An experimental study of the state of strain, deformation and fracture around lined and unlined cylindrical cavities in rock under uniaxial and biaxial static compressive loadings is discussed. Twenty limestone and marble specimens of typical dimensions 36 in. high, 24 in. wide and 3 in. thick with a 4 in. diameter cylindrical hole unlined or lined with hydrostone and aluminum liners were used. Deformation and fracture were monitored with strain gages, differential transformers and photoelastic coatings. Strain distributions and diametral changes as a function of applied load were obtained. Deviations from linear elastic theory were noted and discussed. Crack initiation and propagation were monitored with all three experimental means. Strain concentration factors were, with few exceptions, higher and in some instances appreciably higher than theoretical factors. The presence of the liner, even the weak hydrostone liner, had a strengthening influence, although not always predictable. Depending on the combination of material, geometrical and loading parameters, several types of failure were observed.
