高强度红砂岩峰后分级加载蠕变及强度特征

发布时间：2018-03-25 04:37

本文选题：红砂岩　切入点：峰值卸载　出处：《煤炭学报》2017年07期

【摘要】：通过RLW-2000型伺服流变仪,对一组红砂岩8个试样进行峰后分级加载蠕变试验,研究了红砂岩峰后蠕变基本特性,确定了试样峰后蠕变破坏强度与卸载峰值强度、瞬时强度的关系,分析了蠕变试验曲线与理论曲线内在机制,探讨了试样峰后蠕变破坏的基本形态。结果表明:随着应力水平提高,峰后红砂岩试样瞬时应变呈近线性增加趋势;在相同应力水平下,随着蠕变破坏强度的增加,瞬时应变呈微小增加趋势;随着应力水平提高,试样蠕变应变表现为减小-平稳-增加-急速增加的S曲线增加趋势,最后一级应力水平下,试样呈非衰减蠕变,蠕变应变加速明显;在相同应力水平下,随着蠕变破坏强度增加,蠕变应变呈轻微减小趋势;试样峰后蠕变破坏强度分别达到卸载峰值强度与瞬时强度的84.00%与79.92%,卸载峰值强度是瞬时强度的95.27%;伯格斯流变模型能较好地表征蠕变试验曲线,高蠕变应力水平下蠕变试验曲线与理论曲线相关性大于低蠕变应力水平;试样破坏形态表现为压剪破坏主控面与无规则弱化区的复合,蠕变破坏强度越小,主控面角度与弱化区范围越大,而卸载峰值越大,主控面越明显。
[Abstract]:By using RLW-2000 servo rheometer, a group of 8 samples of red sandstone were subjected to post-peak loading creep tests. The basic characteristics of post-peak creep of red sandstone were studied, and the relationship between post-peak creep failure strength and unloading peak strength and instantaneous strength of the specimen was determined. The inherent mechanism of creep test curve and theoretical curve is analyzed and the basic form of creep failure after peak is discussed. The results show that the instantaneous strain of post-peak red sandstone specimen increases nearly linearly with the increase of stress level. Under the same stress level, with the increase of the creep failure strength, the instantaneous strain shows a slight increase trend, and with the increase of the stress level, the creep strain of the specimen shows an increasing trend of decreasing, steady, increasing and rapidly increasing S curve. At the last first order stress level, the creep strain accelerates obviously, and the creep strain decreases slightly with the increase of creep failure strength at the same stress level. The post-peak creep failure strength of the specimen reached 84.00% and 79.92% of the unloading peak strength and the instantaneous strength, respectively, and the unloading peak strength was 95.27% of the instantaneous strength, and the Bergs rheological model could better characterize the creep test curve. At high creep stress level, the correlation between the creep test curve and the theoretical curve is greater than the low creep stress level, and the failure pattern of the specimen is the combination of the main control plane of compression and shear failure and the irregular weakening zone, and the less the creep failure strength, the smaller the creep failure strength is. The larger the angle of the main control plane and the range of the weakening zone, and the larger the unloading peak, the more obvious the main control plane.
【作者单位】：河南理工大学能源科学与工程学院;煤炭安全生产河南省协同创新中心;
【基金】：国家自然科学基金资助项目(51174078) 河南省教育厅科学技术研究重点基金资助项目(14B440001) 河南省焦作市科技攻关计划资助项目(20151021103453)
【分类号】：TD315

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