Special distribution of water pressure

Special distribution of water pressure

This option allows an independent (manual) input of distribution of loading due to water at the back and in front of structure using ordinates of pore pressure at different depths. The variation of pressure between individual values is linear. At the same time it is necessary to input levels of tables of full saturation of a soil at the back h₁ and in front h₂ of structure including possible decrease of unit weight δ_y in front of structure due to water flow.

Example: Two separated horizon lines of ground water.

There are two permeable layers (sand or gravel) with one impermeable layer of clay in between, which causes separation of two hydraulic horizon lines – see figure:

Example of pore pressure distribution

The variation of pore pressure above the clay layer is driven by free ground water table GWT₁. The distribution of pore pressure below the clay layer results from ratio in the lower separated ground water table GWT₂, where the ground water is stressed. The pore pressure distribution in clay is approximately linear.

The capillary attraction is in the analysis reflected only by increased degree of saturation, and therefore the value of γ_sat is inserted into parameters of soils.

To distinguish regions with different degree of saturation, one may insert several layers of the same soil with different unit weights. Negative pore pressures are not considered. However, for layers with different degree of saturation it is possible to introduce values of shear resistance influenced by suction.