TY - RPRT A1 - Asslan, Milad T1 - Factors Influencing Small-Strain Stiffness of soils and its Determination N2 - This term paper presents a literature review and discusses concepts of the following point: 1- Factors affecting small-strain stiffness in soil; 2- Methods to determine small-strain shear stiffness in laboratory and in-situ; 3- Brief introduction into wave propagation and 4- Bender elements technique to determine shear wave velocity in soil. KW - Soil KW - Shear modulus KW - Bender elements Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20120402-15870 ER - TY - JOUR A1 - Schanz, Tom A1 - Tripathy, Snehasis T1 - Swelling pressure of a divalent-rich bentonite: Diffuse double-layer theory revisited JF - Water Resources Research N2 - Physicochemical forces are responsible for the swelling pressure development in saturated bentonites. In this paper, the swelling pressures of several compacted bentonite specimens for a range of dry density of 1.10–1.73 Mg/m3 were measured experimentally. The clay used was a divalent-rich Ca-Mg-bentonite with 12% exchangeable Na+ ions. The theoretical swelling pressure–dry density relationship for the bentonite was determined from the Gouy-Chapman diffuse double-layer theory. A comparison of experimental and theoretical results showed that the experimental swelling pressures are either smaller or greater than their theoretical counterparts within different dry density ranges. It is shown that for dry density of the clay less than about 1.55 Mg/m3, a possible dissociation of ions from the surface of the clay platelets contributed to the diffuse double-layer repulsion. At higher dry densities, the adsorptive forces due to surface and ion hydration dominated the swelling pressures of the clay. A comparison of the modified diffuse double-layer theory equations proposed in the literature to determine the swelling pressures of compacted bentonites and the experimental results for the clay in this study showed that the agreement between the calculated and experimental swelling pressure results is very good for dry densities less than 1.55 Mg/m3, whereas at higher dry densities the use of the equations was found to be limited. KW - Bentonit KW - Boden KW - Ton KW - Geochemical modeling; Soils; High-pressure behavior; bentonite; clays; expansive clays Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31592 ER - TY - THES A1 - Asslan, Milad T1 - An Experimental Study on the Initial Shear Stiffness in Granular Material under Controlled Multi-Phase Laboratory Conditions N2 - The initial shear modulus, Gmax, of soil is an important parameter for a variety of geotechnical design applications. This modulus is typically associated with shear strain levels about 5*10^-3% and below. The critical role of soil stiffness at small-strains in the design and analysis of geotechnical infrastructure is now widely accepted. Gmax is a key parameter in small-strain dynamic analyses such as those to predict soil behavior or soil-structure interaction during earthquake, explosions, machine or traffic vibration where it is necessary to know how the shear modulus degrades from its small-strain value as the level of shear strain increases. Gmax can be equally important for small-strain cyclic situations such as those caused by wind or wave loading and for small-strain static situations as well. Gmax may also be used as an indirect indication of various soil parameters, as it, in many cases, correlates well to other soil properties such as density and sample disturbance. In recent years, a technique using bender elements was developed to investigate the small-strain shear modulus Gmax. The objective of this thesis is to study the initial shear stiffness for various sands with different void ratios, densities, grain size distribution under dry and saturated conditions, then to compare empirical equations to predict Gmax and results from other testing devices with results of bender elements from this study. KW - Soil KW - Shear modulus KW - Shear wave KW - Soil dynamics KW - Bender elements Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20120402-15842 ER -