Finite element analysis of discontinuities in rock medium

Jade, S and Chandrashekar, HM (1999) Finite element analysis of discontinuities in rock medium. Technical Report. CMMACS/ National Areospace Laboratories, Bangalore, India.

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Nonlinear finite element analysis of the jointed rock has been carried out by representing the joints explicitly to study the mechanical behaviour of discontinuities in rock masses. Three different rocks have been analysed with single and multiple joints for different confining pressures and axial loads. Intact rock mass is modeled using 2-D Plane strain elements and the joint is explicitly modeled using 2-D Gap and Friction elements. The model is subjected to uniform confining pressure on the two vertical sides and uniform axial stress on the top. Isotropic, elasto-plastic material behavior with no strain softening is used in the analysis. The axial load is applied in series of steps or increments. The incremental solution is performed in a step-by-step13; manner until the full-specified loads are applied. In each increment the modified Newton Raphson iterative scheme is performed until the convergence is achieved or maximum iterations are reached. Mohr-coulomb yield criterion is used in the analysis to determine the major principal stress at failure. The inclination of the discontinuity is varied from 0 to 90 degrees with the major principal stress direction. The confining pressure is varied from 0 to 10 MPa. Sensitivity analysis of the model is carried out13; for co-efficient of friction, normal and tangential stiffness at the interface.13; 13; The results obtained from the analysis are then interpreted to obtain the (i) stress and strain curves for different (a) joint inclination angles, (b) confining pressures and (c) number of joints (ii) failure stress versus joint inclination angle for different confining13; pressures, (iii) failure stress versus number of joints and (v) effect of friction, normal and tangential stiffness at the interface. The results obtained from the above analysis are then compared with experimental results to check the accuracy of finite element analysis. The results match well within the limitations of the theoretical and experimental framework. The strength of the FEM technique to the above lies in its13; generality and flexibility to handle all types of loads, sequences of construction, support conditions and different material properties.

Item Type: Monograph (Technical Report)
Uncontrolled Keywords: Finite element analysis;Rock
Subjects: MATHEMATICAL AND COMPUTER SCIENCES > Mathematical and Computer Scienes(General)
Depositing User: Mr. Ravikumar R
Date Deposited: 13 Jul 2006
Last Modified: 13 Aug 2015 07:05

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