地殻応力測定結果にみられる岩盤の不均質性の影響

抄録

Stress relief method has been often adopted to measure the in-situ stress state, and in this method various types of gauge have been used. If different types of gauge are used, different results can be expected. Moreover, stress distribution in an inhomogeneous rock mass is probably not uniform. Although these problems remain, they have not been clearly elucidated with in-situ data. In this study, the results measured in the same site with both hollow inclusion gauges and doorstopper-type 8-element gauges are compared. Consequently, it is shown that both results indicate the same tendency of a horizontally uniaxial compressive stress state. However, there are some differences in the magnitudes of the stresses between the two methods of measurement. Furthermore, upon examining the data obtained in this site in detail and referring to the data of two other sites, the effect of the inhomogeneity in a rock mass is discussed. As a result, it is concluded that the magnitude of in-situ stress in hard intact rock is larger than that in soft weathered rock and the dnfference between them is from 2 to 4MPa.