rss_2.0Studia Geotechnica et Mechanica FeedSciendo RSS Feed for Studia Geotechnica et Mechanica Geotechnica et Mechanica 's Cover of a structure with soil elastic waves released in non-linear hysteretic soil upon unloading<abstract> <title style='display:none'>Abstract</title> <p>High-frequency motion is often observed in small-scale experimental works carried out in flexible containers under simplified seismic loading conditions when single harmonic sine input motions are introduced at the base of a soil specimen. The source of the high-frequency motion has often been sought in experimental inaccuracies. On the other hand, the most recent numerical studies suggested that high-frequency motion in the steady-state dynamic response of soil subjected to harmonic excitation can also be generated as a result of soil elastic waves released in non-linear hysteretic soil upon unloading. This work presents an example of a finite element numerical study on seismic soil–structure interaction representative of an experimental setup from the past. The results show how high-frequency motion generated in soil in the steady-state response, apparently representative of soil elastic waves, affects the steady-state response of a structure, that is, it is presented how the structure in the analysed case resonates with the soil elastic waves. The numerical findings are verified against the benchmark experimental example to indicate similar patterns in the dynamic response of the structure.</p> </abstract>ARTICLE2022-09-22T00:00:00.000+00:00Effect of Time History on Long-Term Deformation of Gypseous Soils<abstract> <title style='display:none'>Abstract</title> <p>The time-dependent behavior of three gypseous soils was investigated. The soils had gypsum content of 66%, 44%, and 14.8%. The mineralogical and chemical properties of the soils were determined. Two series of tests were performed. In the first, collapsibility characteristics were investigated for a long period (60 days) by conducting single and double oedometer tests. In the second series, the effect of relative density on collapse with time was investigated. The samples were compacted to 40%, 50%, and 60% relative density and then tested. The results of collapse tests showed that the relationship between the strain and logarithm of effective stress has two vertical lines. The first one represents the collapse settlement taking place within 24 h, while the second one represents the long-term collapse. The collapse potential (CP) in both single and double oedometer tests increases when the gypsum content increases from 14.8% to 66% and when the initial void ratio increases.</p> <p>The CP–logarithm of time relationship for soaked samples prepared at different relative densities under 800 kPa indicated that the CP increased with time for the soil sample compacted at 60% relative density and the increase was higher than those compacted at 40% and 50% relative density. The curves started with a straight line and then a concave downward curve was observed with a high strain. For samples compacted at 40% and 50% relative densities, the curves were interrupted by little soil collapses, while the third curve exhibited smooth relation following the collapse.</p> </abstract>ARTICLE2022-09-09T00:00:00.000+00:00Effect of suction on the mechanical behaviour of unsaturated compacted clay–sand mixtures<abstract> <title style='display:none'>Abstract</title> <p>In this work, a series of unconfined compression tests at different water contents were performed to investigate the mechanical behaviour of clay–sand mixtures compacted in standard Proctor conditions. For studying the effect of water content and suction on unconfined compressive strength (UCS) and on strain secant modulus (<italic>E</italic>50 modulus) of these mixtures, drying–wetting paths were defined by measuring the soil–water characteristic curves (SWCCs) using osmotic and salt solution techniques and filter paper method. The results highlighted that an increase in sand content of the mixture leads to an increase in the maximum dry densities and a decrease in the optimum water content of the materials. However, at the given state, when clay is mixed with 25% of sand, the UCS and <italic>E</italic>50 modulus increase to 37% and 70%, respectively, compared to those of clayey samples. But when clay is mixed with 50% of sand, the UCS and <italic>E</italic>50 modulus decrease to 38% and 46%, respectively, compared to those of clayey samples. The results also indicate that the UCS and <italic>E</italic>50 increase with a decrease in the water content and an increase in suction, irrespective of the sand content.</p> </abstract>ARTICLE2022-09-09T00:00:00.000+00:00Case studies on Q-slope method use for slope stability analyses<abstract> <title style='display:none'>Abstract</title> <p>The use of the Q-slope value is a relatively new approach for the stability investigations of rock slopes. In this study, four different slopes in Giresun and Ordu cities of Turkey were investigated to assess whether the Q-slope approach is usable for varying slope heights, or not. A back analysis was carried out for a landslide in a case study quarry located in Kovanlik municipality of Giresun city. Carrying out detailed investigations on the geotechnical drill cores and the field studies, the Q-slope value of the rock mass of the Kovanlik quarry was determined as 0.58. According to the Q-slope approach, the slope which had a landslide under the case of 49° general slope angle and 225 m height should have been stable at a general slope angle of 59°. It has been found that the Q-slope approach is not favorable for a high slope with the height of 225 m. Two roadway excavations with steep slope angles and low heights smaller than 25 m were also investigated within this study. According to the Q-slope value, the roadway slopes which are stable for more than 3 years are estimated to be unstable. Therefore, the Q-slope approach was found also misleading for slopes with low heights like those under 25 m. On the other hand, the Q-slope method usability is confirmed obtaining parallel results with the observations from another case study slope with a height of 78 m. Although it has become a popular empirical method in the recent years, it is recommended to revise the Q-slope approach or limit its use depending on the slope height parameter.</p> </abstract>ARTICLE2022-07-27T00:00:00.000+00:00Does water lubrication affect friction differently for rocks and soils? Evidence and open questions<abstract> <title style='display:none'>Abstract</title> <p>The present paper focuses on the shear strength exhibited by rocks and soils when sliding along dry and wet surfaces, with this mechanism of failure being strongly related to the water lubrication phenomenon. It is well known that the frictional behaviour of geomaterials requires multiscale investigation. Under this perspective, experimental evidence of both friction at the grain scale (i.e. interparticle friction) and friction along sliding surfaces of rock and granular soil samples (i.e. surface friction) are analysed by using data from the literature. The review is addressed at linking different scales, stating the differences between rocks and soils in terms of frictional response to sliding and trying to point out still open problems for the research.</p> </abstract>ARTICLE2022-07-27T00:00:00.000+00:00Observation Method in the Control of Stacker Capacity Under Landslide Hazard – A Case Study<abstract> <title style='display:none'>Abstract</title> <p>The article presents both an application and the purpose of the observation method in the control of stacker capacity. It lists the types of the measured (observed) quantities, which serve as a basis for the observation method. It also describes the procedure of the method and discusses its individual steps. It further provides examples of applying the method in defining the capacity levels of a stacking machine ZGOT-11500, based on the recorded surface and subsurface soil displacement values. The article also offers the increment values and speeds for the individual parameters, which serve as a warning against deterioration of the geotechnical condition of the soil. Knowledge of the relationships between the parameters that describe soil deformation and the required defined stacker capacity may serve as a basis for further research and experiments on the observation method, which may increase the safety of stacking operations. The analysis was based on the results of geotechnical and geodetic measurements, as well as on the operating parameters of the stacker, acquired over a period of 5 months.</p> </abstract>ARTICLE2022-07-27T00:00:00.000+00:00Behavior of Vertically Confined Square Footing on Reinforced Sand under Centric Inclined Loading<abstract> <title style='display:none'>Abstract</title> <p>This study presents the behavior of vertically confined square footing on geogrid-reinforced sand under centric inclined loading through a series of experimental tests. The load was applied at 5°, 10° and 20° angles of inclination with the vertical. The tests were conducted on surface footing, footing with confiner and footing with confiner and horizontal reinforcement configurations subjected to inclined loading. Parametric variations like depth of the confiner (d=1B, 1.5B, 2B), number of geogrid layers (N; varies with variation in depth of confiner), and spacing between horizontal reinforcements (Y=0.25B, 0.5B, 0.75B, 1B) have been investigated at the top surface dimension of confiner (D) as 1.0B, 1.5B and 2.0B (where B is the width of the model footing). Results show that combined effect of confiner and horizontal reinforcement increases the ultimate bearing capacity of footing significantly compared to only confiner for all angle of inclinations. It can also be observed that load bearing capacities decrease with increase in angles of inclination and record the minimum improvement at 20° angle of inclination. Improvement in bearing capacities and reduction in settlement of footing analyzed in terms of bearing capacity ratio (BCR) and settlement reduction factor (SRF) are compared for all footing configurations. To summarize, the test results showed that confiner along with reinforcement can be considered as an economic ground improvement technique for shallow foundations to counter against heavily inclined loading.</p> </abstract>ARTICLE2022-07-27T00:00:00.000+00:00Probabilistic Liquefaction Analysis Using Standard Penetration Test<abstract> <title style='display:none'>Abstract</title> <p>The Youd etal liquefaction resistance curves developed in 2001 to characterize the cyclic resistance of soil based on SPT test are the most used in the context of the Seed and Idriss simplified procedure as a deterministic model. These curves were developed from a modified database of Seed etal. in 1985 with the assumption that the actual peak shear stress (τ<sub>d</sub>) induced at depth h is always less than that predicted by the simplified procedure (τ<sub>r</sub>) of Seed and Idriss (rd= τ<sub>d</sub>/τ<sub>r</sub>&lt;1). By using a suite of equivalent linear site response analyses to adjust the dynamic and the simplified shear stress at depth h, Filali and Sbartai showed in 2017 that the dynamic peak shear stress for some earthquakes is greater than the simplified peak shear stress (rd&gt;1). As in this case, the assumption of the simplified procedure is not verified, Filali and Sbartai have proposed a corrector factor (RC) in the range where <italic>r<sub>d</sub></italic>&gt;1 to adjust the deformable and rigid body. In this paper, we will present a probabilistic study for the evaluation of the liquefaction potential using a database based on SPT measurement compiled after the Chi-Chi Taiwan earthquake, in which the cyclic stress ratio is evaluated using the proposed corrector factor. The objective of this study is to present a probabilistic shape of the cyclic resistance ratio (CRR) curves based on the original simplified method of Seed and Idriss and the corrected version and a new formulation for computing the probability of liquefaction.</p> </abstract>ARTICLE2022-06-04T00:00:00.000+00:00Numerical Evaluation of Partially Strengthened Floating Granular Pile Raft With Vertical and Radial Displacement Compatibility<abstract> <title style='display:none'>Abstract</title> <p>In today’s time, construction is the main key for development of any nation, but land resources are getting deplete. Thus, construction on compressible soil is left as a choice. Stone columns or granular piles (GPs) are broadly used to advance the bearing capacity of crummy ground and lessen the displacement of constructionserected on them. GP is the most efficient and cheap for ground improvement. Analysis of single partially strengthened (SPS) floating granular piled raft is presented in this paper in terms of several normalized aspects like vertical and radial displacement impact factors, settlement impact factor (SIF) for any depth, the normalized GP–soil interface shear and radial stresses, the load ratio, i.e., the percentage of the load taken by the GP and raft to the total load, and the normalized contact pressure distribution below the raft, which are evaluated for SPS floating granular piled raft. The SIF for top of GP is noticed to decline with the surge in the values of the strengthening parameters. The interfacial shear stresses get reorganized along the length of the GP.</p> </abstract>ARTICLE2022-05-28T00:00:00.000+00:00Excavations 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+00:00en-us-1