This paper provides the background to the 50th Rankine Lecture. It considers the growth in emphasis of the prediction of ground displacements during design in the past two decades of the 20th century, as a result of the lessons learnt from field observations. The historical development of the theory of elasticity is then described, as are the constitutive frameworks within which it has been proposed that geotechnical predictions of deformation should be carried out. Factors affecting the stiffness of soils and weak rocks are reviewed, and the results of a numerical experiment, assessing the impact of a number of stiffness parameters on the displacements around a retaining structure, are described. Some field and laboratory methods of obtaining stiffness parameters are considered and critically discussed, and the paper concludes with a suggested strategy for the measurement and integration of stiffness data, and the developments necessary to improve the existing state of the art.

Stiffness at small strain: research and practice

A database of some 300 case histories of wall and ground movements due to deep excavations worldwide is presented. Although recognizing the weakness in the approach, a large database is used to exa...

Database for Retaining Wall and Ground Movements due to Deep Excavations

A database of some 300 case histories of wall and ground movements due to deep excavations worldwide is presented. Although recognizing the weakness in the approach, a large database is used to examine general trends and patterns. For still soil sites, movements are generally less than those suggested in the well-known relationships proposed by Clough and his coworkers. However, for walls that retain a significant thickness of soft material but have a high factor of safety against basal heave, movements are similar to those calculated using the Clough charts. In these cases, when soft ground is actually present at dredge level, the Clough charts will underpredict movement and need to be used with care. For the above cases there is no discernible difference in the performance of propped or anchored systems but there is some evidence to suggest top-down systems perform better. In cases where there is a low factor of safety against excavation base heave, large movements can occur, but the Clough charts will ...

Closure of "Database for Retaining Wall and Ground Movements due to Deep Excavations"

The paper presents a series of laboratory tests and evaluates the effect of lime and fly ash on the compressibility and hydraulic characteristics of an expansive soil in Cyprus The tests were perf

Compressibility and hydraulic conductivity of a chemically treated expansive clay

Gypsum: An additive for stabilization of swelling clay soils

A new foundation method is described where columns manufactured in situ by mixing soft clay with unslaked lime are used as foundation for light structures to reduce settlements and to increase the bearing capacity. Methods have been developed for the calculation of total and differential settlements based on results from full-scale tests. The lime columns also function as drains in soft clay which increase the consolidation rate of the soil.

Lime Columns—A New Foundation Method

Sampling methods used in Europe for onshore and offshore structures are reviewed as well as the disturbance of the samples caused by drilling, sampling, stress release, transportation and storage. The definition and classification of sample disturbance are considered as well as the influence of disturbance on shear strength and deformation properties of both cohesive and cohesionless soils under static and cyclic loading.

Soil Sampling in Europe: State-of-the-Art

The lateral earth pressure at rest in a soft cohesive soil as determined by five different methods at Backebol, Sweden is compared and analyzed. The agreement between the results using a thin earth pressure cell and a self-boring pressuremeter was satisfactory. It was found that the results from conventional pressuremeter tests were difficult to interpret. This method as well as the hydraulic fracturing method seems to overestimate the lateral earth pressure at rest for very soft clays. The lateral earth pressure as determined by a total stress cell (Camkometer) installed in an excavated borehole was low and erratic.

Lateral Earth Pressure at Rest in Soft Clay

Several failures of anchored sheet pile walls have occurred in Sweden. Most of these have been caused by insufficient stability or by frost action. Large movements have been observed when piles were driven close to a wall and the driving depth exceeded that of the sheet piles due to the high excess pore pressures which develop during the driving in cohesionless soils. Such failures can be prevented by increasing the driving depth, by decreasing the slope of the anchors, or by using steel H-piles instead of concrete piles. Failure of the anchors caused by the lateral expansion of the soil due to frost action has been observed. It is possible to prevent such failures by drainage or by heating the wall during the winter.

Bengt B. Broms

Papers

Lime Columns—A New Foundation Method

Soil Sampling in Europe: State-of-the-Art

Lateral Earth Pressure at Rest in Soft Clay

Failure of Anchored Sheet Pile Walls

Closure of "Lateral Earth Pressure at Rest in Soft Clay"