| 刘传孝*,张加旺,张美政,张福俊.分级加卸载硬岩短时蠕变特性实验研究[J].实验力学,2009,24(5):459~466 |
| 分级加卸载硬岩短时蠕变特性实验研究 |
| Experimental Study of Short-term Creep Characteristics Base on Step Loading-Unloading Method for Hard Rock |
| 投稿时间：2009-05-03 修订日期：2009-07-22 |
| DOI： |
| 中文关键词: 分级加卸载 应力-应变等时曲线 Gauss分布 相关系数 短时蠕变实验 |
| 英文关键词:step loading-unloading isochronous stress-strain curves Gauss distribution correlative coefficient short-term creep experiment |
| 基金项目:山东省中青年科学家科研奖励基金项目（2006BS08022）;山东农业大学科技创新基金项目(200723468) |
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| 中文摘要: |
| 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。 |
| 英文摘要: |
| 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. |
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