Elastic-plastic Constitutive Model Considering Structural Effects of Deep-sea Energy Soil
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摘要: 深海能源土是指水合物以不同赋存模式填充于孔隙中的海底沉积物。水合物的填充效应会对能源土的密度和孔隙比产生较大影响。水合物的胶结效应会产生随饱和度增大而增大的胶结力,两种效应共同影响着深海能源土的复杂力学特性。同时能源土也是一种特殊的结构性土,其骨架颗粒、孔隙性状和排列方式均会对能源土的强度、应变软化和剪胀剪缩等特性有影响。在CSUH模型的框架下,通过建立与水合物饱和度相关的压硬性参数来反映水合物对能源土压缩特性的影响。其次考虑水合物填充效应的影响,推导出了能源土的实际初始孔隙比计算式,并将其引入至能源土的状态参数中来反映其剪胀特性。最后将用于描述土体损伤效应的结构性参数与水合物饱和度相关的胶结性参数作为硬化规律,建立了一个考虑水合物填充效应的结构性深海能源土的弹塑性本构模型。通过与室内试验结果比较,验证了该模型可有效反映能源土在不同水合物饱和度和围压条件下的应变硬化及软化、体积剪胀剪缩等复杂力学特性。Abstract: Deep-sea energy soil refers to deep-sea sediments where gas hydrates are filled in various modes within the pores. The filling effect of gas hydrates significantly impacts the density and porosity ratio of deep-sea energy soil. Additionally, the cementation effect of gas hydrates generates increasing bonding force with increasing saturation, jointly affecting the complex mechanical properties of deep-sea energy soil. Furthermore, deep-sea energy soil is a distinctive structural soil, wherein the particle framework, pore characteristics, and arrangement influence its strength, strain softening, and characteristics such as shear dilation and contraction. Within the framework of the CSUH model, this research reflected the compressibility characteristics of gas hydrates on energy soil by establishing pressure-hardening parameters related to gas hydrate saturation. Furthermore, considering the influence of gas hydrate filling effects, the actual initial porosity calculation formula for energy soil was derived and incorporated into the state parameters to reflect its shear dilation characteristics. Finally, utilizing structural parameters describing soil damage effects and cementation parameters related to gas hydrate saturation as hardening rules, an elastoplastic constitutive model for structural deep-sea energy soil considering gas hydrate filling effects was established. Comparative analysis with indoor experimental results validates the model's efficacy in effectively reflecting the complex mechanical properties of energy soil under various gas hydrate saturations and confining pressure conditions, including strain hardening and softening, as well as volume shear dilation and contraction.
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Key words:
- deep-sea energy soil /
- structured soil /
- constitutive model /
- damage law
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图 4 胶结性参数与水合物饱和度的关系[24]
图 6 结构性参数cb与水合物饱和度之间的关系[30]
表 1 结构性深海能源土的模型参数
M λ κ ν Z Pc0 β χ0 m ca 1.5 0.135 0.01 0.3 0.85 3.92 4.47 1.2 5 2 表 2 验证2中所采用的模型参数
M λ κ ν Z Pc0 β χ0 m ca 0.98 0.135 0.01 0.3 0.45 3.92 4.47 0.75 3 2 -
[1] KONG L, ZHANG Z, YUAN Q, et al. Multi-factor sensitivity analysis on the stability of submarine hydrate-bearing slope[J]. China Geology,2018,1(3):367-373. doi: 10.31035/cg2018051 [2] 刘锐明, 袁庆盟, 孔 亮, 等. 基于统一硬化参数的深海能源土本构模型[J]. 工程地质报,2019,27(4):811-818. [3] 颜荣涛, 张炳晖, 杨德欢, 等. 不同温–压条件下含水合物沉积物的损伤本构关系[J]. 岩土力学,2018,39(12):4421-4428. [4] WINTERS W J, PECHER I A, WAITE W F, et al. Physical properties and rock physics models of sediment containing natural and laboratory-formed methane hydrate[J]. American Mineralogist, 2004, 89(8): 1221-1227. [5] MASUI A, HANEDA H, OGATA Y. Effects of methane hydrate formation on shear strength of synthetic methane hydrate sediments[C]//International Offshore and Polar Engineering Conference.2005. [6] REES E V L , CLAYTON C R I , PRIEST J A . The effects of hydrate cement on the stiffness of some sands[J]. Géotechnique, 2010, 60(6): 435-445. [7] 颜荣涛, 韦昌富, 傅鑫晖, 等. 水合物赋存模式对含水合物土力学特性的影响[J]. 岩石力学与工程学报,2013,32(S2):4115-4122. [8] YUN T S, SANTAMARINA J C, RUPPEL C. Mechanical properties of sand, silt, and clay containing tetrahydrofuran hydrate[J]. Journal of Geophysical Research: Solid Earth, 2007, 112 (B4):116. [9] 吴 杨, 崔 杰, 廖静容, 等. 不同细颗粒含量甲烷水合物沉积物三轴剪切试验研究[J]. 岩土工程学报, 2021, 43(1):156-164. [10] SULTAN N, GARZIGHLIA S. Geomechanical constitutive modeling of gas hydrate bearing sediments[C]//Proceedings of the 7th International Conference on Gas Hydrates (IGGH 2011). Edinbergh: [s. n. ], 2011. [11] UCHIDA S , SOGA K , YAMAMOTO K . Critical state soil constitutive model for methane hydrate soil[J]. Journal of Geophysical Research Solid Earth, 2012, 117(B3):1-13. [12] 杨期君, 赵春风. 含气水合物沉积物弹塑性损伤本构模型探讨[J]. 岩土力学,2014,35(4):991-997. [13] 吴二林, 韦昌富, 魏厚振, 等. 含天然气水合物沉积物损伤统计本构模型[J]. 岩土力学,2013,34(1):60-65. [14] 周鸣亮, 贺 洁. 层状赋存含水合物沉积物的本构模型研究[J]. 工程地质学报,2022,30(5):1427-1437. [15] 蒋明镜, 肖 俞, 朱方园. 深海能源土微观力学胶结模型及参数研究[J]. 岩土工程学报,2012,34(9):1574-1583. [16] 袁思敏, 王路君, 朱 斌, 等. 考虑固相分解的含水合物沉积物体积应变分析模型[J]. 岩土工程学报,2022,44(6):1044-1052. [17] 颜荣涛, 梁维云, 韦昌富, 等. 考虑赋存模式影响的含水合物沉积物的本构模型研究[J]. 岩土力学,2017,38(1):10-18. [18] DAI J, BANIK N, GILLESPIE D, et al. Exploration for gas hydrates in the deepwater, northern Gulf of Mexico: Part II. Model validation by drilling[J]. Marine & Petroleum Geology, 2008, 25(9): 845-859. [19] 李栋梁, 王 哲, 吴 起, 等. 天然气水合物储层力学特性研究进展[J]. 新能源进展,2019,7(1):40-49. [20] MASUI A, HANEDA H, OGATA Y, et al. The effect of saturation degree of methane hydrate on the shear strength of synthetic methane hydrate sediments[C]//Proceedings of the 5th International Conference on Gas Hydrates. Trondheim: Tapir Academic Press: 2005. [21] JIANG M J, ZHU F Y, LIU F, et al. A bond contact model for methane hydrate-bearing sediments with interparticle cementation[J]. International Journal for Numerical & Analytical Methods in Geomechanics,2015,38(17):1823-1854. [22] 刘 林. 粘土和粒状土统一的UH模型[D]. 北京: 北京航空航天大学, 2018. [23] YAO Y P, LIU L, LUO T, et al. Unified hardening (UH) model for clays and sands[J]. Computers and Geotechnics,2019,110:326-343. doi: 10.1016/j.compgeo.2019.02.024 [24] MIYAZAKI K, SAKAMOTO Y, KAKUMOTO M , et al. Triaxial Compressive Properties of Artificial Methane-Hydrate-Bearing Sediments Containing Fine Fraction[J]. Journal of MMIJ, 2011, 127:565-576. [25] 刘锐明. 基于统一硬化参数的深海能源土本构模型及其ABAQUS二次开发[D]. 青岛: 青岛理工大学, 2019. [26] 刘 林, 姚仰平, 张旭辉, 等. 含水合物沉积物的弹塑性本构模型[J]. 力学学报,2020,52(2):556-566. doi: 10.6052/0459-1879-19-184 [27] 刘 芳, 寇晓勇, 蒋明镜, 等. 含水合物沉积物强度特性的三轴试验研究[J]. 岩土工程学报,2013,35(8):1565-1572. [28] 刘帅帅, 柳艳华, 李丹梅. 土结构性本构模型研究综述[J]. 河南城建学院学报, 2017, 26(6): 1-6. [29] 蒋明镜, 周 卫, 刘静德, 等. 基于微观力学机制的各向异性结构性砂土的本构模型研究[J]. 岩土力学,2016,37(12):3347-3355. [30] 蒋明镜, 刘 俊, 周 卫, 等. 一个深海能源土弹塑性本构模型[J]. 岩土力学,2018,39(4):1153-1158 . [31] 赵亚鹏, 刘乐乐, 孔 亮, 等. 黏质及砂质能源土统一的弹塑性本构模型[J]. 岩石力学与工程学报,2022,41(12):2579-2591.