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摘要:
海底边坡失稳会给人类造成巨大危害，部分海底边坡失稳案例被证实与水合物分解有关。由于海底条件的复杂性，人们很难直接观察水合物分解引起的海底边坡失稳过程。数值模拟可以相对准确地预测水合物分解可能引起的海底边坡失稳状况。通过选用基于ABAQUS软件的有限元强度折减法，模拟海底边坡失稳的过程并得到相应结果，分析了水合物分解程度、水合物带上覆厚度、边坡角度等因素对海底边坡稳定性的影响。结果表明，正常情况下，塑性区首先在坡脚区域出现并逐渐向上发展至坡顶；当水合物分解达到一定程度后，塑性区首先出现在水合物带，随后自水合物带向上发展至坡顶，并和随后在坡脚出现的塑性区形成贯通边坡的塑性带。水合物埋藏越深，越有可能造成大规模的滑坡；边坡角度高于15°时，水合物分解会急剧促进边坡失稳。
Abstract:Hydrate dissociation is a significant factor causing submarine slope slide, which is dangerous to human operation. Due to the complex condition of seabed, it is hard to observe the process of slope slide directly. Numerical simulation is an effective approach to acquire some important parameters such as the slide area, slide scale, sliding distance and safety factors etc. Choosing shear strength reduction technique of the finite element based on the software of ABAQUS, we could not only simulate both the process and result of a slope slide, but also evaluate the influence of hydrate dissociation. By changing the parameters of modeling, the characteristics of seafloor can be considered. Of course, the inducing factor is the interaction between the structure of slope and hydrate dissociation. It can guide the hydrate exploitation process and avoid some possible problems by integration of the theoretical and simulation results.
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物理量 数值 单位 c1 293 kPa c2 1960 kPa c3 1.7 σ′3 1962 kPa σ′t 382 kPa δ1 0.4 δ2 0.2 δ3 0.22 δ4 0.04 e 2.72 e1 548000 kPa e2 265800 kPa e3 450000 kPa γ 
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表 2 神狐海域水合物地层勘探数据及数值模型选用数据(据文献[1, 19, 35, 42])
Table 2. Exploration data and numerical model selected data for hydrate formations in the Shenhu area
参数 神狐海域勘探数据 模型选用数据 水深/m 500~2000 1300~1650 水合物埋深/m 7~350 50~150 海底坡脚/(°) 最高达30 10~25 颗粒密度/(g/cm3) 2.695~2.716 2.700 海水密度/(g/cm3) 1.040 1.040 水合物密度/(g/cm3) 0.980 0.980 水合物饱和度 0.45~0.92 0.8 沉积物孔隙度 0.27~0.63 0.4
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表 3 模型材料强度参数
Table 3. Strength parameters of numerical model
材料 内聚力
/kPa摩擦角
/(°)杨氏模量
/MPa密度
/(g/cm3)沉积层 291.2 18.6 56.3 2.200 水合物层分解程度 未分解 1562.9 26.0 206.0 1.844 分解30% 504.2 22.7 89.7 1.794 分解60% 308.6 19.4 41.2 1.745 分解80% 89.2 17.3 23.7 1.711 分解100% 35.4 15.2 10.28 1.688
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表 4 模拟方案设计
Table 4. Conceptual design of simulation
方案 方案描述 方案1 不含水合物层的均质海底边坡模型 方案2 含水合物且水合物未分解的海底边坡模型 方案3 1区分解30%，其他区域未分解 方案4 1区分解60%，2区分解30%，其他区域未分解 方案5 1区分解80%，2区分解60%，3区分解30%，4区未分解 方案6 1区分解100%，2区分解80%，3区分解60%，4区分解30% 方案7 1、2区分解100%，3、4区分解80%
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表 5 水合物层不同上覆厚度下计算方案
Table 5. Numerical procedure under different overlay thickness of hydrate
计算模型 上覆沉积层厚度/m 水合物分解程度 模型1 50 未分解 1区域分解100%，2区域分解80%，3区域分解60%，4区域分解30% 模型2 80 模型3 120 模型4 150
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表 6 不同边坡角度的模型计算方案
Table 6. Numerical procedure with different slope angel
计算模型 边坡角度/(°) 水合物分解程度 模型5 10 未分解 1区域分解100%，2区域分解80%，3区域分解60%，4区域分解30% 模型6 15 模型7 20 模型8 25
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[1] 何静, 刘学伟, 杨萌萌, 等.海底未固结成岩地层体积密度的估算方法[J].海洋地质与第四纪地质, 2011, 31(5):155-161. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=9aec573c-4ced-4d05-87be-ec13233b406e
HE Jing, LIU Xuewei, YANG Mengmeng, et al. Estimate bulk density of unconsolidated sea-bottom sediments[J]. Marine Geology & Quaternary Geology, 2011, 31(5):155-161. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=9aec573c-4ced-4d05-87be-ec13233b406e
[2] 胡高伟, 李彦龙, 吴能友, 等.神狐海域W18/19站位天然气水合物上覆层不排水抗剪强度预测[J].海洋地质与第四纪地质, 2017, 37(5):151-158. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=3ffe2a0c-682f-445c-b9ff-399376219619
HU Gaowei, LI Yanlong, WU Nengyou, et al. Undrained shear strength estimation of the cover layer of hydrate at site W18/19 of Shenhu area[J]. Marine Geology & Quaternary Geology, 2017, 37(5):151-158. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=3ffe2a0c-682f-445c-b9ff-399376219619
[3] 叶黎明, 罗鹏, 杨克红.天然气水合物气候效应研究进展[J].地球科学进展, 2011, 26(5):565-574. http://d.old.wanfangdata.com.cn/Periodical/dqkxjz201105012
YE Liming, LUO Peng, YANG Kehong. Advances in climatic effects study of gas hydrates[J]. Advances in Earth Science, 2011, 26(5): 565-574. http://d.old.wanfangdata.com.cn/Periodical/dqkxjz201105012
[4] Kvenvolden K A. Gas hydrates—geological perspective and global change[J]. Reviews of Geophysics, 1993, 31(2):173-187. https://www.researchgate.net/publication/251431257_Gas_hydrates-Geological_perspective_and_global_change
[5] Kurihara M, Sato A, Ouchi H, et al. Prediction of gas productivity from eastern Nankai Trough methane hydrate reservoirs[C]//Offshore Technology Conference. Offshore Technology Conference, 2008.
[6] White M D, McGrail B P. A new numerical simulator for analysis of methane hydrate production from geologic formations[C]//Proceedings of 2nd International Symposium on Gas Hydrate Technology, 2006: 1-2.
[7] Moridis G J. A code for the simulation of system behavior in hydrate-bearing geologic media[J]. Stereochemical & Stereophysical Behaviour of Macrocycles, 2014, 10(2): Ⅳ.
[8] Moridis G J, Collett T S, Pooladi-Darvish M, et al. Challenges, uncertainties and issues facing gas production from gas hydrate deposits[J]. SPE Reservoir Evaluation & Engineering, 2011, 14(1):76-112. http://d.old.wanfangdata.com.cn/NSTLQK/NSTL_QKJJ0223144391/
[9] 朱超祁, 贾永刚, 刘晓磊, 等.海底滑坡分类及成因机制研究进展[J].海洋地质与第四纪地质, 2015, 35(6):145-155. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=886d250b-1f44-45ef-b85d-20279449219d
ZHU Chaoqi, JIA Yonggang, LIU Xiaolei, et al. Classification and genetic mechanism of submarine landslide: A review[J]. Marine Geology & Quaternary Geology, 2015, 35(6):145-155. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=886d250b-1f44-45ef-b85d-20279449219d
[10] 吴能友, 黄丽, 胡高伟, 等.海域天然气水合物开采的地质控制因素和科学挑战[J].海洋地质与第四纪地质, 2017, 37(5):1-11. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=7ac0922f-09a0-4694-a851-841b8fc0bf7f
WU Nengyou, HUANG Li, HU Gaowei, et al. Geological controlling factors and scientific challenges for offshore gas hydrate gas hydrate exploitation[J]. Marine Geology & Quaternary Geology, 2017, 37(5):1-11. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=7ac0922f-09a0-4694-a851-841b8fc0bf7f
[11] Li S, Xu X, Zheng R, et al. Experimental investigation on dissociation driving force of methane hydrate in porous media[J]. Fuel, 2015, 160:117-122. doi: 10.1016/j.fuel.2015.07.085
[12] Kamath V A. A perspective on gas production from hydrate[C]// The JNOC's Methane Hydrate International Symposium. Chiba City: Japan National Oil Corporation, 1998: 87-92.
[13] Gupta S, Deusner C, Haeckel M, et al. Testing a thermo-chemo-hydro-geomechanical model for gas hydrate-bearing sediments using triaxial compression laboratory experiments[J]. Geochemistry, Geophysics, Geosystems, 2015, 77(9):229-250. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=3f888c8f531f0528ca6ceaefa5ef7703
[14] Sultan N, Cochonat P, Foucher J P, et al. Effect of gas hydrates melting on seafloor slope instability[J]. Marine Geology, 2004, 213(1):379-401. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=95178084483c365060cb5925a823a9c3
[15] Gupta S, Wohlmuth B, Helmig R. Multi-rate time stepping schemes for hydro-geomechanical model for subsurface methane hydrate reservoirs[J]. Advances in Water Resources, 2016, 91: 78-87. doi: 10.1016/j.advwatres.2016.02.013
[16] Lu L, Zhang X H, Lu X B. Numerical study on the stratum's responses due to natural gas hydrate dissociation[J]. Ships and Offshore Structures, 2017, 12(6): 775-780. doi: 10.1080/17445302.2016.1241366
[17] 周丹.天然气水合物分解对海底结构物稳定性影响的研究[D].大连理工大学, 2012.
http://cdmd.cnki.com.cn/Article/CDMD-10141-1012394319.htm ZHOU Dan. Study on the influence of the seabed structure stability due to natural gas hydrate dissociation[D]. Dalian University of Technology, 2012.
[18] 杨晓云.天然气水合物与海底滑坡研究[D].中国石油大学, 2010.
http://cdmd.cnki.com.cn/Article/CDMD-10425-2010280307.htm YANG Xiaoyun. Study of gas hydrate and submarine landslide[D]. China University of Petroleum, 2010.
[19] 马云.南海北部陆坡区海底滑坡特征及触发机制研究[D].中国海洋大学, 2014.
http://cdmd.cnki.com.cn/Article/CDMD-10423-1014368509.htm MA Yun. Study of submarine landslides and trigger mechanism along the continental slope of the northern South China Sea[D]. Ocean University of China, 2014.
[20] 于桂林.考虑孔压影响的海底能源土斜坡稳定性分析[D].青岛理工大学, 2015.
http://cdmd.cnki.com.cn/Article/CDMD-10429-1016053926.htm YU Guilin. Stability analysis of submarine energy soil slope considering the influence of pore pressure[D]. Qingdao University of Technology, 2015.
[21] 张振飞.海底能源土斜坡稳定性影响因素的敏感性分析[D].青岛理工大学, 2016.
http://cdmd.cnki.com.cn/Article/CDMD-10429-1017017667.htm ZHANG Zhenfei. Sensitivity analysis of influencing factors on stability of submarine energy soil slope[D]. Qingdao University of Technology, 2016.
[22] 刘浩伽, 李彦龙, 刘昌岭, 等.水合物分解区地层砂粒启动运移临界流速计算模型[J].海洋地质与第四纪地质, 2017, 37(5):166-173. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=f66bd1b9-7b64-42c3-9c12-21afa94a75e6
LIU Haojia, LI Yanlong, LIU Changling, et al. Calculation model for critical velocity of sand movement in decomposed hydrate cemented sediment[J]. Marine Geology & Quaternary Geology, 2017, 37 (5):166-173. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=f66bd1b9-7b64-42c3-9c12-21afa94a75e6
[23] Winters W J, Waite W F, Mason D H. Strength and Acoustic Properties of Ottawa Sand Containing Laboratory-Formed Methane Gas Hydrate[M]//Advances in the Study of Gas Hydrates, Springer, Boston, MA, 2004: 213-226.
[24] 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:B04106. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=10.1029/2006JB004484
[25] Yun T S, Santamarina J C. Hydrate growth in granular materials: implication to hydrate bearing sediments[J]. Geosciences Journal, 2011, 15(3): 265. doi: 10.1007/s12303-011-0025-9
[26] Waite W F, Santamarina J C, Cortes D D, et al. Physical properties of hydrate-bearing sediments[J]. Reviews of Geophysics, 2009, 47(4), doi:10.1029/2008RG000279.
[27] Ghiassian H, Grozic J L H. Methane hydrate formation under controlled pressure in conventional triaxial apparatus[C]//Proceedings of the 63rd Canadian Geotechnical Conference, Calgary, Alberta. 2010: 12-16.
[28] Ghiassian H, Grozic J L H. Strength behavior of methane hydrate bearing sand in undrained triaxial testing[J]. Marine and Petroleum Geology, 2013, 43: 310-319. doi: 10.1016/j.marpetgeo.2013.01.007
[29] Winters W J, Waite W F, Mason D H, et al. Methane gas hydrate effect on sediment acoustic and strength properties[J]. Journal of Petroleum Science and Engineering, 2007, 56(1-3): 127-135. doi: 10.1016/j.petrol.2006.02.003
[30] Lin J S, Seol Y, Choi J H. Geomechanical modeling of hydrate-bearing sediments during dissociation under shear[J]. International Journal for Numerical and Analytical Methods in Geomechanics, 2017, 41(14): 1523-1538. doi: 10.1002/nag.v41.14
[31] You K, Flemings P B. Methane hydrate formation in thick sand reservoirs: 1. Short-range methane diffusion[J]. Marine and Petroleum Geology, 2018, 89: 428-442. doi: 10.1016/j.marpetgeo.2017.10.011
[32] Pinkert S, Grozic J L H. Prediction of the mechanical response of hydrate-bearing sands[J]. Journal of Geophysical Research: Solid Earth, 2014, 119(6): 4695-4707. doi: 10.1002/2013JB010920
[33] Pinkert S, Grozic J L H. An analytical-experimental investigation of gas hydrate-bearing sediment properties[C]//Canadian Geotechnical Conference and the 11th Joint CGS/IAHCNC Ground Water Conference, 2013.
[34] Miyazaki K, Masui A, Sakamoto Y, et al. Triaxial compressive properties of artificial methane-hydrate-bearing sediment[J]. Journal of Geophysical Research: Solid Earth, 2011, 116(B6). http://d.old.wanfangdata.com.cn/OAPaper/oai_doaj-articles_ee192397b0aa10dfd760be67479508ab
[35] 邬黛黛, 谢瑞, 杨睿, 等.南海北部神狐海域水合物钻探区沉积物地球化学特征[J].海洋地质与第四纪地质, 2017, 37(6):100-109. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=99ac3f58-cd4d-43ae-a179-d9c60a800929
WU Daidai, XIE Rui, YANG Rui, et al. Geochemistry of the sediments in Shenhu hydrate drilling area, South China Sea[J]. Marine Geology & Quaternary Geology, 2017, 37(6):100-109. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=99ac3f58-cd4d-43ae-a179-d9c60a800929
[36] 李广信.高等土力学[M].清华大学出版社有限公司, 2004.
LI Guangxin. Advanced Soil Mechanical[M]. Tsinghua University Press Co, Ltd, 2004.
[37] Coleman J M, Garrison L E. Geological aspects of marine slope stability, northwestern Gulf of Mexico[J]. Marine Georesources & Geotechnology, 1977, 2(1-4): 9-44. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=10.1080/10641197709379769
[38] Fredlund D G, Krahn J. Comparison of slope stability methods of analysis[J]. Canadian Geotechnical Journal, 1977, 14(3): 429-439. doi: 10.1139/t77-045
[39] Zienkiewicz O C, Humpheson C, Lewis R W. Discussion: Associated and non-associated visco-plasticity and plasticity in soil mechanics[J]. Geotechnique, 1977, 27(1): 101-102. doi: 10.1680/geot.1977.27.1.101
[40] 费康, 张建伟. ABAQUS在岩土工程中的应用[M].中国水利水电出版社, 2010.
FEI Kang, ZHANG Jianwei. Application of ABAQUS in Geotechnical Engineering[M]. China WaterPower Press, 2010.
[41] Kim A R, Kim H S, Cho G C, et al. Estimation of model parameters and properties for numerical simulation on geomechanical stability of gas hydrate production in the Ulleung Basin, East Sea, Korea[J]. Quaternary International, 2017, 459:55-68. doi: 10.1016/j.quaint.2017.09.028
[42] 杨涛, 叶鸿, 赖亦君.南海北部陆坡天然气水合物的沉积物孔隙水地球化学研究进展[J].海洋地质与第四纪地质, 2017, 37(5):48-58. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=86191583-ebd6-4ca4-bf79-024ff81d7dc7
YANG Tao, YE Hong, LAI Yijun. Pore water geochemistry of the gas hydrate bearing zone on northern slope of the South China Sea[J]. Marine Geology & Quaternary Geology, 2017, 37(5):48-58. http://hydz.chinajournal.net.cn/WKD/WebPublication/paperDigest.aspx?paperID=86191583-ebd6-4ca4-bf79-024ff81d7dc7
[43] Jin G, Xu T, Xin X, et al. Numerical evaluation of the methane production from unconfined gas hydrate-bearing sediment by thermal stimulation and depressurization in Shenhu area, South China Sea[J]. Journal of Natural Gas Science and Engineering, 2017, 33: 497-508. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=a6b711878e75d49e8580a0570ce09b98
[44] Jin G, Lei H, Xu T, et al. Simulated geomechanical responses to marine methane hydrate recovery using horizontal wells in the Shenhu area, South China Sea[J]. Marine and Petroleum Geology, 2017, 92: 424-436. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=39ffd28290d57dbfd43ba0fd91bb5060
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