Trust is Good,Control is Better-Hidden Pitfalls in FE-Analysis

摘要

In the course of the back analysis of the stressstrain characteristic of the 153 m high Gepatsch rockfill dam in Austria,several inconsistencies have occurred in the numerical computation. A widespread finite element program,which is designed to elaborate geotechnical problems,was used for the modelling and the analysis of the problem. To analyse the stressstrain behaviour of the dam,the nonlinear constitutive model by Duncan and Chang,which is part of the software package,was applied. The material parameters for the numerical computation had been determined from conventional triaxial compression tests. Before the computation of the dam was realised,numerical single element tests were carried out.By comparing the stress-strain relation from numerical computations with those of the triaxial tests,implausible results in the finite element analysis have been observed.Several program bugs in the implementation of the Duncan-Chang constitutive model could be proved on account of a comparative calculation. The technical expertise was transmitted to the developer of the finite element application which corrected the program bugs and allocated appropriate program updates.Based on the obtained knowledge and experience,the modelling and computation of the Gepatsch rockfill dam could be started. The paper emphasizes the importance of verifying the numerical computations with test results and comparative calculations.It demonstrates the importance of numerical single element tests and delivers an insight in embankment dam modelling and computation.