rss_2.0Studia Geotechnica et Mechanica FeedSciendo RSS Feed for Studia Geotechnica et Mechanica Geotechnica et Mechanica 's Cover in the vicinity of the antiflood embankments – calculating issues<abstract> <title style='display:none'>Abstract</title> <p>According to Polish law, it is prohibited to perform excavations or locate buildings closer than 50 m from the embankment. In order to obtain exemption from this ban, filtration and stability analysis of the embankment and excavation in the flood conditions have to be performed. This paper presents results of the numerical investigations on interactions between excavations and embankment. Complex nature of the problem is presented. Methodology of numerical simulations and real case examples are described.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Nonlinear buckling analysis of network arch bridges<abstract> <title style='display:none'>Abstract</title> <p>The paper presents designing due to the instability in-plane problem of the net-arch bridge. Firstly, three essential nonlinear examples are benchmarked in a finite element software. Secondly, linear and nonlinear buckling analyses are conducted, with the purpose of investigating the impact of nonlinear behavior of cables on steel arch instability, involving a comparison of the critical load factor and form from both the linear buckling and the post-critical third-order theory analyses. The impact of prestress and tension, elevation, and hanger failure on instability is discussed. Moreover, a new method for determining nonlinear buckling form for the net-arch structure is proposed in order to allow implementation of Unique Global and Local Imperfection method in cable structures. Calculations are conducted in the finite element software. The model of the network arch bridge is based on the bridge over Vistula River in Cracow.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Modern methods for monitoring water leakages in water networks<abstract> <title style='display:none'>Abstract</title> <p>The main idea of this article is to adopt the thesis that the main and, at the same time, the most effective (apart from proper maintenance and operation) element of the strategy of limiting water losses in water supply networks is continuous integrated monitoring of the network using the latest achievements of IT technologies, including GIS (Geographical Information System), GPS (Global Positioning System), GSM (The Global System for Mobile Communications) and software based on a cloud platform.</p> <p>Considering the above, the paper highlights the problem of leakages against the background of water deficit in the world and proposes a classification of methods for detecting and estimating the size of leakages. On the basis of available literature sources, selected modern and, in the authors’ opinion, most interesting water loss monitoring systems enabling leak detection and estimation of the amount of wasted water are presented. Then, these methods are analysed, pointing to their strengths and weaknesses in terms of leak detection efficiency.</p> </abstract>ARTICLE2022-03-12T00:00:00.000+00:00Upper Bounds for the Complex Growth Rate of a Disturbance in Ferrothermohaline Convection<abstract> <title style='display:none'>Abstract</title> <p>It is proved analytically that the complex growth rate <italic>σ</italic>= <italic>σ<sub>r</sub></italic>+<italic>iσ<sub>i</sub></italic> (<italic>σ<sub>r</sub></italic> and <italic>σ<sub>i</sub></italic> are the real and imaginary parts of <italic>σ</italic>, respectively) of an arbitrary oscillatory motion of neutral or growing amplitude in ferrothermohaline convection in a ferrofluid layer for the case of free boundaries is located inside a semicircle in the right half of the <italic>σ<sub>r</sub>σ<sub>i</sub></italic>-plane, whose center is at the origin and <disp-formula id="j_sgem-2022-0005_ueq_001"> <alternatives> <graphic xmlns:xlink="" xlink:href="graphic/j_sgem-2022-0005_ueq_001.png"/> <mml:math xmlns:mml="" display="block"><mml:mrow><mml:mtext>radius</mml:mtext><mml:mo> </mml:mo><mml:mo>=</mml:mo><mml:mo> </mml:mo><mml:msqrt><mml:mrow><mml:mfrac><mml:mrow><mml:msub><mml:mi>R</mml:mi><mml:mi>s</mml:mi></mml:msub><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:msubsup><mml:mi>M</mml:mi><mml:mn>1</mml:mn><mml:mo>′</mml:mo></mml:msubsup><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mfrac><mml:mn>1</mml:mn><mml:mrow><mml:msub><mml:mi>M</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:mrow></mml:mfrac></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow><mml:mo>]</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:msubsup><mml:mi>P</mml:mi><mml:mi>r</mml:mi><mml:mo>′</mml:mo></mml:msubsup></mml:mrow></mml:mfrac></mml:mrow></mml:msqrt><mml:mo>,</mml:mo></mml:mrow></mml:math> <tex-math>{\rm{radius}}\, = \,\sqrt {{{{R_s}\left[{1 - M_1^{'}\left({1 - {1 \over {{M_5}}}} \right)} \right]} \over {P_r^{'}}}},</tex-math> </alternatives> </disp-formula> where <italic>R<sub>s</sub></italic> is the concentration Rayleigh number, <italic>P<sub>r</sub></italic><sup>′</sup> is the solutal Prandtl number, <italic>M</italic><sub>1</sub><sup>′</sup> is the ratio of magnetic flux due to concentration fluctuation to the gravitational force, and <italic>M</italic><sub>5</sub> is the ratio of concentration effect on magnetic field to pyromagnetic coefficient. Further, bounds for the case of rigid boundaries are also derived separately.</p> </abstract>ARTICLE2022-03-10T00:00:00.000+00:00Influence of Permanent Deflections on The Vibrations of Bridge Spans in Operating Conditions<abstract> <title style='display:none'>Abstract</title> <p>The paper presents the method and results of numerical simulations of the mutual dynamic interactions between vehicles and the bridge structure, which has defect in the form of excessive permanent deformations. The parametric analyses were carried out taking into account the following parameters: permanent deflections of spans, with a maximum value ranging from 0 to 150 mm, vehicle speed from 10 m/s (36 km/h) to 30 m/s (108 km/h), and two types of heavy vehicle suspension systems, each with very different properties. The presented analyses are based on the characteristics of real motorway bridge structure with permanent deflections of the multi-span main girders, constructed of steel beams and reinforced concrete slab. The proposed procedure of dynamic numerical analysis can also be useful in the assessment of the influence of permanent deflections on the interactions between vehicles and other types of bridge structures.</p> </abstract>ARTICLE2022-03-02T00:00:00.000+00:00Evaluation of sand p–y curves by predicting both monopile lateral response and OWT natural frequency<abstract> <title style='display:none'>Abstract</title> <p>Extending the use of the p–y curves included in the regulation codes API and DNV to design large-diameter monopiles supporting offshore wind turbines (OWTs) was unsuccessful as it resulted in an inaccurate estimation of the monopile behavior. This had prompted many investigators to propose formulations to enhance the performances of Winkler model. In this paper, two case studies are considered. A case consisting of an OWT at Horns Rev (Denmark) supported by a monopile in a sandy soil was studied first. Taking the FEA using ABAQUS as reference, results of WILDOWER 1.0 (a Winkler computer code) using the recently proposed p–y curves giving design parameters were plotted and evaluated. In order to see the ability of proposed p–y curves to predict the monopile head movements, and consequently the first natural frequency (1st NF), a second case study consisting of a monopile supporting an OWT at North Hoyle (UK) was selected. The monopile head stiffness in terms of lateral, rocking, and cross-coupling stiffness coefficients, necessary for the 1st NF, were computed using both ABAQUS and WILDPOWER 1.0. Comparisons with the measured 1st NF showed that with the exception of one p–y model, none of other proposed Winkler methods is able to predict accurately this parameter.</p> </abstract>ARTICLE2022-02-10T00:00:00.000+00:00Importance of seismic wave frequency in FEM-based dynamic stress and displacement calculations of the earth slope<abstract> <title style='display:none'>Abstract</title> <p>Reliable assessment of earthen dams’ stability and tailing storage facilities widely used in the mining industry is challenging, particularly under seismic load conditions. In this paper, we propose to take into account the effect of the dominant frequency of seismic load on the stability assessment of tailing/earthen dams. The calculations are performed by finite element modelling (FEM) with the Mohr–Coulomb failure criteria. To separate the frequency content from other dynamic parameters describing the seismic wave, synthetic waveforms with identical amplitude and attenuation characteristics, but differing spectral characteristics have been used. The analysis has been performed for three different slope angles and two scenarios of seismic wave propagation. Consequently, the changes of total displacement and shear stresses depending on the frequencies have been determined and clearly show that lower frequencies cause higher stress levels and displacement. Finally, the response surface methodology has been applied to determine how different parameters affect the slope stability under dynamic load conditions. Overall, this study is a first step to improve the existing methods to assess slope stability when considering seismic load.</p> </abstract>ARTICLE2022-02-09T00:00:00.000+00:00Displacements of shell in soil-steel bridge subjected to moving load: determination using strain gauge measurements and numerical simulation<abstract> <title style='display:none'>Abstract</title> <p>This paper analyses displacements of a shell in a soil-steel bridge subjected to quasi-static moving loads. The considerations relate to a large span structure located in Ostróda, Poland. In particular, shell displacements during a loading cycle consisting of consecutive passages of a pair of trucks over the bridge are investigated. The results of a full-scale test, that is, the readings from a system of strain gauges arranged along the shell circumferential section, are the basis for determination of shell displacements. The proposed algorithm makes it possible to calculate any component of the displacement using just a simple model of the shell in the form of a linear elastic curvilinear beam. The approach uses real measurements, and thus, it yields results of displacements reflecting the actual mechanical behaviour of the entire composite structure including not only the shell, but also the backfill, the pavement, etc. The calculated state of displacement sets the basis for calibration of the numerical model. Finite element (FE) analyses include staged construction, that is, backfilling the shell by placing successive soil layers, as well as the loading test with the vehicles moving over the bridge. It is demonstrated that the ballasting of the shell during backfilling contributes to the improvement of the simulated behaviour of the object at the stage of operation, that is, when subjected to moving truck load. Thus, the calibration of the FE model is successfully carried out using the results of strain gauge measurements.</p> </abstract>ARTICLE2022-03-31T00:00:00.000+00:00Statistical analysis of mechanical properties on the example of aggregates of Carpathian sandstones<abstract><title style='display:none'>Abstract</title><p>The constantly growing, broadly understood, construction industry requires the use of a large amount of aggregates. The construction of roads, motorways, railway lines and hydrotechnical structures requires the use of aggregates of high quality, which is primarily determined by mechanical properties. The basic parameters describing mechanical properties of aggregates are the Los Angeles (<italic>LA</italic>) fragmentation resistance coefficient and the Micro-Deval (<italic>M</italic><sub><italic>DE</italic></sub>) abrasion resistance coefficient. The <italic>LA</italic> and <italic>M</italic><sub><italic>DE</italic></sub> coefficients depend mainly on the type of rock and its physical and mechanical properties. This has been thoroughly researched and documented as evidenced by the abundant literature in the field. However, the correlation between <italic>LA</italic> and <italic>M</italic><sub><italic>DE</italic></sub> coefficients still gives rise to extensive discussions and some concerns. A number of publications demonstrate dependencies for various types of aggregates. Therefore, research was undertaken to present statistical analysis for one type of aggregate and one geological area.</p><p>This article presents the results of the fragmentation resistance test in the Los Angeles drum and the abrasion resistance test in the Micro-Deval drum of aggregates from Carpathian sandstone deposits. Aggregate samples were divided into three groups according to the location of the deposits and the tectonic unit from which they originated. The obtained results were subjected to static analysis to fit the best mathematical function describing the relationship between the two parameters.</p></abstract>ARTICLE2020-09-24T00:00:00.000+00:00The Use of the Collocation Algorithm for Estimating the Deformations of Soil-Shell Objects Made of Corrugated Sheets<abstract><title style='display:none'>Abstract</title><p>The algorithm presented in this paper is intended for the analysis of deformations of shells in the construction phase of soil-shell objects when strain gauges and geodetic measurements are used. During the construction of such an object, large displacement values occur and the impact of axial forces on the displacement of a corrugated metal sheet is small. Internal forces (strain gauges), as well as the displacements of a selected circumferential band of the shell are determined directly from such observations.</p><p>The paper presents two examples of the analysis of large span shell structures of constructed objects, as well as the assessment of the effectiveness of the finite difference method (FDM) in beam schemes. Good deformation mapping was indicated using the collocation algorithm and the differential approach to the solution when there is a dense mesh and regular distribution of measuring points. In the analysed examples, a significant divergence between the support conditions adopted in the FEM calculation models and the actual static conditions in the objects was indicated. The collocation algorithm is especially designed for such situations. Collocation points in such a solution are used to consider a beam – separated from a structure and without boundary constraints, but with specific changes in curvature – as a reference system, which is determined from the geodetic measurements of two collocation points.</p></abstract>ARTICLE2020-06-26T00:00:00.000+00:00Empirical and theoretical models for prediction of soil thermal conductivity: a review and critical assessment<abstract><title style='display:none'>Abstract</title><p>The paper discusses existing models used to estimate the thermal conductivity of the soil medium. The considerations are divided into three general sections. In the first section of the paper, we focus on the presentation of empirical models. Here, in the case of Johansen method, different relations for Kersten number are also presented. In the next part, theoretical models are considered. In the following part, selected models were used to predict measured thermal conductivities of coarse- and fine-grained soils, at different water contents. Based on these predictions as well as on the authors’ experience, a critical assessment of the existing models is provided. The remarks as well as advantages and disadvantages of those models are summarized in a tabular form. The latter is important from a practical point of view; based on the table content, one can simply choose a model that is suitable for the particular problem.</p></abstract>ARTICLE2020-07-09T00:00:00.000+00:00Risk Reduction of a Terrorist Attack on a Critical Infrastructure Facility of LGOM Based on the Example of the Tailings Storage Facility (OUOW )<abstract><title style='display:none'>Abstract</title><p>This paper identifies the threats and risks of a terrorist attack on a critical infrastructure facility based on the example of <italic>Żelazny Most</italic> Tailings Storage Facility (OUOW). The threat analysis primarily took into account the threats of deliberate human actions. Identification of potential threats concerning the infrastructure surrounding the facility was conducted based on information that is readily available on the Internet. The reasons why it may be a potential target were also justified. Numerical calculations of the stress–deformation scale of the initial state of the reservoir, based on the Biot model with the Kelvin–Voight rheological skeleton, were presented as a starting point for in-depth research on the scale of threats and risks to the reservoir. The presented numerical model can be a starting point for calculating the stability of a reservoir subjected to explosives. The facility constitutes a major element of Lubińsko-Głogowski Okręg Miedziowy (Lubin-Głogów Copper District). OUOW <italic>Żelazny Most</italic> is the biggest such facility in Europe and is utilized to collect tailing waist. When expanded in its southern quarter, the facility will be the biggest in the world.</p></abstract>ARTICLE2020-09-25T00:00:00.000+00:00Vibrations of the Euler–Bernoulli Beam Under a Moving Force based on Various Versions of Gradient Nonlocal Elasticity Theory: Application in Nanomechanics<abstract><title style='display:none'>Abstract</title><p>Two models of vibrations of the Euler–Bernoulli beam under a moving force, based on two different versions of the nonlocal gradient theory of elasticity, namely, the Eringen model, in which the strain is a function of stress gradient, and the nonlocal model, in which the stress is a function of strains gradient, were studied and compared. A dynamic response of a finite, simply supported beam under a moving force was evaluated. The force is moving along the beam with a constant velocity. Particular solutions in the form of an infinite series and some solutions in a closed form as well as the numerical results were presented.</p></abstract>ARTICLE2020-06-29T00:00:00.000+00:00Using Triaxial Tests to Determine the Shearing Strength of Geogrid-Reinforced Sand<abstract><title style='display:none'>Abstract</title><p>Geogrids are widely used in civil engineering projects to reinforce road and railway structures. This paper presents research on the shearing strength of soil samples that have been reinforced with geogrids. The relationship between soil and geogrids is explored and evaluated by modeling the mechanical behavior of heterogeneous materials. For the purposes of this research, data obtained from tests of unreinforced sand samples with triaxial cells were compared with the data obtained from tests of reinforced sand samples. It was found that the shearing strength for reinforced samples was higher (from 9% to 49%) compared to unreinforced samples. Some damage to the geogrid was detected during the experiment, and for this reason, the same tests were numerically simulated for both unreinforced samples and samples reinforced with geogrids. Numerical simulations revealed the main reasons for damage to the geogrids during triaxial testing.</p></abstract>ARTICLE2020-09-25T00:00:00.000+00:00Dynamic Tests in Bridge Health Monitoring<abstract><title style='display:none'>Abstract</title><p>Dynamic tests are one of the most significant diagnostic procedures applied in Bridge Health Monitoring in many countries. The paper presents a proposal of unified classification of the bridge dynamic tests together with review of the testing methods, including tests under designed and controlled loads, arranged short-term tests under normal traffic loads as well as permanent dynamic monitoring by means of built-in gauges mounted on a structure. Classification of bridge dynamic tests is proposed taking into account various types of vibration excitation methods, measured parameters and possible applications of obtained results in the Bridge Health Monitoring. General rules and procedures of bridge dynamic tests are described and discussed.</p></abstract>ARTICLE2020-06-06T00:00:00.000+00:00Analysis of underground stratification based on CPTu profiles using high-pass spatial filter<abstract><title style='display:none'>Abstract</title><p>The issue of the stratification of the underground subsoil is one of the principal geotechnical challenges. The development of the Cone Penetration Tests (CPTu) has resulted in the possibility to record parameters in a quasi-continuous way, which provides a very detailed description of the soil response. Such accurate measurements may therefore be treated as a signal or image and be analysed as such. This paper presents the application of high-pass spatial filters to perform soil stratification on the basis of the static penetration test. The presented algorithm has been tested on the test data set provided by the Organizers of TC304 Student Contest on Spatial Data Analysis (September 22, 2019, Hannover, Germany). It provides reasonable results at negligible computational cost and is applicable to most soils, especially if the contrast between the parameters of the adjacent layers is significant.</p></abstract>ARTICLE2020-09-22T00:00:00.000+00:00The influence of the soil constitutive models on the seismic analysis of pile-supported wharf structures with batter piles in cut-slope rock dike<abstract><title style='display:none'>Abstract</title><p>In coastal regions, earthquakes caused severe damage to marine structures. Many researchers have conducted numerical investigations in order to understand the dynamic behavior of these structures. The most frequently used model in numerical calculations of soil is the linear-elastic perfectly plastic model with a Mohr-Coulomb failure criterion (MC model). It is recommended to use this model to represent a first-order approximation of soil behavior. Therefore, it is necessary to accommodate soil constitutive models for the specific geotechnical problems.</p><p>In this paper, three soil constitutive models with different accuracy were applied by using the two-dimensional finite element software PLAXIS to study the behavior of pile-supported wharf embedded in rock dike, under the 1989 Loma Prieta earthquake. These models are: a linear-elastic perfectly plastic model (MC model), an elastoplastic model with isotropic hardening (HS model), and the Hardening Soil model with an extension to the small-strain stiffness (HSS model).</p><p>A typical pile-supported wharf structure with batter piles from the western United States ports was selected to perform the study. The wharf included cut-slope (sliver) rock dike configuration, which is constituted by a thin layer of rockfill overlaid by a slope of loose sand. The foundation soil and the backfill soil behind the wharf were all dense sand. The soil parameters used in the study were calibrated in numerical soil element tests (Oedometer and Triaxial tests).</p><p>The wharf displacement and pore pressure results obtained using models with different accuracy were compared to the numerical results of Heidary-Torkamani et al.<sup>[<xref ref-type="bibr" rid="j_sgem-2019-0050_ref_028_w2aab3b7d215b1b6b1ab2ac28Aa">28</xref>]</sup> It was found that the Hardening Soil model with small-strain stiffness (HSS model) gives clearly better results than the MC and HS models.</p><p>Afterwards, the pile displacements in sloping rockfill were analyzed. The displacement time histories of the rock dike at the top and at the toe were also exposed. It can be noted that during the earthquake there was a significant lateral ground displacement at the upper part of the embankment due to the liquefaction of loose sand. This movement caused displacement at the dike top greater than its displacement at the toe. Consequently, the behavior of the wharf was affected and the pile displacements were important, specially the piles closest to the dike top.</p></abstract>ARTICLE2020-07-05T00:00:00.000+00:00Testing the rocks loosening process by undercutting anchors<abstract><title style='display:none'>Abstract</title><p>The method of unconventional solid rock loosening with undercutting anchors and the literature analysis of the problem are presented. The tests and test results of the rocks loosening process with a fixed undercutting anchor are described. The tests were carried out within the RODEST project, OPUS 10 competition No. 2015/19/B/ST10/02817, financed by the National Science Centre. Numerical modeling process as well as a series of laboratory and in situ tests were carried out. The test stand equipment and methodology for the in situ tests are presented. The tests were conducted in four mines, which allowed to obtain and determine the following characteristics: <list list-type="order"><list-item><p>loosening force as a function of anchoring depth (for a given type of rock),</p></list-item><list-item><p>the range of rock loosening in a function of anchoring depth (for a given type of rock), and</p></list-item><list-item><p>loosened rock volume as a function of anchoring depth (for a given type of rock).</p></list-item></list></p><p>The in situ test results are compared with the concrete capacity design (CCD) model used for the calculation of anchor load capacity in concrete.</p></abstract>ARTICLE2020-07-09T00:00:00.000+00:00Analysis of the Collapse Gradient of Deep Water Horizontal Wellbore and the Effects of Mud Chemical Activity and Variation in Water Depth<abstract><title style='display:none'>Abstract</title><p>Wellbore collapse is an instability-event that occurs at low mud density and leads to unfavorable economic project, reaching billions of US dollars. Thus, it is important to accurately determine its value, especially in deepwater horizontal wellbores. The main reasons for nontrivial problems with such wellbores are evident: the shale encountered are anisotropic in nature and possess planes of weakness; they react with water-based mud, generate osmotic stresses, swell, and fall unto the wellbore bottom, thereby increasing the non-productive time. To this end, salts are added to reduce the collapse tendency, but it is not currently known what amount of salt addition maintains stability, and does not lead to wellbore fracture; in deepwater, the current trend in global warming means there is a future concern to the industry. As the climate temperature increases, more ice melts from the polar region, the seawater expands and the sea level rises. How to incorporate the corresponding effect on collapse gradient is scarcely known. This study captures the major concerns stated above into wellbore stability analysis. Following the classical approach for geomechanical analysis, Mogi-Coulomb criterion was combined with a constitutive stress equation comprising contributions from mechanical and osmotic potentials of mud and shale. A sophisticated industry model was used to consider the deepwater effect. The results show significant reduction in collapse gradient as the water depth increases, also, larger difference between the mud and shale chemical activities represents higher complexities in the wellbore. In addition, the reduction in the chemical activities of mud limited to 37.5% of the initial value can be practically safe.</p></abstract>ARTICLE2020-04-09T00:00:00.000+00:00Heave analysis of shallow foundations founded in swelling clayey soil at N’Gaous city in Algeria<abstract><title style='display:none'>Abstract</title><p>The design of shallow foundations on swelling soils needs a thorough study to evaluate the effect of swelling potential soil on the final foundation heave. For this reason, a simple analytical approach based on the soil stress state under the foundation can be used to calculate the foundation heave. This paper reports a set of analytical and numerical analysis using the finite-difference code (FLAC 3D), performed on an isolated shallow foundation founded on a swelling soil mass at N’Gaous city in Batna Province, Algeria, subjected to distributed vertical loads. Further, the influence of some parameters on total heave was analyzed, such as the embedded foundation and soil stiffness. The analysis results from the proposed 3D modelling was compared and discussed with analytical results. The numerical results obtained show a good agreement with the analytical solutions based on oedometer tests proposed in the literature, and deliver a satisfactory prediction of the heave of the shallow foundations.</p></abstract>ARTICLE2020-07-07T00:00:00.000+00:00en-us-1