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\"Here is the definitive guide to unsaturated soil by the world's expert in the area of unsaturated soil mechanics. This volume features the latest information and replaces the leading text in the field, also written by this author team. The text offers state-of-the-art information to deal with the practical engineering problems resulting from unsaturated soil. Greater emphasis has been placed on the using the soil-water characteristic curve in solving practical engineering problems, as well as the quantification of thermal and moisture boundary conditions based on weather data\"--

This handbook provides a complete and detailed overview of piling systems and their application. The design and construction of piled foundations is based on Eurocode 7 and DIN 1054 edition 2010 as well as the European construction codes DIN EN 1536 (Bored piles), DIN EN 12699 (Displacement piles) and DIN EN 14199 (Micropiles). These recommendations also deal with - categorisation of piling systems, - actions on piles from structural loading, negative skin friction and side pressure, - pile resistances from static and dynamic pile test loading as well as extensive tables with the pile load-bearing capacity of nearly all piling systems based on values from practical experience, - pile groups, - performance of static and dynamic test loading and integrity tests, - load-bearing behaviour and verifications for piles under cyclical, dynamic and impact actions - quality assurance for construction. An appendix with numerous calculation examples completes the work. As part of the approval procedure for offshore wind energy structures, the Federal Office for Shipping and Hydrography (BSH) demands verifications according to the new Chapter 13 (\"Load-bearing behaviour and verifications for piles under cyclical, dynamical and impact actions\") of the EA Pfahle (the recommendations of the Piling working group - 2nd edition), which deals with external pile resistance for the foundations of offshore wind energy structures and the types of verifications to be provided under cyclical actions. The publication of the EA-Pfahle recommendations by the Piling working group of the German Society for Geotechnics (DGGT), which works with the same members as the piling standards committee NA 00-05-07, is intended to provide assistance for engineers active in the design, calculation and construction of piled foundations. The recommendations can thus be considered as rules of the technology and as a supplement to the available codes and standards.

This book bridges the gap between graduate courses in Geomechanics and those in Numerical Geotechnical Modelling, for practical usage in science and practice. Also explores the thermomechanical consistency of all presented constitutive models.

Long description: Barodesy is a constitutive model for granular materials such as sand and clay. It is based on the asymptotic behaviour of granular media at a constant deformation rate. In this work the existing sand version of Barodesy is improved. For this purpose, the underlying scalar equations are simplified using different concepts from soil mechanics. The improved version is also compared with laboratory tests and different elastoplastic and hypoplastic constitutive relations. Also the stability of slopes and advanced stress paths such as the rotation of the princple stresses are investigated with these models.

The purpose of this book is to bridge the gap between the traditional Geomechanics and Numerical Geotechnical Modelling with applications in science and practice. Geomechanics is rarely taught within the rigorous context of Continuum Mechanics and Thermodynamics, while when it comes to Numerical Modelling, commercially available finite elements or finite differences software utilize constitutive relationships within the rigorous framework. As a result, young scientists and engineers have to learn the challenging subject of constitutive modelling from a program manual and often end up with using unrealistic models which violate the Laws of Thermodynamics. The book is introductory, by no means does it claim any completeness and state of the art in such a dynamically developing field as numerical and constitutive modelling of soils. The author gives basic understanding of conventional continuum mechanics approaches to constitutive modelling, which can serve as a foundation for exploring more advanced theories. A considerable effort has been invested here into the clarity and brevity of the presentation. A special feature of this book is in exploring thermomechanical consistency of all presented constitutive models in a simple and systematic manner.

This book addresses the latest issues in multiscale geomechanics. Written by leading experts in the field as a tribute to Jean Biarez (1927-2006), it can be of great use and interest to researchers and engineers alike. A brief introduction describes how a major school of soil mechanics came into being through the exemplary teaching by one man. Biarez's life-long work consisted of explaining the elementary mechanisms governing soil constituents in order to enhance understanding of the underlying scientific laws which control the behavior of constructible sites and to incorporate these scientific advancements into engineering practices. He innovated a multiscale approach of passing from the discontinuous medium formed by individual grains to an equivalent continuous medium. The first part of the book examines the behavior of soils at the level of their different constituents and at the level of their interaction. Behavior is then treated at the scale of the soil sample. The second part deals with soil mechanics from the vantage point of the construction project. It highlights Biarez's insightful adoption of the Finite Element Codes and illustrates, through numerous construction examples, his methodology and approach based on the general framework he constructed for soil behavior, constantly enriched by comparing in situ measurements with calculated responses of geostructures.

PurposeSoil cracking is a common natural phenomenon. The existence of soil cracks has significant effects on the engineering properties of clayey soil, and can cause significant problems in geotechnical, geological, and environmental aspects. Understanding of the potential mechanisms of soil cracking is essential in assessments of potential damages to earthen infrastructures.Materials and methodWe review the past research efforts devoted to the experimental investigations and applications of fracture mechanics in soil cracking, attempting to provide a better understanding of the formation mechanism of desiccation cracking with a perspective of fracture mechanics.Results and discussionThis review analyzes the influence of soil cracking on soil engineering properties and the significance of soil cracking phenomena. Past and current formulations of soil fracture criteria and their experimental investigation are discussed. This review reveals the factors that affect the mechanisms of soil fracture can be divided into two groups, namely soil intrinsic properties and test-related factors. The applications of fracture mechanics in soil cracking are also discussed with particular focus on soil fracture models that are separately based on linear elastic fracture mechanics (LEFM), elastic plastic fracture mechanics (EPFM), and numerical simulations of soil cracking based on fracture mechanics. Some challenges and prospects of the applications of fracture mechanics in soil cracking are presented.ConclusionsFracture mechanics is a significant method to explain soil crack initiation and propagation. It is expected that researchers can gain better understanding of the range of fracture mechanics applications in soil cracking, and seek improvements and extensions of existing models through this review.

Soil shear strength is the most fundamental property when designing structures in the ground and should be carefully assessed and understood. Several empirical models were introduced to predict the shear strength of unsaturated soils. However, there is uncertainty regarding the applicability and sensitivity of these prediction models. This paper presents a comprehensive verification study to assess the reliability and validity of the existing theoretical models. The results obtained from the prediction models are compared to measured data using thirty experimental data sets. A performance classification program is also conducted to assess the suitability of the analytical models for different soil types as well as over a wide range of matric suctions, saturation degrees, soil densities, soil plasticity, and clay activity. The impact of each single parameter is clarified by the microstructure studies, which also provides insight into the mechanics of unsaturated soils. The results indicated that the applicability of models is more appropriate for sandy soils rather than for clayey ones. The performance of shear strength models tends to decrease with an increase in matric suction, initial density, plasticity index, and clay activity. It is, therefore, recommended that the shear strength estimation models should be carefully selected depending on the soil type and properties. Besides, the analysed results pointed out that the choice to assume the factor χ in the equation of Bishop equals the saturation degree is only suitable for medium-dense soils with low matric suction. This assumption is particularly not effective for clayey soils, or dense soils with high matric suction.

The Mohr–Coulomb (M–C) fracture criterion is revisited with an objective of describing ductile fracture of isotropic crack-free solids. This criterion has been extensively used in rock and soil mechanics as it correctly accounts for the effects of hydrostatic pressure as well as the Lode angle parameter. It turns out that these two parameters, which are critical for characterizing fracture of geo-materials, also control fracture of ductile metals (Bai and Wierzbicki 2008; Xue 2007; Barsoum 2006; Wilkins et al. 1980). The local form of the M–C criterion is transformed/extended to the spherical coordinate system, where the axes are the equivalent strain to fracture , the stress triaxiality η, and the normalized Lode angle parameter . For a proportional loading, the fracture surface is shown to be an asymmetric function of . A detailed parametric study is performed to demonstrate the effect of model parameters on the fracture locus. It was found that the M–C fracture locus predicts almost exactly the exponential decay of the material ductility with stress triaxiality, which is in accord with theoretical analysis of Rice and Tracey (1969) and the empirical equation of Hancock and Mackenzie (1976), Johnson and Cook (1985). The M–C criterion also predicts a form of Lode angle dependence which is close to parabolic. Test results of two materials, 2024-T351 aluminum alloy and TRIP RA-K40/70 (TRIP690) high strength steel sheets, are used to calibrate and validate the proposed M–C fracture model. Another advantage of the M–C fracture model is that it predicts uniquely the orientation of the fracture surface. It is shown that the direction cosines of the unit normal vector to the fracture surface are functions of the “friction” coefficient in the M–C criterion. The phenomenological and physical sound M–C criterion has a great potential to be used as an engineering tool for predicting ductile fracture.

Background and aims Root elongation is generally limited by a combination of mechanical impedance and water stress in most arable soils. However, dynamic changes of soil penetration resistance with soil water content are rarely included in models for predicting root growth. Better modelling frameworks are needed to understand root growth interactions between plant genotype, soil management, and climate. Aim of paper is to describe a new model of root elongation in relation to soil physical characteristics like penetration resistance, matric potential, and hypoxia. Methods A new diagrammatic framework is proposed to illustrate the interaction between root elongation, soil management, and climatic conditions. The new model was written in Matlab®, using the root architecture model RootBox and a model that solves the ID Richards equations for water flux in soil. Inputs: root architectural parameters for Soybean; soil hydraulic properties; root water uptake function in relation to matric flux potential; root elongation rate as a function of soil physical characteristics. Simulation scenarios: (a) compact soil layer at 16 to 20 cm; (b) test against a field experiment in Brazil during contrasting drought and normal rainfall seasons. Results (a) Soil compaction substantially slowed root growth into and below the compact layer. (b) Simulated root length density was very similar to field measurements, which was influenced greatly by drought. The main factor slowing root elongation in the simulations was evaluated using a stress reduction function. Conclusion The proposed framework offers a way to explore the interaction between soil physical properties, weather and root growth. It may be applied to most root elongation models, and offers the potential to evaluate likely factors limiting root growth in different soils and tillage regimes.