Analysis of Geomechanical Properties in Terms of Parametric Discontinuities on Stability of Tunnels Distinct Element Method (Case Study: Water Tunnel of Golab)

Abstract

The discontinuities of the rock mass pose a high impact on its response to the static load and make complexity in modeling in such area. Principal objective of this study is to analyze the stability and sensitivity of Golab transfer tunnel access (transfer water from Zayanderud River to Kashan). This tunnel with a length of 5.1 kilometers and inclination of 13.5 percent is located 120 kilometers from Isfahan city. Geologically, this zone is in the range of sediment structure of Sanandaj-Sirjan. The host rock mass consists of Limestone Mesozoic (Cretaceous). The general characteristics of the joints in the rock represent high distance, low persistence, low opening (2 - 3 mm), average roughness and low weathering. Given purpose of the project and the distinct element method is the most useful for modeling rock mass for static analysis. This paper examines the effect of parametric factors on the stability of tunnels via UDEC software, discrete element and empirical method. After modeling, instability of Golab tunnel by increasing the depth is identified and confirmed. RMR, Q and GSI as experimental procedure were employed to classify the rock mass, based on RMR classification. The route rock mass has been taken in I and II categories and based on the Q classification, the path rock masses are recognized acceptable.