不同盐度下深海能源黏土宏微观力学特性离散元分析  

Discrete element analysis of macro-and micro-mechanical properties of methane hydrate-bearing clay under different salinities

作　　者：李政 蒋明镜 王思远[1] LI Zheng;JIANG Mingjing;WANG Siyuan(School of Civil Engineering,Tianjin University,Tianjin 300350,China;School of Civil Engineering,Suzhou University of Science and Technology,Suzhou 215009,China;State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]天津大学建筑工程学院,天津300350 [2]苏州科技大学土木工程学院,江苏苏州215009 [3]同济大学土木工程防灾国家重点实验室,上海200092

出　　处：《岩土工程学报》2025年第5期926-935,共10页Chinese Journal of Geotechnical Engineering

基　　金：海南省重点研发计划项目(ZDYF2021SHFZ264);国家重大自然灾害防控与公共安全重点专项(2022YFC3003400);国家自然科学基金重大项目(52331010);国家自然科学基金重大项目(51890911)。

摘　　要：能源土的力学行为与水合物相平衡特性紧密相关,相较于砂土,黏土沉积物具有更小的孔径且孔径对水合物相平衡特性有较大的影响。通过引入孔径对相平衡线的影响,建立了胶结型深海能源黏土温-压-力-化三维微观接触模型,并开展了不同盐度下的深海能源黏土的三轴压缩数值模拟试验,对其应力应变曲线、体变、胶结破坏、团粒破碎率和强度特性等宏微观力学行为进行了分析,并与重塑黏土的力学特性进行了对比,讨论了水合物胶结对深海能源黏土力学特性的增强作用。结果表明:①低围压下,随着盐度的升高,深海能源黏土的峰值抗剪强度逐渐减小,且应变软化特征越不明显,同时体变先剪缩后微弱剪胀再剪缩的特点,高围压下其表现为应变硬化及剪缩特性。②随着围压的增大及环境盐度的升高,深海能源黏土的胶结破坏数和团粒破碎率均逐渐增大。③通过对深海能源黏土的强度特性的分析发现,其强度包线呈现典型的非线性特征。The mechanical behavior of methane hydrate bearing soil is closely related to the characteristics of hydrate phase equilibrium.Compared with sand,clay has smaller pore size and the pore size has a great influence on the characteristics of hydrate phase equilibrium.A three-dimensional thermal-hydro-mechanical-chemical bond contact model for grain-cementing type methane hydrate-bearing clay is established by introducing the influences of the pore size on the phase equilibrium line.The numerical simulation of triaxial compression tests on the methane hydrate-bearing clay under different salinities is carried out.The macro-and micro-mechanical behaviors such as stress-strain curve,volume strain,number of bond breakage,aggregate crushing rate and strength characteristics are analyzed and compared with the mechanical properties of remolded clay.The enhancement of bond on the mechanical properties of the methane hydrate-bearing clay is discussed.The results show that(1)Under low confining pressure,with the increase of the salinity,the peak shear strength of the methane hydrate-bearing clay gradually decreases,and the strain softening is less significant.At the same time,the volume strain shows shear contraction first,then weak dilatation and then shear contraction.Under high confining pressure,it shows strain hardening and shear contraction.(2)With the increase of the confining pressure and salinity,the number of bond breakage and the aggregate crushing rate of the methane hydrate-bearing clay gradually increase.(3)Finally,through the analysis of the strength characteristics of the methane hydrate-bearing clay,it is found that its strength envelope presents typical nonlinear characteristics.

关 键 词：深海能源黏土 孔径 离散单元法 三轴压缩 盐度 

分 类 号：TU452[建筑科学—岩土工程]