波浪导致黄河口海床沉积物超孔压响应现场试验研究
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摘要
黄河口海床特殊的工程地质性质与复杂的工程动力稳定性问题,均与海床沉积物在波浪荷载作用下的孔压动力响应密切相关。在现代黄河水下三角洲潮间带岸滩选择4个典型研究点,现场模拟波浪作用对原状海床沉积物实施循环加载,利用孔隙水压力观测、沉积物强度测试、样品采集与实验室土工测试等方法手段,测定黄河口原状海床沉积物在循环荷载作用不同阶段的孔压响应与强度变化。研究发现,黄河口原状海床沉积物在经历循环加载过程中,典型的超孔压响应可分为逐渐累积、部分消散、快速累积、累积液化和完全消散5个阶段,分别对应沉积物强度的衰减、增大、衰减、丧失和恢复过程,沉积物的粒度组成与结构性强弱决定了超孔压的具体响应模式。波浪导致原状海床液化深度受沉积物的干密度、孔隙比、饱和度等初始物理性质影响显著,细颗粒组分的相对含量高低也在很大程度上控制着沉积物的液化特性。
Both the special engineering geological properties and the complex engineering dynamic stability problems are closely related to the wave-induced dynamic response of pore pressure in seabed sediment in the Yellow River estuary. Four typical sites on the intertidal flats of the Yellow River delta are selected to simulate the wave action on the intact seabed sediments. Various testing methods, such as pore water piezometer test, field sediment strength test and sampling/laboratory geotechnical experiments, are employed to determine the variations in pore pressure and strength of the undisturbed seabed sediments at different stages under the cyclic loading. It is shown that during the cyclic loading process, the excess pore pressure response of undisturbed seabed sediment can be separated into 5 stages including gradual accumulation, partial dissipation, rapid accumulation, accumulated liquefaction and complete dissipation, which correspond to five processes of sediment strength variation including attenuation, increase, attenuation, loss and recovery, respectively. The grain size composition and structural strength dominate the excess pore pressure response. The wave-induced liquefied depth of intact seabed sediment is significantly affected by the initial physical properties such as dry density, void ratio, saturation degree, etc. To a large extent, the relative amount of fine grained components also controls the liquefaction characteristics of sediment in the Yellow River estuary.
Both the special engineering geological properties and the complex engineering dynamic stability problems are closely related to the wave-induced dynamic response of pore pressure in seabed sediment in the Yellow River estuary. Four typical sites on the intertidal flats of the Yellow River delta are selected to simulate the wave action on the intact seabed sediments. Various testing methods, such as pore water piezometer test, field sediment strength test and sampling/laboratory geotechnical experiments, are employed to determine the variations in pore pressure and strength of the undisturbed seabed sediments at different stages under the cyclic loading. It is shown that during the cyclic loading process, the excess pore pressure response of undisturbed seabed sediment can be separated into 5 stages including gradual accumulation, partial dissipation, rapid accumulation, accumulated liquefaction and complete dissipation, which correspond to five processes of sediment strength variation including attenuation, increase, attenuation, loss and recovery, respectively. The grain size composition and structural strength dominate the excess pore pressure response. The wave-induced liquefied depth of intact seabed sediment is significantly affected by the initial physical properties such as dry density, void ratio, saturation degree, etc. To a large extent, the relative amount of fine grained components also controls the liquefaction characteristics of sediment in the Yellow River estuary.
引文
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[20]TSAI C P.Wave-induced liquefaction potential in a porous seabed in front of a breakwater[J].Ocean Engineering,1995,22:1-18.
[21]JENG D S.Wave-induced seabed instability in front of a breakwater[J].Ocean Engineering,1997,24(10):887-917.
[22]许国辉,刘会欣,刘锦昆,等.黏粒含量对粉质土液化发生的作用机制[J].海洋地质与第四纪地质,2012,32(3):31-35.XU Guo-hui,LIU Hui-xin,LIU Jin-kun,et al.Role of clay content in silty soil liquefaction[J].Marine Geology&Quaternary Geology,2012,32(3):31-35.
[23]TZANG S,OU S.Laboratory flume studies on monochromatic wave-fine sandy bed interactions:Part 1.Soil fluidization[J].Coastal Engineering,2006,53(11):956-982.
[24]NAM S,GUTIERREZ M,DIPLAS P.Channeling during settling and self-weight consolidation of cohesive sediments[J].Canadian Geotechnical Journal,2008,45(6):867-876.
[2]KELLER G H,ZHEN J,YANG Z S,et al.Mass physical properties of Huanghe delta and southern Bohai sea near-surface deposits,China[J].Marine Geotechnology,1990,9(3):207-225.
[3]贾永刚,单红仙,杨秀娟,等.黄河口沉积物动力学与地质灾害[M].北京:科学出版社,2011.JIA Yong-gang,SHAN Hong-xian,YANG Xiu-juan,et al.Sediment dynamics and geologic hazards in the estuary of Yellow River,China[M].Beijing:Science Press,2011.
[4]冯秀丽,林霖,庄振业,等.现代黄河水下三角洲全新世以来土层岩土工程参数与沉积环境之间的关系[J].海岸工程,1999,18(4):1-7.FENG Xiu-li,LIN Lin,ZHUANG Zhen-ye,et al.The relationship between geotechnical parameters and sedimentary environment of soil layers since Holocene in modern Huanghe subaqueous delta[J].Coastal Engineering,1999,18(4):1-7.
[5]常方强,贾永刚,张建,等.黄河水下三角洲硬壳层特征及其液化过程研究[J].工程地质学报,2009,17(3):349-356.CHANG Fang-qiang,JIA Yong-gang,ZHANG Jian,et al.Soil property and liquefaction process of hard shell seams at subaqueous delta of Yellow River[J].Journal of Engineering Geology,2009,17(3):349-356.
[6]LU N Z,SUHAYDA J N,PRIOR D B,et al.Sediment thixotropy and submarine mass movement,Huanghe delta,China[J].Geo-Marine Letters,1991,11(1):9-15.
[7]冯秀丽,戚洪帅,王腾,等.黄河三角洲埕岛海域地貌演化及其地质灾害分析[J].岩土力学,2004,25(增刊):17-20.FENG Xiu-li,QI Hong-shuai,WANG Teng,et al.Geomorphological evolution and geological disasters analysis in Chengdao sea area of the Yellow River Delta[J].Rock and Soil Mechanics,2004,25(Supp.):17-20.
[8]孙永福,董立峰,宋玉鹏.黄河水下三角洲粉质土扰动土层特征及成因探析[J].岩土力学,2008,29(6):1494-1499.SUN Yong-fu,DONG Li-feng,SONG Yu-peng.Analysis of characteristics and formation of disturbed soil on subaqueous delta of Yellow River[J].Rock and Soil Mechanics,2008,29(6):1494-1499.
[9]冯玉岩,郭秀军,孟庆生,等.黄河口粉土层振动响应过程的电性变化[J].岩石力学与工程学报,2007,26(1):3271-3276.FENG Yu-yan,GUO Xiu-jun,MENG Qing-sheng,et al.Electrical characteristics variation of silty soil strata during vibration response process in Yellow River Estuary[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(1):3271-3276.
[10]冯秀丽,叶银灿,马艳霞,等.动荷载作用下海底粉土的孔压响应及其动强度[J].青岛海洋大学学报,2002,32(3):431-435.FENG Xiu-li,YE Yin-can,MA Yan-xia,et al.Silt pore pressure response and dynamic strength under dynamic loading[J].Journal of Ocean University of Qingdao,2002,32(3):431-435.
[11]张民生,刘红军,李晓东,等.波浪作用下黄河口粉土液化与“铁板砂”形成机制的模拟试验研究[J].岩土力学,2009,30(11):3347-3351.ZHANG Min-sheng,LIU Hong-jun,LI Xiao-dong,et al.Study of liquefaction of silty soil and mechanism of development of hard layer under wave actions at Yellow River Estuary[J].Rock and Soil Mechanics,2009,30(11):3347-3351.
[12]单红仙,段兆臣,刘正银,等.粉质土重复振动液化与效果研究[J].水利学报,2006,37(1):75-81.SHAN Hong-xian,DUAN Zhao-chen,LIU Zheng-yin,et al.Repeated liquefaction and the effect on properties of silt[J].Journal of Hydraulic Engineering,2006,37(1):75-81.
[13]常方强,贾永刚.黄河口粉质土海床液化过程的现场试验研究[J].土木工程学报,2012,45(1):121-126.CHANG Fang-qiang,JIA Yong-gang.In-situ test to study silt liquefaction at the subaqueous delta of Yellow River[J].China Civil Engineering Journal,2012,45(1):121-126.
[14]郑杰文,贾永刚,刘晓磊,等.黄河三角洲沉积物抗侵蚀性动态变化差异研究[J].岩土力学,2011,32(增刊1):290-296.ZHENG Jie-wen,JIA Yong-gang,LIU Xiao-lei,et al.Discrepancy of sediment erodibility variation under waves at Yellow River delta[J].Rock and Soil Mechanics,2011,30(Supp.1):290-296.
[15]MENG X,JIA Y,SHAN H,et al.An experimental study on erodibility of intertidal sediments in the Yellow River delta[J].International Journal of Sediment Research,2012,27(2):240-249.
[16]FINN W D L,SIDDHARTHAN R,MARTIN G R.Response of seafloor to ocean waves[J].Journal ofGeotechnical Engineering,1983,109(4):556-572.
[17]马海鹏,陈祖煜,于沭.上海地区土体抗剪强度与静力触探比贯入阻力相关关系研究[J].岩土力学,2014,35(2):536-542.MA Hai-peng,CHEN Zu-yu,YU Shu.Correlations of soil shear strength with specific penetration resistance of CPT in Shanghai area[J].Rock and Soil Mechanics,2014,35(2):536-542.
[18]中华人民共和国水利部.GB/T 50123-1999土工试验方法标准[S].北京:中国计划出版社,2007.The Ministry of Water Resources of the People's Republic of China.GB/T 50123-1999 Standard for soil test method[S].Beijing:China Planning Press,2007.
[19]栾茂田,张晨明,王栋,等.波浪作用下海床孔隙水压力发展过程与液化的数值分析[J].水利学报,2004,(2):94-100.LUAN Mao-tian,ZHANG Chen-ming,WANG Dong,et al.Numerical analysis of residual pore water pressure development and evaluation of liquefaction potential of seabed under wave loading[J].Journal of Hydraulic Engineering,2004,(2):94-100.
[20]TSAI C P.Wave-induced liquefaction potential in a porous seabed in front of a breakwater[J].Ocean Engineering,1995,22:1-18.
[21]JENG D S.Wave-induced seabed instability in front of a breakwater[J].Ocean Engineering,1997,24(10):887-917.
[22]许国辉,刘会欣,刘锦昆,等.黏粒含量对粉质土液化发生的作用机制[J].海洋地质与第四纪地质,2012,32(3):31-35.XU Guo-hui,LIU Hui-xin,LIU Jin-kun,et al.Role of clay content in silty soil liquefaction[J].Marine Geology&Quaternary Geology,2012,32(3):31-35.
[23]TZANG S,OU S.Laboratory flume studies on monochromatic wave-fine sandy bed interactions:Part 1.Soil fluidization[J].Coastal Engineering,2006,53(11):956-982.
[24]NAM S,GUTIERREZ M,DIPLAS P.Channeling during settling and self-weight consolidation of cohesive sediments[J].Canadian Geotechnical Journal,2008,45(6):867-876.