CAJ | 학술논문

由单向抗压强度实验及8级加卸载短时蠕变实验,得到蠕变下限为27MPa的细砂岩试样典型的坚硬岩石脆性断裂特征.应力-应变等时曲线线性回归函数的相关系数均高于0.92,长期强度与瞬时强度之比达94.39%,证明细砂岩试样的整体蠕变特性不强.应力-轴向应变等时曲线线性回归函数的平均相关系数高出应力-径向应变等时曲线线性回归函数的平均相关系数3.92%,因此其轴向非线性蠕变特性相对于径向非线性蠕变特性更弱.随着时间延续,细砂岩试样的非线性蠕变特性总体服从负Gauss分布规律,具有明显的时间效应.随加载应力水平的提高,应力-轴向应变等时曲线和应力-径向应变等时曲线线性拟合函数的平均相关系数下降幅度分别为0.97%和0.67%,线性相关性普遍降低.所以细砂岩试样的非线性蠕变程度随加载应力水平的提高而提高,载荷效应明显.
유단향항압강도실험급8급가사재단시연변실험,득도연변하한위27MPa적세사암시양전형적견경암석취성단렬특정.응력-응변등시곡선선성회귀함수적상관계수균고우0.92,장기강도여순시강도지비체94.39%,증명세사암시양적정체연변특성불강.응력-축향응변등시곡선선성회귀함수적평균상관계수고출응력-경향응변등시곡선선성회귀함수적평균상관계수3.92%,인차기축향비선성연변특성상대우경향비선성연변특성경약.수착시간연속,세사암시양적비선성연변특성총체복종부Gauss분포규률,구유명현적시간효응.수가재응력수평적제고,응력-축향응변등시곡선화응력-경향응변등시곡선선성의합함수적평균상관계수하강폭도분별위0.97%화0.67%,선성상관성보편강저.소이세사암시양적비선성연변정도수가재응력수평적제고이제고,재하효응명현.
Based on experimental results of uniaxial compression and short-term creep using 8-step loading-unloading method, fine sandstone specimen, which lower creep limit is 27MPa, present typical brittle breakage properties of hard rock. The correlative coefficients of linear regression function for isochronous stress-strain curve are all higher than 0.92, and the ratio of long-term strength to instantaneous strength reaches 94.39%, which indicate that the whole creep of fine sandstone specimen is weak. The average correlative coefficients of linear regression function for isochronous stress- axial strain curve are 3.92% higher than that of average correlative coefficients of linear regression function for isochronous stress- radial strain curve, so nonlinear creep property of the fine sandstone specimen in axial direction is correspondingly weaker than that in radial direction. Negative Gauss distribution can be applied collectively to nonlinear creep of fine sandstone specimen, which has obvious time effect. With increasing loading, the reduction degrees of average correlative coefficients of linear fitting functions of isochronous stress-axial strain curve and isochronous stress-radial strain curve are 0.97% and 0.67% respectively, which indicates the linear correlation decreases commonly. Thus, the degree of nonlinear creep for fine sandstone specimen increases along with loading stress with obvious stress effect.