A aplicação de pintura de ligação entre camadas asfálticas é prática comum em obras de pavimentos novos ou restaurações, sendo importante para garantir a aderência entre as camadas. Esse tratamento da interface geralmente é feito com emulsão asfáltica, que faz com que a estrutura do pavimento trabalhe como um sistema monolítico, evitando problemas de trincamento precoce por fadiga, ou escorregamentos. Esse trabalho tem como objetivo estudar a variabilidade de comportamento dos revestimentos asfálticos quanto à aderência na interface, tendo em vista a taxa aplicada de pintura de ligação, o tipo de emulsão (convencional ou modificada por polímero), a superfície de contato entre as camadas e a presença, ou não, de um sistema anti-reflexão de trincas (geotêxtil e grelha de fibra de vidro). A aderência foi medida por meio do ensaio de cisalhamento direto Leutner, em amostras produzidas em laboratório e extraídas de pista. Foram produzidas placas com dupla camada de revestimento asfáltico, sendo a camada superior um CBUQ (Concreto Betuminoso Usinado a Quente) e a inferior, ora SAMI (Stress Absorbing Membrane Interlayer), ora CBUQ, variando a taxa de aplicação de pintura de ligação na interface (0,0; 0,25; 0,5 e 0,75 L/m2) e o tipo de emulsão aplicada (RR-1C, RR- 1C-E e RR-2C-E), além de testar duas diferentes dimensões para as amostras cilíndricas ensaiadas (100 e 150 mm de diâmetro). Os ensaios de cisalhamento direto foram feitos com carregamento monotônico, à taxa de deslocamento de 50mm/min e à temperatura de 20ºC. Realizou-se o mesmo ensaio também com velocidade de 1 mm/min para avaliar a influência desse parâmetro nos resultados de aderência para as três emulsões testadas. As amostras de pista, com 100 mm de diâmetro, foram retiradas de um trecho experimental na Rodovia Ayrton Senna (SP- 070), do km 38,000 ao 39,500. Os resultados do teste de aderência em laboratório demonstraram influência do tipo de emulsão, da presença de geotêxtil/grelha na interface, do diâmetro da amostra, da textura superficial entre camadas e da velocidade de ensaio nos valores de tensão cisalhante máxima e na taxa ótima de aplicação de emulsão. Os valores de taxa ótima de pintura de ligação foram maiores quando na presença de geotêxtil na interface e para superfícies de contato com maior macrotextura. Quanto à aderência, as amostras com grelha não apresentaram diferença significativa comparadas ao uso de interface somente com pintura de ligação, enquanto as amostras com geotêxtil na interface resultaram em valores bem 8 inferiores de tensão cisalhante máxima. Para ensaios com diferentes tipos de pintura de ligação, as amostras com emulsão modificada nem sempre apresentaram melhores resultados em relação às amostras com emulsão convencional. / Asphalt tack coat is commonly applied at the interface between asphalt layers during new pavement construction or overlay to ensure proper bond between the layers. This treatment at the interface, usually done with asphalt emulsion, allows the pavement structures to function as a monolithic system, avoiding problems like premature fatigue cracking, or slippage. This study aims to evaluate: (i) the influence of the tack coat type (neat or polymer modified asphalt emulsion), (ii) the application rate, (iii) the surface type, and (iv) the presence, or not, of an anti-reflective cracking interlayer (geotextile and fiber glass grid), in the adhesion properties between asphalt concrete layers. The adhesion between layers was tested through the Leutner shear test in laboratory and field samples. A double-layer system was produced with HMA as the top layer and SAMI (Stress Absorbing Membrane Interlayer), or HMA, as the bottom layer, varying the tack coat type (RR-1C, RR-1C-E e RR-2C-E), the application rate at the interface (0,0; 0,25; 0,50 and 0,75 L/m²) and the samples diameter (100 and 150 mm diameter). It was used the standard shear displacement rate of 50 mm/min, and the test temperature was set at 20°C. The same procedure was run with a displacement rate of 1 mm/min to evaluate its influence on the adhesion of three asphalt emulsions used as the tack coat. An experimental test section was constructed on Rodovia Ayrton Senna (SP-070), from km 38,000 to 39,500, and core samples (100 mm diameter) were extracted. The results of maximum shear stress demonstrate the influence of the tack coat type, the surface type, the sample diameter, the test displacement rate and the presence of a geotextile/grid on the adhesion at the interface between the asphalt layers,. Samples with grid at the interface presented similar results when compared with the samples with only tack coat at the interface. Samples with geotextile, however, presented significant lower values of maximum shear stress. The Leutner results showed that not always the modified asphalt emulsions present higher shear strength when compared to the neat asphalt emulsions.

The objective of this research was to apply a previously recommended laboratory testing protocol to specific aggregate base materials that are also the subject of ongoing full-scale field testing. The scope of this research involved three aggregate base materials selected from three sites where full-scale field testing programs have been established. The first and second field sites included five different geogrid types, categorized as either biaxial or triaxial, in a singlelayer configuration, while the third site included only the triaxial geogrid type in either a singleor double-layer configuration. Geogrid-stabilized and unstabilized control specimens were evaluated using the American Association of State Highway and Transportation Officials T 307 quick shear testing protocol. Measurements of load and axial displacement were recorded and used to develop a stress-strain plot for each specimen tested. The peak axial stress, the modulus to the peak axial stress, the modulus of the elastic portion of the curve, and the modulus at 2 percent strain were then calculated. Statistical analyses were performed to investigate differences between geogridstabilized specimens and unstabilized control specimens and to investigate differences between individual geogrid products or geogrid configurations. Depending on the method of data analysis, the quick shear test results indicate that geogrid stabilization, with the effect of geogrid stabilization averaged across all of the geogrid products evaluated in this study, may or may not improve the structural quality of the aggregate base materials evaluated in this study. The results also indicate that, regardless of the method of analysis, one geogrid product or configuration may be more effective than another at improving the structural quality of a given aggregate base material as measured using the quick shear test. All results from this research are limited in their application to the aggregate base material types, geogrid products, and geogrid configurations associated with this study. Additional research is needed to compare the results of the laboratory quick shear testing obtained for this study with the structural capacity of the geogrid-stabilized and unstabilized control sections that have been constructed at corresponding full-scale field testing sites. Specifically, further research is needed to determine which method of laboratory data analysis yields the best comparisons with field test results. Finally, correlations between the results of quick shear testing and resilient modulus need to be investigated in order to incorporate the findings of the quick shear test on geogrid-stabilized base materials into mechanistic-empirical pavement design.

During shearing of stiff clays, plate-shaped clay particles are parallel-oriented in the direction of shear reaching the minimum resistance of &ldquo / residual shear strength&rdquo / . The residual shear strength envelopes of stiff clays are curved, but for practical purposes represented by linear envelopes. This study investigates the nonlinearity of the residual shear strength envelope using experimental evidence (i) from laboratory reversal direct shear tests on two stiff clays (Ankara clay and kaolinite) at 25 to 900 kPa effective normal stresses and (ii) from laboratory data collected from literature. To evaluate the importance of nonlinearity of the envelope for geotechnical engineering practice, by limit equilibrium method, (a) case histories of reactivated landslides are analyzed and (b) a parametric study is carried out. Conclusions of this study are: (1) The residual shear strength envelopes of both Ankara clay and kaolinite are nonlinear, and can be represented by a power function (cohesion is zero). (2) At least 3 reversals or cumulative 20 mm shear displacement of direct shear box is recommended to reach residual condition. (3) Empirical relations between plasticity index and residual friction angle can accurately estimate the residual strength of stiff clays. (4) Nonlinearity is especially important for landslides where average effective normal stress on the shear plane is less than 50 kPa, both for translational and rotational failures. For such slopes using a linear strength envelope overestimates the factor of safety (more significantly for the case of high pore pressures). (5) As the plasticity index increases, the power &ldquo / b&rdquo / of the nonlinear shear strength envelope decreases, indicating more significant nonlinearity. For less plastic materials, using linear and nonlinear shear strength envelopes does not affect the factor of safety.

The frictional behavior of soil-construction material interfaces is of significant importance in geotechnical engineering applications such as retaining structures, pile foundations, geosynthetic liners, and trenchless technologies. Since most failures initiate and develop on the interfaces, special attention is required to predict the capacity of these weak planes in the particular application. Pipe-jacking and microtunneling technologies are being more widely used over the past decade and there is significant interest to predict the jacking forces and jacking distances achievable in order to achieve more efficient design and construction. This study focuses on the evaluation of the frictional characteristics and factors affecting the shear strength of pipe-soil interfaces. Eight different pipes made from fiber reinforced polymer (FRP), polycrete, steel, concrete, and vitrified clay were tested in the experimental program. For this purpose, a new apparatus was designed to conduct conventional interface direct shear testing on pipes of different curvature. This device allows coupons cut from actual conduits and pipes to be tested in the laboratory under controlled conditions. The apparatus includes a double-wall shear box, the inner wall of which is interchangeable to allow for testing against surfaces of different curvatures. By considering a narrow width section, the circular interface of pipes was approximated with a surface along the axial direction and the boundary is defined by the inner box. Roughness tests were performed using a stylus profilometer to quantify the surface characteristics of the individual pipes and relate these to the interface shear behavior. The surface topography showed different degrees of variability for the different pipes. To extend the range of roughness values tested and force the failure to occur in the particulate media adjacent to the interface, two artificial pipe surfaces were created using rough sandpapers. Interface shear tests were performed using the new apparatus with air-pluviated dense specimens of Ottawa 20/30 sand. Additional tests were performed using Atlanta blasting sand to evaluate the effect of particle angularity. The effect of normal stress and relative density were also examined. The interface strength was shown to increase with surface roughness and finally reach a constant value above a certain critical roughness value, which corresponded to the internal strength of the soil itself. This represented the failure location moving from the interface into the soil adjacent to the interface. Both the strength and the shearing mechanism were thus affected by the surface topography. It was also shown that the interface shear strength was affected by particle angularity, relative density and normal stress.

As propriedades do solo cotidianamente podem não ser adequadas às características e às necessidades de projeto. É apresentada, como alternativa, a técnica de reforço com inclusão de elementos fibrosos à matriz de solo cimentado e não cimentado. Ainda, embora comuns, o comportamento do solo frente a solicitações cíclicas não é completamente conhecido. Nesse sentido, o estudo do comportamento de hidratação e da resposta cisalhante cíclica de um resíduo de mineração cimentado reforçado com fibras é objetivado. Para tanto, medidas de retração química, medidas de rigidez ao longo da hidratação e ensaios simple shear monotônicos e cíclicos foram realizados com resíduo de mineração cimentado e não cimentado, reforçado com fibras e não reforçado. O resíduo, oriundo da mineração de ouro, um silte arenoso com traços de argila, foi cimentado com diferentes teores de cimento Portland, entre 0% e 10% em relação à massa de solo seco, e reforçado com 0% e 0,5%, em relação à massa de sólidos secos, de fibras de polipropileno de 50mm de comprimento e 0,1mm de espessura, equivalentes a um índice aspecto de 500. Os resultados demonstraram que as fibras não afetaram o processo de hidratação das misturas de resíduo de mineração cimentadas, que apresentam tendência de atenuação logarítmica da retração química com o tempo. Quanto maiores as relações água/cimento, maior o nível de retração química. A inclusão de fibras a misturas de resíduo de mineração cimentadas, da mesma forma, não afetou a evolução dos valores de rigidez inicial, que crescem com tendência logarítmica em função do tempo e aumentam com o acréscimo do nível de cimentação. Sob condições monotônicas de cisalhamento, a adição de fibras conferiu ao material cimentado e não cimentado comportamento de endurecimento. Sob condições cíclicas de deformação cisalhante controlada, as fibras não afetaram a resposta cisalhante das amostras não cimentadas e provocaram aumento dos valores da tensão cisalhante das amostras cimentadas após sucessivos ciclos de esforços. Sob condições cíclicas de tensão cisalhante controlada, a adição de fibras às misturas não cimentadas proporcionou o aumento da resistência aos ciclos de esforços e às misturas cimentadas provocou aumento dos níveis de deformação cisalhante. A concordância das mesmas envoltórias de resistência tanto às trajetórias de tensões dos ensaios monotonônicos quanto às trajetórias dos ensaios cíclicos sob diferentes condições de carregamento possibilitou a obtenção dos mesmos parâmetros de resistência das misturas analisadas sob diferentes condições de carregamento. / The soil properties commonly may not suit the project characteristics and requirements. It is presented, as alternative, the improvement technique of fibrous elements inclusion to the cemented and uncemented soil matrix. Moreover, although common, the behaviour of soil under cyclic loads is not completely known. In this sense, the study of the hydration behaviour and the cyclic shear response of fibre reinforced cemented mine tailings is the main objective of this research. Therefore, chemical shrinkage measurements, stiffness measurements during hydration and monotonic and cyclic simple shear tests were conducted on fibre reinforced and unreinforced cemented and uncemented mine tailings. The tailings, produced from gold mining, are classified as a sandy silt with traces of clay and were cemented with different amounts of Portland cement, ranging from 0% to 10% by dry weigh of soil, and reinforced with 0% and 0.5% by dry weigh of solids of polypropylene fibers 50mm long and 0.1mm thick, equivalent to an aspect ratio of 500. The results showed fibres did not affect the hydration process of cemented mine tailings mixtures, which presents logarithmic attenuation of chemical shrinkage over time. The greater the water / cement ratio, the higher the level of chemical shrinkage. The inclusion of fibers to cemented mine tailings, likewise, did not affect the evolution of initial stiffness values, that raise logarithmic over time and increase with the increase of the cementation level. Under monotonic shear conditions, the addition of fibers confers hardening behaviour to the uncemented and cemented materials. Under shear strain controlled cyclic conditions, fibres did not affect the shear response of uncemented samples and increased shear stress values of cemented samples after successive load cycles. Under shear stress controlled cyclic conditions, the fibres addition to the uncemented mixtures increased the resistance to load cycles and to the cemented mixtures increased levels of shearing strain. The agreement of the same strength envelopes to both monotonic and cyclic stress paths, under different cyclic loading conditions, allows the use of the same strength parameters of mixtures analyzed under different loading conditions.

As propriedades do solo cotidianamente podem não ser adequadas às características e às necessidades de projeto. É apresentada, como alternativa, a técnica de reforço com inclusão de elementos fibrosos à matriz de solo cimentado e não cimentado. Ainda, embora comuns, o comportamento do solo frente a solicitações cíclicas não é completamente conhecido. Nesse sentido, o estudo do comportamento de hidratação e da resposta cisalhante cíclica de um resíduo de mineração cimentado reforçado com fibras é objetivado. Para tanto, medidas de retração química, medidas de rigidez ao longo da hidratação e ensaios simple shear monotônicos e cíclicos foram realizados com resíduo de mineração cimentado e não cimentado, reforçado com fibras e não reforçado. O resíduo, oriundo da mineração de ouro, um silte arenoso com traços de argila, foi cimentado com diferentes teores de cimento Portland, entre 0% e 10% em relação à massa de solo seco, e reforçado com 0% e 0,5%, em relação à massa de sólidos secos, de fibras de polipropileno de 50mm de comprimento e 0,1mm de espessura, equivalentes a um índice aspecto de 500. Os resultados demonstraram que as fibras não afetaram o processo de hidratação das misturas de resíduo de mineração cimentadas, que apresentam tendência de atenuação logarítmica da retração química com o tempo. Quanto maiores as relações água/cimento, maior o nível de retração química. A inclusão de fibras a misturas de resíduo de mineração cimentadas, da mesma forma, não afetou a evolução dos valores de rigidez inicial, que crescem com tendência logarítmica em função do tempo e aumentam com o acréscimo do nível de cimentação. Sob condições monotônicas de cisalhamento, a adição de fibras conferiu ao material cimentado e não cimentado comportamento de endurecimento. Sob condições cíclicas de deformação cisalhante controlada, as fibras não afetaram a resposta cisalhante das amostras não cimentadas e provocaram aumento dos valores da tensão cisalhante das amostras cimentadas após sucessivos ciclos de esforços. Sob condições cíclicas de tensão cisalhante controlada, a adição de fibras às misturas não cimentadas proporcionou o aumento da resistência aos ciclos de esforços e às misturas cimentadas provocou aumento dos níveis de deformação cisalhante. A concordância das mesmas envoltórias de resistência tanto às trajetórias de tensões dos ensaios monotonônicos quanto às trajetórias dos ensaios cíclicos sob diferentes condições de carregamento possibilitou a obtenção dos mesmos parâmetros de resistência das misturas analisadas sob diferentes condições de carregamento. / The soil properties commonly may not suit the project characteristics and requirements. It is presented, as alternative, the improvement technique of fibrous elements inclusion to the cemented and uncemented soil matrix. Moreover, although common, the behaviour of soil under cyclic loads is not completely known. In this sense, the study of the hydration behaviour and the cyclic shear response of fibre reinforced cemented mine tailings is the main objective of this research. Therefore, chemical shrinkage measurements, stiffness measurements during hydration and monotonic and cyclic simple shear tests were conducted on fibre reinforced and unreinforced cemented and uncemented mine tailings. The tailings, produced from gold mining, are classified as a sandy silt with traces of clay and were cemented with different amounts of Portland cement, ranging from 0% to 10% by dry weigh of soil, and reinforced with 0% and 0.5% by dry weigh of solids of polypropylene fibers 50mm long and 0.1mm thick, equivalent to an aspect ratio of 500. The results showed fibres did not affect the hydration process of cemented mine tailings mixtures, which presents logarithmic attenuation of chemical shrinkage over time. The greater the water / cement ratio, the higher the level of chemical shrinkage. The inclusion of fibers to cemented mine tailings, likewise, did not affect the evolution of initial stiffness values, that raise logarithmic over time and increase with the increase of the cementation level. Under monotonic shear conditions, the addition of fibers confers hardening behaviour to the uncemented and cemented materials. Under shear strain controlled cyclic conditions, fibres did not affect the shear response of uncemented samples and increased shear stress values of cemented samples after successive load cycles. Under shear stress controlled cyclic conditions, the fibres addition to the uncemented mixtures increased the resistance to load cycles and to the cemented mixtures increased levels of shearing strain. The agreement of the same strength envelopes to both monotonic and cyclic stress paths, under different cyclic loading conditions, allows the use of the same strength parameters of mixtures analyzed under different loading conditions.

As propriedades do solo cotidianamente podem não ser adequadas às características e às necessidades de projeto. É apresentada, como alternativa, a técnica de reforço com inclusão de elementos fibrosos à matriz de solo cimentado e não cimentado. Ainda, embora comuns, o comportamento do solo frente a solicitações cíclicas não é completamente conhecido. Nesse sentido, o estudo do comportamento de hidratação e da resposta cisalhante cíclica de um resíduo de mineração cimentado reforçado com fibras é objetivado. Para tanto, medidas de retração química, medidas de rigidez ao longo da hidratação e ensaios simple shear monotônicos e cíclicos foram realizados com resíduo de mineração cimentado e não cimentado, reforçado com fibras e não reforçado. O resíduo, oriundo da mineração de ouro, um silte arenoso com traços de argila, foi cimentado com diferentes teores de cimento Portland, entre 0% e 10% em relação à massa de solo seco, e reforçado com 0% e 0,5%, em relação à massa de sólidos secos, de fibras de polipropileno de 50mm de comprimento e 0,1mm de espessura, equivalentes a um índice aspecto de 500. Os resultados demonstraram que as fibras não afetaram o processo de hidratação das misturas de resíduo de mineração cimentadas, que apresentam tendência de atenuação logarítmica da retração química com o tempo. Quanto maiores as relações água/cimento, maior o nível de retração química. A inclusão de fibras a misturas de resíduo de mineração cimentadas, da mesma forma, não afetou a evolução dos valores de rigidez inicial, que crescem com tendência logarítmica em função do tempo e aumentam com o acréscimo do nível de cimentação. Sob condições monotônicas de cisalhamento, a adição de fibras conferiu ao material cimentado e não cimentado comportamento de endurecimento. Sob condições cíclicas de deformação cisalhante controlada, as fibras não afetaram a resposta cisalhante das amostras não cimentadas e provocaram aumento dos valores da tensão cisalhante das amostras cimentadas após sucessivos ciclos de esforços. Sob condições cíclicas de tensão cisalhante controlada, a adição de fibras às misturas não cimentadas proporcionou o aumento da resistência aos ciclos de esforços e às misturas cimentadas provocou aumento dos níveis de deformação cisalhante. A concordância das mesmas envoltórias de resistência tanto às trajetórias de tensões dos ensaios monotonônicos quanto às trajetórias dos ensaios cíclicos sob diferentes condições de carregamento possibilitou a obtenção dos mesmos parâmetros de resistência das misturas analisadas sob diferentes condições de carregamento. / The soil properties commonly may not suit the project characteristics and requirements. It is presented, as alternative, the improvement technique of fibrous elements inclusion to the cemented and uncemented soil matrix. Moreover, although common, the behaviour of soil under cyclic loads is not completely known. In this sense, the study of the hydration behaviour and the cyclic shear response of fibre reinforced cemented mine tailings is the main objective of this research. Therefore, chemical shrinkage measurements, stiffness measurements during hydration and monotonic and cyclic simple shear tests were conducted on fibre reinforced and unreinforced cemented and uncemented mine tailings. The tailings, produced from gold mining, are classified as a sandy silt with traces of clay and were cemented with different amounts of Portland cement, ranging from 0% to 10% by dry weigh of soil, and reinforced with 0% and 0.5% by dry weigh of solids of polypropylene fibers 50mm long and 0.1mm thick, equivalent to an aspect ratio of 500. The results showed fibres did not affect the hydration process of cemented mine tailings mixtures, which presents logarithmic attenuation of chemical shrinkage over time. The greater the water / cement ratio, the higher the level of chemical shrinkage. The inclusion of fibers to cemented mine tailings, likewise, did not affect the evolution of initial stiffness values, that raise logarithmic over time and increase with the increase of the cementation level. Under monotonic shear conditions, the addition of fibers confers hardening behaviour to the uncemented and cemented materials. Under shear strain controlled cyclic conditions, fibres did not affect the shear response of uncemented samples and increased shear stress values of cemented samples after successive load cycles. Under shear stress controlled cyclic conditions, the fibres addition to the uncemented mixtures increased the resistance to load cycles and to the cemented mixtures increased levels of shearing strain. The agreement of the same strength envelopes to both monotonic and cyclic stress paths, under different cyclic loading conditions, allows the use of the same strength parameters of mixtures analyzed under different loading conditions.

This diploma thesis deals with the reliability of lead-free solder joints at a different interconnection structures. The first goal is to design the test cases shape BGA (FC) for testing the strength of lead-free solder joints at shear test in link with design of measuring method to detection shear strength during isothermal aging of lead-free solder joints. Following this shear stressing is investigating influence material and process compatibility, ie. pads finishing, material of solder and integrate of temperature (this mean thermal energy supplied during soldering) to lead-free solder joint strength.

Vibration compaction is the most effective way of compacting coarse-grained materials. The effects of vibration frequency and amplitude on the compaction density of different backfill materials (No. 4 natural sand, No. 24 stone sand and No. 5, No. 8, No. 43 aggregates), were studied in this research. The test materials were characterized based on the particle sizes and morphology parameters using digital image analysis technique. Small-scale laboratory compaction tests were carried out with variable frequency and amplitude of vibrations using vibratory hammer and vibratory table. The results show an increase in density with the increase in amplitude and frequency of vibration. However, the increase in density with the increase in amplitude of vibration is more pronounced for the coarse aggregates than for the sands. A comparison of the maximum dry densities of different test materials shows that the dry densities obtained after compaction using the vibratory hammer are greater than those obtained after compaction using the vibratory table at the highest amplitude and frequency of vibration available in both equipment. Large-scale vibratory roller compaction tests were performed in the field for No. 30 backfill soil to observe the effect of vibration frequency and number of passes on the compaction density. Accelerometer sensors were attached to the roller drum (Caterpillar, model CS56B) to measure the frequency of vibration for the two different vibration settings available to the roller. For this roller and soil tested, the results show that the higher vibration setting is more effective. Direct shear tests and direct interface shear tests were performed to study the impact of particle characteristics of the coarse-grained backfill materials on interface shear resistance. A unique relationship was found between the normalized surface roughness and the ratio of critical-state interface friction angle between sand-gravel mixture with steel to the internal critical-state friction angle of the sand-gravel mixture.

Heavy forestry machines have great immediate effect on soil properties. This increases the interest to develop approaches that help understanding better the interaction between the forest machines and the terrain and consequently develop the forwarders to be gentle to the environment. The most predominant indications of soil disturbances caused by harvesting are mainly rutting and soil compaction. It is critical to understand and evaluate these damages to be able to protect the remaining trees and improve their tree growth rate. Comprehending the bearing capacity of the soil and the interaction between tire and soil are the key issues to develop forest machines that preserve the terrain. The first step to accomplish this goal is to compare the rut depth theoretical data from empirical models with the rut depth data from a full scale field test, the models suitable to predict rut depth is descripted. Tree roots reinforce the forest floor and significantly increase the bearing capacity of the soil. The contribution from root layer to the soil bearing capacity depends on the number, diameter, orientation of the roots and their mechanical properties. To improve the root tensile strength model, a root bending and stretching laboratory test has been carry out and compared with FEM-based results. The existing Valmet 860. 3 Adams MBS model is finally used to study the suitability of the model to predict rut depth. A comparison between several existing methods to predict rut depth is also shown. / Tunga skogsmaskiner har stor omedelbar effekt på markens egenskaper. Detta ökar intresset för att utveckla strategier som underlättar förståelsen av samverkan mellan skogsmaskiner och terrängen och därmed utveckla framdrivning av dessa maskiner som är skonsam mot miljön. De dominerande indikationerna på markstörningar orsakade av hjulbaserade skogsmaskiner är främst spårbildning och jordkompaktering. Det är viktigt att förstå och utvärdera dessa skador för att kunna skydda de kvarvarande träden och förbättra deras tillväxt. Att förstå markens bärighet och samspelet mellan däck och mark är de viktigaste frågorna för att utveckla skogsmaskiner som skonar terrängen. Det första steget för att uppnå detta mål är att jämföra spårdjup vilka är framtagna med empiriska modeller med data för spårdjup från ett fullskaligt fälttest, där de modeller som lämpar sig för att förutsäga spårdjup är beskrivna. Trädrötter förstärker skogsmarken och ökar avsevärt jordens bärighet. Bidraget från rotlagret till jordens bärförmåga beror på antalet rötter, deras diameter samt rötternas orientering och deras mekaniska egenskaper. För att förbättra modellen för rötternas mekaniska egenskaper har rotböjning och rottöjning studerats i ett laboratorietest och vidare jämförts med FEM-baserade resultat. Den befintliga MBS modellen av skotaren Valmet 860.3 har slutligen används för att studera lämpligheten av modellen för att förutsäga spårdjup. En jämförelse mellan flera olika metoder för att förutsäga spårdjup visas också.