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| 砂质能源土剪切特性的宏细观研究 |
| Macro and micro study on shear characteristics of sandy energy soil |
| 投稿时间：2023-11-26 修订日期：2024-03-09 |
| DOI： |
| 中文关键词: 能源土 三轴试验 离散元数值模拟 剪切强度 宏细观力学特性 |
| 英文关键词: energy soil triaxial test discrete element numerical simulation shear strength macro and micro-mechanical properties |
| 基金项目:泥质粉砂型深海能源土剪切渗流-耦合特性及其本构模拟与应用研究 |
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| 中文摘要: |
| 天然气水合物是一种极具潜力的清洁能源，并大量赋存于深海沉积物中（即能源土）。天然气水合物的大量开采导致能源土力学特性劣化，进而诱发海底工程地质灾害。针对上述问题，本文通过室内试验和离散元数值模拟相结合的方法探讨能源土宏细观力学特性的演化规律。首先，开展了室内三轴剪切试验，分析不同饱和度和有效围压条件下能源土剪切强度的变化规律。其次，基于PFC数值模拟软件建立了能源土三轴剪切离散元模型，明确了剪切过程中颗粒间接触力链、位移场、速度场、转动场的分布规律，进一步从细观层次揭示了能源土力学特性的演化规律。研究表明：能源土的强度随水合物饱和度和有效围压的增加而增大，且水合物饱和度越大、有效围压越低，软化现象越明显；水合物的胶结作用对能源土力学特性影响显著；试样的强度、变形特性与颗粒间接触、位移、速度、转动等细观运动状态有关；围压越大，试样内部的剪切带越不明显。研究成果可为能源土细观力学特性的研究提供参考。 |
| 英文摘要: |
| Natural gas hydrate is a kind of clean energy with great potential and exists in deep sea sediments (energy soil) in large quantities. The mass exploitation of natural gas hydrate leads to the deterioration of mechanical properties of energy soil, and then induces submarine engineering geological disasters. In response to the above problems, The evolution law of macro and micro mechanical properties of energy soil was studied by means of laboratory test and discrete element numerical simulation. Firstly, laboratory triaxial tests were carried out to analyze the variation of shear strength of energy soil under the different saturation and effective confining pressure. Secondly, a triaxial discrete element model of energy soil was established based on the PFC numerical simulation software, and the distribution laws of the contact force chain, displacement field, velocity fieldand rotation field among particles were clarified during the shear process, then the evolution law of mechanical properties of energy soil was revealed from the mesoscopic level. The results show that the strength of energy soil increases with the increasing of saturation and effective confining pressure. The phenomenon of strain softening is more pronounced with increasing hydrate saturation and decreasing effective confining pressure. The cementation of hydrate has significant influence on the mechanical properties of energy soil. The strength and deformation of the sample are related to the mesoscopic motion states such as contact, displacement, velocity and rotation between particles. The larger the confining pressure is, the less obvious the shear band is in the specimen. The results of the research can provide a reference for the study of micro-mechanical properties of energy soil. |
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