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1.
A general analytical solution to the one-dimensional consolidation problem for unsaturated soil under various loading conditions
Jiwei Li, Changfu Wei, Yanlin Zhao, 2018, original scientific article

Abstract: A general analytical solution is developed for the onedimensional consolidation problem of unsaturated soil under various time-dependent loading conditions based on a differential transformation method (DTM). In particular, analytical solutions are obtained for different relationships between the coefficients in the governing equations for unsaturated soil consolidation. The Fourier series expansion technique is adopted to account for both the continuous differentiable loading and the periodic piecewise loading. A comparison between the results of the current solution and the existing theoretical solution indicates that the proposed solution yields excellent results, while it is straightforward to obtain the analytical solution of the unsaturated consolidation problems. It was also found that the variations in the coefficients in the governing equations can significantly influence the dissipation of both the excess pore-air pressure and the excess pore-water pressure, though the magnitudes of their variations are different.
Keywords: one-dimensional consolidation problem, unsaturated soil, analytical solution, time-dependent loading
Published: 11.10.2018; Views: 37; Downloads: 6
.pdf Full text (814,44 KB)

2.
Modified coefficient of subgrade reaction to laterally loaded piles
Ayhan Gurbuz, 2018, original scientific article

Abstract: An accurate prediction of the load capacity of a laterally loaded pile at a permissible displacement is an important concern at the design stage. In contrast to many sophisticated methods, Broms’ method based on moment equilibrium has been preferred by engineers to predict the load capacities of laterally loaded piles due to both its simplicity and because it is established on a way of hand calculation. However, Broms’ method typically overestimates a pile’s lateral load capacity as it requires a constant coefficient of horizontal subgrade reaction (nh) into analyses, regardless of the magnitude of the pile’s top displacement. In this study, modified coefficients of subgrade reactions(nh*) that are sensitive to the pile’s top displacement in cohesionless soils are first proposed to improve the performance level of Broms’ method for the prediction of the load capacity of a laterally loaded pile as the pile’s top displacement increases. The modified values of nh* are calibrated using 45 independently free-head, single-driven, full-scale pile tests from 23 sites in cohesionless soils. It is demonstrated that Broms’ method with nh* would correctly estimate a pile’s lateral load-deflection behavior with accuracy levels similar to more complicated methods.
Keywords: Broms' method, coefficient of horizontal subgrade reaction, p-y curves, strain wedge model
Published: 11.10.2018; Views: 19; Downloads: 5
.pdf Full text (735,27 KB)

3.
A simplified method to analyze pile-supported and geosynthetic-reinforced embankments and the influence significance analysis of the design parameters
Liu Feicheng, Zhang Jianjing, Yan Shijie, Cao Licong, 2018, original scientific article

Abstract: A simplified method for evaluating a pile-supported embankment reinforced with geosynthetic (PGRS embankment) is proposed in this paper. The method takes into account not only the arching effect, the membrane effect of the deflected geosynthetic, and the subsoil reaction, but also the pile head settlement, which makes the method applicable for floating piles, as well as piles seated on a firm soil layer. The settlement of the subsoil surface is considered to consist of two parts: (a) the settlement of the subsoil surface equals that of the pile cap with no deformation in geosynthetic yet; (b) the subsoil surface subsides along with the geosynthetic deforming, and the deflected geosynthetic being considered as catenary shaped. The formula for the maximum differential settlement between the subsoil surface and the piles is worked out by analyzing the force equilibrium of the geosynthetic and the stress-strain relationship of the geosynthetic at the edge of the pile cap. The comparison of the calculated results with the observed data and the six current analytical methods has been implemented to verify the proposed method. The influence of the tensile stiffness of the geosynthetic, compression modulus of soft soil, soft soil thickness, embankment height, internal friction angle of the embankment fill and the pile spacing on the subsoil reaction, the stress concentration ratio (SCR) and the tension of the geosynthetic are investigated using the proposed method. The influence significance of these factors has been investigated using the evaluation theory of binary variance analysis for the non-repeatability tests, which helps optimize the design of the PGRS embankment.
Keywords: pile-supported embankment, geosynthetic, simplified method, influence significance, binary variance analysis
Published: 11.10.2018; Views: 13; Downloads: 4
.pdf Full text (1,23 MB)

4.
Effect of particle roundness and morphology on the shear failure mechanism of granular soil under strip footing
Babak Karimi Ghalehjough, Suat Akbulut, Semet Çelik, 2018, original scientific article

Abstract: This study investigates the effect of particles roundness and morphology on the shear failure mechanism of soil. A strip footing was modeled under laboratory conditions. Calcareous soil was tested with three roundness classes: angular, rounded and well-rounded shapes with sizes of 0.30 mm to 4.75 mm. These were divided into six different groups at three relative densities of 30%, 50% and 70%. A series of photographs was taken during the tests and analyzed using the particle image velocimetry (PIV) method to understand the soil-deformation mechanism. The results showed that increasing the sample sizes increased the affected area of the soil. At the same time, increasing the relative density caused a punching failure mechanism that went towards the general failure. The shear failure mechanism of the soil changed from general toward punching shear failure with increasing particle roundness. This effect was larger with the smaller materials. Underneath the affected layers of soil, the angular samples were deeper than the rounded and well-rounded samples. The affected depth in the angular soil was approximately 1.5B in the smallest size group. This was more than 3B and near 4B in the largest size group. Both the sides and the underlying soil layers should be considered on angular soils. The area under the footing becomes more important than the side parts after increasing the roundness of the particles.
Keywords: particle roundness, morphology of particles, shear failure mechanism, strip footing, PIV method, ultimate bearing capacity
Published: 11.10.2018; Views: 14; Downloads: 4
.pdf Full text (701,47 KB)

5.
Evaluation of the constriction size reduction of granular filters due to upstream cohesive base-soil erosion
Samira Azirou, Ahmed Benamar, Abdelkader Tahakourt, 2018, original scientific article

Abstract: This study is devoted to filter-constrictions analysis and its application with respect to void and constrictions reduction during soil filtration. The experimental investigation involves combined Hole Erosion-Filtration tests using several soils and filters. The base soils are lean clays and the granular filters are selected according to the usual filtration criteria. The combination of the experimental data for porosity variation and the analytical results from the Constriction Size Distribution (CSD) analysis was used to evaluate the constrictions size reduction subsequent to the filtration process. The filtration depth was also estimated according to the retained soil mass and the porosity reduction deduced from the measured hydraulic conductivity. An analytical model of the CSD was applied to the experimental results in order to assess the constrictions reduction. As regards the obtained results, a nonuniform constriction reduction was suggested according to the effective filtration depth, advocating a dynamic filter action.
Keywords: granular filter, internal erosion, constriction, porosity, filtration index
Published: 11.10.2018; Views: 15; Downloads: 5
.pdf Full text (653,76 KB)

6.
A geostress measurement method based on an integrated drilling and optical microscopic imaging system
Jinchao Wang, Chunying Wang, Zengqiang Han, Yiteng Wang, Xinjian Tang, 2018, original scientific article

Abstract: Conventional geostress measurement methods are limited by deficiencies including the measurable depth, the complexity, and the long duration of operation. To address these problems and achieve the measurement of geostress in deep wells under conditions of complex high pressures and high temperatures, we propose a new measurement method for geostress based on an integrated drilling and optical microscopy system. Its innovative integrated structure eliminates the problems associated with complex procedures and depth limits, and avoids rock creep caused by long delays, significantly improving the accuracy and range of the measurements. It works by using microscopic imaging and direct contact probes to capture the changes of a borehole’s cross-sectional outlines before and after stress relief. The resulting images are analyzed with search circles to obtain the positions of probe apices, which can be fitted into ellipses that describe the outlines, and calculate the state of the stress. The validity and accuracy of the method was verified by in-door tests and field applications in the ZK1 borehole. The results show that: (1) the integrated system can be used to measure micrometer-grade deformations; (2) the searchcircle approach can accurately obtain the positions of probe apices; and (3) the stress measurement method based on the system is accurate and feasible.
Keywords: geostress, probe, optical microscopy, measurement while drilling, search circle
Published: 11.10.2018; Views: 22; Downloads: 5
.pdf Full text (1,26 MB)

7.
Shear modulus of clay-sand mixtures using bender element test
Ali Firat Cabalar, M. M. Khalaf, Zuheir Karabash, 2018, original scientific article

Abstract: Bender-element (BE) tests were conducted on clay-sand mixtures to investigate the variation of small strain-shear modulus (Gmax) with the sand content and the physical characteristics (size, shape) of the sand grains in the mixtures. Three different gradations (0.6–0.3 mm, 1.0–0.6 mm and 2.0–1.0 mm) of sands having distinct shapes (rounded, angular) were added to a low-plasticity clay with mixture ratios of 0% (clean clay), 10%, 20%, 30%, 40%, and 50%. For the purposes of performing a correlation analysis, unconfined compression (UC) tests were also carried out on the same specimens. The tests indicated that both the Gmax and unconfined compressive strength (q u) values of the specimens with angular sand grains were measured to be lower than those with rounded sand grains, for all sizes and percentages. As the percentage of sand in the mixture increases, the Gmax values increase, while the qu values decrease. The results further suggested that the Gmaxvalues decrease as the q u values decreases as the size of the sand grains reduces.
Keywords: sand, clay, bender element, unconfined compressive strength
Published: 11.10.2018; Views: 10; Downloads: 5
.pdf Full text (844,22 KB)

8.
Spletna slovenščina pri Slovencih v Nemčiji
Saška Štumberger, 2018, professional article

Abstract: V prispevku je na gradivu objav skupine Slovenci v Nemčiji na Facebooku analizirana spletna slovenščina Slovencev v Nemčiji. Člani skupine so pripadniki mlajše generacije, ki so se v Nemčijo preselili pred kratkim in pogosto izmenjujejo informacije o upravnih postopkih. Zaradi okoliščin sporočanja je v besedilih kot prevladujoča jezikovna zvrst predvidena raba knjižnega in pogovornega jezika ter z višjim deležem strokovne leksike s področja uprave.
Keywords: slovenščina, spletna slovenščina, izseljenci, družbena omrežja, strokovna leksika, knjižni jezik, Slovenci v Nemčiji
Published: 11.10.2018; Views: 12; Downloads: 3
.pdf Full text (513,05 KB)

9.
Dostopnost Ustave RS za ljudi z motnjami v duševnem razvoju
Živa Jakšić Ivačič, Barbara Kadunc, Špela Mlakar, Špela Schmid, 2018, professional article

Abstract: Konvencija o pravicah invalidov zahteva, da so vse informacije dostopne invalidom v njim razumljivi obliki. Namen prispevka je evalvirati proces prirejanja Ustave Republike Slovenije v lahko berljivo in razumljivo obliko s poudarkom na udeležbi lektorjev z motnjami v duševnem razvoju. Štiri člene ustave smo priredile v dve obliki, pri preverjanju pa smo ugotovile, da si lektorji želijo vseh informacij, ki so v izvirnem besedilu člena, vendar v njim razumljivi obliki. Izrazili so željo, da bi ob prvi različici priredbe, zvesti izvirnemu besedilu, imeli tudi razlagalno različico.
Keywords: Konvencija o pravicah invalidov, Ustava RS, lahko branje, lektorji, motnje v duševnem razvoju
Published: 11.10.2018; Views: 11; Downloads: 4
.pdf Full text (526,52 KB)

10.
Uresničevanje dvojezičnega izobraževanja gluhih otrok v slovenskem šolskem sistemu
Matic Pavlič, 2018, original scientific article

Abstract: Pristopi k izobraževanju gluhih otrok se razlikujejo glede na učni jezik in vključenost v večinsko okolje. Slovenski izobraževalni sistem ne omogoča vsem gluhim otrokom zadostnega stika s polno zaznavnim jezikom, da bi lahko nemoteno usvojili prvi jezik, v literaturi pa se premalo poudarja nova spoznanja o dvojezičnem oziroma dvomodalnem usvajanju znakovnega in govornega jezika. Oboje predstavlja ta članek, ki se zavzema za popolno uresničitev dvojezičnega izobraževanja gluhih in podaja razloge za tak pristop.
Keywords: slovenski znakovni jezik, izobraževanje otrok s posebnimi potrebami, usvajanje jezika, dvojezičnost, polžev vsadek, inkluzija
Published: 11.10.2018; Views: 11; Downloads: 3
.pdf Full text (442,24 KB)

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