不同加载速率红砂岩峰后蠕变特性试验研究

发布时间：2018-04-05 21:16

本文选题：岩石力学　切入点：加载速率　出处：《煤炭学报》2017年S1期

【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。
[Abstract]:The post-peak creep properties of low-strength rock are complex. The post-peak incremental uniaxial creep tests of 9 red sandstone samples with two loading rates were carried out by RLW-2000 triaxial rheometer in laboratory.The characteristics of instantaneous strain and creep strain at different stress levels and loading rates behind rock samples are analyzed, the relationship between instantaneous strength and post-peak creep failure strength is determined, and the basic forms of failure instability of red sandstone samples at different stages are discussed.The results show that under the same stress loading condition, the greater the loading rate, the smaller the change of instantaneous strain, the larger the increment of attenuation creep strain, the smaller the increment of constant velocity creep strain, and the more the level of creep stress increases.The instantaneous strain of red sandstone sample shows the overall decreasing trend of fast decreasing, slow decreasing, slow increasing and fast increasing, while the creep strain after peak of red sandstone sample shows a nonlinear increasing trend of flat increasing and rapid increasing.The creep failure strength of post-peak rock sample is close, the creep failure strength of rock sample is equal to that of instantaneous strength, the creep failure strength of rock sample is 89.73 percent of the instantaneous strength, and the compressive and shear failure of rock sample under instantaneous compression failure is similar to that of post-peak creep creep, and the creep failure strength of rock sample after peak is relatively close to that of rock sample.The failure block of rock sample is large, the main fracture surface of post-peak creep failure is complex, the smaller the loading rate is, the more obvious the local weakening characteristic of post-peak creep rock sample is, but the main failure instability is the compression shear instability of the main fracture surface.
【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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