Geostatistical approach for statistical descripion of uplift pressures: Part I

The possibilities of the use of structural reliability analysis in concrete dam design and assessment is investigated in Sweden. For such analysis, statistical descriptions of the loads and resistances are necessary. Uplift pressure has a large impact on safety, and is difficult to quantify. This paper describes the methodology of a geostatistical approach to simulate the uplift pressure, and an example is given of the results. In ‘Geostatistical approach for statistical description of uplift pressures: Part II’, these results are described in more detail. In the approach used, simulation of the hydraulic conductivity beneath the concrete dam (2D) was performed by means of geostatistics. The spatial dependence was described using a variogram, and input data was the mean value, and variance, of the hydraulic conductivity and spatial range. For a given field of hydraulic conductivity a finite element model could be used to derive the uplift pressure, uplift force and uplift moment. Since the variance and spatial range was unknown, a thorough sensitivity analysis was performed by analyzing twenty-nine combinations of variance and range. For each combination, 1000 realizations of random fields of the hydraulic conductivity were derived, and the uplift was found for each. The resulting histograms for uplift force and uplift moment were best fitted to a Beta distribution. For increasing range, the uplift force distribution transforms from narrow and normal-like to wide and rectangular in shape, while the uplift moment distribution becomes more triangular