engleski

Underground stress analysis using mapped infinite elements

In the large spectrum of practical engineering geomechanical problems, there is always a question how to treat unbounded continua in the most rational way to get accurate results. This paper considers the use of mapped infinite elements in conjuction with finite elements in both linear and non-linear stress analysis sumarising previous research on the use of mapped infinite elements in the linear elastic and non-linear stress analysis. Material non-linear behaviour is described by Perzyna's elasto-visco-plastic model in videly accepted standard finite element formulation. Additional attention is given to gravity loading and its common action with other loadings. The gravity loading can be treated in two different ways: (a) by evaluating element nodal forces from the actual values of gravity stresses in Gauss points or element volume weight ; (b) by incorporating gravity stress from Gauss points directly in the total stress vector as initial ones. In the linear and non-linear analysis when the problem is disretized only with finite elements both strategies give the same results. Discretizing the half-space under consideration with infinite elements too, only the second strategy gives the correct results. The applicability of the suggested technique is examined and the benefits of employing proposed finite/infinite element approach in both linear and non-linear analysis is then illustrated by the solution of few unbounded geomechanical problems.

unbounded domain; mapped infinite elements; underground opening; stress analysis

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