Rock Quality Analysis using Empirical Techniques (RMR & Q-SYSTEM) along the Headrace of a Hydropower Project in Kalam, Swat, Pakistan

Abstract

The principal goals of this research were to examine the rock mass classification (RMC) and characterization as well as the support assessment for the proposed headrace tunnel route of an approximately 11 km long hydropower project (HPP) in Kalam valley, Khyber Pakhtunkhwa (KP), Pakistan. It was important to look at the key discontinuity factors for the classification of rock masses. To accomplish the aim, field discontinuity surveys were carried out to obtain rock mass parameters, and collected samples along the proposed tunnel route. Furthermore, characterization and classification of rock mass have been done using empirical techniques (ET) such as Beiniawski's Rock Mass Rating (RMR) and Barton's Tunnelling Quality Index (Q). The rock types were identified as Kalam Quartz Diorite, Gabbro and Granodiorite from literature. The prominent discontinuity sets were evaluated by exporting discontinuity data to DIPS. Quality Index was determined by calculating, its parameters, Quality Index values range between 3.74-17.00, 3.74 (poor at DS-04), 7.08-7.33 (fair at DS-01, DS-11 and DS-18) and 10.07-17.00 (good at DS-02, DS-09, DS-13, DS-14, DS-17 and DS-19), whereas, rock mass classification values ranges from 47-60 (fair at DS-01, DS-02, DS-04, DS-09, DS-11, DS-13, DS-14, DS-18, DS-19) to 64 (good at DS-17). The rock support according to the RMR scheme suggests fully grouted systematic bolting 3 to 4 m in length and 1.5 to 2.5 m spaced and 50-100 mm shotcrete in the crown and 50 mm in sides, while Q-system suggests spot bolting to Systematic bolting with 40-100 mm unreinforced shotcrete.