张寅，李哲，宋士康，等.自然与饱水状态下砂岩压缩破坏力学特性及声发射特征[J].煤田地质与勘探，2022，50(2)：98−105. DOI: 10.12363/issn.1001-1986.21.06.0341
引用本文: 张寅，李哲，宋士康，等.自然与饱水状态下砂岩压缩破坏力学特性及声发射特征[J].煤田地质与勘探，2022，50(2)：98−105. DOI: 10.12363/issn.1001-1986.21.06.0341
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ZHANG Yin，LI Zhe，SONG Shikang，et al.Mechanical properties and acoustic emission characteristics of sandstone under natural and saturated conditions[J].Coal Geology & Exploration，2022，50(2)：98−105. DOI: 10.12363/issn.1001-1986.21.06.0341
Citation: ZHANG Yin，LI Zhe，SONG Shikang，et al.Mechanical properties and acoustic emission characteristics of sandstone under natural and saturated conditions[J].Coal Geology & Exploration，2022，50(2)：98−105. DOI: 10.12363/issn.1001-1986.21.06.0341
shu

自然与饱水状态下砂岩压缩破坏力学特性及声发射特征

Mechanical properties and acoustic emission characteristics of sandstone under natural and saturated conditions

    摘要
  • 摘要: 为研究自然与饱水状态下不同粒径砂岩损伤破坏过程中的力学特性和声发射特征，对自然和饱水状态下3种粒径砂岩进行单轴压缩试验和声发射试验，研究其单轴应力状态下力学特性和声发射特征。试验结果表明：在自然状态下，粗粒砂岩平均抗压强度为54.23 MPa，中粒砂岩为53.56 MPa，细粒砂岩为59.46 MPa；饱水后，粗粒砂岩平均抗压强度为35.62 MPa；中粒砂岩为31.79 MPa，细粒砂岩为29.10 MPa。饱水后，粗粒砂岩、中粒砂岩和细粒砂岩的弹性模量分别降低19.6%、32.7%和33.7%；泊松比分别增加9.6%、10.4%和19.5%。所有试样各阶段声发射能量曲线变化趋势与各阶段受力破坏程度具有较高的一致性，声发射能量峰值都出现在应力峰值附近，其中饱水后弹性变形阶段声发射总能量发生不同程度的减少，粗粒砂岩为67.4%，中粒砂岩为32.4%，细粒砂岩为29.3%。饱水试样损伤演化阶段较自然状态声发射总能量发生明显下降，粗粒砂岩最为明显，降幅为73.5%，中粒砂岩为36.0%，细粒砂岩为62.0%。饱水后失稳破裂阶段声发射能量值较自然状态依旧出现不同程度的减少，粗粒砂岩为30.7%，中粒砂岩为29.5%，细粒砂岩为38.3%。砂岩饱水后力学特性与声发射特征变化是试样微观结构变化在宏观层面的体现；用砂岩单轴破坏过程中声发射能量峰值可以很好地表征砂岩脆性，将为岩石脆性研究提供新的思路。

     

    Abstract: In order to study the mechanical properties and acoustic emission (AE) characteristics of sandstone with different grain sizes in the process of damage and failure under saturated and natural conditions, we carried out uniaxial compression tests and AE tests on three kinds of sandstone under saturated and natural conditions to study the mechanical properties and AE characteristics under the uniaxial stress state. The test results show that the average compressive strength of coarse-grained sandstone, medium-grained sandstone, and fine-grained sandstone are 54.23 MPa, 53.56 MPa, 59.46 MPa respectively under natural conditions, and 35.62 MPa, 31.79 MPa and 29.10 MPa under saturated conditions. After saturation, the elastic modulus of them decreases by 19.6%, 32.7% and 33.7%, respectively, and the Poisson’s ratio increases by 9.6%, 10.4% and 19.5%, respectively. The variation trend of AE energy curve of all samples at each stage is consistent with the degree of stress failure at each stage, and the peak value of AE energy appears near the peak value of stress. The total AE energy in the elastic deformation stage of saturated samples decreases to 67.4% for coarse-grained sandstone, 32.4% for medium-grained sandstone and 29.3% for fine-grained sandstone. Compared with that of sandstone in the natural state, the total AE energy in the damage evolution stage of saturated samples decreases significantly by 73.5% in coarse-grained sandstone, 36.0% in medium-grained sandstone and 62.0% in fine-grained sandstone. The value of AE energy in the unstable rupture stage also reduces by 30.7% in coarse-grained sandstone, 29.5% medium-grained sandstone and 38.3% fine-grained sandstone. The changes of mechanical properties and AE characteristics of sandstone after saturation are the reflection of microstructural changes in the macro level. The peak value of AE energy in the process of uniaxial failure of sandstone can be used to characterize the brittleness of sandstone, providing reference for the study of rock brittleness.

     

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