Development of Risk Analysis Procedure for Subsurface Risk Management in Urban and Industrial Areas

Planning, construction, and operation of engineering structures in densily built urban areas can be seriously affected by ground conditions. Notably settlement, subsidence or ground collapse by abandoned mines or karst and suffosion may result in the collapse of buildings and consequently lead to large financial losses and casualties. These hazards can be intensified by human activities, such as underground construction activities or groundwater withdrawal. Management and abatement of these hazards is of primary importance for a safe and sustainable development of cities, the more so when it concerns industrial plants or disposal facilities. An important mean by which to facilitate management of hazardous ground conditions is to integrate risk analysis and monitoring activities in such a way that timely actions can be taken directed towards alleviating the most vulnerable engineered components of structures, either during the construction fase or afterwards when controlled settlement or movement has to remain within bounds. Both the Netherlands and Russia face difficult ground conditions. In the Netherlands soft soils necessitate a very careful lay-out of construction and ground improvement activities, especially so in urban areas. This in fact can hamper necessary developments like underground constructions for transport or public services. One of the problems concerning soil subsidence and collapse in Russia is related to karst and suffosion. Karst and suffosion results from the dissolution of limestone, resulting in large voids and adverse strength conditions. Karst complicates the subsurface space development, due to unforeseen ground collapse and subsidence, destroying complete buildings. These phenomena are currently registered even in areas that were earlier considered to be karst-proof This proposal relates to a joint-scientific project by a team of Russian and Dutch experts aiming at developing an integrated risk analytic methodology to manage hazards due to soil subsidence, settlement and ground collapse. The project will primarily be directed towards the development of a generic risk-based decision methodology for ground movement and ground collapse, integrated with a monitoring strategy and based on an inverse modelling strategy making use of the monitoring results to update the risk based decision and management model. The methodology will be applied to the specific issues posed by karst-prone urban centres in Russia. Suitable development requires a better understanding of the karst and suffosion processes, the influence of groundwater, the geomechanical behaviour in relation to loading and stress, geostatistical mapping of the karstvoids, optimization of a monitoring network in a risk based approach.