GATE 2023 Soil Mechanics & Foundation Engineering Quiz 69

The diameter of enlarged bore or bulb for under reamed piles used in expansive soils is generally taken as

Consider the following statements,

1). Settlement of individual pile can be greater than settlement of pile group.

2). Under–reamed pile is designed as bearing pile.

Which of the above statements is/are correct?

A nine-pile group arranged in a square pattern is used as a foundation for a column in sand. Piles are 300 mm in diameter and placed at a spacing of 900 mm in each direction. What will be the settlement of pile group, if the settlement of single pile is 5 mm ?

Statement 1: The skin friction resistance of pile is higher in stiff clays than in soft clays.

Statement 2: The value of adhesion coefficient (α) is smaller in stiffer over consolidated clays.

What is the value of negative skin friction for a group of 4 piles of 30 cm diameter, 8 m long and spacing 70 cm c/c and having undrained shear strength of soil as 30 kN/m²? (Take unit weight of soil as 16 kN/m³)

A concrete pile has size 40 cm × 40 cm, ultimate load carrying capacity of pile is 1200 kN,  and ∝ is 50 kN/m² and 0.6 respectively. What is the length of pile?