Quasi-Static Experiments Designed to Explain Strength of Rock in an Explosion
Abstract
In the failure of rock in an underground nuclear explosion it has often been assumed that failure occurs in compression which has led to difficulties in modeling. The Bridgman ring experiment, in which a hard rubber ring slipped over a steel rod was observed to split when subjected to a hydrostatic confining pressure, was repeated using pyrex glass rings. Three cases were studied: 1) in which both ring and rod were unjacketed, 2) in which the inner wall of the ring was sealed from the pressure medium, and 3) in which both rod and ring were completely jacketed. In the first two cases, the ring was observed to split abruptly, with a single axial crack when confining pressure reached a critical level. In the third case no abrupt failure occurred but a number of axial cracks were found to have formed, grown stably, but did not penetrate the outer wall of the ring. The first two cases are explained by hydraulic fracturing of the ring. Observations and analysis indicate that in the third case the cracks initiated at flaws on the inner surface of the ring and propagated outwards in a stable manner. This case, in which a tensile crack propagates in an all around compressive stress field, provides some insight into axial cracking of rock in triaxial compression and tensile failure of rock under radial shock loading. These results are suggestive but not conclusive as regards the seismic coupling problem.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1985
- Accession Number
- ADA166198
Entities
People
- Christopher H. Scholz
Organizations
- Lamont–Doherty Earth Observatory