Typescript (photocopy). / Digitized by Kansas Correctional Industries

Doctor of Philosophy / In this thesis an examination is made of the vibro-replacement technique for the stabilisation of cohesive soils. Improvement is achieved by the formation of stiffer columns of granular material within the soil deposit using a large cylindrical vibrator referred to as a vibroflot. Granular piles (also termed stone columns) are used either singly or in small groups to supoort isolated footings or large numbers are installed in a regular array to support widespread loads. Each of these modes of application are investigated.

This thesis examines the pre and post failure deformation behaviour of landslides in cut, fill and natural soil slopes, and of the deformation behaviour of embankment dams. The deformation behaviour of landslides and embankment dams have been analysed from a database of case studies from a number of classes of slope (and dam) and material type. The database included some 450 landslides in cuts, fills and natural slopes, and some 170 embankment dams. For landslides in soil slopes, methods and guidelines have been developed for use in the analysis, evaluation and prediction of the pre and post failure deformation behaviour. They take into consideration the factors influencing and the mechanics controlling the deformation behaviour for the classes of slope and material types, which are different for pre and post failure. Pre-failure deformations are largely controlled by the effective stress conditions within the slope, changes in the boundary conditions and the response of the soil to those changes in boundary conditions. Whether the soil, under the effective stress conditions imposed within the slope, is contractive (and saturated or near saturated) or dilative on shearing, has a significant influence on the pre failure deformation behaviour. The post failure deformation behaviour is strongly influenced by the mechanics of failure (including whether the soil is contractive or dilative on shearing), the source area slope angle, the downslope geometry, the orientation of the surface of rupture, the material properties and slide volume. Guidelines are presented for prediction of 'rapid' and 'slow' post failure velocity. For embankment dams, methods and guidelines have been developed for evaluation and prediction of the deformation behaviour during and post construction for selected embankment types. They take into consideration the influence of material type and placement methods, material strength and compressibility properties, embankment zoning geometry, embankment height, and reservoir operation, amongst other factors. Guidelines have been developed to assist in the identification of 'abnormal' deformation behaviour, which can be related to internal deformations or a marginal stability condition and the onset to failure.

Thesis (Ph.D.)--Rensselaer Polytechnic Institute, 1996. / Adviser: Ahmed-W. Elgamal. Includes bibliographical references.

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The effects of three concentration levels of Formula 125 at three different percents of maximum dry density on various engineering properties of a silty clay soil were investigated through a laboratory study. Different types of soil stabilization methods are briefly discussed. Details of laboratory procedure and tests using different testing equipments are also given. Data relating the cost and effectiveness are compiled for comparison purposes. It was found that Formula 125 is very effective on most of the tests that were performed.

An experiment was set up at Alfred College, in Eastern Ontario, to investigate methods of correcting the negative effects of deep compaction of fine textured soils. / The site was divided into two fields of four treatments with three replicates of each. Treatment 1 was control, treatment 2 subsoiled, treatment 3 compacted and treatment 4 compacted then subsoiled. In year 1 barley was sown in both fields, underseeded with alfalfa in Field 1. The following year alfalfa was grown in Field 1 and corn using minimum tillage in field 2. / Measurements included cone penetration resistance, dry bulk density, and crop yields. / It was found that compaction had a significant effect on lowering yields. However, due to the experiment methodology in the measuring of cone penetration resistance and dry bulk density plus a blocking effect in the corn field, the results were inconclusive statistically as to whether the subsoiling in combination with minimum tillage and alfalfa had an effect of decompacting the soil profile.