Numerical Simulation of Direct Test for Rock
The shear behaviour of rock joint is a combination of complex phenomena such as normal dilation, asperity shearing or sliding, contact area undergoing shearing or sliding and stiffness of the surrounding rock mass. Hence, a constitutive model for joint behaviour has to consider a large number of assumptions and uncertainties. Considerable efforts have been made in the past by various researchers to explain the shear behaviour of rock joint. Based on their laboratory, analytical and numerical studies various shear strength models have been proposed by them. In the present study numerical modeling is done for simulating the experimental conditions. Numerical study is performed based on the Distinct Element Method (DEM) and using the Universal Distinct Element Code (UDEC) developed by ITASCA Consulting Group Inc. Direct shear test were carried out on numerically simulated rock joint using UDEC. The shear behavior of rock joint examined with asperity like 15-15 and 30-30 at different normal stress. The result of the laboratory shear test performed on the sample with asperity 15-15 and 30-30 at different normal stress is compared with the shear behaviour and failure process of numerically simulated rock joint. Indian Geotechnical Conference – 2010, GEOtrendz December 16–18, 2010 IGS Mumbai Chapter & IIT Bombay
SHEAR BEHAVIOUR OF JOINTED ROCK: A STATE OF ART
The rock joints are mechanical discontinuities of geological origin. The presence of joints, fractures and other plane of weakness reduce the shear strength of rock. Realistic evaluation of the shear strength of rock joints plays an important role in the design of deep underground openings in jointed rocks, stability analysis of rock slopes, rock socketed piles, anchored rock slopes. Various parameters like, joint roughness, scale, stiffness of the surrounding rock mass, shear rate, condition of the joint i.e. unfilled joint/infilled joint, infill type, infill thickess and drainage condition of the infill material influence the shear behaviour of rock joint. The influence of these parameters on shear strength of jointed rock has been studied by different researchers such as Patton (1966), Barton & Choubey (1977), Indrartna & Haque (1998, 1999), and Weildeniya (2005). Based on their laboratory, analytical and numerical studies various shear strength models have been proposed. In this paper a critical review is attempted to study the influence of these parameter on the shear behavior of jointed rock. It has been observed that for non planar joint where the dilation of the joint is resisted by surrounding rock mass, CNS is a proper boundary condition to investigate the shear behavior of joint than the CNL boundary condition and CNS boundary condition will result in higher shear strength. The effect of infill material and its thickness is to reduce the shear strength of the rock joint. Shear rate, influences significantly the shear behavior of rock joint.
Constitutional Identity in the EU— A Shield or a Sword?
This Article consists of five sections. In the first section, it describes why identity questions matter, particularly in Europe. In the second section, the Article tackles the issue of multiple structural ambiguities affecting the concept of constitutional identity in the European constitutional vocabulary. In the third section, the Article explores trends concerning the use of constitutional identity in the European legal discourse and practice, including the development of alternative interpretations and applications of the notion of constitutional identities in the Member States. The fourth section of the Article combines the analytical accounts outlined in the second section with the trends identified in the third section, contending that different conceptions and applications of constitutional identity have varying effects on the European composite constitutional adjudication system and that the institutional and procedural framework should be calibrated accordingly. The final section of this Article draws some conclusions.