Max dia 600mm [ IS 2911 PART(1) SEC(1) ]
As the name suggests, driven pile are installed by driving a casing pipe whose outer diameter represents nominal diameter of the pile. The casing pipe is driven by single acting drop hammer wih the required height of fall determined by the state of compaction of the soil strata.This is obtained from the soil investigation report based on the N-value. Once the casing reaches the hard strata beyond which the rate of penetration is very small (This is termed as set. The set is defined as the penetration for a given number of blows; say for example this can be 10mm for the final 10 blows) concrete is poured with the help of chute cart, and the casing is extracted progressively, simultaneously tamping the tube as the tube is extracted.
The three main advantages are:
* The state of compaction is assessed as the tube is driven by observing the number of blows required for a constant depth of penetration
* The energy imparted to the soil by driving the tube compacts the surrounding soil which helps in the increase of friction capacity of the pile
* The tamping of the tube while extraction creates serrations in the pile shaft which ensures the mobilization of the shaft friction.