Geotechnical risks analysis in water transfer tunnel of the Kerman – Iran

Abstract

The long water transfer tunnel of Kerman in the length of 63.5 kilometers is a part of the longterm water supply project of the city of Kerman, which should be conveyed water from Safa and Sarmeshk dam reservoir to the Kerman water treatment plant. Due to the high length and depth of this tunnel, it may face difficulties during excavation. In this paper, a method for probabilistic quantifying these problems is proposed. Using the computational model it is possible to determine the uncertainties of the geological prediction, the distribution of the geotechnical parameters and the rock mass characterization. Each model provides a physical value in which one aspect of the rock mass response, such as displacements, depth of failure zone, level of squeezing, intensity of rock burst and etc is described. In this paper, the rock mass of the tunnel path is divided into calculation segments according to the rock mass types and influencing factors and its parameters are studied in the form of probabilities distribution. By using empirical correlations and computer simulation, the strength and the behavior of the rock mass in tunnel path are assessed in the form of probability, and finally the results are demonstrated in quantities. According to the obtained results, during tunnel excavation, the risk of failure, serious instability, squeezing and rock burst are predicted the position and the quantity probability of the expressed risks at different parts of the tunnel route are determined.