Carl Wersäll

Small-Scale Testing of Frequency-Dependent Compaction of Sand Using a Vertically Vibrating Plate

Vibratory rollers generally operate at a fixed vibration frequency. It is hypothesized that the compaction of soil could be made more efficient if the frequency could be adapted to specific project ...

Cumulative lateral soil displacement due to pile driving in soft clay

Installation of preformed piles in clay causes lateral displacements of soil and of foundations of nearby structures embedded in the ground. The problem has been assessed by first analyzing the displacement effects of a single pile based on model tests and numerical analyses. Lateral soil displacement can be predicted using cavity expansion theory. Model tests were performed to study lateral displacements of soil due to installation of a group of piles. The results of theoretical analyses and model tests were compared with field measurements. A method is proposed to estimate cumulative lateral soil displacements caused by the installation of a pile group. The effect of sloping ground on lateral soil movements is addressed. Prediction of lateral soil displacement due to installation of several rows of piles in clay is illustrated by a practical example.

Frequency Variable Surface Compaction of Sand Using Rotating Mass Oscillators

The influence of vibration frequency was studied in 110 small-scale compaction tests conducted using a vertically oscillating plate. The underlying soil was dry sand, or sand close to the optimum water content. The results showed that there is a resonant amplification, providing a slightly higher degree of compaction. Frequency has a major influence on soil compaction. An iterative method for calculating the dynamic response of the plate, incorporating strain-dependent properties of the soil, is also presented. The calculated frequency response agrees fairly well with measured quantities.

Vibration Source Localization along Railway Tracks

Ground-borne vibration from railway traffic is an increasing problem in urbanized areas and measures are often needed to minimize its effects on the environment. An important question when dealing with railway problems is to identify the source(s) of vibration emitted along the railway track. Once this information is available, it is often possible to mitigate the problem by improving stiffness of the railway track and/or to upgrade worn-out or damaged rail sections and turnouts.

Soil Heave Due to Pile Driving in Clay

Soil heave due to pile driving in clay is discussed and, in particular, its influence on adjacent piles. Finite element studies and results of model tests are presented and compared with field measurements. It is demonstrated that in the vicinity of the driven pile, the soil is displaced mainly in the lateral direction, similar to soil subjected to passive earth pressure. General rules of estimating soil heave inside and outside a pile group are examined. A method is proposed for estimating soil heave when driving a group of piles. Practical application of predicting soil heave is illustrated by an example.