不同加载速率红砂岩峰后蠕变特性试验研究 |
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引用本文: | 辛亚军,安定超,李梦远,郝海春. 不同加载速率红砂岩峰后蠕变特性试验研究[J]. 煤炭学报, 2017, 42(Z1): 60-67 |
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作者姓名: | 辛亚军 安定超 李梦远 郝海春 |
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作者单位: | 1.河南理工大学 能源科学与工程学院,河南 焦作 454000; 2.煤炭安全生产河南省协同创新中心,河南 焦作 454000 |
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基金项目: | 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资助项目(14B440001);河南省焦作市科技攻关计划资助项目(20151021103453) |
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摘 要: | 低强度岩石峰后蠕变特性复杂,在实验室通过RLW-2000型三轴流变仪,对2种加载速率9个红砂岩样进行峰后增量加载单轴蠕变试验,分析岩样峰后不同应力水平与不同加载速率下瞬时应变与蠕变应变特征,确定瞬时强度与峰后蠕变破坏强度关系,探讨不同阶段红砂岩样破坏失稳基本形态。结果表明:在相同应力加载条件下,加载速率越大,瞬时应变变化越小,衰减蠕变应变增量越大,等速蠕变应变增量越小;随着蠕变应力水平的提高,红砂岩样瞬时应变表现为快速减小-缓慢减小-缓慢增加-快速增加的整体减小趋势,而红砂岩样峰后蠕变应变则表现为平缓-增加-急速增加的非线性增加趋势,且非衰减蠕变具有明显蠕变3阶段特征;峰后岩样蠕变破坏强度较为接近,离散性小,岩样峰后蠕变破坏强度平均达到了瞬时强度的89.73%;瞬时压缩破坏岩样呈现压剪破坏,岩样破坏块度大,峰后蠕变破坏主控破裂面形态复杂,加载速率越小,峰后蠕变岩样局部弱化特征越明显,但破坏失稳以主破裂面压剪失稳为主。
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关 键 词: | 岩石力学 加载速率 峰值卸载 峰后蠕变 蠕变破坏强度 失稳形态 |
收稿时间: | 2016-10-18 |
Study of red-sandstone post-peak creep test in different loading rates |
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Abstract: | Due to the complex creep properties on low-strength post-peak rock,a uniaxial incremental loading creep test was conducted on two groups of nine red-sand rock specimens in two loading rates by RLW-2000 rock triaxial rheology test system.The characteristics of post-peak instantaneous and creep strain were analyzed in different stresses,the relationship between instantaneous strength and long-term one was determined,and the basic rock failure morphology was discussed in different stress stages.The results showed that in same loading,the higher the rate was,the smaller instantaneous strain change was;the more the attenuation creep-strain increment was,the smaller the isokinetic one was.With the stress increasing,the instantaneous strain reduced through reducing rapidly,slowly,and then increasing slowly,rapidly,while the post-peak creep strain increased linearly through slowly,average,and then rapidly,which had obviously three stages.The creep failure strength of post-peak rock specimens was similar,the discreteness was small,which was averagely 89.73% of instantaneous one;Instantaneous compress specimen failed in compressing and shearing,and failure rock block was larger.Main post-peak creep failure surfaces were complex:the lower the loading rate was,the more obviously partial specimen was weaken in post-peak creep,and the instability type was mainly compress-shear failure along main fracture surface. |
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Keywords: | rock mechanics loading rate peak unloading post-peak creep creep failure strength instability morphology |
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