Excavations and embankments are the most common ground transport structures, operational reliability and durability of which is determined by the stability of their sides and slopes. The first article deals with the features of stress-strain state and changes in stability of ground transport structures (excavations) based on modeling according to the certified program of finite element method GenIDE32. At modeling the layer-by-layer excavation of homogeneous soil from excavations with finite geometrical sizes was carried out. In the excavation edge array, in the field of displacement vector ui, appeared are poorly studied phenomena in the form of «rotation circles» or short vortices. These phenomena, discovered in model experiments (Yu.I. Soloviev, 1956), require detailed research in the future. Graphic results of the calculations performed allow one to see the appearance and development of zones of «plasticity» or limit state in the form of zones of «shift-compression», «compression-shift» and «stretching». Shift-compression zones and vice versa are shown as shaded finite elements at an angle crosswise, while stretch zones are shown as shaded vertically, horizontally and vertically, and horizontally finite elements. These zones, in the process of modeling, are drawn in the edges of the projections of a slide with vertical and horizontal cracks. The contours of the landslide prisms show themselves well when the average relative volume deformation values of ε are displayed on the screen. The display of this value in two colors defines the landslide contours in this figure. Sliding lines with the minimum value of the stability coefficient kst min pass near the borders, where values of this parameter are equal to zero. In this figure, in the upper part of the array, you can see the places where vertical cracks are formed. The analysis also uses graphs of stress-strain state trajectories in the space of stress tensor invariants σij and relative deformations εij in significant nodes and finite elements, located, including, in places of sliding lines with kst min. They make it possible to see from the volume and shape deformation graphs where the system with the calculated condition is located, for example, from the condition at which the body of the landslide was formed.
Off-standard soil-geological systems stability assessing issues under complex conditions is being discussed in this article. Modern methods and tools analytical review for assessing the embankment slope stability was performed here. Embankment work peculiarities in the areas of the permafrost soil spread were discussed in this paper. Special attention is paid to the embankments stability issue on a thawed foundation. The design features of the embankments on permafrost soils with the frozen soils preservation or partial thawing have been studied here. Two variations of sliding surface design-level static circuit are presented in this paper: base – earth bed and base – earth bed – road dressing. The main reasons that lead to the soil slopes stability loss of soil slopes are presented here. Based on the field research results, the embankment soil stress-related characteristics and the earth bed base were determined. Those results became the basis for embankment slope stability mathematical modeling and assessment. In software packages, GeoStab (demo) and Geo5 (educational license), based on the finite element method and the field research results, digital embankment models were built on a weak foundation. The «earth bed – road dressing» system stability calculation under the standard uniformly distributed load has been performed. Two system strengthening options are proposed to increase its stability: reinforcement with soil anchors and geosynthetic materials. The hypothesis sufficiency about the influence of the pavement road dressing state on the embankment stability was also tested here. Two models of the system and the base – earth bed – road dressing are discussed: without cracks on the track and with cracks on the track. It has been elucidated that coating imperfection affects the system stability only in the presence of medium or larger strength earthquakes. Recommendations for strengthening the embankment slopes operating in difficult soil-geological conditions were given in this article.
Excavations and embankments are the most common ground transport structures, operational reliability and durability of which is determined by the stability of their sides and slopes. The first article deals with the features of stress-strain state and changes in stability of ground transport structures (excavations) based on modeling according to the certified program of finite element method GenIDE32. At modeling the layer-by-layer excavation of homogeneous soil from excavations with finite geometrical sizes was carried out. In the excavation edge array, in the field of displacement vector ui, appeared are poorly studied phenomena in the form of «rotation circles» or short vortices. These phenomena, discovered in model experiments (Yu.I. Soloviev, 1956), require detailed research in the future. Graphic results of the calculations performed allow one to see the appearance and development of zones of «plasticity» or limit state in the form of zones of «shift-compression», «compression-shift» and «stretching». Shift-compression zones and vice versa are shown as shaded finite elements at an angle crosswise, while stretch zones are shown as shaded vertically, horizontally and vertically, and horizontally finite elements. These zones, in the process of modeling, are drawn in the edges of the projections of a slide with vertical and horizontal cracks. The contours of the landslide prisms show themselves well when the average relative volume deformation values of ε are displayed on the screen. The display of this value in two colors defines the landslide contours in this figure. Sliding lines with the minimum value of the stability coefficient kst min pass near the borders, where values of this parameter are equal to zero. In this figure, in the upper part of the array, you can see the places where vertical cracks are formed. The analysis also uses graphs of stress-strain state trajectories in the space of stress tensor invariants σij and relative deformations εij in significant nodes and finite elements, located, including, in places of sliding lines with kst min. They make it possible to see from the volume and shape deformation graphs where the system with the calculated condition is located, for example, from the condition at which the body of the landslide was formed.
This paper considers features in forming stress -strain state (SSS) and stability of soil transport structures (cut and embankment) on the basis of calculation with the certified finite element method (FEM) GenIDE32. Numerical calculations make it possible to see the whole process of modeling organization of a soil structure: places where “plasticity” zones appear and develop, gradual formation of a landslide body. The analysis of SSS uses graphs of changes of SSS trajectories in the space of invariants of stress tensor σij and relative deformations εij in important nods and finite elements located at the sliding lines. At each step of modeling stability of depression or embankment is evaluated. Many signs indicate the termination of the landslide body formation. Noted in figures and graphs evolution of a landslide prism allows one to understand where the system is from the condition at which the landslide body formed: kstmin=1,00±0,02≈[kst]=1,00.
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