This paper attempts to provide a risk management framework for evaluating an underground facility in rock mass. The development and training of this framework is based on analysis of data from two major underground cavern projects in India. Failures associated and mitigation measures in each of these projects are revisited. Using factual data from these projects, risk assessment is addressed with suitable quantification tool, Decision Tree based on entropy. Risk assessment model is developed using attributes of geological conditions namely rock mass class, Q, joint set orientation and shear zones associated with various causes of failure. The results of this model emphasized allocation necessary resources and cost as per the priority, i.e. parent attribute - significant and child attribute - based on its level.
The enormous demand of infrastructural facilities can metamorphose the engineering intellect to seek newer technologies, concepts, materials and space opportunities in providing safer and reliable facilities. In Indian context, underground structures has deeper role as its projected land use is 403 persons/km2 which is 2.5 times that of most populous country, China (Anon, 2015). Most of the population is concentrated in the town and cities wherein high rise buildings are a norm. This growth and urbanization demand larger network of mass transit systems, recreational and commercial facilities like car parks, warehouses, power, water and sewage distribution, industry, etc., which can be realized from definite progress into underground environment. This steady exploitation of space provides significant challenges to the rugged yet sensitive fabric of earth's crust due to uncertainties associated with the complex nature of geological conditions and rock mass response. These uncertainties are translated into hazards of potential rock mass instabilities, necessitating the need for measures to manage risk by eliminating, mitigating, accepting or transferring it.
Each underground construction has varying degree of risk based on its actual site conditions. This paper is based on the formalized process of identifying risk and evaluating their consequences followed by preparation of prediction model based on appropriate strategies as per Figure 1 (Anon, 2009). A rational approach is to analyse and understand the hazards of structures in similar conditions and functional requirements to develop a prediction model which can identify risks in future projects. This paper presents a simple methodology for development of risk assessment based prediction model developed using data from two executed projects and application of this model to predict for proposed project.
