The evaluation of slopes stability of Poltava river valleys loess plateau


  • S. V. Bida Yuri Kondratyuk Poltava National Technical University, Poltava

Abstract

 The geological structure of the Poltava loessial plateau (tableland) is characteristic of Central Ukraine. From the plateau top there occur loessial soils that are underlain by water-resistant clay layers. On the overlying bed of clay layers there occurs the discharge of subsoil waters on river valley slopes. Flows of groundwater negatively affect loessial soils, compromising their strength. The with stand ability of slopes breaks and distortions happen. It is impossible to have the measure of the slope’s durability using standard methods for determination of soil strength characterization. Due to the analysis of flow-induced effect of groundwater aquifers on loessial soils we have found out the mechanism of their load-yield curve change. The object of this work was to carry out the model analysis of stress-strain state of the slope of Poltava loessial plateau in order to estimate its durability taking into account these mechanisms. To simulate the soil we have chosen the model of elastoplastic structure, which gained widespread currency thanks to easy handling and quite high accuracy of calculation. The implementation of such model by means of finite-element technique allows creating the computational domain of desired configuration and size, to take into account the peculiarities of soil bedding and to give every engineering-geological element its strength characteristics. So as to size up the with stand ability, we have simulated stress-strain state of the slope, situated in Poltava-town, in the off-street Instytutskyi proriz, using the plane elastic problem. The computational domain of the slope is presented as a polygon, which upper edge repeats the profile of the slope. We have chosen the size of calculation zone in such a way, so that interface conditions would not influence the development of landslides. After the creation the calculation area is divided by the finite element mesh. The choice of the mesh density is made based on the analysis of design model and development zone of plastic deformations. Infill drilling is made if necessary and in the places, where the strain-stress state has to be estimated with maximum precision. The calculation data have given an opportunity to evaluate the with stand ability of the slope with consideration for the stress reduction of loessial soils and to receive the pattern of soil slip development. The formation of slicken sided surface, moving direction and bulk up of the soil were completely on a par with soil slip development in the real situation. We have ascertained, that with stand ability coefficient in such a case is 0,84, while in the case of defining the with stand ability of the slope using with stand ability characteristics, received by means of standard techniques, the with stand ability coefficient is 1,54. Thus, we have confirmed the correctness of with stand ability characterization, received with the help of structural strength method, taking into account the influence of the seepage flow of groundwater aquifers.Keywords: slopes, landslide, loess soils, the characteristics of strength, the coefficient of stability

Author Biography

S. V. Bida, Yuri Kondratyuk Poltava National Technical University, Poltava
Yuri Kondratyuk Poltava National Technical University, Poltava

References

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Published
2016-05-31
How to Cite
Bida, S. (2016). The evaluation of slopes stability of Poltava river valleys loess plateau. Journal of Geology, Geography and Geoecology, 24(1), 13-19. https://doi.org/https://doi.org/10.15421/111602