Application of numerical modelling to the comprehensive analysis of slope stability

Paper deals with the comprehensive methodology for the numerical simulation of potentially unstable slopes combining engineering geological, hydrological, hydrogeological and geotechnical computational model for the assessment of slope stability. Engineering geological model based on available survey data characterizes the rock environment using individual quasi-homogenous units. Model is defined on the basis of documented lithostratigraphic units in exploration probes and field relief documented by advanced methods, including satellite radar interferometry and laser surface scanning. On the basis of engineering geological model, the hydrological model using MIKE SHE software (Finite Difference Method) was performed. Hydrological model includes simulation of surface runoff, evapotranspiration and flow in unsaturated near-surface zone. The model was calibrated on the basis of available field data. Outputs from this model were used as input initial conditions of the following hydrogeological model. Software FEFLOW based on the Finite Element Method was subsequently used to the creation of hydrogeological model focused on the water flow and distribution of pore pressures of groundwater in individual quasi-homogeneous units in saturated zone. The infiltration condition determined by the hydrological model is considered and a flow model with variable saturation is applied. Finally, the geotechnical stability model of slope following the engineering geological, hydrological and hydrogeological models was performed. The occurrence of plastic and failure zones (assuming elastic-perfectly plastic Mohr-Coulomb constitutive model) inside the slope was simulated by using software MIDAS GTS NX based on the Finite Element Method. Stability factor SSRF (Shear Strength Reduction Factor) is evaluated based on the Shear Strength Reduction Method) as the ratio of actual shear strength and minimum shear strength required to maintain stability. Paper deals also with the comparison of stability factor of natural slope obtained from 3D and 2D numerical model. Generally, in the case of natural slope the condition of plane strain is not fulfil, 2D model is not realistic and 3D model is needed, especially in case of concave morphology of slope

Numerical simulation of the thermal response of seabed sediments to geothermal cycles in Suvilahti, Finland

Renewable thermal energy from seabed sediment is used for heating and cooling houses in Suvilahti, Vaasa, Finland. Innovative coaxial polyethylene pipes (Refla) filled with heat collection fluid are laid horizontally in the sediment layer. This study aims to evaluate the adequacy and possible overuse of this shallow geothermal energy. This entailed a numerical analysis of the heat relations of a “coaxial closed-loop geothermal system (CCGS)" to investigate the thermal behavior of the sediment. The numerical model was developed in Midas GTS NX software with a thermal analysis module. The objective was to understand temperature fluctuation in the sediment, which is influenced not only by geothermal energy exploitation, but also by seasonal weather. The numerical model, due to its design, provided information mainly about changes in sediment temperature due to the geothermal energy exploitation during the different seasons. The results show that in the first third of the total length of the Refla pipes, the sediment environment is significantly affected by energy exploitation's temperature loading. It is advisable to exclude the first third from an analysis of total geothermal energy reserves. The remaining two-thirds of the length shows potential to provide sustainable, long-term geothermal energy (GE) exploitation at the current rate.© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed

A rigorous variant of the shear strength reduction method and its geotechical applications

This paper is focused on a new optimization variant of the shear strength reduction (OPT-SSR) in non-associated Mohr-Coulomb plasticity. The OPT-SSR method mimics the limit analysis problem and enables to compute the factor of safety without performing an elasto-plastic analysis. It is shown that this optimization problem is well defined and closely related to recently developed Davis approaches used in combination with the standard SSR method. Next, the duality between the static and kinematic principles of OPT-SSR is introduced. For the numerical solution, a regularization method is suggested

Application of numerical modelling to the comprehensive analysis of slope stability

Paper deals with the comprehensive methodology for the numerical simulation of potentially unstable slopes combining engineering geological, hydrological, hydrogeological and geotechnical computational model for the assessment of slope stability. Engineering geological model based on available survey data characterizes the rock environment using individual quasi-homogenous units. Model is defined on the basis of documented lithostratigraphic units in exploration probes and field relief documented by advanced methods, including satellite radar interferometry and laser surface scanning. On the basis of engineering geological model, the hydrological model using MIKE SHE software (Finite Difference Method) was performed. Hydrological model includes simulation of surface runoff, evapotranspiration and flow in unsaturated near-surface zone. The model was calibrated on the basis of available field data. Outputs from this model were used as input initial conditions of the following hydrogeological model. Software FEFLOW based on the Finite Element Method was subsequently used to the creation of hydrogeological model focused on the water flow and distribution of pore pressures of groundwater in individual quasi-homogeneous units in saturated zone. The infiltration condition determined by the hydrological model is considered and a flow model with variable saturation is applied. Finally, the geotechnical stability model of slope following the engineering geological, hydrological and hydrogeological models was performed. The occurrence of plastic and failure zones (assuming elastic-perfectly plastic Mohr-Coulomb constitutive model) inside the slope was simulated by using software MIDAS GTS NX based on the Finite Element Method. Stability factor SSRF (Shear Strength Reduction Factor) is evaluated based on the Shear Strength Reduction Method) as the ratio of actual shear strength and minimum shear strength required to maintain stability. Paper deals also with the comparison of stability factor of natural slope obtained from 3D and 2D numerical model. Generally, in the case of natural slope the condition of plane strain is not fulfil, 2D model is not realistic and 3D model is needed, especially in case of concave morphology of slope

Experimental Analysis of Stresses in Subsoil below a Rectangular Fiber Concrete Slab

<p>This paper is focused on sensitivity analysis of the behavior of subsoil foundation systems by considering the variant properties of a fiber concrete slab that result in different relative stiffness of the whole cooperating system. The character of the slab and its properties are very important for the character of external load transfer. However, the character of the subsoil also cannot be neglected because it determines the stress-strain behavior of the entire system and, consequently, the bearing capacity of the structure. The sensitivity analysis was carried out based on experimental results, which included both the stress values in the soil below the foundation structure and settlements of the structure that are characterized by different quantities of fibers in it. Flat GEOKON dynamometers were used for the stress measurements below the observed slab, the strains inside the slab were registered by tensometers, and the settlements were monitored geodetically. This paper is focused on the comparison of soil stresses below the slab for different quantities of fibers in the structure. Results obtained from the experimental stand can contribute to more objective knowledge of the soil-slab interaction, the evaluation of real carrying capacity of the slab, the calibration of corresponding numerical models, the optimization of quantity of fibers in the slab and finally, contribute to higher safety and more economical designs of slabs.</p&gt