The initial effective stresses on a saturated soil element at a certain depth in a soil mass are ${}_1^{{?}^{\text{'}}}=$

$80$kPa,${}_2^{\text{'}}=$

$40$kPa, and ${}_3^{\text{'}}=40$kPa. The groundwater level is below the depth of the soil element. A

sudden outward movement of a retaining wall that was retaining the soil resulted in the

following changes in stresses: ${}_1=0$kPa,

parallel to wall