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李志成, 刘建锋, 邓朝福, 曾寅. 含杂质盐岩三点弯曲变形破坏特征试验研究[J]. 岩土工程学报, 2018, 40(S2): 101-106. DOI: 10.11779/CJGE2018S2021
引用本文: 李志成, 刘建锋, 邓朝福, 曾寅. 含杂质盐岩三点弯曲变形破坏特征试验研究[J]. 岩土工程学报, 2018, 40(S2): 101-106. DOI: 10.11779/CJGE2018S2021
LI Zhi-cheng, LIU Jian-feng, DENG Chao-fu, ZENG Yin. Experimental study on deformation and failure characteristics of salt rock three-point-bending samples with impurities[J]. Chinese Journal of Geotechnical Engineering, 2018, 40(S2): 101-106. DOI: 10.11779/CJGE2018S2021
Citation: LI Zhi-cheng, LIU Jian-feng, DENG Chao-fu, ZENG Yin. Experimental study on deformation and failure characteristics of salt rock three-point-bending samples with impurities[J]. Chinese Journal of Geotechnical Engineering, 2018, 40(S2): 101-106. DOI: 10.11779/CJGE2018S2021

含杂质盐岩三点弯曲变形破坏特征试验研究

Experimental study on deformation and failure characteristics of salt rock three-point-bending samples with impurities

  • 摘要: 为探究盐岩在弯曲条件下的变形破坏特征及其所受杂质含量的影响,利用四川大学MTS815岩石力学综合试验系统,对两组杂质含量不同盐岩单边直裂纹弯曲试样(SENB)进行了三点弯曲循环加卸载试验及全过程声发射同步监测。试验研究表明,含杂卤石杂质盐岩弯曲抗拉强度和弯曲弹模均高于纯盐岩,杂质盐岩抵抗裂纹扩展能力强于纯盐岩;盐岩的弯曲变形破坏可分为弹性变形的弹性阶段、塑性变形和裂纹起裂的屈服阶段、峰后裂纹稳定扩展阶段、残余阶段四个阶段;杂质对盐岩弯曲塑性变形与断裂破坏有很大影响。基于能量率的声发射特征参数能够较好反映盐岩弯曲条件下的变形破坏,与其变形破坏过程各阶段相对应,声发射具有阶段性特征,除弹性段外其他各阶段声发射均活跃;相比纯盐岩,由于杂质造成的摩擦以及杂质对塑性变形的弱化,杂质盐岩三点弯曲变形声发射更为活跃;声发射源三维定位揭示了盐岩三点弯曲下的损伤分布,其分布存在与应力状态有关的声发射空白区,其分布形态受杂质影响。

     

    Abstract: In order to investigate the deformation and failure characteristics of salt rock under bending conditions and the influences of impurity content, the loading-and-unloading three-point-bending tests as well as the synchronous acoustic emissions (AE) monitoring are performed on two groups of salt rock single edged notched beam (SENB) samples with different impurity contents using the rock mechanics test system MTS815 in Sichuan University. The test results show that the bending tensile strength and the bending elastic modulus of the impure salt rock with polyhalite are higher than those of pure salt rock, and the impure salt rock is better to resist the crack propagation than the pure salt rock. And the deformation and failure process of the bending salt rock consists of four stages, elastic deformation stage, yield stage with plastic deformation and crack initiation, crack propagation stage at post-peak and residual stage. Moreover, the impurity has a great influence on the plastic deformation and fracture failure of the bending salt rock. By selecting energy count rate as the AE characteristic parameter, the deformation and failure of the bending salt rock can be well reflected. Corresponding to the process of deformation and failure, AE presents the periodical characteristics at different stages, and the AE activities are active at every stage except the elastic deformation stage. Compared to those of the pure salt rock, the AE activities of the impure salt rock are more active because of the friction effect and the plastic deformation weakening effect caused by impurities. What’s more, the AE source location in three dimensions well reveals the damage distribution of salt rock under the three-point-bending condition. And in the distribution, there are AE blank are asrelated to the stress state. For the distribution, its form is greatly affected by the impurities.

     

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