为了得到不同有效围压和水合物饱和度对含水合物沉积物强度和刚度的影响规律,并得出相应数学表达式,以南海北部沉积物土样级配作为参考,配制人工泥质粉细砂,利用自主研发的含水合物沉积物三轴试验机,制备不同饱和度的含CO2水合物沉积物,在1, 2, 4 MPa有效围压下等向固结并进行三轴剪切试验。由于围压能自动根据气压的变化而变化,所以在水合物生成过程中有气体消耗但有效围压保持不变。试验结果表明:初始弹性模量随水合物饱和度的增加而增加,与有效围压无关;初始泊松比随着有效围压增加而减小,而随水合物饱和度的增加而增加;黏聚力随水合物饱和度的增加而增加,而内摩擦角与水合物饱和度无关。在邓肯-张模型的基础上,引入参数水合物饱和度,建立了含水合物沉积物的非线性弹性本构模型。最后,用试验数据对模型进行了验证,其结果符合较好。
Abstract
Triaxial shear tests were conducted on self-prepared hydrate-bearing sediments to obtain the influences of effective confining pressure and saturation on the strength and rigidness of hydrate-bearing sediments. The test specimens were made from artificial clayey fine sand in reference to the particle size distribution of sediment in the north part of South China Sea. CO2 hydrate-bearing sediments with different saturations were prepared by a self-developed triaxial test machine, and the triaxial shear tests were carried out under the effective confining pressure of 1 MPa, 2 MPa, and 4 MPa. As confining pressure changes automatically with gas pressure, the effective confining pressure remained unchanged during the formation of hydrate when gas was consumed. The experimental results reveal that the initial elastic modulus increased with the rising of hydrate saturation, while independent of the effective confining pressure. The initial Poisson ratio decreased with the increase of effective confining pressure while grew with the rising of hydrate saturation. The strength index cohesive force increased with the increase of hydrate saturation, while the internal friction angle was independent of hydrate saturation. In addition, the nonlinear elastic constitutive model for hydrate-bearing sediment was established by introducing a parameter hydrate saturation based on Duncan-Chang’s model, and the proposed model was validated by test data.
关键词
含水合物沉积物 /
泥质粉细砂 /
三轴试验 /
力学行为 /
本构模型
Key words
hydrate-bearing sediments /
clayey sand /
triaxial test /
mechanical behavior /
constitutive model
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] MAKOGO Y F. Natural Gas Hydrate:A Promising Source of Energy[J]. Journal of Petroleum Science and Engineering, 2010, 2(1): 49-59.
[2] ZHAO J F,YAO L,SONG Y C,et al. In situ Observations by Magnetic Resonance Imaging for Formation and Dissociation of Tetrahydrofuran Hydrate in Porous Media[J]. Magnetic Resonance Imaging,2011,29(2):281-287.
[3] MASLIN M, OWEN M, BETTS R, et al. Gas Hydrates: Past and Future Geohazard[J]. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2010,368(1919): 2369-2393.
[4] JIA Y G,Zhu C Q, LIU L P, et al. Marine Geohazards: Review and Future Perspective[J].Acta Geologica Sinica, 2016, 90(4): 1455-1470.
[5] WAITE W F, SANTAMARINA J C, CORTES D, et al. Physical Properties of Hydrate-bearing Sediment[J]. Advanced Earth and Space Science, 2009, 47(4):23-35.
[6] CHOI J H, DAI S, CHA J H, et al. Laboratory Formation of Non-cementing Hydrates in Sandy Sediments[J]. Geochemistry Geophysics Geosystems, 2014, 15(4): 232-245.
[7] YONEDA J, MASUI A, KONNO Y, et al. Mechanical Properties of Hydrate-bearing Turbidite Reservoir in the First Gas Production Test Site of the Eastern Nankai Trough[J]. Marine and Petroleum Geology, 2015, 66(2): 471-486.
[8] HYODO M, YONEDA J, YOSHIMATO N, et al. Mechanical and Dissociation Properties of Methane Hydrate-bearing Sand in Deep Seabed[J]. Soil and Foundation, 2013, 53(2): 299-314.
[9] 张旭辉, 王淑云, 李清平, 等. 天然气水合物沉积物力学性质的试验研究[J]. 岩土力学, 2010, 31(10): 3069-3074.
[10]CHOI J H, DAI S, LIN J S, et al. Multistage Triaxial Tests on Laboratory-formed Methane Hydrate-bearing Sediments[J]. Journal of Geophysical Research: Solid Earth, 2018, 123(5): 3347-3357.
[11]王淑云,鲁晓兵. 水合物沉积物力学性质的研究现状[J]. 力学进展,2009, 39(2): 176-188.
[12]刘昌岭, 孟庆国, 李承峰, 等.南海北部陆坡天然气水合物及其赋存沉积物特征[J]. 地学前缘, 2017, 24(4): 41-50.
[13]UCHIDA S, SOGA K, YAMAMOTO K. Critical State Soil Constitutive Model for Methane Hydrate Soil[J]. Journal of Geophysical Research: Solid Earth, 2012, 117(3): 3209-3221.
[14]YAN R T, WEI C F. Constitutive Model for Gas Hydrate-bearing Soils Considering Hydrate Occurrence Habits[J]. International Journal of Geomechanics, 2017, 17(8), doi: 10.1061/(ASCE)GM.1943-5622.0000914.
[15]SANCHEZ M, GAI X, SANTAMARINA J C. A Constitutive Model for Gas Hydrate-bearing Sediments Incorporating in Elastic Mechanisms[J]. Computers and Geotechnics, 2017, 84(8): 28-46.
[16]KIMOTO S, OKA F, FUSHITA T. A Chemo-thermo-mechanically Coupled Analysis of Ground Deformation Induced by Gas Hydrate Dissociation[J]. International Journal of Mechanical Science, 2010, 52(2): 365-376.
[17]NASHED O, SABIL K M, ISMAIL L, et al. Hydrate Equilibrium Measurement of Single CO2 and CH4 Hydrate Using Micro DSC[J]. Journal of Applied Sciences, 2014, 14(23): 3364-3368.
[18]KHLEHNIKOV V N, ANRONOVS S V, MISHIN A S, et al. A New Method for the Replacement of CH4 with CO2 in Natural Gas Hydrate Production[J]. Natural Gas Industry B, 2016, 3(5): 445-451.
[19]KOMATSU H, OTA M, SMITH R L, et al. Review of CO2-CH4 Clathrate Hydrate Replacement Reaction Laboratory Studies:Properties and Kinetics[J]. Journal of Taiwan Institute of Chemical Engineers, 2013, 44(4): 517-537.
[20]石要红, 张旭辉, 鲁晓兵, 等. 南海水合物黏土沉积物力学特性试验模拟研究[J]. 力学学报, 2015, 47(3): 521-528.
[21]DUNCAN J M, CHANG C Y. Nonlinear Analysis of Stress and Strain in Soils[J]. ASCE Soil Mechanics and Foundation Division Journal, 1970, 96(5): 1629-1653.
[22]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.
[23]KULHAWAY F H, DUNCAN J M. Stress and Movement in Oroville Dam[J]. Journal of the Soil Mechanics and Foundation Division, 1972, 98(7): 653-665.
基金
国家自然科学基金项目(41602312,41572293);国家专项海洋地质调查二级项目(DD20190231)
PDF(7451 KB)
