## Pile tip torsional capacity

## Pile tip torsional capacity

(OP)

I was reading a paper which stated the pile tip torsional capacity was as follows:

T

Where:

T

π = pi (3.14...)

D = Pile diameter

L = Pile length

γ = Material unit weight (concrete in the example)

δ = Interface friction angle at pile tip

I understand where everything apart from the (D/3) part comes from. Can anyone shed some light on what the (D/3) part relates to/how it is derived?

EDIT: Essentially the above comes down to:

T

Where:

τ = shear stress

I'm not sure why shear stress is multiplied by D/3.

T

_{t}= π.(D/2)^{2}.L.γ.(D/3).tan(δ)Where:

T

_{t}= Pile tip torsional capacityπ = pi (3.14...)

D = Pile diameter

L = Pile length

γ = Material unit weight (concrete in the example)

δ = Interface friction angle at pile tip

I understand where everything apart from the (D/3) part comes from. Can anyone shed some light on what the (D/3) part relates to/how it is derived?

EDIT: Essentially the above comes down to:

T

_{t}= τ.(D/3)Where:

τ = shear stress

I'm not sure why shear stress is multiplied by D/3.

## RE: Pile tip torsional capacity

www.qsystemsengineering.net

## RE: Pile tip torsional capacity

I can't actually remember the reference now, I'm afraid.

## RE: Pile tip torsional capacity

π.(D/2)2: the pile end area;

π.(D/2)2xL.γ: the contact vertical force between the pile end and the soil

π.(D/2)2xL.γ*tan(δ): the contact shear force between the pile end and the soil

D/3: the force arm.

## RE: Pile tip torsional capacity