Program Schedule

Geotechnics involves a number of interlinked activities from initial desk studies/investigations through characterisation/analysis and, importantly, linking design to construction means and methods. This complex interplay between different skills and activities can be succinctly summarised by ‘The Geotechnics Triangle (i)’. Success requires the Geotechnics Triangle to be kept in balance. Lack of attention or skills in any part of the Triangle often leads to failure. Effective communication between specialists and non-specialists also plays a pivotal role. This presentation will traverse across the Triangle, from initial studies through to foundation construction, and give mini case history examples of how projects failed when key aspects in the Triangle were not given proper attention. A feature of Geotechnics failures is that they can be ‘Black Swan’ events (ie have disproportionate consequences well beyond any project risk contingencies) – this needs to be better recognised by the wider industry. Some suggestions will be offered about how we can reduce risks and rise to future challenges.
(i) The  practical implementation of the Geotechnical Triangle represents the key aspects of geotechnical engineering : ground (+groundwater) profile, ground characterisation, appropriate analytical models, with well winnowed empiricism at its heart, and crucially linking design to construction. O’Brien and Burland, 2012. ICE Manual of Geotechnical Engineering.

In central Gothenburg at Masthuggskajen, a peninsular in the Göta River is currently under construction. The peninsular consists of three construction pits enclosed by a pile deck. The soil conditions are predominated by Gothenburg clay, a soft normal-consolidated clay which is well-known to cause stability issues and movement to nearby structures when conducting soil-related construction.
The soil conditions combined with strict requirements for maximum allowed movement of nearby existing structures were cause to some headache for the design of especially one of the construction pits. This construction pit will be the primary focus of the presentation.
An extensive monitoring program has been established to monitor the movements of the sheet piles and nearby existing structures during construction. The measurements will be compared to the calculated movements.
Other struggles and lessons learnt will be presented as well.

Buckling of piles has been an issue for a long time in Sweden and most of the Nordic countries due to the very loose clays of Scandinavia and Finland, in connection with the historic use of slender piles of both concrete and steel. This has made structural bearing capacity equally important to geotechnical bearing capacity. Since the -70s and the works of Bernander/Svensk, analytical calculations of pile buckling in clay and loose soils, taking second order effects into account, have been in use. This leads to focusing on bed modulus and implicitly, shear strength in clay. What means do we have to find the “right” values? Calculations are not only made in ULS, but also in SLS, following EN 1992 and 1993 respectively, but also not allowing yield in the soil. A single focus on geotechnical bearing capacity in those circumstances can, however rare, lead to the collapsing of the superstructure. An example is presented.
Recent studies made by the Swedish Pile Commission has focused on composite piles of concrete filled steel pipe piles. In the line of the work the studies show that the yield in material for buckling piles might need to be taken into account in a stricter way than before. This is affecting not only composite piles. For piles supported by surrounding soils, designed and limited by yield in materials taking second order effects into account might not be in line with EN 1994.

For large scale or important infrastructure projects wind tunnel testing, concrete testing etc. are a given. However, for the most important part, the foundations, testing is routinely dismissed as being too costly or not needed! The only exception is ground anchors where testing is codified. Testing of foundation piles should be mandatory to avoid failures and allow for optimization (cost saving), robustness and ease of construction. The lecture provides examples of the benefits of testing combined with timely and sufficient ground investigations as a basis for piling foundations.

As the authors have been highlighting in previous papers, many parameters play a role in the final pile performance, from adequate soil investigation to performance monitoring and testing. The correct understanding of pile construction, though, remains crucial. During construction, some unexpected behaviour can occur, and the soil reaction to pile installation can sometimes be completely different than anticipated. The authors propose to review several issues affecting the daily practice of pile construction, such as bleeding, overflighting, necking of displacement piles, etc…on which they have been performing decades of analysis and research, in order to try to give some guidance.
A final comment will be dedicated to how codes and contract practices can help or not in this matter.

Two projects are presented, one that rendered in lots of extra costs and delays and another a success project. The outcome from both projects were strongly dependent on the relationship and interaction between the client and contractor. The on-site development and refinement of the design helped to a great extent to strengthen the confidence between designer, contractor and client.
Soil improvement with dry deep mixing was performed at six peat areas along the A2 Motorway in Poland, near the city of Poznan. The purpose was to reduce settlements and improve stability. In early September 2003, excessive settlement was experienced. Therefore, preliminary investigations of all other peat areas were conducted with the aim to investigate column quality. Due to anticipated deterioration and limited time to complete the motorway, it was decided to exchange all installed columns to alternative technical solutions.
Another case study is presented on dynamic compaction of rockfill during construction of the new Stockholm Norvik container and ro-ro port. The compaction on land was performed with a 20-tonne pounder using a drop height of 20 metres. The dynamic compaction under water was performed using the same pattern, but due to limited water depths the drop height was 10 m. An attempt to estimate the maximum depth of influence was made by adjusting the well-known Menard empirical relationship between drop height, weight and compaction depth.

The presentation will review a diverse range of projects across 4 continents, chosen amongst the many the author has been working on for more than 45 years in the UK and overseas as both a Deep Foundations contractor and consultant, geotechnical advisor to clients, main contractors and insurers, and Expert Witness on several Arbitrations. An assessment of the driving factors leading to problems on each project will be given. This assessment identifies the common main factors as those relating to design, workmanship, lack of coordination between the parties, inexperienced designer or contractor, and unforeseen ground conditions.
Other factors will then be discussed including contractual relationships, who supplies key materials, and how best to minimise risks and optimise opportunities.

The Port of Hamburg is Germany´s largest seaport. Its main infrastructure is maintained by and operated at the responsibility of Hamburg Port Authority (HPA), public-law institution, which was established in 2005 as part of the merging of various Hamburg authorities with port-related duties. This responsibility puts HPA in the role of a contracting authority that manages a project volume of several hundred million Euros per year. The contracts awarded cover design and construction works of all kinds of civil engineering projects within the Port of Hamburg.
As several of these projects had not been delivered within budget or on schedule or did not provide value for money, HPA investigated the reasons for these grievances. A major reason was found in the traditional contractual relationships. Furthermore, the success of a project is greatly influenced by the early integration of all project participants especially contractors. Therefore, HPA has started to implement a different contractual model, which is internationally known as Integrated Project Delivery (IPD). Being the first in Germany HPA has now become a role model for other contracting authorities following its example.