Mechanics of a sandy subsoil subjected to cyclic loadings

Abstract

SUMMARYA simple model for compaction of a sand, that may be useful in various geotechnical applications is presented. The model has been formulated in terms of the cyclic stress and strain amplitudes. The compaction properties of a dry sand are characterized by a common compaction curve described by two coefficients.The second aim of this paper is to show some applications of the theory proposed. The attention has been restricted to the two extreme cases of practical importance, namely to the behaviour of a dry sand (or a saturated sand but in free draining conditions), and to the behaviour of saturated sand in undrained conditions. Some numerical algorithms showing how to deal with those problems are presented and illustrated on the following examples: settlement and pore pressure generation in a soil stratum subjected to an earthquake, settlement of a foundation, pore pressure generation and liquefaction in a sea-bed.The results obtained suggest that the model proposed, as well as a method of dealing with boundary value problems can serve as a useful tool for the analysis of a sandy subsoil subjected to cyclic loadings.

A Model for Automatic Control of Vibratory Plate Compactor

“…It means that it may be seen that the best compaction depends on the largest value of the vibration amplitude, similar to the observations made by Sawicki et at [8]. From the above we conclude that automatic control should assure the largest possible amplitude of the compactor during the whole of the compaction process.…”

“…The first important observation is that the compaction depth depends upon the magnitude of the compactor amplitude. Sawicki et at [7,8] present the relation between the irreversible strain cP, number of cycles N and shear strain amplitude y (Fig. 4).…”

Modelling of Post-flotation Tailings Liquefaction Induced by Paraseismic Events

“…(1), which makes it possible to determine model parameters D 1 , D 2 for the soil tested. Numerous investigations carried out on various types of non-cohesive soils have confirmed the existence of such a curve, however for a range of loading cycles limited to several hundreds, only, see (Sawicki and Świdziński 1989(Sawicki and Świdziński , 2007(Sawicki and Świdziński , Świdziński 2006. Considering that the model is used to describe the response of soil subjected to an earthquake whose duration corresponds to approximately one hundred cycles, the application of the model to that case is fully justified.…”

“…In the past, the C/L model has been applied to numerous boundary value problems corresponding to various engineering issues related to the cyclic response of saturated sands in undrained conditions, see e.g. (Sawicki and Świdziński 1989, 2007, Przewłócki and Knabe 1995, Sawicki 2004. The model parameters were determined for samples of tailings taken from the facility.…”

Serviceability of suction caisson founded offshore structures

“…The evolution of foundation stiffness under a periodic loading has been considered by a number of authors. Analogous work conducted by Sawicki and Swidzinski, (1989) on the stiffness of a sand element under tri-axial loading conditions and by Li et al, (2010) on the stiffness of a model pile system have both used a logarithmic relationship to describe the change in foundation stiffness with number of loading cycles. Using the same logarithmic relationship, the observed changes in non-dimensional stiffness with increasing number of loading cycles could be described by the following equation:…”