UNIFIED SOLUTION FOR EXPANSION OF CYLINDRICAL CAVITY IN STRAIN-SOFTENING MATERIALS WITH DIFFERENT ELASTIC MODULI IN TENSION AND COMPRESSION

For strain-softening materials with different elastic moduli in tension and compression, two governing parameters are introduced to take into account the difference in modulus and strain-softening properties. Based on twin shear unified strength theory, this paper derives unified solutions to calculate the stress and displacement fields of expansion of cylindrical cavity. Influences of several factors are analyzed including differences in elastic moduli in tension and compression, difference in models and strain-softening rates, and the development of plastic zone. The results show the ultimate expansion pressure, stress and displacement fields and the development of plastic zone depend on the elastic modular, models and strain-softening properties. If classic elastic theory and single model are adopted and strain-softening properties are neglected, large errors may be resulted in.