State of Stress and the Relation to Tectonics in the Central Savannah River Area of South Carolina.

摘要

An element of the seismic hazard assessment program at the Savannah River Plant (SRP), South Carolina, was the measurement of the in situ state-of-stress existing in the crystalline basement rock below the site. Hydraulic fracturing stress and related geophysical measurements including borehole televiewer logs were performed in a series of wells at various locations on the SRP site. Prior to the start of the field program, scoping studies using laboratory measured rock properties and the estimated regional stresses in a boundary element program were performed to predict if wellbore breakouts would occur in the borings depth. At the depths of the wells, the laboratory strength of the rock was great enough to prevent failure unless the in situ stresses were very high. The in situ stress field measured at the site is similar to that found at comparable depths in the region, where S(sub H) > S(sub h) > S(sub v) and the maximum horizontal stress is oriented NE-SW. The measured stress state indicated high horizontal stresses that could cause reverse faulting on favorably oriented pre-existing planes of weakness. This reverse faulting is consistent with the observed structure of the basement rock on site. 22 refs., 5 figs., 2 tabs.