Sebastian Olesiak and Joanna Hydzik-Wiśniewska
The paper evaluates the effectiveness of reinforcing a damaged earth structure with making counterfort drains in its slope. The system of counterfort drains changed the soil properties significantly over a long-term use. The evaluation was based on many years of field and laboratory tests and stability analysis. The field tests concerned the observation of N WST probing resistance change, and the laboratory tests concerned the change in soil consistency and water content. The paper presents the results of tests that were conducted over 13 years.
The article attempts to develop a preliminary practical framework for urban criteria in terms of the population, economy and spatial location of the smallest towns in Poland. Despite being of little significance, the fact that they lie near the border between being rural settlements and towns makes them an interesting subject for research and more detailed analysis. The current phenomenon of urban status being obtained by ever-smaller settlements is causing conceptual disorder. Therefore, the article may serve as an early contribution to a discussion about the need to define and unify urban criteria on a national scale. The qualitative and descriptive guidelines contained in official acts are insufficient and too general, which is why quantitative methods were used in the present research. Despite the limited data available, research on the topic of urbanity has proven the imperfection of the Polish administrative system and confirmed the premise that town status may be conferred inappropriately in numerous cases.
Soumia Bellil, Khelifa Abbeche and Ouassila Bahloul
The study of collapsible soils that are generally encountered in arid and semi-arid regions remains a major issue for geotechnical engineers. This experimental study, carried out on soils reconstituted in the laboratory, aims firstly to present a method of reducing the collapse potential to an acceptable level by treating them with different levels of bentonite–cement mixture while maintaining the water content and degree of compactness, thus reducing eventual risks for the structures implanted on these soils. Furthermore, a microscopic study using scanning electron microscopy was carried out to explore the microstructure of the soil in order to have an idea of the phenomena before and after treatment. The results show that treatment with a bentonite–cement mixture improves the geotechnical and mechanical characteristics, modifies the chemical composition of the soil, reduces the collapse potential and the consistency limits. The microstructural study and the X-ray energy dispersive spectroscopy analysis clearly illustrate an association of elementary particles in the soil aggregates, whereby the arrangement of these aggregates leads to the formation of a dense and stable material.
Jolanta Anna Prusiel and Krzysztof Gierej
The article presents the analysis of complex stress states in the concrete structure of grain silos, caused by non-centric emptying. The authors present a combination of loads from the pressure of bulk solid on the silo chamber according to Eurocode 1, Part 4 , which should be taken into account when emptying on large eccentricities in action assessment class 3 (AAC3) silos. For the example of a cylindrical wheat silo with a height of 25 m and a diameter of 10 m, the researchers carried out an analysis regarding the impact of the size of the eccentric discharge outlet on the distributions of forces and bending moments in a reinforced concrete wall.
Joanna Maria Badach, Anna Stasiak and Andrzej Baranowski
In civil societies, urban movements are one of the tools in the process of spatial governance. In Poland, urban activism is beginning to develop together with a budding participation in public life. Therefore, there is a need to assess the scope and effects of the urban movements’ actions. The aim of the study was to determine and evaluate their impact on the spatial development in three Polish cities - Poznań, Gdańsk and Gdynia, especially in regard to the procedures in local urban planning and the process of participation. On the basis of the data collected during research and community interviews conducted in these cities, the following factors were analysed: the background and current profile of urban movements, the extent, regularity and effectiveness of their actions, the planning and spatial development initiatives undertaken, their cooperation with the local authorities and their contribution to the enhancement of participatory mechanisms.
In the present manuscript, unsteady magnetohydrodynamic (MHD) flow over a moving porous semi-infinite vertical plate with time-dependent suction has been studied in the presence of chemical reaction and radiation parameters. Time-dependent partial differential equations in the dimensionless form are solved numerically through mathematical modelling in COMSOL Multiphysics. The results are obtained for velocity, temperature and concentration profiles at different times. Steady state results are also presented for different values of physical parameters. The parameters involved in the problem are useful to change the characteristics of velocity, heat transfer and concentration profiles. The numerical solution of partial differential equations involved in the problem is obtained without sacrificing the relevant physical phenomena.
There are many classifications of atmospheric circulation types. In Poland, the most important one, used by Polish weather services, is the classification of circulation types developed by Lityński. This paper proposes four modifications to the currently used algorithm for determining atmospheric circulation types. The proposed algorithms have been compared and it has been shown which one produces a catalogue of circulation types in which the division of the distribution of the values of the three indices (the zonal index Ws, meridional index Wp and cyclonicity index Cp) into three classes is the closest to being equally likely. In 1986-2015, the classification scheme that deemed to be the best, differed in above 19% of cases from the currently used classification.
In this work, the input-output method of dynamic parameters' identification is experimentally tested. A method based on the transformation of a dynamic problem into a static problem by means of integration of the input and output signal was presented. The problem discussed in this article is the identification of the coefficients of stiffness matrices and eigenfrequencies of a discrete dynamic system subjected to kinematic input. The experimental analysis was carried out on a three-storey slab-and-column structure, which constitutes a physical model of a building. The vibrations of the model were excited kinematically by an earthquake simulator. The device has a computer-controlled, movable table top, which can move independently in three directions, that is, horizontally, vertically, and rotationally around the vertical axis.
Agnieszka Joanna Sosnowska
Plant succession is quite a common phenomenon in Poland, especially in agricultural landscapes. At the turn of the 21st century there was a significant increase in the area of fallow lands. That increased the area occupied by ruderal and segetal vegetation. The development of vegetation on post-agricultural lands transforms soils. The aim of this paper is to determine changes in vegetation and soil properties that occur as a result of secondary succession on post-agricultural lands in loess landscapes