UNIFIED SOLUTION FOR THE EXPANSION OF SPHERICAL CAVITY IN STRAIN-SOFTENING MATERIALS WITH DIFFERENT ELASTIC MODULI IN TENSILE AND COMPRESSION

For strain-softening materials with different elastic moduli of tensile compression, two controlling parameters were introduced to take into account the different moduli and strain-softening properties. By means of twin shear unified strength theory, unified solutions for calculating stress and displacement fields of expansion of spherical cavity were derived. The effects caused by different elastic moduli in tensile and compression, by different models and strain-softening rates on stress and displacement fields, and by the development of plastic zone were analyzed. The results show that the ultimate expansion pressure, stress and displacement fields, and development of plastic zone vary with the changes of elastic moduli, models, and strain-softening properties. If classical elastic theory and single model are adopted and strain-softening properties are neglected, large errors may be induced.