Evaluation of stresses based on overburden and in-situ measurements

摘要

The Central Soil and Materials Research Station (CSMRS), New Delhi has conducted a number of stress measurements for many hydroelectric and highway projects being constructed/completed in the Himalayan region of India, Nepal and Bhutan. This paper deals with the comparison of in-situ stress measurements by flat jack tests and hydraulic fracturing tests. The measured vertical stress was more than the stress due to overburden of rock cover and horizontal stress was higher than the vertical stress in general. The average vertical stress as measured by hydraulic fracturing test was almost two times the overburden stress. It is concluded that there was very large variation in the results of in-situ stress by flat jack test as compared to hydraulic fracturing. The case study of another project in the same vicinity has been presented along with interpretation of data and a comparison with estimated stresses based on overburden.