(a) Explain the applications of low strain and high strain dynamic pile load tests. (b) A 0.8 m diameter concrete pile is driven at a site as shown in Figure below, where the water table is at the ground surface. The pile's design uplift load is 800 kN. Assume No is 35 for the sand layer. Pile-soil interaction factor a in clay is 0.6. Pile-soil interface friction angle in sand is 75% of the friction angle of sand.
(i) Determine the pile's required length to support the uplift load if the factor of safety is 2.5. Note: Round pile length to the nearest 0.5 m.
(ii) Check whether the calculated pile length is sufficient to carry an axial load of 2 MN with a factor of safety of 3.0. (iii) If 10 piles are used with a pile cap as a group, calculate the axial load carrying capacity of the pile group. The centre to centre spacing between piles in the group is 1.0 m.