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Über dieses Buch

This book describes the development of a constitutive modeling platform for soil testing, which is one of the key components in geomechanics and geotechnics. It discusses the fundamentals of the constitutive modeling of soils and illustrates the use of these models to simulate various laboratory tests. To help readers understand the fundamentals and modeling of soil behaviors, it first introduces the general stress–strain relationship of soils and the principles and modeling approaches of various laboratory tests, before examining the ideas and formulations of constitutive models of soils. Moving on to the application of constitutive models, it presents a modeling platform with a practical, simple interface, which includes various kinds of tests and constitutive models ranging from clay to sand, that is used for simulating most kinds of laboratory tests. The book is intended for undergraduate and graduate-level teaching in soil mechanics and geotechnical engineering and other related engineering specialties. Thanks to the inclusion of real-world applications, it is also of use to industry practitioners, opening the door to advanced courses on modeling within the industrial engineering and operations research fields.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Constitutive Relations of Saturated Soils: An Overview

Abstract
In this chapter, some of the typical mechanical behaviors of saturated soils are introduced and summarized, starting with the most basic materials known as “remolded soils”: compression behavior, shear behavior, influence of intermediate principal stress, induced anisotropy, noncoaxiality, small-strain stiffness, cyclic behavior, time dependency, temperature effects, and water chemistry effects. Then, additional mechanical properties are gradually introduced with constitutive modeling methods for intact natural soils, namely, inherent anisotropy, soil structure, and destructuration. Finally, special problematic soils (i.e., organic soft soil, quick clay) are introduced with their special mechanical properties and constitutive modeling approaches. Each basic characteristic is presented with its definition or basic description, and then, the testing methods with the interpretation of test results, as well as commonly used constitutive modeling methods, are introduced.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Chapter 2. Fundamentals of Stress and Strain

Abstract
The essence of soil constitutive modeling is the establishment of the stress–strain relationship for soils. In this chapter, the continuum hypothesis of soil as an assembly of grains is first introduced, then the stress and strain concepts, as well as their expressions of some important stress or strain variables used in constitutive modeling are briefly discussed, and finally, the practical stress–strain analysis module developed in the ErosLab platform is presented.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Chapter 3. Introduction of Laboratory Tests for Soils

Abstract
This chapter summarizes six common laboratory tests, including the oedometer test, triaxial test, simple shear test, biaxial test, true triaxial test, and hollow cylinder torsional shear test, and their associated stress and strain paths for developing constitutive models and calibration are also introduced. Additionally, the operation for simulating each test in the ErosLab platform is introduced for in-depth understanding and practice.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Chapter 4. Fundamentals of Elastoplastic Theory

Abstract
This chapter presents the classic constitutive modeling method known as the conventional elastoplastic theory with different components, such as the elastic stress–strain relationship, the elastoplastic relationship, which includes the yield surface, flow rule, and hardening rule, and Drucker’s stability hypothesis, convexity, and orthogonality. Some typical numerical methods for solving plastic problems are also presented, such as the general explicit solution, the cutting plane method-based implicit solution, and the closest point projection method-based implicit solution.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Chapter 5. Elastoplastic Modeling of Soils: From Mohr-Coulomb to SIMSAND

Abstract
Most constitutive models of soils are developed under the framework of elastoplasticity. This chapter presents the step-by-step modeling methodology from Mohr-Coulomb to SIMSAND. First, the experimental phenomena of shear behavior for normally consolidated or loose soils and for overconsolidated or dense soils are presented. Capturing the shear characteristics of soils, the Mohr-Coulomb model is presented to discuss the significance of the model parameters. By implementing nonlinear elasticity, nonlinear plastic hardening, and nonlinear stress–dilatancy, the development of a nonlinear Mohr-Coulomb model is presented. Further considering the critical state feature of soils, the model is extended to the SIMSAND model. For practical purposes, the development of the MATLAB code for simulating triaxial tests using SIMSAND is presented. Finally, some elastoplastic models in the EROSLAB platform are presented for practical applications.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Chapter 6. Elastoplastic Modeling of Clayey Soils: From MCC to ASCM

Abstract
This chapter presents a step-by-step modeling methodology for clayey soils from the modified Cam-clay model (MCC) to the anisotropic structured clay model (ASCM). First, the experimental behavior of clayey soils under compression is presented. Then, a typical MCC model capturing both the shear and compression characteristics of clayey soils is presented, and the significance of the model parameters is discussed. By implementing the nonlinear stress–strain relationship through the bounding surface method, the effect of structures on plasticity (i.e., anisotropic yield surface, cementation/bonding, and adhesive cohesion) and the effect of structures on elasticity, the development of the ASCM model is presented. For practical purposes, the development of the MATLAB code for simulating triaxial tests using ASCM is presented. Finally, the MCC and ASCM models in the EROSLAB platform are presented for practice.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Chapter 7. Viscoplastic Modeling of Soft Soils

Abstract
First, a one-dimensional elastic viscoplastic model is developed based on the experimental results of strain rate dependency in oedometer tests. Using this model, the coherence of strain rate dependency, creep, and stress relaxation is established. Then, the model is extended for structured clays by accounting for the effect of interparticle bonds. A three-dimensional viscoplastic model called ANICREEP is presented under the framework of Perzyna’s overstress theory, and the choice of the scaling function is discussed. The developed ANICREEP model also accounts for anisotropy and destructuration. To simulate the different tests, a general explicit algorithm is presented. The development of a MATLAB code for simulating the triaxial tests is also presented. Finally, the ANICREEP model in the ErosLab Platform is presented for practical exercises.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Chapter 8. Hypoplastic Modeling of Sand Considering the Time Effect

Abstract
In this chapter, a newly constructed constitutive model is presented for modeling the time-dependent behavior of granular materials. The model consists of dividing the stress tensor into an inviscid stress using a hypoplastic formulation and a viscous stress with a high-order term representing the strain acceleration. Then, different laboratory tests on granular soils are simulated to evaluate the model performance, i.e., a series of constant strain rate triaxial tests and a stepwise strain rate triaxial test on Toyoura sand, a stepwise strain rate triaxial test on Chiba gravelly soil, and creep tests under different stress levels on Toyoura sand. Comparisons between the experimental and numerical results show the capability of the model in describing the strain rate and acceleration effects, as well as the creep behavior of granular materials. Moreover, the coupling between the inviscid stress and viscous stress enables the evolution of the strain rate increase in the creep tests. Consequently, the three stages of creep, namely, primary, secondary, and tertiary creep, can be well described. Finally, the model, named HYPOSAND, is presented in the ErosLab platform as a practical exercise.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Chapter 9. Multiscale Modeling of Soils

Abstract
This chapter presents the multiscale modeling methodology for soils from micro to macro. First, the multiscale feature of soils within the general framework of the multiscale approach to granular materials is presented. Then, the fundamentals of micromechanics are presented in more detail, including interparticle contact laws, definitions of the strain tensor, effective stress tensor and fabric tensor, averaging and localization operators, and homogenization integration. As an example, the micromechanics-based Chang–Hicher (CH) model is presented with experimental validation. Some possible developments of models based on the CH model are presented considering the capillary force, the chemical force in grouted sand, the surface energy force, and the mechanical force in clayey materials. Finally, the MicroSoil model in the ErosLab platform is presented for a practical exercise.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Chapter 10. Practice of the ErosLab Modeling Platform

Abstract
In this chapter, the ErosLab platform is first briefly introduced. Then, the numerical scheme of stress–strain mix control is presented, followed by the operations of the ErosLab platform. Subsequently, three examples of simulations, the oedometer test, triaxial test, and simple shear test, are conducted using the ErosLab platform following the above operations. These examples demonstrate the powerful ability of the ErosLab platform in constitutive modeling of laboratory tests. Finally, an example of UMAT allowing users to develop and test their own constitutive models is described, which demonstrates how the platform is open to users.
Zhen-Yu Yin, Pierre-Yves Hicher, Yin-Fu Jin

Backmatter

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