韩振华, 张路青, 周剑, 等. 2021. 黏土矿物颗粒特征对含水合物的沉积物力学特性影响研究[J].工程地质学报, 29(6): 1733-1743. doi: 10.13544/j.cnki.jeg.2021-0052.
    引用本文: 韩振华, 张路青, 周剑, 等. 2021. 黏土矿物颗粒特征对含水合物的沉积物力学特性影响研究[J].工程地质学报, 29(6): 1733-1743. doi: 10.13544/j.cnki.jeg.2021-0052.
    Han Zhenhua, Zhang Luqing, Zhou Jian, et al. 2021. Effect of clay mineral grain characteristics on mechanical behaviours of hydrate-bearing sediments[J].Journal of Engineering Geology, 29(6): 1733-1743. doi: 10.13544/j.cnki.jeg.2021-0052.
    Citation: Han Zhenhua, Zhang Luqing, Zhou Jian, et al. 2021. Effect of clay mineral grain characteristics on mechanical behaviours of hydrate-bearing sediments[J].Journal of Engineering Geology, 29(6): 1733-1743. doi: 10.13544/j.cnki.jeg.2021-0052.

    黏土矿物颗粒特征对含水合物的沉积物力学特性影响研究

    EFFECT OF CLAY MINERAL GRAIN CHARACTERISTICS ON MECHANICAL BEHAVIOURS OF HYDRATE-BEARING SEDIMENTS

    • 摘要: 含水合物的沉积物力学参数是水合物储层稳定性评价的基础数据。我国南海神狐海域含水合物的沉积物中含大量的黏土,深入了解黏土矿物对沉积物力学特性的影响对水合物开采具有十分重要的意义。基于PFC三轴压缩模拟,首先分析了沉积物中不含水合物时,黏土矿物颗粒特征的力学效应,然后分析了水合物对颗粒的胶结作用和围压对沉积物力学特性的影响。结果表明,不含水合物模型的偏应力-应变曲线呈明显的应变硬化特征。黏土矿物的含量、颗粒形状和排列对沉积物三轴压缩特性具有显著影响。黏土矿物含量的增多对沉积物力学强度具有明显的降低作用,黏土矿物形状为条形的沉积物强度和弹性模量要明显高于圆颗粒模型,在细观上受颗粒平均接触数影响,条形黏土颗粒的定向排列使模型的力学参数具有各向异性。水合物对颗粒的胶结作用可显著提高模型的峰值强度和弹性模量,随着颗粒胶结程度的增大和围压的减小,含水合物的沉积物的破坏方式由塑性破坏向脆性破坏转换。

       

      Abstract: The mechanical parameters of hydrate-bearing sediments are the key parameters for the stability evaluation of hydrate formation. The hydrate-bearing sediments in Shenhu area of South China Sea contain large amounts of clay mineral. It is of great significance to understand the effects of clay minerals on the mechanical properties of sediments for hydrate mining. Based on triaxial compression simulation in the PFC code,we first analyzed the mechanical effects of clay mineral to the sediment without hydrate. Secondly,we analyzed the cementation effect of hydrate to mineral grains and the influence of confining pressure on the mechanical properties of the sediment. Our results indicated that the deviator stress-strain curve of the model without hydrate shows obvious strain hardening characteristics. The clay mineral content,grain shape and grain arrangement have significant effects on the triaxial compression characteristics of the sediment. The increase in the content of clay mineral has a significant effect on reducing the mechanical strength of sediments. The peak strength and elastic modulus of the sediments with strip-shaped clay grain are significantly higher than those of the sediment with round-shaped clay grain,which are related to the average co-ordination number in the microscopic view. The directional arrangement of the strip-shaped clay grains makes the mechanical parameters of the model to be anisotropic. The cementation effect of hydrate on the grains can significantly increase the peak strength and elastic modulus of the model. With the increase of the interparticle cementation degree and the decrease of confining pressure,the failure mode of the hydrate-bearing sediments changes from plastic failure to brittle failure.

       

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