Numerical modeling of the vegetation and atmosphere effect on the behaviour of civil infrastructure embankments

The soil-vegetation-atmosphere interaction is a dynamic process, which governs the continuous change of soil hydrological conditions. These changes directly affect the seasonal and long-term performance of infrastructure cut and embankment slopes. It has been established that the combined effect of vegetation and precipitation induces seasonal cycles of shrinkage and swelling, which give rise to serviceability issues and consequential high maintenance costs. Numerous researchers attempted to incorporate the effect of the soil-vegetation-atmosphere system interaction in the analysis of boundary value problems. The goal was to improve the understanding of the effects of this complex interaction on the hydro-mechanical response of infrastructure embankments. However, the proposed approaches were unable to quantitatively reproduce the observed hydraulic behaviour. Within the framework of the present thesis, a different approach is proposed. It is based on the fully coupled flow-deformation analysis, combined with unsaturated soil mechanics theory and sophisticated climatic boundary conditions, implemented within the ICFEP numerical code. Two types of unsaturated constitutive models were applied, elasto-plastic unsaturated Mohr-Coulomb type model and advanced BBM model. The instrumented railway embankment located in the UK, suffering from poor track ride quality related to the presence of vegetation on the slopes, is used for validation purposes. The comparative analysis suggests that proposed models are plausible representative of reality. Subsequently, a comprehensive parametric analysis is conducted. The results indicate that unsaturated hydraulic properties of clay fill represent the key factors governing the embankment response to seasonal wetting-drying patterns

Analysis of mat foundation on inclined multi-layer subgrade

This paper work discusses different types of mat foundation procedures. The goal of this work is to overcome shortcomings of traditional models like "rigid plate model" and Winkler model that are commonly used in design practice. The use of modified Winkler model that follows iterative procedure enables to minimize shortcomings of simpler models and to obtain more realistic behavior of foundation-soil system. The purpose of this work is to present the procedure of implementation of modified Winkler model in software for structure analysis, that are usually supplied with classical Winkler model

Stabilizacija visoko plastične gline primenom tečnog hemijskog aditiva Polybond

U radu su prikazani rezultati laboratorijskih ispitivanja mogućnosti stabilizacije gline visoke plastičnosti primenom tečnog hemijskog aditiva Polybond, kao i stabilizacije tla kombinacijom letećeg pepela iz TE Kostolac i Polybonda. U cilju utvrđivanja efekata stabilizacije sprovedena su opsežna laboratorijska ispitivanja fizičko-mehaničkih karakteristika stabilizovanog tla (jednoaksijalna čvrstoća, parametri smičuće čvrstoće, CBR, modul stišljivosti, potencijal bubrenja, koeficijent vodopropusnosti, otpornost na dejstvo mraza). Rezultati istraživanja jasno ukazuju na pozitivne efekte stabilizacije gline Polybondom i potvrđuju stavove da se isti može uspešno primeniti kao stabilizator glinovitih vrsta tla u različitim praktičnim primenama kao što su: stabilizacija slabo nosivog tla, izgradnja nasipa i geotehničkih konstrukcija male vodopropusnosti, poboljšanje mehaničkih osobina gornjih slojeva donjeg stroja saobraćajnica itd

Sanacija temeljne konstrukcije stambenog objekta u Zemunu primenom MEGA šipova

U radu je dat prikaz sanacionog rešenja temeljne konstrukcije jednog stambenog objekta u Zemunu. Do oštećenja objekta došlo je usled neravnomernog sleganja temeljnog tla lesoidnog porekla kao posledica havarije na vodovodnoj infrastrukturi. Sleganjem tla je bilo obuhvaćeno nekoliko objekata koji su pretrpeli znatna oštećenja. U radu je dat detaljan prikaz usvojene sanacione mere za objekat u Dobanovačkoj ulici broj 34d , koja se bazirala na primeni "Mega" šipova

Soil-nailing-tehnika stabilizacije zemljanih masa

Soil-nailing tehnika se vec dugi niz godina u svetu uspešno koristi za stabilizaciju i ojacenje zemljanih masa. U nizu geoloških formacija soil-nailing potpornim konstrukcijama se daje prednost u odnosu na tradicionalne metode podgradivanja. Nažalost u našoj zemlji potencijal ove metode do sada nije potpuno iskorišcen. Ideja autora ovog preglednog rada bila je da inženjere i projektante gradevinske struke bliže upozna sa mogucnostima koje ova inovativna tehnologija pruža. U radu su sažeto prikazane osnovne karakteristike, istorijat razvoja, tehnicki aspekti, oblasti primene i prednosti i ogranicenja sistema soil-nailing. Soil nailing is being successfully used for many years all over the world to improve stability of excavated vertical cuts and existing slopes. In a wide variety of ground conditions soil nail walls present advantages over traditional retaining structures. Unfortunately in our country the potential benefits of this method have not been fully exploited. This review is intended to introduce practitioners to the possibilities that this innovative technology can offer. The paper summarizes the major features, history and development, technical aspects, application fields and benefits and limitations of soil nailing

A comparative analysis of pile design using eurocode 7 and national code of practice

Standard SRPS EN 1997-1 je krajem 2018. godine preveden i usvojen, dok je izrada nacionalnih priloga u završnoj fazi. S tim u vezi kao i zbog brojnih nedoumica stručne javnosti u vezi sa primenom EN 1997-1, autori su u ovom radu dali pojašnjenja procesa projektovanja aksijalno pritisnutih šipova prema EN7. Razlike između domaćeg pravilnika i EN7 ilustrovane su kroz numerički primer, čiji je primarni cilj uporedna analiza dužina šipova prema tradicionalnom postupku(globalni faktor sigurnosti) i prema EN7 (parcijalni faktori). Sprovedene analize potvrdile su podobnost preporučene vrednosti modelskog faktora γM date u nacrtu nacionalnog priloga.The standard SRPS EN 1997-1 was translated and adopted at the end of 2018, while the development of national annexes is in the final stage. In this regard, and due to concerns of engineering community about the application of EN 1997-1, the authors of this paper have provided clarification of the design process of axially loaded compression piles according EN7. The differences between the national code of practice and EN7 are illustrated through a design example, which aimed to compare pile lengths obtained applying the traditional procedure (global security factor) and to EN7 (partial factors). The performed analyses confirmed the suitability of the recommended value of the model factor γM provided in the draft national annex

Utilization of ash from power plants for high embankments on soft soil

The ash landfills are a major environmental issue. The use of ash for the highway and railway substructure achieves a double benefit: it significantly reduces the deposited quantities of ash as well as the consumption of natural materials such as crushed stone, gravel and sand. The investigation of engineering properties of fly ash from the power plant in Serbia was conducted at the Laboratory of Soil Mechanics at the Faculty of Civil Engineering in Belgrade. Relevant physical and mechanical properties of ash and mixtures with binders (cement/lime) were investigated. The ash was also tested from the aspect of the potential environmental impact, which primarily depends on the leaching behaviour of the present trace elements. The results of the study showed that fly ash meets technical and environmental requirements and that has the potential for use in highway substructure, such as construction of embankments and stabilization of soft soils. Benefits of utilization of ash and slag was shown in the case of the construction of a high embankment on soft soil on the highway section Obrenovac-Ub in Serbia

Stabilizacija visoko plastične gline primenom tečnog hemijskog aditiva Polybond

U radu su prikazani rezultati laboratorijskih ispitivanja mogućnosti stabilizacije gline visoke plastičnosti primenom tečnog hemijskog aditiva Polybond, kao i stabilizacije tla kombinacijom letećeg pepela iz TE Kostolac i Polybonda. U cilju utvrđivanja efekata stabilizacije sprovedena su opsežna laboratorijska ispitivanja fizičko-mehaničkih karakteristika stabilizovanog tla (jednoaksijalna čvrstoća, parametri smičuće čvrstoće, CBR, modul stišljivosti, potencijal bubrenja, koeficijent vodopropusnosti, otpornost na dejstvo mraza). Rezultati istraživanja jasno ukazuju na pozitivne efekte stabilizacije gline Polybondom i potvrđuju stavove da se isti može uspešno primeniti kao stabilizator glinovitih vrsta tla u različitim praktičnim primenama kao što su: stabilizacija slabo nosivog tla, izgradnja nasipa i geotehničkih konstrukcija male vodopropusnosti, poboljšanje mehaničkih osobina gornjih slojeva donjeg stroja saobraćajnica itd

The alternatives to traditional materials for subsoil stabilization and embankments

Major infrastructure projects require significant amount of natural materials, often followed by the soft soil stabilization using hydraulic binders. This paper presents the results of a laboratory study of alternative waste materials (fly ash and slag) that can be used for earthworks. Results of high plasticity clay stabilization using fly ash from Serbian power plants are presented in the first part. In the second part of the paper, engineering properties of ash and ash-slag mixtures are discussed with the emphasis on the application in road subgrade and embankment construction. Physical and mechanical properties were determined via following laboratory tests: Specific gravity, grain size distribution, the moisture–density relationship (Proctor compaction test), unconfined compressive strength (UCS), oedometer and swell tests, direct shear and the California bearing ratio (CBR). The results indicate the positive effects of the clay stabilization using fly ash, in terms of increasing strength and stiffness and reducing expansivity. Fly ashes and ash-slag mixtures have also comparable mechanical properties with sands, which in combination with multiple other benefits (lower energy consumption and CO2 emission, saving of natural materials and smaller waste landfill areas), make them suitable fill materials for embankments, especially considering the necessity for sustainable development

Stabilizacija prašinaste gline primenom pepela iz termoelektrane "Kolubara", Srbija

U radu su prikazani neki rezultati laboratorijskih ispitivanja stabilizacije prašinaste gline primenom elektrofilterskog pepela iz termoelektrane "Kolubara". Vršena su ispitivanja fizičkih i mehaničkih karakteristika tla, kao što su: granulometrijski sastav, granice konzistencije, odnos vlažnosti i suve zapreminske težine, jednoaksijalna čvrstoća, parametri smičuće čvrstoće, CBR i moduli deformabilnosti. Rezultati istraživanja su pokazali da se primenom pepela kao stabilizatora povećava CBR vrednost tla, što je naročito značajno za primenu u putogradnji