A review and case studies of factors affecting the stability of wooden foundation piles in urban environments exposed to construction work

Wooden foundation piles have been used since Roman times to solidify infirm soils prior to construction of heavy monuments like churches, buildings and bridges. These are known to have a long service life in waterlogged anaerobic environments where most biological wood decay processes, except for slow bacterial degradation, are repressed. However, large scale urban ground work may change the biogeochemical stability of the soil, increasing the microbial decay of the piles and resulting in settling damages to historic buildings. This paper evaluates and synthesizes present knowledge within this cross-disciplinary field in order to understand the complex processes during ground work that have detrimental consequences for foundation pile durability. We conclude that soil types, ground water levels and water flow, as well as the hydrogeological matrix are important parameters for understanding the stability of a site. These factors will affect the oxygen content available for development of more intense decay by erosion bacteria or additional attacks by aggressive wood rotting fungi. These interactions and thresholds should be studied further. Knowledge of local environments can determine the vulnerability of burial sites prior to disturbance, and enables taking preventative measures to counter effects thereof.