Traditionally, void ratio, e has been used as a state variable for predicting the liquefaction behaviour of soils under the Critical State (Steady State) framework. Recent publications show that void ratio, e may not be a good parameter for characterizing sand with fines as the steady state, SS data points move downward in e-log(p) space up to certain fines content termed as threshold fines content, TFC. Thus, it was difficult to apply SS concept on sand with fines as a small variation of fines content may lead to different SS line. Many researchers proposed to used equivalent granular void ratio, e* as an alternative state variable (i.e. in lieu of void ratio, e) in attempt to obtain a narrow trend line for SS data points irrespective of fc provided fc  TFC. The e* is obtained from e. For the conversion from e to e*, one need a parameter b which presents the active fraction of fines in overall force structure of sand. However, predicting the b is problematic. Most, if not all, of the b reported were determined by case-specific back-analysis, that is, the b-value was selected so that the test results for a given sand-fines type could be correlated with the equivalent granular void ratio, e* irrespective of fines content. This thesis examines the factors that affecting the b value by examining published work on binary packing. This leads to a simple semi-empirical equation for predicting the value of b based onparticle size ratio,  and fines content, fc. Published data and experimental results on Sydney sand appears to be in support of the proposed equation. The single relation of SS data points in e*-log(p) space for sand with fines is referred as Equivalent Granular Steady State Line, EG-SSL. The EG-SSL is then used to define the equivalent granular state parameter,*. A good correlation observed between * and q-p, q- q responses in undrained shearing. The e* and * are also used to modified a state dependent constitutive model. Seven model input parameters are needed in addition four to critical state input parameters. These parameters are obtained from drained test. The model is used to predict q-pand q- q responses for flow, non-flow and limited flow behaviour for 0% to 30% fines contents. The model predictions are in good agreement with experimental results. The effect of fines types (in terms of plasticity and angularity) on the prediction equation of b are also examined with four different types of fines. A negligible effect of fines type on the prediction equation of b is observed. The link between monotonic and cyclic loading behaviour for sand with fines are also examined with emphasis on cyclic instability and strain hardening behaviour after quasi steady state, QSS for a range of fines contents (provided that fc < TFC). It is found that a single set of rules could be used to correlate monotonic and cyclic behaviour for a range of fines contents at same *.

Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 165-175). Also available in electronic format on the Internet.

Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 151-155). Also available in electronic format on the Internet.

Thesis (M.Eng.)--Memorial University of Newfoundland, 1993. / Typescript. Bibliography: l. 115-123. Also available online.

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006. / Mayne, Paul W., Committee Chair ; Goldsman, David, Committee Member ; Lai, James, Committee Member ; Rix, Glenn J., Committee Member ; Santamarina, J. Carlos, Committee Member.

Thesis (M.Eng.)--University of Pretoria, 2004. / Includes summary. Includes bibliographical references (leaves 92-100).

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 355-372).

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 160-167. / by Mark David Bucknam. / M.S.

Yes / Most previous studies on seabed liquefaction around offshore pipelines focused on investigating the wave-induced pore pressure variation in sandy seabed, while limited studies have been conducted for silty seabed. In this study, laboratory experiments are conducted to investigate wave-induced pore pressure within silty bed around the buried or partially/fully backfilled pipeline. Results show that residual pore pressure is the dominant factor that causes the liquefaction in silty soil. For buried pipeline, liquefaction first occurs at the pipeline bottom, then propagates upwards and downwards vertically. Comparing with the buried pipeline, the liquefaction potential is reduced when the pipeline is placed in a trench. To protect pipeline from liquefaction, backfill is recommended. Experiments show that the residual pore pressure significantly decreases as backfill depth increases. Fully backfilled pipeline is the best choice for silty seabed. Furthermore, backfill material with coarser particle size than native soil provides better protection for pipeline. In this study, there is no residual pore pressure around the pipeline periphery for three backfill soils (d50 = 0.15 mm; 0.3 mm; and 0.5 mm) tested. Results indicate that for the range of this experimental study, d50 = 0.15 mm is the best backfill material that provides the most protection for the underneath pipeline. / National Postdoctoral Program for Innovative Talents granted by China Postdoctoral Science Foundation (Grant No. BX20190105) and the Fundamental Research Funds for the Central Universities (Grant No. B200202062).

Small amounts of cementation in a sand increase its ability to sustain static and dynamic loads, even in a liquefaction type environment. This has been shown in previous research examining the behavior of both naturally cemented and artificially prepared samples. Cemented sands are present in many parts of the world and can be caused by either a variety of cementing agents or by cold welding at points of grain contact. They are generally quite difficult to sample, but artificially cemented sands have been shown to aptly model the behavior of natural materials, and allow for better test controls. Consequently, artificial samples were used exclusively for the present investigation which has three major objectives: to investigate the effects of a weakly cemented lens within a stronger mass; to determine how cementation affects the volume change characteristics of statically loaded samples; and, to describe the pore pressure generation of sands subjected to cyclic loading. Prior to commencing the test program, a number of index tests were performed on the uncemented and cemented sand used during the laboratory investigation. It was revealed that cementation leads to increased void ratios which distort relative density calculations used to compare cemented and uncemented samples of similar dry unit weight. The practice of identifying samples by dry unit weight was adopted for this report. Static triaxial compression tests were performed on 17 samples. Test results indicate that although the magnitude of volumetric strain at failure does not seem to be dictated by the level of cementation, there is a relationship with cementation and the rate of volume change at failure. A weak lens was seen to lower the static strength of the stronger mass. 26 stress controlled cyclic triaxial tests revealed that a weak lens lowers the liquefaction resistance of the stronger mass. The cyclic strength of the nonhomogeneous material, however, is higher than the independent strength of the weak lens. A weak lens has greater influence at relatively higher levels of cyclic stress. Pore pressure generation in cemented sands are seen to be controlled by strain. At shear strain levels below about 1%, cemented sands behave similarly to uncemented sands with pore pressures increasing more rapidly beyond that amount of strain. Consequently, pore pressure development during cyclic loading is described by a broken-back curve which is defined in the early stages by existing empirical relationships for uncemented sand. Pore pressure prediction may then be achieved using an equation for cemented sand, such as that developed in the present work. / Master of Science