to resist upward movements.
4.Damage piles consisting of uncased or thinly cased green concrete due to the lateral forces set up in the soil, for example, necking or waisting. Concrete cannot be inspected after completion. Concrete may be weakened if artesian flow pipes up shaft of piles when tube is withdrawn.
5.Light steel section or Precast concrete shells may be damaged or distorted by hard driving.
6.Limitation in length owing to lifting forces required to withdraw casing, nose vibration and ground displacement may a nuisance or may damage adjacent structures.
