SOIL MECHANICS AND FOUNDATION ENGINEERING-III (CE 434)

PILE FOUNDATIONS  Classification based on the function  End bearing piles  Friction piles  Compaction piles  Tension piles or uplift piles  Anchor piles  Fender piles or dolphins  Batter piles  Sheet piles

 Classification based on materials and composition  Concrete piles  Precast  Cast in situ  Driven piles: Cased or Uncased  Bored piles: pressure piles and under reamed piles  Timber Piles  Steel Piles  H-piles  Pipe piles  Sheet piles  Composite piles  Concrete and timber  Concrete and steel

BEARING CAPACITY OF DEEP FOUNDATION  Theoretical Approach  Pile Load Test Approach  The Pile Driving Resistance Approach

Theoretical Approach Soil Type Clean sand Silty sand Sandy silt

Problem  A 600mm diameter pile is to be installed at a site that is characterized by two sand layers. The top layer is 12m thick, has a  =20kN/m 3 and  =30 0. The bottom layer is 20m thick, has a  =22kN/m 3 and  =35 0. The ground water table is at the ground surface. Compute the Unit End Bearing and the Unit Skin Friction at depths of 10, 15, 20 and 25m below the ground surface. Use N q =20 for  =30 0 and N q =50 for  =35 0. Take  =  and K=1.0. Also Calculate the Ultimate Load of the Pile if the length of the pile is 25m.

Pile Load Test Approach

Problem  Data from a pile load test on a 300mm diameter pile is given below. Determine the design load on the pile. Load (kN) Settlement (mm)