Dynamic Response of Lined and Unlined Underground Openings.
A brief review of the recent development of stress-wave-cavity interaction problems pertinent to protective construction of underground openings. It concludes that with elastic, homogeneous, isotropic earth media, the dynamic stress concentration factors for cylindrical, elliptical, and square holes are about 10 to 20 percent higher than those for their corresponding static cases. Elastic liners increase the strength of the hole in relatively soft earth, but not in hard earth such as granite. The sphere is the optimal shape.