Risk Management in Deep Excavation

Urban decision-makers such as private owners or public section (e.g. municipality) are encouraged to optimize the use of land in underground which has opportunity of economic or social benefits such as Metro stations, multi-story commercial buildings with parking lots or shops in underground. These decisions can be endangered in construction processes. There are few scientific and formal reports about irrecoverable damages, fatalities and geotechnical engineering researches to predict side soil displacements, strength, and their allowable quantities to reach an improved design technique for retaining supports and soil stability. But construction processes may face possible risks such as geotechnical, structural and productivity risks which have additional cost and increased duration. Therefore, risk management in deep excavation is a crucial field to study and there isn‘t any collective scientific resource on that subject. This thesis have prepared a collective resource from related scientific fields, summary of case studies, and case histories in deep excavation to be use in risk management. The objectives are geotechnical, structural, and construction productive risk identification, risk occurrence probability, and risk consequence that are the parameters of risk assessment, which is require for risk response plan in risk management. In this manner, construction methods and equipment in deep excavation are summarized and classified by a proposed facade vision. A deterministic method is proposed for geotechnical risk occurrence probability estimation based on factor of safety concept. A method is proposed for classifying deep excavation damages and estimating expected internal, external, and accidental damages as a consequence in deep excavation is proposed. In order to identifying risks, site investigation and underground identification is overviewed and a model based on range of parameters for classification and identification of clays, granular soils, and intermediate soils is developed which are required for sensitivity analysis as a method of risk assessment. For risk identification and analysis, different geotechnical failure modes, structural failures and their effects on adjacent land and building such as settlement, cracks, is overviewed and collected. The repair state classification and dewatering effects are overviewed, and collected as well. Method of estimating expected internal, external, and accidental induced-damages in deep excavation is proposed and compared in each stage. Also risks and uncertainties in productivity such as production rate, work duration, and unit cost is discussed for considering the preparation of response plan in construction of deep excavation. Geotechnical risk occurrence probability estimation and risk consequences in deep excavation are innovative proposed method. Site geotechnical investigation and identification for risk management in deep excavation is innovative expanded method. Cost risk management in deep excavation is innovative expanded method.