花崗岩の弾性率とその評価
岩盤の変形性の評価法に関する基礎的研究 (第2報)
1987 年 103 巻 1187 号 p. 9-15
詳細
1987 年 103 巻 1187 号 p. 9-15
To discuss the validity of theoretical expressions, shown in eq.(1), for rock deformability obtained in the 1st report, a series of experimental studies on the elastic moduli of rock is performed.
To evaluate the theoretical expressions requires the knowledge of the crack density Φ, the intrinsic elastic moduli E and ν, the frictional coefficient μ on the crack surface, and the state coefficient q. q proposed in the 1st report is the ratio of the crack density of open cracks to that of total cracks.
Four kinds of granite specimens with different crack concentration were employed in experiments. Modal analysis, hydrostatic compression test, and observation of cracks on the polished surface of specimens were carried out. By analyzing these results, the crack density and the intrinsic elastic moduli of the specimen were evaluated and the theoretical values of effective elastic moduli were calculated in two cases, that q=1.0 and q=0.0, by using eq.(1). q=1.0 corresponds to the case that all pre-existing cracks are open and q=0.0 corresponds to the case of closed cracks. The former condition gives the minimum values of the elastic moduli and the latter one gives the maximum values.
The tangential elastic moduli of the specimen were measured as a function of the applied stress by uniaxial compression test. The maximum. and minimum values of elastic moduli obtained experimentaly were comnared with the thenretiral vallieq Reasonable agreement was obtained (shown in Table 3 and Table 4).
It is concluded that the theory proposed has a promise to estimate rock deformability quantitatively.
