| 冻融循环作用下砂岩蠕变特性及损伤模型研究 |
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| 引用本文： | 陈国庆,万亿,裴本灿,米冠宇.冻融循环作用下砂岩蠕变特性及损伤模型研究[J].工程地质学报(英文版),2020,28(1):19-28. |
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| 作者姓名： | 陈国庆 万亿 裴本灿 米冠宇 |
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| 作者单位： | 地质灾害防治与地质环境保护国家重点实验室(成都理工大学)，成都 610059，中国 |
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| 基金项目： | 国家自然科学基金资助项目41572283国家自然科学基金资助项目41521002国家自然科学基金资助项目41972284 |
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| 摘 要： | 青藏高原高寒地区岩体长期稳定性受冻融作用影响显著,有必要开展冻融岩石的时效性特征研究。为探讨砂岩在冻融循环作用下的蠕变劣化特性,基于不同冻融循环次数后石英砂岩及红砂岩单轴蠕变试验结果,深入分析了冻融循环对砂岩各蠕变阶段的影响特征。研究表明,在非屈服应力条件下,试样在衰减蠕变阶段的蠕变时长随着冻融循环次数的增加而明显减小,对应蠕变量及蠕变速率增大;在屈服应力条件下,试样进入加速蠕变阶段的应力阈值随着冻融循环次数的增加而逐渐降低,对应从稳定蠕变到加速破坏所经历的时间更短,破坏时累计的应变增量更大;在长期荷载作用下,试样的宏观破裂形态随循环次数的增加逐步由单一斜剪切破坏模式向共轭断面拉剪复合型破坏模式演化。根据试验结果,提出了具有冻融与长期受荷劣化特征的非定常性黏弹性系数损伤演化方程,将其引入西原模型构建了考虑冻融损伤的砂岩蠕变本构模型。利用冻融后红砂岩蠕变试验数据对模型进行了参数辨识与比较分析,验证了模型的正确性及适用性。通过对模型参数进行拟合分析,揭示了黏弹性冻融损伤系数随冻融循环次数的变化规律,表明了长期受荷损伤参数具有控制加速蠕变幅度的重要作用。研究结果对于高寒山区岩体长期稳定性评价具有一定意义。
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| 关 键 词： | 砂岩 冻融循环 蠕变试验 损伤力学 本构模型 |
| 收稿时间： | 2019-08-28 |
THE CREEP CHARACTERISTICS AND DAMAGE MODEL OF SANDSTONE UNDER FREEZE-THAW CYCLES |
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| CHEN Guoqing,WAN Yi,PEI Bencan,MI Guanyu.THE CREEP CHARACTERISTICS AND DAMAGE MODEL OF SANDSTONE UNDER FREEZE-THAW CYCLES[J].Journal of Engineering Geology,2020,28(1):19-28. |
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| Authors: | CHEN Guoqing WAN Yi PEI Bencan MI Guanyu |
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| Institution: | State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China |
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| Abstract: | The long-term stability of rock in the alpine area of Qinghai-Tibet Plateau is significantly affected by freeze-thaw action. Accordingly it is necessary to study the time-dependent mechanical characteristics of the rock under freeze-thaw cycles. In this study,we conducted the uniaxial creep experiments on the red sandstone samples subjected to different freeze-thaw cycles. We further analysed the previous studies about quartz sandstone and investigated the effect of freeze-thaw cycles on each creep stage of sandstone. The results show the follows. The creep time of the samples during the deceleration creep decreases with an increasing number of freeze-thaw cycles under the condition of non-yield stress,corresponding to the increase of creep deformation and rate. The threshold stress for the rock samples entering accelerated creep decreases gradually with increasing freeze-thaw cycles under the condition of yield stress,the corresponding time from stable creep to acceleration creep gets more shorter,and the accumulated strain becomes more greater when rock failure. The macro-failure mode of the samples gradually evolves from a single oblique shear failure mode to a conjugate section tension-shear composite failure mode with increasing freeze-thaw cycles. The damage evolution equation about unsteady viscoelastic coefficient with the characteristics of freeze-thaw damage and time-dependent deterioration was proposed based on the experimental results. We introduced the Nishihara model to establish the creep constitutive model of sandstone considering freeze-thaw damage. The parameters of the model were identified by using the creep experimental data of red sandstone. The comparisons verify the correctness and applicability of the model. By fitting and analysing the identified parameters of the model,the law of viscoelastic coefficients varying with freeze-thaw cycles was revealed. The damage parameters under long-term load which plays an important role in controlling the amplitude of accelerated creep was shown. The research results have certain significance for long-term stability evaluation of rock mass in alpine area. |
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| Keywords: | Sandstone Freeze-thaw cycles Creep experiment Damage mechanics Constitutive model |
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