1. School of Energy Science and Engineering,Henan Polytechnic University,Jiaozuo　 454000,China; 2. The Collaborative Innovation Center of Coal Safety Production of Henan Province,Jiaozuo　 454000,China

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。

The post-peak stage-loading creep test was conducted on eight red-sandstone specimens by the RLW-2000 type servo rheometer system in the laboratory,the basic creep characteristics of post-peak red-sandstone was studied, the relationships of post-peak creep-failure strength and peak unloading strength,instantaneous strength were deter-mined,the internal mechanism of test creep curve and theoretical one was analyzed,the basic form of post-peak creep failure was discussed. The results showed that as stress level increased,post-peak instantaneous strain increased near-linearly. Instantaneous strain increased slightly with creep failure strength increasing at the same stress stage. As stress level increasing,creep strain increased as S type of decreasing-steady-increasing-rapid increasing trend,while non-at-tenuation creep occurred and creep strain increased obviously at last stress stage. As creep-failure strength increasing, creep strain decreased slightly at the same stress stage. Post-peak creep-failure strength was 84. 00% and 79. 92% of peak unloading strength and instantaneous one,respectively,and peak unloading strength was 95. 27% of instantaneous strength. Burgers rheological mode was better for fitting to the creep curve test,the relationship of creep test curve and theoretical one was larger at the high creep stress stage than the lower one. Specimen failure form showed the com-posite of main compression-shear failure surface and no-rule weaken zone,the lower creep-failure strength was,the lar-ger main failure angle and weaken zone,and the higher peak unloading value was,the more obvious main failure sur-face.

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)；

Xin Yajun,An Dingchao,Li Mengyuan,et al. Creep and strength characteristics of post-peak stage loading in high strength red-sandstone [J]. Journal of China Coal Society,2017,42(7):1714-1723.