Practical Advice for Foundation Design – Micropiles for Structural Support

Certain details of micropile design remain unresolved between various practitioners and such disagreements have limited the acceptability of micropiles in certain quarters. Detailed micropile design is an extremely lengthy and often complex subject, especially when micropile groups are concerned or seismic issues must be addressed. The paper provides a simplified step-by-step design approach discussing initial evaluation of feasibility, review of data, loading combinations and general considerations. Thereafter the final design steps are discussed. These include geotechnical strength limit states, other structural considerations, service limit states, corrosion protection, and some seismic considerations.

Installation of Steel Sheet Piles

This manual provides an introduction to the methods of installing sheet piling, based upon the common experiences of the European Sheet Piling Producers. A Knowledge of the characteristics of the steel and the section are not enough to guarantee good results prior to installation. The aim of this document is therefore to briefly describe the practical information to be considered to ensure proper product installation.

It aims to show the importance of predicting the drivability of pile sections after full evaluation of the ground conditions. This is followed by an inventory of the existing driving systems, from impact hammers to vibratory pile drivers and special systems.

The manual then provides a description of driving methods, ancillary equipment, including guide frames and guideline procedures to assist in providing good practice when installing sheet piles. Finally some common installation problems are illustrated and special aspects of driving briefly outlined.

BENTONITE SUPPORT FLUIDS IN CIVIL ENGINEERING

Bentonite is the name used for a range of clays that can swell and gel when dispersed in water. The name “bentonite” originates from the discovery of this type of clay near Fort Benton, USA, in the 19th Century. This was a natural sodium bentonite, and has been mined extensively for many years in Wyoming and Dakota for oil well drilling applications.

Bentonite is now used extensively throughout the world in civil engineering, but the cost of transporting original “Wyoming” bentonite from the USA has led to the use of alternatives from other sources. A large proportion of bentonite now used is therefore from other parts of the world.

It is important to recognise that the properties of bentonites from different sources vary, and to take these variations into account when deciding on the suitability of a particular bentonite for a specific purpose.

The purpose of this document is to provide information that will enable a decision to be made as to whether or not a particular bentonite will produce a satisfactory support fluid, and to give guidance on the preparation, use, re-use and disposal of the bentonite slurry, and also on methods of testing.

NEW DEVELOPMENTS IN DESIGN METHODS OF PILE FOUNDATIONS

The design methods of pile foundations are addressed in this paper. The limit states for pile design are considered. The different methods for the verification of limit states are described. The evaluation of geotechnical parameters for pile design, by field and laboratory tests is analysed. The foundation movements to avoid the occurrence of an ultimate limit state or a serviceability limit state are addressed. The most popular tests to assess the quality control of piles are described. Two examples of application related with the foundations design of Guadiana bridge and New Tagus bridge are presented.

GEOTECHNICAL INPUT FOR DESIGN OF POST-TENSIONED SLAB FOUNDATIONS ON EXPANSIVE SOILS USING THE NEW INTERNATIONAL BUILDING CODE

USE OF INNOVATIVE IDEAS IN GEOTECHNICAL ENGINEERING

This keynote lecture describes the use of innovative ideas and concepts in geotechnical engineering. The message of this lecture is that innovation in engineering does not necessarily have to be new ways of doing things. Rather, it is more important to create value to projects by learning and applying ideas and concepts (whether old or new) in an innovative manner. A number of examples are given based on the author’s recent experience, ranging from site investigation method, laboratory testing, numerical analysis, piled raft and pile group foundations, and soft ground engineering.

Transportation Security

Insight on 2D versus 3D modelling of surface foundations via strength of materials solutions for soil dynamics

To simplify the analysis, three-dimensional soil structure interaction problems are often modelled by considering a two dimensional slice without changing the material properties of the soil. This procedure, although convenient, is of questionable validity because two dimensional modeling inherently overestimates the radiation damping for translational and rocking motions. To make matters worse, two dimensional modelling always entails an underestimation of the dynamic spring coefficient for the translational motions. The damping ratio of the two dimensional case, which is proportional to the ratio of the damping coefficient to the spring coefficient, will thus be even larger. Thus, reliance upon a two dimensional analysis based on an equivalent slice of a strip foundation may result in a dangerously non conservative design.