円錐孔底ひずみ法との比較に基づくコアを用いた地圧測定法の石灰岩への適用性評価

Abstract

Three-dimensional in-situ stresses in a hard limestone lying about 700 m below the surface were estimated by five core-based methods (ASR, DSCA, PSHA, DRA and AE method) and a stress relief method (Conical-ended borehole method ; CEBM). The confidence intervals of the results by CEBM were estimated, and then, the results by the core-based methods were compared to those by the CEBM to examine the reliability of the core-based methods for this particular rock. The ASR method was difficult to estimate reliable in-situ stresses in this hard limestone whose Young's modulus ranged from 40 GPa to 80 GPa. A more accurate measuring system was required to apply ASR method to such a hard rock. The DSCA (OC), the PSHA and the DRA (Δemax )(e) method estimated the in-situ stresses relatively consistent with those by the CEBM. The agreement of the results by both the conventional DRA and the AE method with those by the CEBM was poor for the rock.