Abstract
This thesis is divided into two main parts. The first part which extends to Chapter 6, deals with estimating settlements on sand using results of penetration tests. Chapters 1 to 4 deal with the deformation characteristics of sand deposits. The stress-strain behaviour of sand is explained. The factors which influence the deformation behaviour of sand are reviewed together with the methods of determining the deformation characteristics and the stress distribution theories. It is found that the deformation of a sand, subjected to load depends on a large number of variables and for this reason, the stress-strain behaviour is exceedingly complex. Chapters 5 and 6 deal with the prediction of settlement of structures on sand, using the results of the Standard Penetration and Quasi-Static (Dutch) Cone tests. Some of the widely used methods are reviewed. A study is carried out on 26 case records, in order to examine how the methods worked and to determine their validity. The results of the study show that none of the methods is accurate and generally many of the methods overestimate settlements. The second part of this thesis which extends from Chapters 7 to 15 involves an experimental programme which studies some of the factors affecting the dynamic penetration resistance of a saturated fine sand. Emphasis is focused on two factors, namely the influence of overconsolidation on dynamic penetration and pore water pressures generated during dynamic penetration testing. A comprehensive literature review of the main topics of the experimental research is presented. Previous work on the construction of calibration chambers is presented. A review is given on the effects of preconsolidation on penetration resistance of sand and the generation of pore water pressure during dynamic penetration testing. Penetration tests are carried out in the laboratory, both in a small apparatus and in a large calibration chamber. A major part of the research is devoted to the design, construction and commissioning of the testing equipment. Detailed description of the testing chamber and the penetrometer is given in Chapter 11. Details of converting the two Rowe cells to form a soil container are given in Chapter 12. Other laboratory tests have included classification tests, maximum and minimum densities, K[0]- consolidation tests and drained triaxial tests. The penetration test results show that overconsolidation of a sand specimen does have an effect on the penetration resistance. It is however shown that the compressibility of the sand specimen is not reflected in the penetration resistance; and it is thought that for this reason, the prediction of settlements based on penetration testing is usually inaccurate. The measurement of pore water pressures generated during dynamic penetration has given interesting results. The results indicate that the density of the specimen has a crucial influence on the generated pore pressures. High positive pore pressures with long durations develop in specimens prepared in a loose state. Liquefaction can occur in these specimens as a result of such high positive pore pressures. In specimens prepared in dense or very dense states, generally only negative pore pressures are observed.