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1 
Numerical solution of threedimensional consolidation黃澤恩, Wong, Chakyan. January 1968 (has links)
published_or_final_version / Civil Engineering / Master / Master of Science in Engineering

2 
Field study on influence of atmospheric parameters and vegetation on variation of soil suction around tree vicinityHe, Shu Yu January 2018 (has links)
University of Macau / Faculty of Science and Technology. / Department of Civil and Environmental Engineering

3 
Exploring criticalstate behaviour using DEMHuang, Xin, 黃昕 January 2014 (has links)
The critical state soil mechanics (CSSM) framework originally proposed by Schofield & Wroth (1968) has been shown to capture the mechanical behaviour of soils effectively. The particulate implementation of the discrete element method (DEM) can replicate many of the complex mechanical characteristics associated with sand. This research firstly shows that the CSSM framework is useful to assess whether a DEM simulation gives a response that is representative of a real soil. The research then explores the capacity of DEM to extend understanding of soil behaviour within the CSSM framework.
The influence of sample size on the criticalstate response observed in DEM simulations that use rigidwall boundaries was examined. The observed sensitivity was shown to be caused by higher void ratios and lower contact densities adjacent to the boundaries. When the void ratio (e) and mean stress (p’) of the homogeneous interior regions were considered, the influence of sample size on the position of the critical state line (CSL) in elog(p’) space diminished.
A parametric study on the influence of the interparticle friction (μ) on the loaddeformation response was carried out. The macroscale stressdeformation characteristics were nonlinearly related to μ and the particlescale measures (fabric, contact force distribution, etc.) varied systematically with μ. The limited effect of increases in μ on the overall strength at high μ values (μ>0.5) is attributable to transition from slidingdominant to rollingdominant contact behaviour. A μ value higher than 0.5 leads to a CSL in elog(p’) space that does not capture real soil response.
Truetriaxial simulations with different intermediate stress ratios (b) were performed. The dependency of strength on b agreed with empirical failure criteria for sands and was related to a change of buckling modes of the strong force chains as b increased. DEM simulations showed that the position of the CSL in elog(p’) space depends on the intermediate stress ratio b. This sensitivity seems to be related to the dependency of the directional fabric anisotropy on b. The link between the state parameter and both soil strength and dilatancy proposed by Jefferies & Been (2006) was reproduced in DEM simulations.
A new rotational resistance model was proposed and it was shown that the new model can qualitatively capture the influence of particle shape on the mechanical behaviour of sand. However, it was shown that the effect of rotational resistance is limited and to quantitatively compare the DEM simulation results with laboratory testing data, e.g., the criticalstate loci, it is necessary to use nonspherical particles. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

4 
CONSTITUTIVE MODELLING FOR ANISOTROPIC HARDENING BEHAVIOR WITH APPLICATIONS TO COHESIONLESS SOILS (INDUCED, KINEMATIC, NONASSOCIATIVENESS).SOMASUNDARAM, SUJITHAN. January 1986 (has links)
A constitutive model based on rateindependent elastoplasticity concepts is developed to simulate the behavior of geologic materials under arbitrary threedimensional stress paths, stress reversals and cyclic loading. The model accounts for the various factors such as friction, stress path, stress history, induced anisotropy and initial anisotropy that influence the behavior of geologic materials. A hierarchical approach is adapted whereby models of progressively increasing sophistication are developed from a basic isotropichardening associative model. The influence of the above factors is captured by modifying the basic model for anisotropic (kinematic) hardening and deviation from normality (nonassociativeness). Both anisotropic hardening and deviation from normality are incorporated by introducing into the formulation a second order tensor whose evolution is governed by the level of induced anisotropy in the material. In the stressspace this formulation may be interpreted as a translating potential surface Q that moves in a fixed field of isotropic yield surfaces. The location of the translating surface in the stressspace, at any stage of the deformation, is given by the 'induced anisotropy' tensor. A measure to represent the level of induced anisotropy in the material is defined. The validity of this representation is investigated based on a series of special stress path tests in the cubical triaxial device on samples of Leighton Buzzard sand. The significant parameters of the models are defined and determined for three sands based on results of conventional laboratory test results. The model is verified with respect to laboratory multiaxial test data under various paths of loading, unloading, reloading and cyclic loading.

5 
An accelerated conjugate direction procedure for slope stability analysisMusa, Zulkarnain, 1964 January 1988 (has links)
CSLIP2 (De Natale, 1987) is the only slope stability program that utilizes a "direction set" optimization routine in its search for the minimum safety factor. However, CSLIP2 which employs Powell's Conjugate Direction Method permits only the horizontal and vertical directions (x and y) to be used as the initial direction set. The efficiency of the existing search routine is improved by replacing the xy coordinate directions with initial directions that are parallel to and perpendicular to the principal axis of the safety factor contours.

6 
A thermomechanical approach to constitutive modeling of geomaterialsZhao, Qian, 赵倩 January 2011 (has links)
Modeling of the mechanical behavior of geomaterials is a fundamental yet very
difficult problem in geotechnical engineering. The difficulty lies in that the
engineering behavior of geomaterials is strongly nonlinear and anisotropic,
depending on confining pressure, void ratio, stress history, and drainage conditions.
A traditional approach to the modeling of geomaterials is to formulate empirical
equations to fit experimental data. Generally, this approach is not able to provide
physical insights into the diverse responses observed in the soil mechanics
laboratories. Another conventional approach is to make use of the classical
plasticity theory, established mainly for metals, to develop constitutive models for
geomaterials. While this approach is capable of shedding light on the mechanisms
involved, it has been recognized that such models may violate the basic laws of
physics.
The objective of this thesis is to apply a new approach to constructing constitutive
models for geomaterials, by making use of thermomechanical principles. The
essence of the new approach is that the constitutive behavior of geomaterials can be
completely determined once two thermomechanical potentials, i.e. the free energy
and dissipation rate functions, are specified. The yield function and flow rule in the
classical plasticity theory can be established from the two potentials, and the
models so derived satisfy the basic laws of physics automatically. In this thesis, the
theoretical framework for constructing thermomechanical models is introduced.
Several concepts in relation to plastic work, dissipated and stored energy are
discussed. Both the isotropic and anisotropic models are formulated and realized in
this framework and the generated predictions are compared with the test data of a
series of triaxial compression tests on sand. To address the important density and
pressuredependent behaviors of sand in the framework, a statedependent
thermomechanical model is developed, by introducing the state parameter into the
dissipation rate function such that a unique set of model parameters is able to
predict the behaviors of sand for a wide variation of densities and pressures. Finally,
a thermomechanical model for predicting the complex unloading and reloading
behaviors of sand is developed by modifying the hardening laws, and the
performance of this model is investigated. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

7 
INFLUENCE OF INTERFACE BEHAVIOR IN DYNAMIC SOILSTRUCTURE INTERACTION PROBLEMS.ZAMAN, MD. MUSHARRAFUZ. January 1982 (has links)
Under static of dynamic loadings, the junction (interface) between a structurefoundation system can experience contact, slip, separation and rebonding modes of deformations. Two interface models are proposed for simulation of interface behavior in finite element analysis of dynamic soilstructure interaction problems. The first element called the thinlayer element has (small) finite thickness. Geometrically, this element is similar to the continuum (soil or structural) element; however, its constitutive relations are defined differently. The normal behavior is defined as a function of the material properties and stressstrain characteristics of the neighboring continuum element. The shear behavior is defined in terms of observed shear stressrelative displacement behavior expressed as function of factors such as normal stress, number of cycles of loading and amplitude of load (or displacements). MohrCoulomb criterion is used to define activated sliding strength of interface. Modes of deformations are simulated by using appropriate stress redistribution iterative schemes. The second model called the mixed interface element has zero thickness. Both displacements and tractions are treated as primary unknowns. Constraints associated with modes of deformations are included using a variational approach. An incremental solution scheme is proposed. Material parameters related to the proposed models are evaluated from the results of sandconcrete interface tests in a Cyclic MultiDegreeofFreedom shear device. Accuracy of the proposed models are verified with respect to a number of example problems. In general, consistent and satisfactory results are obtained. For further verification and evaluation of these models, several soilstructure interaction problems are solved and detailed results are presented. It is observed that behavior of structurefoundation systems can be significantly influenced by interface conditions. An analysis based on bonded interface condition appears to underestimate actual response. Hence, it will be appropriate to include interface behavior in the analysis and design of structures subjected to dynamic and earthquake loadings.

8 
Predicting the ultimate axial resistance of single driven pilesBrown, Rollins Patrick 17 March 2011 (has links)
Not available / text

9 
A behavioral study of gabion retaining wallsSublette, William Robert January 1979 (has links)
No description available.

10 
Stressstrain models for soils based on plasticity theoryKavvadas, Michael January 1980 (has links)
Thesis (M.S.)Massachusetts Institute of Technology, Dept. of Civil Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 151155. / by Michael Kavvadas. / M.S.

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