Pressuremeter test in calcareous soil : Fahey, M; Airey, D W Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13–18 August 1989V1, P413–420. Publ Rotterdam: A A Balkema, 1989

Abstract

The design of foundations for offshore structures founded on calcareous soils has proved to be a challenging area for the geotechnical profession. The Australian experience has been that all of the conventional ideas of soil behaviour must be critically examined before applying any of them to foundations in calcareous soils, and also that the methods used to derive design parameters for foundations in these soils must be re-examined. Pressuremeter testing is now being accepted as a tool for providing design parameters for a whole range of soil types. The test has the attraction of providing what are regarded as fundamental soil parameters, though the relevance of these parameters must be assessed for each new soil type. The test provides a value for the shear modulus (G) in all soil types. However, the strength parameters obtained depend on the assumed drainage conditions of the soil during the test, and at present are generally limited to whether the test is completely drained or completely undrained, hence yielding either a drained friction angle (phi) or an undrained shear strength (s(sub)u). The paper examines the results of pressuremeter tests in calcareous soils, and discusses the parameters which the test can provide in such soils. While the tests presented are believed to be practically fully drained, the response cannot be explained solely on the basis of a frictional strength, mainly because of inter-particle cementation. Methods of using the pressuremeter results directly in the design of offshore structures are considered, and some conclusions regarding the potential benefits of pressuremeter testing in calcareous soils are drawn (A).