The range of problems that geotechnical engineers must face is increasing in complexity and scope. Often, complexity arises from the interaction between the soil and the environment – the topic of this lecture. To deal with this type of problem, the classical soil mechanics formulation is progressively generalised in order to incorporate the effects of new phenomena and new variables on soil behaviour. Recent advances in unsaturated soil mechanics are presented first: it is shown that they provide a consistent framework for understanding the engineering behaviour of unsaturated soils, and the effects of suction and moisture changes. Building on those developments, soil behaviour is further explored by considering thermal effects for two opposite cases: high temperatures, associated with the problem of storage and disposal of high-level radioactive waste; and low temperatures in problems of freezing ground. Finally, the lecture examines some issues related to chemical effects on soils and rocks, focusing i...

Soil–environment interactions in geotechnical engineering

Angles of friction and dilatancy of sand

A discussion of a paper with the aforementioned title by Murff and Hamilton, published in this journal (Volume 119, Number 1, January 1993), is presented The discussion focuses on laterally loaded piles in layered soils Maugeri, Castelli, and Motta assert that the authors' method overpredicts the ultimate lateral resistance on the pile Discussion is followed by closure from the authors

P-ultimate for undrained analysis of laterally loaded piles. discussion and closure

Review of fundamental principles in modelling unsaturated soil behaviour

Interpretation of unsaturated soil behaviour in the stress – Saturation space, I: Volume change and water retention behaviour

Three-dimensional finite element analyses were performed to study the behavior of piles in sloping ground under undrained lateral loading conditions. Piles of different diameter and length in sloping cohesive soils of different undrained shear strength and several ground slopes were considered. Based on the results of the finite element analyses, analytical formulations are derived for the ultimate load per unit length and the initial stiffness of hyperbolic p-y curves. New p-y criteria for static loading of piles in clay are proposed, which take into account the inclination of the slope and the adhesion of the pile-slope interface. These curves are used through a commercial subgrade reaction computer code to parametrically analyze the effect of slope inclination and pile adhesion on lateral displacements and bending moments. To validate the proposed p-y curves, a number of well documented lateral load tests are analyzed. Remarkable agreement is obtained between predicted and measured responses for a wide range of soil undrained shear strength and pile diameter, length, and stiffness.

Undrained Lateral Pile Response in Sloping Ground

The undrained bearing capacity of foundations on or near slopes is commonly calculated using empirical equations or from design charts which have been produced based on limit equilibrium or upper bound plasticity calculations. Many of the available methods do not take account of important parameters that affect the undrained bearing capacity factor, such as the distance of the footing from the slope, the slope height, or the soil properties. This paper presents finite element analyses of strip footings on or near undrained soil slopes performed in order to investigate the influence of the various parameters that affect undrained bearing capacity. The results of the analyses are compared to available methods. It is found that while some of these methods compare well with the finite element results for certain combinations of geometrical parameters and soil properties, they cannot produce sufficiently accurate results as they either do not take account of all of the affecting parameters or are generally not conservative. Based on the finite element results, design charts, equations, and a design procedure are proposed for the calculation of the undrained bearing capacity factor N c as a function of the undrained shear strength and the bulk unit weight of the soil, the footing width, the distance of the footing from the slope, the slope angle and the slope height.

Undrained Bearing Capacity of Strip Footings on Slopes

Constitutive models for partially saturated soils often assume linear relationships for the variation of shear strength with suction and the shape of the partially saturated isotropic compression lines. It has been established, however, that for some soils these relationships are nonlinear. The shape of the isotropic compression line for partially saturated conditions is of particular importance, as it is directly related to the amount of potential collapse that a soil will experience upon wetting. When boundary value problems are analyzed, ignoring this nonlinearity can lead to very inaccurate predictions, and such models are of limited applicability. None of the current models have been demonstrated to predict collapse behavior in a satisfactory manner, especially at high values of stress and suction. In this paper, an exponential expression for partially saturated isotropic compression lines is implemented in an existing elastoplastic framework for saturated and partially saturated soils. As a result, ...

Konstantinos Georgiadis

Papers

Undrained Lateral Pile Response in Sloping Ground

Undrained Bearing Capacity of Strip Footings on Slopes

Three-Dimensional Constitutive Model for Partially and Fully Saturated Soils

Development of p–y curves for undrained response of piles near slopes

The influence of load inclination on the undrained bearing capacity of strip footings on slopes