| 太行山东麓北拒马河冲积扇结构探测及地震砂土液化判别 |
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| 引用本文：刘莎莎,丰成君,谭成轩,邓亚虹,戚帮申,孟静,张鹏,宋焱勋,慕焕东,周永恒.2022.太行山东麓北拒马河冲积扇结构探测及地震砂土液化判别[J].地球学报,43(1):82-92. |
| DOI：10.3975/cagsb.2021.091403 |
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| 基金项目:中国地质调查局地质调查项目“通州—石家庄活动构造带区域地质调查”(编号: DD20190317);国家自然科学基金项目(编号: 41772275) |
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| 中文摘要:北拒马河冲积扇及邻近地区位于太行山东麓, 地表覆盖全新世(Qh)松散砂土与粉土, 该区域地下水埋深较浅, 潜在地震最大震级达6.5级, 在地震作用下存在发生砂土液化危险性。通过野外地质调查、工程地质钻探和高密度电阻率法勘探揭示北拒马河冲积扇地层结构特征。在此基础上, 采用原位标准贯入试验和室内动三轴试验评价北拒马河冲积扇饱和砂土和粉土的液化危险性。结果表明: (1)北拒马河冲积扇由三组沉积旋回组成: 第一组为分布于北拒马河南支古河道内的全新世河流相砂、砂砾石、砾石层; 第二组为埋深15 m左右的晚更新世—全新世冲洪积相沉积层, 上部为亚砂土, 下部为细、粉砂; 第三组为埋深 15 m以下的晚更新世洪积相沉积层, 上部为淤泥质亚黏土, 中部为亚砂土、细粉砂, 下部为卵砾石层。 (2)北拒马河冲积扇饱和砂土与粉土存在液化危险性, 由标贯法液化判别结果可知, 冲积扇南缘砂土液化等级为轻微, 冲积扇东缘靠近涿州市区砂土液化等级为中等。(3)北拒马河冲积扇砂土的液化风险随震级与地震烈度增大而增大, 在近场6.5级地震作用下产生Ⅶ、Ⅷ度地震烈度时, 北拒马河冲积扇会发生砂土液化 |
| 中文关键词:饱和砂土 砂土液化危险性 动三轴试验 标准贯入试验 抗液化剪应力法 |
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| Structural Exploration and Seismic Sand Liquefaction Assessment of North Juma River Alluvial Fan in the Eastern Piedmont of Taihang Mountains |
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| Abstract:The North Juma River alluvial fan and its adjacent areas are located at the eastern piedmont of Taihang Mountains. The surface of this area is covered by Holocene loose sand and silt, and the groundwater depth is relatively shallow. This area is susceptible to earthquake with a maximum magnitude of 6.5. Sand liquefaction may occur due to an earthquake. Field geological survey, engineering geological drilling, and high-density resistivity methods are used to explore the stratigraphic structure characteristics of North Juma River alluvial fan. Accordingly, the liquefaction risk of saturated sand and silt in the North Juma River alluvial fan is assessed using in-situ standard penetration test and indoor dynamic triaxial test. Based on the findings of research: (1) The alluvial fan of the North Juma River is composed of three groups of sedimentary cycles: The first group is Holocene fluvial sand, sand gravel, and gravel stratum distributed in the paleochannel of the southern branch of the North Juma River; The second group is the Late Pleistocene to Holocene alluvial-proluvial facies sedimentary stratum with a buried depth of about 15 m. The upper part of the alluvial-proluvial facies sedimentary stratum is comprised of sub-sand while the lower part is comprised of fine, silt sand; The third group is the late Pleistocene proluvial facies sedimentary stratum with a buried depth of more than 15 m. The upper part of the proluvial facies sedimentary stratum is comprised of silty loam, the middle part is comprised of sandy soil and fine silt, and the lower part is comprised of pebbles. (2) There is a liquefaction risk of saturated sand and silty sand in North Juma River alluvial fan. Based on the liquefaction evaluation results of the standard penetration method, the sand liquefaction level on the southern margin of the alluvial fan is slight, and the eastern margin of the alluvial fan near Zhuozhou City is medium. (3) The liquefaction risk of sand in the alluvial fan of North Juma River increases with an increase in earthquake magnitude and intensity. When the earthquake intensity of Ⅶ and Ⅷ occurs due to a near-field earthquake of M6.5, sand liquefaction will occur in the alluvial fan of North Juma River. |
| keywords:saturated sand liquefaction risk of sand dynamic triaxial test standard penetration test anti-liquefaction shear stress method |
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