QUESTION $6$

$($a$)$ Define the term vertical pressure as applied in soil mechanics $.$

$(1$ mark$)$

$($b$)$ What are the components that make up the vertical pressure in a soil under equilibrium conditions $($ when water is not flowing$)?$

$(2$ marks$)$

$($c$)$ Write the equation that links vertical pressure with these two components. $(1$ mark$)$

$($d$)$ A layer of sand $4,5m$ deep overlies a thick layer of clay. The water table is $2m$ below the top of the sand. Above the water table, the sand has an average void ratio of $0,52$ and an average degree of saturation of $0,37.$ The clay has a water content of $42\%.$

Calculate the total, effective and pore water pressures on a horizontal plane $9m$ below the ground surface $.$

$(21$ marks$)$