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ABSTRACT ABSTRACT: Western Iran is a semi-arid region which suffers from periodic water shortages. To address water needs, a number of sites that may be suitable for the construction of storage dams have been identified. This paper highlights the geological-geomechanical characterization of the rock masses exposed in the dam abutments and foundation area at the Khorram-Roud Dam in Hamadan, Western Iran. A comprehensive engineering geology and rock mechanics study was executed at the dam site. Different rock mass classification systems including RMR, Q, RQD, GSI, RMi and DMR were applied to characterize and provide a basis for estimating deformation and strength properties of the rock masses for preliminary design calculations. Based on results from this study, a set of geotechnical suggestions were proposed for a further more detailed investigation of potential stability problems, as well as a program for impermeation and consolidation grouting. In conclusion, the studied dam site has been proposed as an appropriate site for construction of a rock-fill dam. 1 INTRODUCTION Western Iran is a semi-arid region with a limited water supply and suffers from periodic water shortages. In the last few years, water demands have increased because of a high rate of population growth, together with greater demands from industrialization. To satisfy future water needs, Ministry of Energy personnel have selected a number of sites that could be suitable for construction of storage dams to be used primarily for domestic recharge of groundwater and irrigation. This article presents the geological-geomechanical characterization of the rock masses exposed at the dam abutments and foundation area at the proposed Khorram-Roud Dam in Hamadan, Western Iran. The geological-geomechanical characterization of the rock masses comprises comprehensive engineering geology and rock mechanics studies conducted in the study area including surface geology, jointing fabric study, borehole drilling and logging, and field and laboratory geotechnical testing.
ABSTRACT ABSTRACT: The group of Alvand granitic rocks is distributed widely around the city of Hamadan, western Iran, and a number of important civil engineering structures have been founded on and in this rock group. Thus, the weathering characteristics of Alvand granites are of considerable practical importance. The granites are generally medium to coarse-grained and porphyritic, light-grey to buff in colour. To assess the influence of weathering on the geomechanical characteristics of these rocks, a sampling and testing program was carried out. Field work involved assessment of the rock mass weathering grades, execution of simple field tests and collection of representative samples from different weathering grades. This paper presents the results of laboratory investigations, including weathering characteristics and physical, chemical and mechanical properties. Interrelationships are determined for all test results. From the field and laboratory studies, robust linear relationships are found between the weathering degree of the tested samples and their geomechanical properties. 1 INTRODUCTION The geomechanical properties of rocks vary considerably depending on the rock type, nature of discontinuities and weathering. The effects of weathering on the geomechanical properties of rocks have been studied by numerous investigators and various weathering indices and classifications have been proposed. In nature, the inevitable process of weathering produces significant changes in almost all the chemical and physical properties of rocks and it is universally recognized that this process will have affected many of the geomechanical properties of the rock mass (Gupta & Rao 2001). The main aim of the present study was to demonstrate the effect of weathering on the geomechanical properties of Alvand grantitic rocks. The group of Alvand granitic rocks is distributed widely around the city of Hamadan, western Iran, and a number of important civil engineering structures have been founded on and in this igneous rock group.