$(30$ Points$)$ A bored nil turbines support a wind shewn in the figure below. The load of the wind turbine is approximately $250$ tons. Our company has only one drilling machine with a diameter of $0\mathrm{.}65m.$ If the pile tip is to be socketed into the dense sand layer, please:,

a$)$ Calculate tip capacity of the pile, $(5$ Points$)$

b$)$ Calculate skin friction capacity of the pile in sand layer using the $$ method for the section in clay layer$)(10$ points$)$

culate skin friction capacity of the pile in sand layer using the $$ method for the section in clay layer. $(10$ Points$)$

d$)$ Calculate the minimum number of piles needed to carry the wind turbine load safely? $(5$ Points$)$

$0\mathrm{.}65m$