Structural Engineering

Pile penetration ratio and chisel energy level are two methods that are used to decide on the termination of pile depth in the construction site:

1. Pile Penetration Ratio (PPR) for Rotary Piling

Equation for the determination of pile termination point in construction site:

PPR=(2⋅π⋅N⋅T⋅t)/(A⋅d)                           Equation 1

PPR: Pile penetration ratio, kN m/m^2/ cm

N: RPM

T: Torque corresponding to RPM, kN.m

t: Time duration in minutes, normally 10 min

A: Pile cross-section area, m^2

D: Pile penetration, cm

2. Chiseling Energy Concept

Use the following expression to estimate the response of founding rock strata in terms of Energy Level:

E=(W⋅h⋅n⋅N)/(A⋅d)                         Equation 2

Where:

E: Chisel energy level, kN.m/m^2/cm

W: Weight of chisel, kN

h: Fall of the chisel in meters given in every blow (m)

n: Reduction factor, 0.8–1.0 based on likely drag on chisel due to slurry, submerged weight of chisel in high groundwater, winch rope friction, and type of muck (clayey or sandy), based on rock type.

N: No. of blows in the stipulated duration, usually half an hour

A: Nominal pile cross-sectional area, m^2

D: Penetration into the rock strata in that stipulated duration, cm