List of top Geotechnical Engineering Questions on Deep foundations

In the context of pavement material characterization, the CORRECT statement(s) is/are

A group of 9 friction piles are arranged in a square grid maintaining equal spacing in all directions. Each pile is of diameter 300 mm and length 7 m. Assume that the soil is cohesionless with effective friction angle \(\phi' = 32^\circ\). What is the center-to-center spacing of the piles (in m) for the pile group efficiency of 60%?

A square concrete pile of 10 m length is driven into a deep layer of uniform homogeneous clay. Average unconfined compressive strength of the clay, determined through laboratory tests on undisturbed samples extracted from the clay layer, is 100 kPa. If the ultimate compressive load capacity of the driven pile is 632 kN, the required width of the pile is \(\underline{\hspace{2cm}}\) mm. (in integer)
(Bearing capacity factor \( N_c = 9 \), adhesion factor \( \alpha = 0.7 \))
A group of total 16 piles are arranged in a square grid format. The center-to-center spacing (s) between adjacent piles is 3 m. The diameter (d) and length of embedment of each pile are 1 m and 20 m, respectively. The design capacity of each pile is 1000 kN in the vertical downward direction. The pile group efficiency \( \eta_g \) is given by: \[ \eta_g = 1 - \frac{\theta}{90} \left[ (n-1)m + (m-1)n \right] \frac{1}{mn} \] Where m and n are the number of rows and columns in the plan grid of pile arrangement, and \( \theta = \tan^{-1} \left( \frac{d}{s} \right) \). The design value of the pile group capacity (in kN) in the vertical downward direction is _________ \text{. (round off to the nearest integer)}