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    九江地区长江沿岸工程地质特征与岸坡稳定性探讨

    Engineering geological characteristics and bank slope stability in the Jiujiang region along the Yangtze River

    • 摘要: 通过野外地质调查、地球物理探测、工程地质钻探等手段,研究九江地区湖口—彭泽长江沿岸的地层结构、岩溶发育、岸坡工程地质特征与岸坡稳定性。长江边岸与圩堤均位于长江南岸Ⅰ级阶地,地表为第四系全新统冲积层,为一套河湖相沉积物,淤泥层厚,边岸与圩堤地基属软弱土层,工程承载力低,易产生不均匀沉陷、砂土液化和渗透变形,导致边岸与圩堤滑塌。综合分析认为,湖口—彭泽芙蓉的岸坡稳定性差,长江崩岸的原因主要为:长江南岸大部分圩堤处于迎流顶冲段,水流淘刷较严重; 长江航道靠南段,岸坡长期受行船波浪淘刷,造成岸坡坡面陡直,稳定性差; 地层上部为夹薄砂层的粘性土层,下部为细砂层,抗冲性差; 汛期岸滩土体饱和,长江水位低,河滩地内水外渗造成岸坡失稳。以粘土为主的岸坡,应加强有效排水和减缓坡比; 有砂层的岸坡结构型岸坡,应对结合部位砂层、枯水位附近及水位变幅带内的砂层进行防冲刷、防掏蚀保护。

       

      Abstract: Based on comprehensive studies of field geological investigation, geophysical exploration, engineering geological drilling, this paper discussed the stratigraphic structure, karst development, engineering geological characteristics and bank slope stability of bank slope between Hukou and Pengze in the Jiujiang region along the Yangtze River. Both the bankside and polder embankment of the Yangtze River are located in terrace I at the south bank of the Yangtze River. The ground surface is the Quaternary Holocene alluvium, which is a set of lacustrine sediment, with thick silt layer. The foundations of bankside and polder embankment belong to the soft soil layers, which has low engineering bearing capacity, are subject to producing uneven settlement, sand liquefaction and seepage deformation, then resulting in collapse of bankside and polder embankment. Comprehensive analysis suggests that the bank slope stability between Hukou and Furong of Pengze County is poor and the main factors resulting in collapse of Yangtze River bank are: Most polder embankment at the south bank of the Yangtze River is in upstream or head-wave areas, which are seriously scoured by water flow. Bank slope close to the south of the Yangtze River waterway is frequently scoured by the ship wave, causing the steep bank slope and the poor stability. Clayey layer intercalated with thin sand layers in the upper stratum, with fine sand layer at bottom, suggests poor anti-scourability. The saturated soil of beach is during flood season and the low water level of Yangtze River may cause the water exosmosis in flood land induces bank slope instability. For the bank slope mainly consisting of clay, the effective drainage should be strengthened and the slope ratio should be reduced. For the bank slope containing sand layers, protection measures should be constructed in the areas such as sand layers, low water level and variation of water level to prevent scouring and corrosion.

       

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