薄土夹层作为围堰封底层的降水可行性与阻水效应研究  

Study on the dewatering feasibility and water blocking effect of thin soil interlayer as the bottom layer of cofferdam

作　　者：李宗铭 李国锋[2] 李宁[1] LI Zongming;LI Guofeng;LI Ning(Institute of Geotechnical Engineering,Xi’an University of Technology,Xi’an 710048,Shaanxi,China;State Key Laboratory of Ecological Water Conservancy in Northwest Arid Regions,Xi’an University of Technology,Xi’an 710048,Shaanxi,China)

机构地区：[1]西安理工大学岩土工程研究所,陕西西安710048 [2]西安理工大学西北旱区生态水利国家重点实验室,陕西西安710048

出　　处：《水利水电技术（中英文）》2024年第8期69-80,共12页Water Resources and Hydropower Engineering

基　　金：国家自然科学基金(52179111,52309144)。

摘　　要：【目的】为了探究含薄土夹层的水下砂层作为桥墩围堰封底层时的降水可行性及其阻水效应问题,【方法】采用FLAC^(3D)分别模拟分析了混凝土封底和薄土夹层封底围堰施工的全过程,并分析了薄土夹层厚度、渗透系数、连续性、钢管桩长度、薄土夹层顶与钢管桩底距离、混凝土垫层厚度变化等对围堰钢管桩水平变形、坑底隆起变形及坑底渗水量的影响。【结果】结果表明:有、无薄土夹层时钢管桩均在围堰主墩施工完成阶段在桩顶以下14 m处达到最大水平变形,且分别为16.36 mm和20.72 mm,均满足规范要求;在薄土夹层厚度为4 m、渗透系数为5×10^(-9)cm/s、薄土夹层沿水平方向跨度为55 m、钢管桩长度为40 m、薄土夹层顶与钢管桩间距为0 m、混凝土垫层厚度为3 m的情况下,薄土夹层的阻水效果最好。【结论】薄土夹层具有很好的阻渗性,其作为围堰封底层进行降水施工是可行的,相关研究成果可为类似的工程提供参考和借鉴。[Objective]In order to explore the precipitation feasibility and water blocking effect of the underwater sand layer with thin soil interlayer as the bottom layer of the pier cofferdam,[Methods]FLAC^(3D)was used in this paper to simulate and analyze the entire construction process of the concrete bottom sealing cofferdam and the thin soil interlayer bottom sealing cofferdam,and analyzed the thickness of the thin soil interlayer,the permeability coefficient,the continuity,the length of the steel pipe pile,the distance between the top of thin soil interlayer and the bottom of the steel pipe pile,steel pipe pile and concrete cushion thickness variation on horizontal deformation of steel pipe pile,uplift deformation of pit bottom and seepage of pit bottom.[Results]The result show that the steel pipe piles reach the maximum horizontal deformation at 14 m below the pile top in the completion stage of the main pier of cofferdam with and without thin soil interlayer,and the deformation is 16.36 mm and 20.72 mm respectively,which both meet the requirements of the code.When the thickness of the thin soil interlayer is 4 m,the permeability coefficient is 5×10^(-9)cm/s,the horizontal span of the thin soil interlayer is 55 m,the length of the steel pipe pile is 40 m,the distance between the top of the thin soil interlayer and the steel pipe pile is 0 m,and the thickness of the concrete cushion is 3 m,the water resistance of the thin soil interlayer is the best.[Conclusion]Thin soil interlayer has good permeability resistance,and it is feasible to use it as the bottom layer of cofferdam seal for dewatering construction,and relevant research result can provide reference for similar projects.

关 键 词：钢管桩围堰 施工降水 数值模拟 薄土夹层 影响因素 

分 类 号：TV52[水利工程—水利水电工程]