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软硬互层状岩石类材料双轴压缩蠕变特性试验研究*
Experimental study on creep behavior of interbedded rock-like material with soft and hard layers under biaxial compression
投稿时间:2022-05-14  修订日期:2022-06-22
DOI:
中文关键词:  软硬互层  双轴压缩试验  蠕变  分级加载
英文关键词:soft and hard interlayer  biaxial compression test  creep  step loading
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
作者单位邮编
包焱坤 中南大学 资源与安全工程学院 410083
李地元 中南大学 资源与安全工程学院 410083
张鹏飞 中南大学 资源与安全工程学院 410083
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中文摘要:
      自然界中分布着广泛的复合层状岩体,其具有显著的结构不连续性、非均质性和各向异性特征。为揭示软硬互层状岩体在双轴压缩下的蠕变特征,采用相似模型试验,制作了软硬互层状岩石类试样,开展了三种不同侧向应力水平条件下平行于层理方向的轴向分级加载双轴压缩蠕变试验,并利用数字图像相关技术(DIC)进行了试样表面变形观测。研究发现,软硬互层状岩石类材料的蠕变包括减速蠕变、等速蠕变、加速蠕变三个阶段,且减速蠕变阶段与等速蠕变阶段占比较大,而加速蠕变阶段占比较小。随着侧向应力的增加,试样的蠕变破坏强度逐渐降低,而蠕变应变增加率随之增加。应力水平差异对试样蠕变特征有着显著的影响,当侧向应力相同,随着轴向应力的增加,轴向应变也随之增加;当轴向应力相同,轴向应变与侧向应变随着侧向应力的增加先减小后增大。通过DIC技术监测试样表面变形,发现当侧向应力水平较低时,试样的轴向应变主要取决于硬岩层,而当侧向应力水平超过软岩抗压强度后,软岩层内部裂纹的产生会导致试样宏观破坏提前发生。研究结果可为软硬互层状岩体工程建设及围岩长期稳定性分析提供理论参考。
英文摘要:
      There are a wide range of composite layered rock masses in nature, which are characterized by structural discontinuity, heterogeneity and anisotropy. In order to reveal the creep characteristics of soft and hard layered rock under biaxial compression, the samples of soft and hard interbedded rock were prepared by means of similarity model test. Biaxial compression creep tests were carried out under axial graded loading parallel to the bedding direction under three different lateral stress levels. The surface deformation of the specimens was observed by digital image correlation (DIC) technique. It is found that the creep of soft and hard interbedded rock materials includes three stages: decelerated creep, isometric creep, and accelerated creep. Decelerated creep and isometric creep account for a large proportion, while accelerated creep accounts for a small proportion. With the increase of lateral stress, the creep failure strength decreases gradually, while the creep strain increase rate increases. The creep characteristics of specimens are significantly affected by different stress levels. When the lateral stress is the same, the axial strain increases with the increase of axial stress. When the axial stress is the same, the axial strain and lateral strain decrease first and then increase with the increase of lateral stress. DIC technology was used to monitor the surface deformation of the sample. It was found that when the lateral stress level was low, the axial strain of the sample mainly depended on the hard rock. When the lateral stress level exceeded the compressive strength of the soft rock, the cracks in the soft rock would lead to the macroscopic failure of the sample in advance. The research results can provide theoretical reference for engineering construction of interbedded rock mass and long-term stability analysis of surrounding rock.
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