Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

2-D Stress-Stratin Analysis for Underground Excavations in Rock with Non-linear Elasto-Plastic Behavior Using FEM (Finite Element Method)

Document Type : Original Research Paper

Authors
Morteza Ahmadi
Mohsen Moshary
Mining Dept. Engineering Faculty, Tarbiat Modarres University, Tehran, Iran
Abstract
In this research, two-dimensional analysis is applied to surrounding underground excavations that behave in nonlinear elasto-plastic manner. A computer program (FEP: Finite Element Program) was developed based on finite element method. The main output of applying the FEP is the calculation of the value of stress and strain in elasto-plastic conditions. The principles of FEM in stress analysis are first described, then the principles of solid mechanics explained, and consequently the final formulas of finite element analysis are derived. Main formulas of plasticity are defined and then combined with elastic formulas to acquire the FEM elasto-plastic formulas. The details of subroutines can be found after the theoretical discussion. Finally, the ability of software was examined by execution of the FEP with theoretical and practical examples. A good agreement is observed when the FEP is compared with other program (Ansys) and empirical methods. Criteria definition of rock mechanics is the main advantage of the FEP with respect to other softwares.
Keywords
Finite element
Elasto-plastic behavior
Underground excavation
Stress - strain analysis

Subjects

ANSYS 5.6.2 Software,.Lynn Rowles, Ansys. Inc., Couthpointe, 275. Technology Drive, Canonsburg, PAUSA, 15317, www. Ansys. Com.
Hoek, Brown, 1980- “Underground Excavtion in Rock”, Ins. Min. and Metall, London.
Owen, D.R.J., Hinton, E., 1980- “Finite Element in Plasticity”, Pineridge Press, Swansea, U.K.
Ponde, G. N., Beer, G. & williams, J.R., 1990- “Numerical Methods in Rock Mechanics”, Johin Wilely & Sons LTD.
Reddy, J. N.,1993- “An Introduction to Finite Element Method”, Chapter 7, PP. 248, Published by MC. Graw Hill.
Smart, J.D. & Sager, J. W.,1972- “Instrumentation on Recent Corps Tunnelling Projects”, Pro. Firest North American Rapid Excavation and Tunnelling Conference, AIME., Vol, 1, pp. 623-657.
Scientific Quarterly Journal of Geosciences
Volume 14, Issue 56
Summer 2005, Vol. 12, No. 56
Summer 2005
Pages 180-187