Recognizing critically damaged quay wall structures using a three-dimensional numerical model

Abstract

Many quay walls in Amsterdam have surpassed their structural lifetime and have started showing signs of damage. The city of Amsterdam is currently tackling the problem and have published a plan of action. This plan includes the renovation of hundreds of kilometres of quay walls. Given this enormous amount, it is necessary to prioritize certain quay walls over others based on the severity of their damage. Some quay walls have reached total collapse, of which the most recent case involves the "Grimburgwal" quay. The municipality has no accurate view of the current condition of quay walls in Amsterdam. On top of that, the vast majority of quay walls have not been assessed on their safety. It is known that the most vulnerable quay walls types consist of masonry walls, supported by wooden foundation structures. Given that the quay wall renovation project requires prioritisation, it is necessary to gain more information on how the most vulnerable walls are recognised. Preferably, a method should be developed in which only visual cues given by the masonry wall are required, as it is quick and relatively cheap. To gain information on what these visual cues might be, a three-dimensional finite element model is made to run simulations on possible behaviours of quay walls. In this thesis, it is attempted to model a quay wall as realistically as possible. Several different deterioration conditions will be applied to see how the masonry responds. The 3D model is built using a parametric model coded in Python. This code can be used to run simulations in the finite element software DIANA FEA. Many behavioural aspects have been incorporated into the model, with the purpose to make the model more realistic. The model consists of a masonry wall, planks on which the wall rests, and supporting piles. The behaviour of each component has been applied in the code and have been obtained through other literature and European norms. The model is loaded by simulating the weight of the soil and its effect on the quay wall structure. The masonry is simulated using a smeared cracking model (macro-model). Long-term deterioration of quay walls is simulated by changing the material properties of each respective component. This thesis focuses on three deterioration conditions: 1. Non-uniform pile degradation: application of broken piles, simulated by removal of those piles from the model. This is subdivided into two categories: removal of entire rows (a row consisting of a front, middle and end pile) and removal of front piles only. 2. Non-uniform soil removal: formation of soil pits at the foundation level, which result in decreased bedding around the foundation piles. 3. Uniform degradation: application of uniform deterioration along a stretch of quay walls. The simulations yield fairly consistent cracking patterns, in which the same crack fields appear in each simulation depending on the chosen case mentioned before. Displacement patterns are also documented and presented in all cases. The quay wall model is able to display in-plane and out-of-plane movement simultaneously. The effect of each parameter on the crack/displacement patterns are analysed as well. This includes masonry and wood quality. The results show that the largest in-plane settlements are reached by damaged piles, while the largest out-of-plane displacements are caused by a loss of soil bedding around the piles. The results can be used to provide better insight on how quay walls with poor quality present themselves in real life and what their cause might be. This research contributes to the possibility of improving recognition of quay walls which find themselves in critical condition, which can then be prioritized for renovations. For future research, it is recommended to see whether time-dependent simulations can be run, to see if it makes a difference in the outcome of displacement/cracking patterns. Another important recommendation is to look into deterioration rates of materials, which could be used as another indicator for critically damaged quay walls.