A Model for Automatic Control of Vibratory Plate Compactor
of the most Application of automatic control into compaction eglenineering works. This isoduel to problem compared with other machines used in civil g the difficulties in getting proper feedback, consisting of a transfer to the compactor and information on the state of the soil being just under compaction. The The paper presents an approach to this difficult and practically ti p ort nt p h have been discussion contains evaluation of several different responses possibility of a1 in information on g used so far in compaction analysis. compactor without Additionally, involving mathematical model of soil is mechanical behaviour of c pacto considered.
Mechanics of a sandy subsoil subjected to cyclic loadings
A 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.
Non-linear seismic response and liquefaction
The essential cause of the growth of pore pressure during cyclic loading is identified as an ‘autogenous’ shrinkage or densification of the solid phase of the soil and this is related to a strain path parameter. Introduction of this ‘shrinkage’ coupled with an elasto-plastic behaviour of the soil skeleton allows a full non-linear dynamic analysis to be conducted up to the point of structural failure for any earthquake input. Explicit time marching procedures are used. The procedure outlined is applicable to all problems of complex geometry and for conditions of undrained or partially drained behaviour at a moderate computational cost.