Geostatic Stress, Uplift Pressure
Stress analysis is based on the existence of soil layers specified by the user during input. The program further inserts fictitious layers at the locations where the stress and lateral pressure (GWT, points of construction, etc.) change. The normal stress in the ith layer is computed according to:
where: | hi | - | thickness of the ith layer |
γi | - | unit weight of soil |
If the layer is found below the groundwater table, the unit weight of soil below the water table is specified with the help of input parameters of the soil as follows:
- for option "Standard" from the expression:
where: | γsat | - | saturated unit weight of soil |
γw | - | unit weight of water |
- for the option "Compute from porosity" from the expression: |
where: | n | - | porosity |
γs | - | specific weight of soil | |
γw | - | unit weight of water |
where: | V | - | volume of soil |
Vp | - | volume of voids | |
Gd | - | weight of dry soil |
Unit weight of water is assumed in the program equal to 10 kN/m3 or 0.00625 ksi.
Assuming inclined ground behind the structure (β ≠ 0) and layered subsoil the angle β, when computing the coefficient of earth pressure K, is reduced in the ith layer using the following expression:
where: | γ | - | unit weight of the soil in the first layer underground |
γi | - | unit weight of the soil in the ith layer underground | |
β | - | slope inclination behind the structure |