不同应力路径下灰岩卸荷损伤特性演化规律研究
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陈天楠(1998—),男,硕士研究生。主要从事岩土工程方面的研究。E-mail:1026585049@qq.com

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TU452

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国家自然科学基金项目(U2034203, 51979218);中国水利水电科学研究院水利部水工程建设与安全重点实验室开放研究基金(NO.202001)资助


Influence of Stress Path on Unloading Mechanical Properties of Limestone
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    摘要:

    为探究应力路径对灰岩卸荷力学特性的影响机制,考虑恒偏压卸围压、恒轴压卸围压及加轴压卸围压三种卸荷应力路径,分别进行了卸荷试验和数值模拟,分析了不同卸荷应力路径下灰岩的能量释放规律及细观损伤演化规律。研究结果表明:(1)卸荷应力路径对灰岩宏观力学特性影响显著,恒偏压卸围压路径下,岩样卸荷强度最低, 变形模量与泊松比变化趋势最缓,但变化幅度最大,而加轴压卸围压路径下,其卸荷强度最大,但变形参数变化幅度较小;(2)三种卸荷应力路径下,卸荷过程中耗散能占比大小依次为恒偏压卸围压>恒轴压卸围压>加轴压卸围压,弹性应变能占比大小则为加轴压卸围压>恒轴压卸围压>恒偏压卸围压,说明外力所做的功在恒偏压卸围压方案下多转化为耗散能用于裂纹发育,对应破坏时的损伤变量最大,而加轴压卸围压方案下多转化为弹性应变能储存于岩样内部,卸荷破坏更为突然;(3)数值模拟结果分析发现,恒偏压卸围压方案下,卸荷过程中的裂纹总数量和张拉裂纹占比最大,卸荷损伤程度最高,对应的损伤变量最大,而加轴压卸围压方案下岩样的裂纹数量最少,损伤变量最小,卸荷过程中岩样内部的细观损伤发育规律进一步说明了应力路径对其宏观力学特性的影响。

    Abstract:

    To explore the influence mechanism of the stress path on the unloading mechanical properties of limestone, we considered three unloading stress paths: unloading with a constant bias pressure unloading confining pressure, unloading with a constant axial pressure unloading confining pressure, and unloading under axial pressure andconfining pressure. This paper conducted unloading tests and numerical analyses, and analyzed the energy release law and meso-damage evolution law of limestone under different unloading stress paths. The research results show that:(1) The path of unloading stress has a significant impact on the macro-mechanical properties of limestone. Under a constant bias pressure unloading confining pressure condition, the rock sample exhibits the lowest unloading strength, and the deformation modulus and Poisson's ratio show a slower rate of change. However, it exhibits the largest range of change. Under axial pressure unloading confining pressure path, the unloading strength is the largest. However, the variation of deformation parameters is relatively small. (2) Among the three unloading stress paths, the proportion of dissipation energy during the unloading process follows the order: constant bias pressure unloading confining pressure>constant axial pressure unloading confining pressure>axial pressure unloading confining pressure. The distribution of elastic strain energy is as follows: axial pressure unloading confining pressure>constant axial pressure unloading confining pressure>constant bias pressure unloading confining pressure. The findings indicate that the work performed by the external force is primarily converted into dissipation energy during crack development under constant bias pressure unloading confining pressure. Furthermore, the corresponding failure exhibits the highest damage variable. In contrast, when subjected to axial pressure unloading confining pressure, the energy is primarily converted into elastic strain energy, which is then stored within the rock sample. The failure during unloading occurs more abruptly in this case. (3) According to the numerical simulation results, under constant bias pressure unloading confining pressure, there is a higher total number of cracks and the proportion of tension cracks during the unloading process., Additionally, the degree of damage during unloading is the highest, with a larger value for the corresponding damage variable. In contrast, under axial pressure unloading confining pressure, the number of cracks and the damage variable of the rock sample are the smallest. Furthermore, the meso-damage development law within the rock sample during the unloading process further insight into the impact of stress path on its macroscopic mechanics.

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陈天楠,邓华锋,李建林,刘立鹏,陈兴周,李涛.不同应力路径下灰岩卸荷损伤特性演化规律研究[J].防灾减灾工程学报,2023,43(6):1434-1444

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  • 收稿日期:2022-04-15
  • 最后修改日期:2022-05-27
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  • 在线发布日期:2024-01-11
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