DESIGN AND ANALYSIS OF DEEP FOUNDATION

WEEK 10

• DESIGN OF BORED PILE

• DESIGN OF GROUP AND RAKE PILE

• PILE SETTLEMENT

Learning Outcomes

Student should be able to:

• Design bored pile. (CO3-PO10)

• Design pile group. (CO3-PO10)

• Design rake pile.(CO3-PO10)

• Estimate pile settlement (CO3-PO10)

Bored Pile Design

In Kenny Hill residual soil ie sedimentary soil

Fsu = KsNs

Fbu = KbNb

Chiu and Perumalawamy (1987) used Ks = 2.5 Kb = 50

When socketed into rock, the skin and end bearing shall be based On the allowable friction and end bearing values

Structural Capacity is taken as F = 0.25fcuAWhere fcu = concrete strength at 28 days

A = cross sectional area of bored pile

Optimise by designing geotechnical capacity to equal structural capacity

SETTLEMENT OF PILE

PILE SPACING

MINIMUN OF 3 DIAMETER CENTRE TO CENTRE OF PILE

FOR NON-CIRCULAR –CENTRE TO CENTRE SPACING

SHOULD BE AT LEAST BE SAME AS THE PERIMETER

LATERAL LOAD ON PILES

A pile resists lateral load by mobilising passive pressure of Surrounding soil.

The soil reactions depends on1) Stiffness of the soil2) Stiffness of the pile3) Fixity of the ends of the pile

Two categories:1) Short or rigid piles2) Long or elastic piles

Rake Pile

• Resist lateral loading in axial.