Some Aspects of the Mechanical Behaviour of Mixtures of Kaolin and Coarse Sand

Civil engineering, Soil sciences

Kumar, Garimella Vijaya

University:University of Glasgow

关键词: Civil engineering, Soil sciences;   

Others  :  http://theses.gla.ac.uk/74993/1/11007914.pdf

来源: University of Glasgow

【 摘 要 】

The work presented in this thesis describes an investigation into the mechanical behaviour of kaolin and coarse sand mixtures with a major component of experimental work. The objective of the research is to investigate the extent to which the mechanical response is controlled by the clay phase. After the initial introductory chapter, subsequent chapters present studies made of different aspects of mechanical behaviour. Chapter 1 gives the introduction to the research and presents a basis for the study as' well as the aim of the research. The methodology used in accomplishing the aims is presented. Chapter 2 looks at the influence of the coarse fraction on the index properties of clay soils. This study involves laboratory testing using a fall cone to determine the liquid limit of clay-sand mixtures. The extent to which the index properties of the mixtures are controlled by the clay phase alone is considered. Chapter 3 presents one dimensional consolidation characteristics of clay/sand mixtures with an aim to discover a threshold clay content at which the interaction between sand particles becomes dominant during consolidation. The consolidation was carried out in a hydraulic oedometer or in a consolidation tube using incremental loading. Chapter 4 is concerned with permeability characteristics of clay/sand mixtures in order to develop a generalised approach to predict changes in permeability with the aim again to discover the extent to which the response is controlled by the clay phase. This study involves laboratory testing of various mixtures using computer controlled flow through a hydraulic oedometer. Permeability tests were performed by applying constant flow rates - providing, in addition, data which could be used to check the validity of Darcy's law. Chapter 5 deals with the general stress: strain response of clay/sand mixtures from drained and undrained shear tests performed at different overconsolidation ratios in a conventional triaxial apparatus with an aim to present a description of the response of the mixtures within the general framework of critical state soil mechanics. Chapter 6 is concerned with simple finite element analyses of the effects of coarse fraction on shear behaviour of normally consolidated mixtures. These results are compared with experimental and theoretical predictions. In Chapter 7 it is concluded that for clay contents above about 30-40% the mechanical behaviour of the mixture is controlled by the clay phase alone and that no interaction of the sand particles occurs. The sand particles do, however, act as volume fillers and volumetric deformations in consolidation and drained shear tests must be corrected to allow for the actual volume of clay matrix that is present. Numerical and theoretical analyses have not proved successful in matching the patterns of response that are clearly shown from the experimental study.