55. Influence of Geology on Deformability Characteristics of Rock Mass – A Case Study

In practice it is found that the rock differs from most of the engineering materials, in that it contains joints, bedding planes, shear zones, folds and faults. Since the rock masses cannot be fabricated according to the project requirements; the properties has to be established by in-situ and laboratory investigations. The laboratory tests carried out on small samples of intact rock gives some of the parameters: they cannot compensate the in-situ investigations. In design and construction of engineering structures over or inside the rock, in-situ rock mass parameters are required viz.; deformability, shear and other strength characteristics. Of these parameters, it is important to know the deformability characteristics of the rock mass for assessing expected displacements during excavation, to check stability and also to design proper rock support measures. Deformability characteristics mainly depends on the loaded area, loading system, adapted technique and methodology by which the modulus of deformation (Ed) and modulus of elasticity (Ee) are estimated. These modulus parameters are essential for the most of the rock engineering works especially; civil and mining engineering, which encompasses design of tunnels, underground chambers, dam foundation, mines and nuclear power plants etc. Generally, empirical methods are widely used to evaluate the deformability characteristics. The limitationwith these methods is that, sometimes it gives varying modulus values of rock masses for the same site. Hence, it is required to conduct in-situ investigations to estimate actual values of the same. In this paper, influence of geology on deformability characteristics of rock mass has been studied by conducting plate load tests at Kotlibhel H.E. Project, stage IA, further the evaluated results were compared with those calculated from empirical relations.