DETERMINATION OF PORE PRESSURE IN POORLY FILTERING SOILS BY LINEAR INTERPOLATION

Abstract

The article is devoted to the issue of definition in situ vertical effective stress in weakly filtering soils (WFS). Shown. that the calculation of the vertical effective stress in soils, taking into account the weighing action of water, is valid only for the special case of the hydrostatic distribution of pore pressure over depth. In this regard, it is proposed to determine the vertical effective stress by the difference between total and pore pressure, in accordance with the principle of effective stresses of K. Terzagi, as more universal. The existing variants of pore pressure calculations in weakly filtering soils are considered. The example shows that zeroing the pore pressure leads to an overestimation of the in situ effective stress in the WFS, and the hydrostatic distribution, as a rule, leads to its underestimation. A computational method for determining the vertical effective stress in the WFS by linear interpolation is presented. Formulas for determining pore pressure and vertical effective stress in the WFS layer are proposed. The features of the application of the interpolation method for different values of groundwater levels in aquifers in depth are considered. A necessary condition for calculating the pore pressure by interpolation is information about the level of groundwater in the underlying aquifer, which must be taken into account when performing engineering-geological surveys. Examples of comparison of the results obtained by various calculation methods with the data of direct measurements of pore pressure by the dissipation method and the method of filled wells are given. The analysis showed that the values of pore pressure in the WFS layers calculated by linear interpolation correspond to direct measurements of pore pressure to the greatest extent. Thus, the linear interpolation method is the most reliable calculation method and can be recommended for use when performing geotechnical calculations.