The results of the research show that either the EDTA-(NH4)C03 procedure or the multivariate regression equation could be used to estimate the Zn supplying powers of Virginia soils. It was pointed out that the critical levels obtained for the procedures are considered tentative and that the calibration should be continued as more field data become available. / Master of Science

The increased popularity of using reinforcement in embankment fills and slopes has created a need for studies of the interaction between the reinforcement and surrounding soil to provide an improved basis for limit equilibrium design methods. The purpose of this study was to develop a plane strain triaxial apparatus and associated equipment to study the interaction of soil and reinforcement. The plane strain apparatus was designed to model an element of soil situated along a slip surface in a reinforced embankment. The device constructed is capable of testing a sample 9.4 inches square and 23 inches high with full-size reinforcing materials included. A 30,000-pound capacity load frame and a 20,000-pound capacity electric load cell were also constructed during this study. Drawings of the equipment constructed and a design method for the load cell are included. Preliminary tests on unreinforced and reinforced samples under a confining pressure of 10 psi were performed to check the equipment operation. These tests show that the equipment functions as planned. Modifications desirable to improve the performance of the equipment are given. / M.S.

No description available.

No description available.

A decade has passed since the development of the self-boring pressuremeter (SBPM). Even though the device has been recognized by the geotechnical engineering profession as having high promise for evaluating in-situ stress-strain behavior of soils, its use is limited. In large part, this is due to the fact that there are important unanswered questions about the SBPM test. One of the major issues concerns the influence of drainage in the soil as it is sheared. In clays, the test is assumed to be undrained, but there is no way to control this other than by the rate of loading and no method has been put forth heretofore to define the required rate. This dissertation addresses the drainage issue by applying a numerical model capable of simulating the pressuremeter test under variety of conditions. To develop parameters for the soil model, a comprehensive laboratory testing effort was needed. The validity of the numerical model and the soil parameters is established by comparing it to SBPM tests performed in the field. The numerical model uses the finite element method in a special code capable of handling large strains, consolidation effects, and nonlinear soil behavior. Particular attention is addressed to the issue of pore pressure development and its dissipation. Relative influences of important soil parameters such as the permeability are checked against various rates of loading in the SBPM test. The results demonstrate that drainage likely occurs in most cases using conventional test procedures, and that this, in turn, leads to an error in interpretation of SBPM data. Based on the findings in the analyses, a procedure is proposed which should lead to a more rational method of performing the SBPM test where nearly undrained conditions are desired. / Ph. D.

published_or_final_version / Civil Engineering / Master / Master of Philosophy

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Civil and Structural Engineering / Doctoral / Doctor of Philosophy

The whole of this thesis is my work unless specifically indicated to the contrary in the text, and has not been submitted in part or in whole to any other University. Some thirty years ago the author operated a deep sounding machine, one of the first in the country, on a misty lake in Ireland and marvelled at the way subsoil information could be garnered. The magic of the moment never entirely passed and when the opportunity arose to use the technique in Natal the die was cast. The development of the national road system surged in the early 1970's and since many of these roads on the Natal coastal routes crossed extensive recent alluvial deposits, the geotechnical problems of instability and settlement became major factors in the road design. Traditional methods of investigation consisted of boreholes with sampling and laboratory testing. Whilst these were satisfactory, provided they were of adequate quality, they were relatively expensive if sufficiently detailed models of the subsoil were to be obtained for design purposes. Cone penetration testing provided a potential a solution and this led to research work conducted over a period of twenty five years which continues today. The initial development of ideas for improvements to the mechanical equipment took place whilst the author was carrying out preliminary investigations for freeway routes over the coastal alluvial deposits. This was followed by a period devoted largely to cone penetration testing research and deVelopment and to embankment design methods at the National Institute for Transport and Road Research, and to the initial registration for a Master's degree under the supervision of Professor K Knight in 1975. This research programme was completed as originally envisaged, but not submitted because during its course the author conceived the idea of the piezometer cone. This proved to be such an exciting prospect that the research and development continued for a number of years until piezometer cone testing has now become almost routine for geotechnical investigations on alluvial deposits. In 1983, due to Professor Knight's retirement from the University, Mr Phillip Everitt was appointed as the supervisor. At that stage piezometer testing was becoming accepted internationally and new aspects and information frequently appeared. It was apparent, however, that the essential proof of the system for the prediction of embankment performance was to use it at embankments where the performance had been monitored. Eventually grants were provided by the Department of Transport for this, which enabled two research projects to be conducted during 1989 - 1990 and 1991 - 1992. After completion of the first of these a presentation of the author's work on cone penetration testing since the mid 1960's was made to the Faculty of Engineering at the University of Natal. The Executive Committee of the University Senate subsequently approved, in August 1991, that the registration be upgraded to doctoral status. Mr Everitt's encouragement during this extended period has been a vital factor in ensuring an outcome for this task and the author wishes to express his gratitude for this. / Thesis (Ph.D.)-University of Natal, Durban, 1992.