EXPERIMENTAL STUDY ON STRENGTH AND DEFORMATION PROPERTIES OF HOLLOW CYLINDRICAL SPECIMENS OF MARBLES
大理岩孔道试样的强度及变形特性的试验研究

A series of pseudo-triaxial compression tests on hollow specimens of marble with fine and medium crystals without considering inner pressure were carried out to study the effects of nonuniform stresses on the bearing capacity and deformation.There are no essential differences in the deformation behavior between solid and hollow specimens when the axial deformation is small.With the deformation increasing,failure in the hollow specimen starts from the hole wall for the minor principal stress;and the bearing capacity drops off.According to the stress state based on the analysis of linear elastic mechanics and the assumption of failure synchronization in the whole specimen,the strength provided by Coulomb criterion is a smaller estimated one.The strength property of hollow cylinder specimen is influenced by following factors.On the shear failure surface of specimen,normal force and shear force provided by confining pressure and axial load respectively are determined by the balance of the total forces and have no relation with hole.The hole just induces the nonuniform distribution of stresses.The bearing area becomes small for the hole;and the strength provided by confining pressure will increase.On the other hand,the failure in the specimen happens step by step;the bearing capacity of the whole specimen provided by cohesion or material strength will be less than that of the solid specimen,and decreases with confining pressure and inner diameter increasing.The experimental results provide a reference to understand the strength criteria,numerical calculation and failure of tunnel and well.