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Abstract. The article discusses the potential for using numerical simulation to assess the development of deformation and pore pressure changes in a levee as a result of the increase and decrease of the flood wave. The simulation made in FLAC 2D did not take into account the filter-erosion deformation associated with seepage in the levee. The simulations were carried out for a field experimental storage consisting of two combined levees, which was constructed with the help of homogeneous cohesive materials with different filtration coefficients. Calculated and measured pore pressure changes were analysed at 4 monitoring points. The water level was increased to 4 m in 96 hours and decreased in 120 hours. The characteristics of the calculated and measured pore pressure changes over time were similar. The maximum values of the calculated and measured pore pressure were almost identical. The only differences were the greater delay of the experimental levee response to changes in water level increase compared to the response of the numerical model. These differences were probably related to filtering-erosion effects during seepage in the levee.

In this study, we present the preliminary results of deep profiling of pore pressure in the near surface formations of the Carpathian flysch, on the Tęgoborze-Just landslide near Nowy Sącz in Southern Poland. The aim of the study is to identify zones with significant changes in pore pressure influenced landslide processes. These pore pressure changes correspond to a greater change in the degree of saturation or water flow paths. Profiling was performed in four series using a CPTU static probe with a NOVA Acoustic cone. The measurement of pore pressure in flysch formations is very complicated due to the strong heterogeneity of the medium properties and variable water conditions, which are strongly influenced by the intensity of precipitation. The tests were carried out in a colluvium to a depth of approx. 5.0 m, i.e. to the border of a less weathered bedrock, under varying water conditions. The results obtained indicate the presence of four zones of significant changes in pore pressure. The location of these zone is consistent with the location of the greater displacement measured with the inclinometer. There is a greater probability that these weak zones may form a rupture surface.

The slopes of open-pit mines are often at risk of failure. To identify this hazard, stability analyses are performed. An important element of these stability analyses is the reliable selection of input parameter values for the calculations. This selection is difficult because the slopes of the open pit are disturbed by mining activities. In such conditions, rheological processes, intensified by weathering, develop in open-pit slopes. This study is aimed at setting the strength parameters for the stability analysis of open-pit slopes with a developed slide process, using the random set method. The study was performed on the example of the open pit of the Bełchatów lignite mine, central Poland. A four-stage methodology, according to the random set method, was proposed. The methodology covered the following: site investigation, sensitivity analyses, shear strength reduction (SSR) analyses using numerical calculations, and probability analyses of the factor of safety (FoS) calculation results. The setting of the input parameters took into account the peak and residual strength parameters for each lithological unit in the physical model of the open-pit slope. Samples for laboratory tests were taken from the cores of nine test boreholes. The sensitivity analysis included all peak and residual strength parameters for each lithological unit in the body. As a result of the sensitivity analysis, specific strength parameters were adopted that would have a great impact upon the results of the calculations. Selected sets of parameter values were then used for the FoS calculations. The resultant FoS values revealed the probable slide planes. The positions of the slide planes were consistent with the interpreted slide surfaces based on the control boreholes and terrain observations. Knowledge of the slide planes positions and the values of the strength parameters enabled the designing of a securing approach for this landslide, and the taking of preventive measures to reduce this risk.

In this study, we present an analysis of the causes of a landslide along a railway track in the Polish Lowlands. The landslide damaged the railway track and caused significant material losses. Digital models of the terrain surface before and after the landslide were elaborated. Remote sensing using LIDAR aerial technique and a terrestrial laser scanner was performed to determine the morphology. Soil mass behaviour was analysed by 3D numerical simulation. A numerical model was created based on geotechnical tests. Taking into account the behaviour of the dry and wet models, the numerical simulation showed the most probable scenario of mass movement. The main reasons for the landslide were rainwater infiltration in the track basement and the unfavourable morphology of the area on which the railway embankment was located. The study demonstrates that combined methods—laser scanning, geotechnical testing of the soil material, and 3-dimensional numerical simulation—enabled the assessment of the causes of the analysed landslide.