Effect of soil layer structure with fluvial sedimentary facies on sand liquefaction
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摘要: 目前相关规范主要依据工程场地单点的测试数据进行砂土液化判别，而实际的三维土层结构可能非常复杂。研究土层结构对砂土液化的影响机制，有利于提高砂土液化判别结果准确度。分析2008 年5 月28 日发生的松原MS地震和2010—2011 年新西兰坎特伯雷地震序列中砂土液化点的分布，结果显示：砂土液化点主要位于高弯度河流的沉积相地层，凹岸侧蚀、凸岸沉积形成的边滩具有典型的二元结构，其顶部分布的黏土类不透水层有利于下伏饱和粉细砂等易液化土层的超孔隙水压累积；而辫状河流沉积相中，上覆黏土类不透水层间断分布特征明显。针对河流不同沉积相的土层结构建立简化场地模型，使用FLAC3D 进行砂土液化数值模拟，揭示出不同土层结构中超孔隙水压力的累积、消散和渗流过程机制，结果表明，河流沉积相土层结构对砂土液化场点的分布和地表变形具有显著影响。在合理的工程地质分区基础上，现有的液化判别方法有必要考虑场地的土层结构的影响。Abstract: The sand liquefaction potential is evaluated with the in-situ test data of one single borehole in the relative codes, however, the real three-dimensional structure of the engineering site is very complex. It is helpful to increase the accuracy of the sand liquefaction evaluation by studying the effect of the soil layer structure on the liquefaction. By analyzing the distribution of the sites of the sand liquefaction manifestation caused in Songyuan MS5.7 earthquake on the 28 May, 2008 and the 2010−2011 Canterbury earthquake sequence, it is discovered that most of the sites are located on the inside bend of the meandering river. The dualstructure exists in the point bar formed by the lateral erosion of the outside bend and the deposition of the inside bend. The impermeable（including weakly permeable） clay layer is covered on top of the saturated fine sand, which is easy to cause the accumulation of the excess pore pressure. The discontinuous distribution of the impermeable clay layer is obvious in the braided fluvial facies. The simplified model is built for soil layer structures with the different fluvial sedimentary facies. The FLAC3D software is used to study the mechanism of the accumulation and dissipation of the pore pressure, and the seepage flow process. The distribution of sand liquefaction manifestation and the ground surface deformation is highly affected by the the soil layer structure with the fluvial sedimentary facies. It is necessary to consider the influence of the soil layer structure in the sand liquefaction evaluation methods on the basis of engineering geological zoning.
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图 10 不同土层结构模型的砂土液化引起的地表位移变形
（a） 黏土层连续分布；（b） 黏土层2 m间断分布；（c） 黏土层6 m间断分布；（d） 黏土层10 m间断分布；（e） 黏土层部分分布；（f） 互层黏土层6 m间断分布
Figure 10. surface deformation due to sand liquefaction in different soil layer structure models
（a） Continuous clay layer；（b） Clay layer with 2 m gap；（c） Clay layer with 6 m gap；（d） Clay layer with 10 m gap；（e） Clay layer with partial distribution；（f） Clay layer with 6 m gap of interlayer clay layer
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图 1 高弯度河流沉积三维空间结构形式（引自Burns等，2017）
Figure 1. Three-dimensional spatial structure of meandering river deposit （after Burns et al，2017）
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图 3 松原地震砂土液化点分布
Figure 3. Distribution of sand liquefaction points in Songyuan earthquake
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图 4 高弯度河流边滩的形成机理（引自Allen，1970）
Figure 4. Formation mechanism of high bend river bank （ after Allen，1970）
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图 5 Canterbury 地震序列引起的砂土液化点分布（引自Bucci et al，2018）
Figure 5. Distribution of liquefaction points of sand in Canterbury earthquake sequence （after Bucci et al，2018）
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图 6 2011年2月基督城地震引起的Palinurus 路边场地液化现象（引自Brady，2017）
Figure 6. Liquefaction of Palinurus roadside site caused by the Christchurch earthquake in February 2011 （after Brady，2017）
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图 7 基于静力触探数据绘制的Palinurus路场地AA′剖面（引自Brady，2017）
Ic为特性指数；qc为锥尖阻力；FS为侧壁阻力
Figure 7. AA′ section of Palinurus road site based on static cone penetration data （after Brady，2017）
Ic is index of classification；qc is cone tip resistance；FS is frictional resistance
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图 8 砂土液化数值计算模型选取的地震动时程
Figure 8. Time-history of ground motion selected by numerical calculation model of sand liquefaction
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图 9 不同土层结构模型（左）及其砂土液化超孔隙水压力的扩散过程（右）
（a） 黏土层连续分布；（b） 黏土层2 m间断；（c） 黏土层6 m间断
Figure 9. The different site models （left） and the corresponding seepage paths of pore pressure （right）
（a） Continuous clay layer；（b） Clay layer with 2 m gap；（c） Clay layer with 6 m gap
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图 9 不同土层结构模型（左）及其砂土液化超孔隙水压力的扩散过程（右）
（d） 黏土层10 m间断；（e） 黏土层部分分布；（f） 互层黏土层6 m间断的模型
Figure 9. The different site models （left） and the corresponding seepage path of pore pressure （right）
（d） Clay layer with 10 m gap；（e） Clay layer with discontinuous cap；（f） Interbedding clay layer with 6 m gap
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图 11 黏土层2 m间断的模型单元监测点编号
Figure 11. Series number of observing zones in the model with 2 m gap of clay layer
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图 12 黏土层2 m间断分布模型中不同监测单元的孔隙水压力（a—c）和加速度（d）曲线
Figure 12. The observation value of pore pressure （a−c） and acceleration （d） in model with 2 m gap of clay layer
表 1 模型中土体材料的物理力学参数
Table 1 Material parameters for the soil deposit in the model
土体类型 摩擦角φ/° 内聚力C/kPa 剪胀角Ψ/° 渗透系数K/（m2·Pa−1·s） 体积模量K/Pa 剪切模量G/Pa 粉细砂 32 0 0 6×10−9 3×107 1×107 黏土 28 90 0 5×10−13 3×106 1×106 
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杜修力,路德春. 2011. 土动力学与岩土地震工程研究进展[J]. 岩土力学,32(增刊2):10–20. Du X L,Lu D C. 2011. Research progress in soil dynamics and geotechnical seismic engineering[J]. Rock and Soil Mechanics,32(S2):10–20 (in Chinese).
陈育民,刘汉龙,周云东. 2006. 液化及液化后砂土的流动特性分析[J]. 岩土工程学报,28(9):1139–1143. doi: 10.3321/j.issn:1000-4548.2006.09.017 Chen Y M,Liu H L,Zhou Y D. 2006. Analysis on flow characteristics of liquefied and post-liquefied sand[J]. Chinese Journal of Geotechnical Engineering,28(9):1139–1143 (in Chinese).
陈育民,刘汉龙,邵国建,赵楠. 2009. 砂土液化及液化后流动特性试验研究[J]. 岩土工程学报,31(9):1408–1413. doi: 10.3321/j.issn:1000-4548.2009.09.014 Chen Y M,Liu H L,Shao G J,Zhao N. 2009. Laboratory tests on flow characteristics of liquefied and post-liquefied sand[J]. Chinese Journal of Geotechnical Engineering,31(9):1408–1413 (in Chinese).
李平,田兆阳,薄景山,李孝波,张宇东,辜俊儒,周春澍. 2019. 松原5.7级地震砂土液化研究[J]. 土木工程学报,52(9):91–99. Li P,Tian Z Y,Bo J S,Li X B,Zhang Y D,Gu J R,Zhou C S. 2019. Study on sand liquefaction of the magnitude-5.7 Songyuan earthquake[J]. China Civil Engineering Journal,52(9):91–99 (in Chinese).
王维铭. 2013. 场地液化特征研究及液化影响因素评价[D]. 哈尔滨: 中国地震局工程力学研究所: 8. Wang W M. 2013. Study on Liquefaction Characteristics and Liquefaction-Influencing Factors Assessment[D]. Harbin: Institute of Engineering Mechanics, China Earthquake Administration: 8 （in Chinese）.
章守恭,李玉蓉. 1980. 砂坡液化稳定问题的动三轴液化试验研究[J]. 岩土工程学报,2(3):74–81. doi: 10.3321/j.issn:1000-4548.1980.03.009 Zhang S G,Li Y R. 1980. A study of the sand bank stability in liquefying tests with the dynamic Tri-axial apparatus[J]. Chinese Journal of Geotechnical Engineering,2(3):74–81 (in Chinese).
董道涛. 2021. 小河弯弯何处寻[J]. 中国三峡,(7):114–117. doi: 10.3969/j.issn.1006-6349.2021.07.010 Dong D T. 2021. Where to find the bend of the river[J]. Three Gorges of China,(7):114–117 (in Chinese).
Allen J R L. 1970. Studies in fluviatile sedimentation:A comparison of fining-upwards cyclothems,with special reference to coarse-member composition and interpretation[J]. J Sediment Res,40(1):298–323.
Brady R C. 2017. Puzzling patterns of liquefaction manifestation （or lack thereof） following the 2011 Christchurch earthquake[R]//U.S.-New Zealand-Japan International Workshop, Liquefaction-Induced Ground Movement Effects. Bekeley: University of California.
Bray J D,Macedo J. 2017. 6th Ishihara lecture:Simplified procedure for estimating liquefaction-induced building settlement[J]. Soil Dynam Earthq Engg,102:215–231. doi: 10.1016/j.soildyn.2017.08.026
Bucci M G,Villamor P,Almond P,Tuttle M,Stringer M,Ries W,Smith C,Hodge M,Watson M. 2018. Associations between sediment architecture and liquefaction susceptibility in fluvial settings:The 2010−2011 Canterbury earthquake sequence,New Zealand[J]. Eng Geol,237:181–197. doi: 10.1016/j.enggeo.2018.01.013
C. Burns C E,Mountney N P,Hodgson D M,Colombera L 2017. Anatomy and dimensions of fluvial crevasse-splay deposits:Examples from the Cretaceous Castlegate Sandstone and Neslen Formation,Utah,USA.[J]. Sediment Geol,351:21–35. doi: 10.1016/j.sedgeo.2017.02.003
Sasaki Y,Towhata I,Tokida K I,Yamada K,Matsumoto H,Tamari Y,Saya S. 1992. Mechanism of permanent displacement of ground caused by seismic liquefaction[J]. Soils Foundat,32(3):79–96. doi: 10.3208/sandf1972.32.3_79
Soroush A, Koohi S. 2004. Numerical analysis of liquefaction-induced lateral spreading[C]//13th World Conference on Earthquake Engineering. Vancouver B C: 2123.
Thevanayagam S. 2001. Role of intergranular contacts on the mechanisms causing liquefaction and slope failures in silty sands[C]//Annual Project Summary Report. Washington D C: US Geological Survey, Department of Interior.
Wotherspoon L M,Orense R P,Green R A,Bradley B A,Cox B R,Woode C M. 2015. Assessment of liquefaction evaluation procedures and severity index frameworks at Christchurch strong motion stations[J]. Soil Dynam Earthq Eng,79:335–346. doi: 10.1016/j.soildyn.2015.03.022
Zhang G,Robertson P K,Brachman R W I. 2002. Estimating liquefaction-induced ground settlements from CPT for level ground[J]. Canad Geotechn J,39(5):1168–1180. doi: 10.1139/t02-047
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