Ouestion $1$:

The soil layers beneath the ground surface of a proposed building site are as follows: $($i$)$ Medium sand,

with a thickness of $2m$ and ${}_{\text{s}\text{a}\text{t}}=20k\frac{N}{m^3}$; $($ii$)$ Clay, with a thickness of $2m$ and $=19k\frac{N}{m}$; $($iii$)$

Coarse sand with confined aquifer, the water pressure of the confined aquifer is $2\mathrm{.}0m$ above the ground

surface $({}_w=10k\frac{N}{m^3}).$ The ground water table is at a depth of $1m$ below the ground surface. Answer

the following questions:

$($a$)$ When the excavation depth reaches $1m,$ is there any risk of heaving at the bottom of the

excavation?

$($b$)$ The groundwater level is lowered within the medium sand layer to excavate the soil and place the

foundation at a depth $1\mathrm{.}5m$ bottom. For ensuring that that there are no construction problems, how

many meters should the confined water level within the coarse sand layer be lowered?

Coarse sand with confined aquifer in this layer