How can the historic quay walls of Amsterdam be(come) future-proof?

Historically and in present time the canal system is a vital element of the Amsterdam city infrastructure. It is part of the city’s DNA and is a dominant factor in the unique atmosphere of the inner city. The canal borders Amsterdam are vertical masonry walls with timber pile foundations. Due to their age and changed conditions, many quay walls are to be considered as sub-standard, and potentially unsafe. Also recent incidents show the importance of taking immediate action on the topic.

The City of Amsterdam is responsible for the management and maintenance of a great number of bridges and quays. However, the fact of the matter is: for about 200 km of quay walls and 850 bridges there is not enough information available as of yet on what state they are in and what load they can still handle. To illustrate, there are no sufficient records of the composition of the soil around these walls; an important factor that determines the state of the quays.

Therefore, together with TU Delft, we are involved in assisting the municipality of Amsterdam in order to make steps that provide a better view of the structure and subsurface conditions of the quay walls. Aimed at tackling the urgent task to mitigate the unsafe conditions with appropriate technical solutions.

Assessing the structural and safety conditions to prioritize renovation and replacement

In short, the goal of this research project is to develop technical solutions to better our understating of the structural and shallow subsurface conditions affecting the behavior of historical quay walls. This research contributes to the safety and renovation/replacement strategy of the historic quay walls in the city of Amsterdam.

In practice it seems to be hard to prove that these quay walls are safe. In some cases it is not even possible to prove with the current engineering models that these quay walls are stable without safety margins at all. This is very undesirable but because an important part of the uncertainty lies in soil and structure data (i.e. soil layering, presence of cavities, number of rows of piles, depth of pile tips), there is certainly potential for improving the assessment of the old quay walls without all of these having to be rigorously replaced. The latter is a huge task and requires entire streets and canals blocked which results in logistical problems and disruption of the daily life of the city.

The project consists of two interrelated parts: the first part concerns the structural modelling of a the quay wall using a fast analytical model representative of the ‘true’ behaviour of a quay wall. The second part is concerned with the application of existing and new geophysical and geotechnical techniques for near-surface soil characterization. Together, the two parts constitute a perfect assessment tool to have a reliable indication of the structural condition and safety of historical quay walls in Amsterdam and to prioritize those that require renovation and replacement.

A large scale quay wall experiment: 'Proof load test'

To validate the quay wall tool and gain more insight in the typical behaviour of a historical quay wall, a large scale proof load test on a quay section is planned. The location of the test site is found at the Amstelkwartier.

In this experiment, a 90m quay wall section is divided in different segments and loaded in various ways to achieve the desired failure mechanism. The entire quay wall section is equipped with measuring equipment which makes it possible to monitor each individual quay segment during loading. Finally each quay segment will fail due to the increase in load. Such a large scale quay wall experiment has never been done before which makes the project even more unique.

The time and date of this experiment are not yet determined.

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