THE MAIN OBJECTIVE OF THIS STUDY IS TO DEVELOP A MATHEMATICAL MODEL UTILISING THE ADINA CODE WHICH CAN PREDICT INTERACTIONS BETWEEN CONCRETE BACKFILL AND HOST GEOLOGIES FOR UNDERGROUND RADWASTE REPOSITORIES.
THE WORK IS A PARALLEL PROGRAMME TO THE CONTRACT FI1W015700 UK AND MAY USE PHYSICAL TEST DATA DERIVED FROM THAT PROGRAMME FOR ANALYSIS DEVELOPMENT AND UNIFICATION PURPOSES.
A mathematical model has been developed for use within the ADINA finite element code to predict the time dependent performance of concrete as a backfilling and sealing material of underground repositories for radioactive waste. The evaluation of creep and shrinkage strains is based on the CEB-FIP model code together with Illston's approach to delayed and transitional thermal strains. The method adopted in assessing the creep contributions of the general constitutive equations was that of the effective creep rate.
The finite element material model developed (ADINA-RAD) is general and could be applied to various types of structure and loading. The model accounts for the ageing of concrete, multiaxial creep and creep recovery, the effect of external environmental humidity and changing internal temperatures. The model compares favourably with available published experimental data for maturing concrete but requires considerable further validation against a wider range of experimental results.
THE WORK PROGRAMME SHALL COMPRISE:
1. LITERATURE REVIEW OF RECENT INTERNATIONAL WORK TO ENSURE THAT THE MATHEMATICAL MODELS DEVELOPED USING ADINA REPRESENT A REASONABLE STATE OF THE ART IN TERMS OF BOTH ANALYTICAL APPROACH AND REPRESENTATION OF THE PHYSICAL PHENOMENA.
2. INVESTIGATION OF THE NEWLY AVAILABLE FEATURES PROVIDED IN THE LATEST RELEASE OF THE ADINA CODE AND CONSIDERATION OF THEIR APPROPRIATENESS TO MODELLING REPOSITORY INTERACTION BEHAVIOUR.
3. AGREEMENT, IN CONSULTATION WITH COMMUNITY PARTNERS, UPON APPROPRIATE GENERIC DISPOSAL SCENARIOS IN BOTH HARD ROCK AND ARGILLACEOUS HOSTS.
4. STUDY OF RANGE OF MECHANICAL AND THERMAL INTERACTIONS BETWEEN THE HOST MATERIAL, THE BACKFILL AND CANISTERED WASTE, INCLUDING LONG-TERM CREEP EFFECTS.
5. ASSESSMENT OF THE DEVELOPMENT OF DAMAGE IN AND ADJACENT TO THE BACKFILL MATERIAL, AND HOW THE DAMAGE MAY INCREASE WITH TIME BOTH SHORT-TERM FROM EARLY THERMAL EFFECTS FROM CEMENT AND WASTE AND VERY LONG-TERM FROM LITHOSTATIC CREEP EFFECTS.