| Popis: |
A large number of in situ stress measurements have been conducted in Rainier Mesa at the Nevada Test Site. Most of the measurements were made using the hydraulic fracture technique, but some comparisons with overcoming were also performed. Many of the hydraulic fractures were mined out and their behaviour was directly observed. The results show that horizontal in situ stresses in the mesa depend upon the depth, material properties, topography, bedding and faults. Large stress changes occur over distances much less than a metre, particularly near interfaces and faults. Bedding and topography were found to reorient stresses by as much as 45°. This paper gives a case study of work at the Nevada Test Site and documents the variations in the stress field due to these geologic features. |
