rss_2.0Studia Geotechnica et Mechanica FeedSciendo RSS Feed for Studia Geotechnica et Mechanica Geotechnica et Mechanica 's Cover bearing capacity of shallow strip footing embedded in slope resting on two-layered soil<abstract><title style='display:none'>Abstract</title><p>In this paper, the limit equilibrium method with the pseudo-static approach is developed in the evaluation of the influence of slope on the bearing capacity of a shallow foundation. Particle swarm optimisation (PSO) technique is applied to optimise the solution. Minimum bearing capacity coefficients of shallow foundation near slopes are presented in the form of a design table for practical use in geotechnical engineering. It has been shown that the seismic bearing capacity coefficients reduce considerably with an increase in seismic coefficient. Be sides, the magnitude of bearing capacity coefficients decreases further with an increase in slope inclination.</p></abstract>ARTICLE2021-09-07T00:00:00.000+00:00Laboratory tests and analysis of CIPP epoxy-resin internal liners used in pipelines – part I: comparison of tests and engineering calculations<abstract> <title style='display:none'>Abstract</title> <p>Tests that were carried out in order to obtain knowledge of the actual values of strength parameters obtained by CIPP liners that are used to repair pipelines. Specimens of liners made of high quality polyester felt cured with epoxy resin were subjected to tests. The scope of the performed studies corresponded with the scope of acceptance tests, which are carried out in the investment process during quality control of renovation works. Specimens of liners taken from sewers with 3 different diameters, i.e. 200mm, 350mm and 500mm were selected as representative for underground sewage networks. The obtained results enabled the calculations carried out in the course of design work to be verified, and differences between the model values of the strength parameters obtained from the calculations, and real values that are burdened with irregularities resulting from the conditions prevailing at a construction site and which were obtained for specimens taken from their built-in locations to be compared.</p> <p>The tests confirmed that it is possible to renovate - using CIPP liners - sewers with a lot of structural and material damage that negatively affects a liner‘s geometry. The implementation of the reinforcing internal coating in a sewer enables its further safe operation. The direct application value of the research involves the enlargement and clarification of knowledge concerning the actual load-bearing capacity of CIPP liners.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Safety analysis of the Żelazny Most tailings pond: qualitative evaluation of the preventive measures effectiveness<abstract> <title style='display:none'>Abstract</title> <p>In this paper, a qualitative safety analysis of the Żelazny Most tailings pond is addressed. This object is one of the largest facilities of this type in the world being a crucial element in the technological line of copper production in KGHM Polska Miedź S.A. The assessment of the effectiveness of two types of preventive measures, i.e., relief wells and loading berms, is investigated based on displacement and stability analysis of two 2D cross-sections in a technical section of the dam. The study shows that the considered preventive measures generally have a positive impact on increasing the safety level of the structure during its further raise. In particular, their effectiveness is most evident when they are applied simultaneously. It is eventually suggested that the selection of final solutions to be applied on the facility should be based on the quantitative 3D analysis.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Application of the thermoporoelasticity model in numerical modelling of underground coal gasification influence on the surrounding medium<abstract> <title style='display:none'>Abstract</title> <p>The purpose of this paper was to present the thermoporoelasticity model adapted for application in modelling processes, where phase transition may occur, such as during underground coal gasification (UCG). The mathematical model of the medium (soil/rock with pores filled with liquid/gas) in non-isothermal conditions is based on Biot's poroelasticity model. The poroelasticity model is expanded here by the influence of temperature and adjusted to the case where both liquid and highly compressible fluid are present in pores by using the gas laws. This requires considering temperature-dependent physical quantities such as pore fluid density, heat transfer coefficient and viscosity as functions of temperature. Based on the proposed mathematical model and the finite element method, a numerical model was built for the purpose of computing processes occurring in the vicinity of the UCG generator. The result of the authors’ work is a three-dimensional (3D) model, which was not only modified, but derived straight from the laws of thermodynamics, where fields of displacement, temperature and fluid flow are coupled. The model makes it possible to determine results significant to modelling of the UCG process, the reach of the gaseous phase's presence in pores, subsidence values, temperature distribution and directions and rate of seepage, without losing the simplicity and elegance of Biot's original concept. Next, the results of simulations for a hypothetical deposit to estimate the environmental impact of UCG are presented. After applying specific geometry and parameters, the model can be useful for verifying if the chosen technology of UCG in specific conditions will be safe for the environment and infrastructure.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Termite Mound Soils for Sustainable Production of Bricks<abstract> <title style='display:none'>Abstract</title> <p>The article presents the alternative use of termite mound soils (TMSs) as full replacement for clay soils in brick production. TMSs from two localities, Jawaj and Sene, in Ethiopia were investigated for bricks production. The TMSs samples contained high SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3.</sub> The TMSs bricks were fired at different temperatures from 500 to 1,000°C. The obtained mean compressive strengths (σ), 18 and 14 MPa, were observed for bricks made from TMSs from Jawaj and Sene, respectively, at the optimum firing temperature of 700°C. The σ of TMSs bricks decreased as the firing temperature increased above 700°C, while for conventional clay soil brick, the σ increased with temperature beyond 700°C. The water absorptions and saturation coefficients of fired TMSs bricks decreased with increased firing temperature. The TMSs bricks meet the standard specification of dimension tolerance only along the height. All the TMSs bricks made from the two localities were not efflorescent. TMSs from Jawaj and Sene sites can be used as a raw material to replace the long-used clay soils for bricks production as a construction material for houses construction in rural and urban areas.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00The effect of the pre-wetting of expanded clay aggregate on the freeze-thaw resistance of the expanded clay aggregate concrete<abstract> <title style='display:none'>Abstract</title> <p>This paper presents experimental research on expanded clay aggregate concrete. The aim of the investigations was to determine if the pre-wetting of expanded clay aggregate has an effect on the freeze-thaw durability of the expanded clay aggregate concrete. Five concrete series based on the same concrete mix design were made and tested. The degree of pre-wetting of the aggregate was varied: dry aggregate was used in the first series, aggregate with a moisture content of 10% was used in series IA and IB and aggregate with a moisture content of 25% was used in series IIA and IIB. Also the approach to the production process was varied: in series A the water contained in the aggregate was taken into account in the global water-cement ratio (consequently a reduced amount of water was added to the mix), whereas in series B the nominal amount of water was added to the mix (as in the case of dry aggregate). The freeze-thaw resistance criterion was based on the assessment of the decrease of compressive strength and increase in weight loss after exposure to freeze-thaw cycles. The expanded clay aggregate concrete's strength and mass decrements caused by freeze-thaw cycling were used as the measure of its freeze-thaw resistance. The investigations have shown that the pre-wetting of expanded clay aggregate has an effect on the freeze-thaw durability of the expanded clay aggregate concrete. The differences of concrete compressive strength decrease related to freeze-thaw durability may be 2 to 5 times greater when inadequate method of calculating mixing water for concrete is used.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Load capacity of the mixed bench and slab foundation. Numerical simulations and analytical calculation model<abstract> <title style='display:none'>Abstract</title> <p>The paper presents results of a numerical investigation on load capacity of the mixed bench and slab shallow foundations (often used in the process of the modernization of the old, antique buildings, which are suffering from lack of the load capacity). The main trouble with use of existing analytical approaches is a non-unique foundation level of the bench and slab, they could even be founded on different geotechnical layers. Proposed analytical model based on Brinch Hansen (EC-7) approach could deal with such a problem. Results of 2D and 3D numerical modelling (ultimate load of the foundation) are compared to the obtained by using the proposed approach. Influence of the soil above the foundation level is also investigated. Different width to length ratios of the foundation are analyzed (from “short” to “long” foundations). Usability of the proposed analytical model in engineering practice is proved by numerical simulations; the obtained results are on the safe side with quite acceptable margin of additional safety.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Impact of subgrade and backfill stiffness on values and distribution of bending moments in integral box bridge<abstract> <title style='display:none'>Abstract</title> <p>The article presents parametric analysis regarding the impact of subgrade and backfill stiffness on values and distribution of bending moments in the structural elements of a small integral box bridge made of cast in situ reinforced concrete. The analyzed parameters are the modulus of subgrade reaction under and behind the bridge structure (k<sub>v</sub> k<sub>h</sub>). At the beginning, the author presents the integral box bridge and selected parts of the bridge design. In particular, the author focuses on the method of modeling of the subgrade stiffness parameters under and behind the bridge structure, as well as their impact on the values and distribution of bending moments in the bridge structural elements. The bridge was designed by the author and built on the M9 motorway between the towns of Waterford and Kilcullen in Ireland. In conclusions, the author shares his knowledge and experience relating to the design of small integral bridges and culverts and puts forward recommendations as to further research on these type of structures in Poland.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Behaviour of eccentrically inclined loaded rectangular foundation on reinforced sand<abstract> <title style='display:none'>Abstract</title> <p>This study presents the behaviour of model footing resting over unreinforced and reinforced sand bed under different loading conditions carried out experimentally. The parameters investigated in this study includes the number of reinforced layers (<italic>N</italic> = 0, 1, 2, 3, 4), embedment ratio (<italic>D<sub>f</sub></italic>/<italic>B</italic> = 0, 0.5, 1.0), eccentric and inclined ratio (<italic>e</italic>/<italic>L</italic>, <italic>e</italic>/<italic>B</italic> = 0, 0.05, 0.10, 0.15) and (<italic>a</italic> = 0°, 7°, 14°). The test sand was reinforced with bi-axial geogrid (Bx20/20). The test results show that the ultimate bearing capacities decrease with axial eccentricity and inclination of applied loads. The test results also show that the depth of model footing increase zero to <italic>B</italic> (<italic>B</italic> = width of model footing), an increase of ultimate bearing capacity (UBC) approximated at 93%. Similarly, the multi-layered geogrid reinforced sand (<italic>N</italic> = 0 to 4) increases the UBC by about 75%. The bearing capacity ratio (<italic>BCR</italic>) of the model footing increases with an increasing load eccentricity to the core boundary of footing; if the load eccentricities increase continuity, the <italic>BCR</italic> decreases. The tilt of the model footing is increased by increasing the eccentricity and decreases with increasing the number of reinforcing layers.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00An Analytical Study of Partially Strengthened Single End-Bearing Granular Pile Near the Top and Bottom<abstract> <title style='display:none'>Abstract</title> <p>Stone columns (or granular piles, GPs) are progressively being utilized for ground improvement, mostly for pliant edifice such as road mounds, oil depot, and so forth. The present analysis is done by introducing strengthening at both the ends of GP, i.e., bottom and top end so that the bulging problem will be solved and the beneficiary effect of the bearing stratum can be utilized by the bottom strengthening feature. Analysis of a single partially strengthened, at both top and bottom, end-bearing GP is presented in this article in terms of displacement affecting component for the top (DACT) of GP, percentage load transferred to the base (PLTB) of strengthened GP, and normalized shear stress (NSS). The PLTB of the strengthened GP was found to increase considerably. The NSS was found to reduce at the top end of GP and is found to be redistributed along the length of GP.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Geostatistical analysis of spatial variability of the liquefaction potential – Case study of a site located in Algiers (Algeria)<abstract> <title style='display:none'>Abstract</title> <p>The city of Algiers (Algeria) is a highly seismic area, and therefore, soil liquefaction poses a major concern for structures resting on sandy soil. A campaign of 62 static penetration tests or cone penetrometer tests (CPT) was carried out on a site located in the commune of Dar El Beïda in Algiers. The soil Liquefaction Potential Index (LPI) values were assessed, for each borehole, based on the simplified procedure of Seed and Idriss. On the other hand, the geographic information system and geostatistical analysis were used to quantify the risk of soil liquefaction at the studied site. It is worth mentioning that the (LPI) was taken as a regionalized variable. In addition, the experimental variogram was modeled on the basis of a spherical model. Also, the interpolation of the LPI values in the unsampled locations was performed by the Kriging technique using both isotropic and anisotropic models. Kriging standard deviation maps were produced for both cases. The cross-validation showed that the anisotropic model exhibited a better fit for the interpolation of the values of the soil liquefaction potential. The results obtained indicated that a significant part of the soil is liable to liquefy, in particular in the northwestern region of the study area. The findings suggest that there is a proportional relationship between the risk of liquefaction and the increase or decrease in seismic acceleration.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Usefulness of the CPTU method in evaluating shear modulus changes in the subsoil<abstract><title style='display:none'>Abstract</title><p>This article contains the analysis of the correlation between the cone resistance <italic>q<sub>c</sub></italic> from CPTU tests and shear modulus <italic>G<sub>0</sub></italic> determined from seismic tests SDMT and SCPTU. The analysis was performed for sands located in Poland, characterised by differential grain size distribution and origin. The significant impact of the independent variables; grain size, preconsolidation stress <italic>σ’<sub>p</sub></italic>, geostatic vertical stress <italic>σ’<sub>v0</sub></italic> and relative density index on the dependencies analysed, were examined in three stages. Firstly, a general relationship between the cone resistance and shear modulus <italic>G<sub>0</sub></italic> was established; in the second stage, an analysis was carried out in selected groups of subsoil; and in the third stage, the influence of other independent variables was taken into account. In each stage, the functional form of the dependency was determined, and their statistical significance was assessed throughout coefficient of determination R<sup>2</sup>. For more variables, multivariable regression analysis was applied for assessment. Conducted analysis showed that the overall view of the relation between the cone resistance <italic>q<sub>c</sub></italic> and shear modulus <italic>G<sub>0</sub></italic> has low evaluation of the statistical significance. This fact is consistent with the theoretical assessment of this relationship. To obtain a satisfactory assessment of this dependency, it is necessary to construct empirical equations for individual groups of soil, taking into account other independent variables; preconsolidation stress <italic>σ’<sub>p</sub></italic>, vertical stress <italic>σ’<sub>vo</sub></italic> and relative density index. This approach allows to assess the local correlation relationship, which is very useful during the geological project.</p></abstract>ARTICLE2021-08-10T00:00:00.000+00:00Characteristic parameters of soil failure criteria for plane strain conditions – experimental and semi-theoretical study<abstract><title style='display:none'>Abstract</title><p>The paper concerns the characteristic parameters of the selected isotropic failure criteria, i.e. Mohr–Coulomb, Drucker–Prager, Matsuoka–Nakai and Lade–Duncan. The parameters are determined directly from the failure criteria and stress measurements or by semi-theoretical approach, assuming that the soil obeys the associated flow rule and using the plane strain condition. In the latter case, the parameters can be expressed as functions of the plane strain internal friction angle, which is determined from measurements. The principal stress tensor components, corresponding to the soil peak strength and necessary to obtain the failure criteria parameters, are measured in a series of true triaxial, plane strain tests, on coarse Skarpa sand samples of different initial relative density, subjected to various confining pressures.</p></abstract>ARTICLE2021-08-10T00:00:00.000+00:00Efficiency of ventilated facades in terms of airflow in the air gap<abstract><title style='display:none'>Abstract</title><p>The gradual exploitation of the natural environment has forced most developed countries to promote ecological solutions and the development of sustainable construction. Ventilated facades perfectly match into this trend, and with their appropriate design, they bring real energy savings. This paper analyzes numerically the influence of the inflowing air, mimicking the wind, on the efficiency of heat removal from the ventilated space and heat transmission by thermal radiation and conduction through the consecutive layers of the external wall. For the purpose of comparison, two variants of ventilated facade were adopted: open and closed joints, at different wind speeds prevailing outside. The results obtained show that in windless weather, the ventilated facade with open joints shows higher heat removal efficiency and thus lower heat transmission to the building interior. At higher wind speeds of 5 m/s, the open-joint and closed-joint ventilated facades achieve similar heat transfer efficiency, and the prevailing temperature inside the building for the two technologies is almost identical. Subsequent increments of incoming wind on the building result in minimal differences in the heat transmission to the building interior, representing changes of about 0.1°C at increments of another 5 m/s of incoming wind. Conscious use of this facade technology, along with appropriate urban design of cities, can help reduce the energy needed to cool buildings during the summer period.</p></abstract>ARTICLE2021-08-09T00:00:00.000+00:00FEM modelling of the static behaviour of reinforced concrete beams considering the nonlinear behaviour of the concrete<abstract><title style='display:none'>Abstract</title><p>This paper presents a finite element (FE) method of modelling reinforced concrete beams. The proposed model takes into account the phenomena characteristic of reinforced concrete structures, such as the interaction between two materials (concrete and steel), the cracking caused by mechanical loads and the variation of the Young's modulus under increasing load. A relevant numerical FE analysis was carried out in the ABAQUS system using the concrete damaged plasticity (CDP) model. The character of Young's modulus variation due to increasing stress intensity level was taken from the author's own research. The results of the FE calculations were compared with the results yielded by the author's numerical bar model.</p></abstract>ARTICLE2021-07-25T00:00:00.000+00:00Evaluation of Tunnel Contour Quality Index on the Basis of Terrestrial Laser Scanning Data<abstract><title style='display:none'>Abstract</title><p>The Tunnel Contour Quality Index (TCI) is an index established by Kim and Bruland for an effective management of a tunnel contour quality. It is estimated on a basis of measurements of two contour profiles within a single blasting round, using a laser profiler. However, the representativeness of measurement results obtained that way for the assessment of a contour quality of the entire blasting round is disputable. Terrestrial laser scanning (TLS) technology, combined with available numerical surface modeling tools, enables development of three-dimensional models of a monitored surface. The article reports results of TCI calculations based on TLS data. The presented TLS technique is based not only on selected cross-sections of the tunnel contour but also on the description of the morphology of the tunnel contour surface. The case study concerns measurements of the “Mały Luboń” tunnel niche, located in Naprawa, Poland. The TCI values for three blasting rounds were determined in accordance with Kim and Bruland's guidelines and were compared to TCI values determined with the proposed TLS technique. On a basis of this comparison, it can be concluded that the results obtained with the TLS technique are more reliable and representative for description of the contour quality of the entire blasting round than results obtained with the laser profiling technique.</p></abstract>ARTICLE2021-07-06T00:00:00.000+00:00A comprehensive approach to the optimization of design solutions for dry anti-flood reservoir dams<abstract><title style='display:none'>Abstract</title><p>The article proposes the methodology of designing dams of dry flood control reservoirs. The algorithm is developed so as to meet all the requirements given in the Eurocode 7 and, at the same time, to be efficient in terms of necessary calculation time. Furthermore, the presented numerical procedure enables the optimization of design solutions, e.g. the depth and length of the anti-filtration barrier, by means of parametric analyses. The approach assumes the use of numerical methods, in particular, finite element (FE) analysis. Three-dimensional (3D) reconstruction of the terrain topography and subsoil layer arrangement performed in step (1) sets the base for further analyses. In step (2), the filtration phenomena are assessed based on the 3D analysis of a transient groundwater flow. In step (3), the state of displacement is evaluated and the stability is verified for all the relevant phases of construction and operation of the facility, in particular, in the course of simulated flood detention. The analyses in step (3) are carried out on 2D models corresponding to the design cross-sections of the dam. This significantly reduces the computation time (compared to 3D analysis) and, at the same time, provides a safe estimate of factor of safety. The performance of the proposed algorithm is shown on the numerical examples of the computations concerning the dam of Szalejów Górny dry anti-flood reservoir located in Poland.</p></abstract>ARTICLE2021-06-29T00:00:00.000+00:00Laboratory tests and analysis of CIPP epoxy resin internal liners used in pipelines – part II: comparative analysis with the use of the FEM and engineering algorithms<abstract><title style='display:none'>Abstract</title><p>In the case of underground network infrastructure it can be seen that objects functioning in the second technical condition, according to DWA-ATV 143-2, and subjected to rehabilitation with the use of close-fit trenchless technologies are capable of withstanding external loads. The main external load that is taken into account in engineering calculations in the case of conduits in the second technical condition is external groundwater pressure.</p><p>In order to compare design parameters obtained with the use of various calculation methods, a comparative analysis was conducted in order to determine the values of critical pressure. The calculations were carried out using popular engineering algorithms.</p><p>In addition, analyses using the Finite Element Method and Abaqus software as a computational tool were carried out for the purpose of verifying laboratory tests. This paper aims to broaden knowledge concerning the possibility of performing control numerical analyses for close-fit liners installed in pipelines that are in the second technical condition according to DWA-ATV 143-2.</p><p>The analyses were carried out on ten 3D models. The models were parameterized in order to reflect the CIPP samples in the most accurate way. The computational models were built based on assumptions, which are commonly used in this type of scientific analysis, regarding material parameters and their interactions.</p><p>The direct value of the performed engineering calculations and numerical analyses is the extension of knowledge in the field of strength parameters that are obtained by various material groups of close-fit liners. Comparative analysis of the results of laboratory tests and numerical analyses, and the conclusions that result from them, constitute the basis for the optimization of the design process and the individual approach to issues related to the use of liners that strengthen underground pipelines.</p></abstract>ARTICLE2021-05-11T00:00:00.000+00:003D DEM simulations of basic geotechnical tests with early detection of shear localization<abstract><title style='display:none'>Abstract</title><p>This paper deals with elementary geotechnical tests: triaxial and direct shear of cohesionless sand using the discrete element method (DEM). The capabilities of the numerical DEM code are shown, with a special focus on the early phenomena appearance in localization zones. The numerical tests were performed in 3D conditions with spherical grains. Contact moments law was introduced due to simulate not perfectly round sand grains. The influence of different physical parameters was studied, e.g. initial density or confining pressure. The sieve curve corresponded to the Karlsruhe sand [<xref ref-type="bibr" rid="j_sgem-2020-0010_ref_001_w2aab3b7d176b1b6b1ab2b1b1Aa">1</xref>]; however, in some tests, it was linearly scaled. Special attention was laid on the behaviour of the sand grains inside localization, e.g. rotation, porosity, fluctuations, etc. and forces redistribution. Emphasis was given on the pre-failure regime and early localization predictors.</p></abstract>ARTICLE2020-12-04T00:00:00.000+00:00Influence of Waste Toothbrush Fiber on Strength and Freezing–Thawing Behavior in High Plasticity Clay<abstract><title style='display:none'>Abstract</title><p>The use of waste materials in civil engineering applications has gained importance nowadays. Consuming limited natural resources and increasing waste disposal costs have led researchers to evaluate waste materials for different geotechnical applications. In this respect, some waste materials are used as reinforcement in soils to improve their engineering properties. The main objective of this paper was to investigate the usability of waste polypropylene fiber as a reinforcement material in high plasticity fine-grained soils. For this purpose, waste toothbrush bristle (WTB) was used as a polypropylene fiber reinforcement material and added to fine-grained soil at ratios of 0.2%, 0.4%, 0.6% and 0.8% by dry total weight. The effect of WTB on freezing–thawing behavior and unconfined compression strength of unreinforced and reinforced clayey soil was evaluated. The results indicated that addition of WTB to high plasticity clay improved its behavior against freezing–thawing. Also, undrained shear strength increases with respect to increment in WTB ratio.</p></abstract>ARTICLE2020-10-23T00:00:00.000+00:00en-us-1