Development of a Rock Groutability Index Based on the Rock Engineering Systems (RES): A Case Study

Abstract

Penetration grouting is used to improve rock conditions under dams and foundations. So far no comprehensive ranking has been presented for the rock groutability assessment. However, a need for an index is tangible to classify the jointed rock masses from cement-based grouting conditions point of view. In this paper an attempt has been made to propose a rock groutability index (RGI) based on the rock engineering systems (RES). RES is an approach to evaluate the interrelationship between the factors affecting rock engineering activities. After discussing the rock grouting mechanism and identifying all the effective factors, an interaction matrix is introduced to study the groutability of rock masses. Thereafter, the interaction intensity and dominance of each factor in the system is determined to classify these factors. As a result, an index is presented to predict the groutability potential of rock masses. Bakhtiari Dam of Iran was selected as a case study and the proposed index was used to rank the seven geological units of Sarvak formation in this dam. It was observed that the rock groutability index could suitably predict rock masses condition from grouting point of view. For the purpose of evaluation, cross correlations was carried out between the Lugeon values with RGI. It was showed that with increasing Lugeon values the RGI decreases linearly with good correlation coefficients.