路基疏桩补偿“协力”设计

石名磊 王伟 张瑞坤

石名磊,王伟,张瑞坤. 2021. 路基疏桩补偿“协力”设计[J]. 工程地质学报,29(1):247-255. doi:10.13544/j.cnki.jeg.2020-015 doi: 10.13544/j.cnki.jeg.2020-015
引用本文: 石名磊,王伟,张瑞坤. 2021. 路基疏桩补偿“协力”设计[J]. 工程地质学报,29(1):247-255. doi:10.13544/j.cnki.jeg.2020-015 doi: 10.13544/j.cnki.jeg.2020-015
Shi Minglei, Wang Wei, Zhang Ruikun. 2021. The compensation and “cooperative” designing of scattered piles for subgrade[J]. Journal of Engineering Geology, 29(1): 247-255. doi: 10.13544/j.cnki.jeg.2020-015
Citation: Shi Minglei, Wang Wei, Zhang Ruikun. 2021. The compensation and “cooperative” designing of scattered piles for subgrade[J]. Journal of Engineering Geology, 29(1): 247-255. doi: 10.13544/j.cnki.jeg.2020-015

路基疏桩补偿“协力”设计

doi: 10.13544/j.cnki.jeg.2020-015
详细信息
    作者简介:

    石名磊(1962-), 男, 博士, 教授, 硕士生导师, 主要从事道路与岩土工程相关的科研与教学工作. E-mail: 101004213@seu.edu.cn

  • 中图分类号: P642

THE COMPENSATION AND "COOPERATIVE" DESIGNING OF SCATTERED PILES FOR SUBGRADE

  • 摘要: 为研究路基疏桩补偿软土地基的协配机制, 本文提出了疏桩补偿软土地基协力概念模型, 借助Mathematica软件进一步阐明了软土地基临界荷载的边载坡率和硬壳层关联机制, 通过理论分析建立了基于软土地基临界荷载的路基疏桩协力的疏桩承载力检算方法。疏桩间距与桩长协配设计实例分析, 不仅验证了路基疏桩补偿软土地基协力基桩承载力检算方法的可行性, 并揭示了疏桩路基坡趾被动区稳定不利地貌加剧失稳的破坏机制。研究结果表明, 提出的协力概念模型和基桩承载力检算方法具有较好的适用性, 同时阐明了超载预压方案慎用的必要性, 强调了控制路基填筑加载速率的重要性。
  • 图  1  水泥搅拌桩破坏模式(Broms, 1999)

    Figure  1.  Possible failure modes of cement mixing pile (Broms, 1999)

    图  2  不同阶段侧向变形与沉降变化量的关系(陈继彬等, 2013)

    Figure  2.  Relationship between lateral deformation and settlement at different stages(Chen et al., 2013)

    图  3  被动区软土侧移与路堤荷载水平关系

    Figure  3.  Relationship between lateral displacement of soft soil in passive zone and embankment load

    图  4  桩身最大弯矩与荷载水平

    Figure  4.  Maximum bending moment and load level of piles

    图  5  软土疏桩路基稳定概念模型

    Figure  5.  Conceptual model for the stability of soft soil scattered pile subgrade

    图  6  条形荷载塑性区开展示意图

    Figure  6.  Development diagram of strip load plastic zone

    图  7  条形均布荷载下塑性区开展情况

    Figure  7.  Development of plastic zone under uniformly distributed load

    a. pk/Su0=2; b. pk/Su0=3; c. pk/Su0=4; d. pk/Su0=5

    图  8  临塑荷载比边坡坡率关联机制

    Figure  8.  Correlation mechanism between the ratio of critical edge pressure and slope

    a. 1 ︰ 0.75; b. 1 ︰ 1.0; c. 1 ︰ 1.5; d. 1 ︰ 2.0

    图  9  临塑荷载比顶板埋深关联机制(无边载pk=5Su0)

    Figure  9.  Correlation mechanism between the ratio of critical edge pressure and buried depth of subgrade roof

    a. Dc=1 m; b. Dc=2 m; c. Dc=3 m; d. Dc=5 m

    图  10  路基纵向剖面示意

    Figure  10.  Longitudinal profile of subgrade

    图  11  路基北侧苇塘地貌

    Figure  11.  Landform of weitang on the north side of the subgrade

    图  12  桥头连接过渡段苇塘地貌一侧路基病害分布

    Figure  12.  Distribution of subgrade diseases on the side of bridge head

    表  1  最大侧移变化量Δymax与地基沉降变化量Δs关系(Tavenas et al., 1979)

    Table  1.   Relationship between maximum lateral shift change Δymax and ground settlement change Δs

    场区 路堤特征 位移特征(Δymaxs)
    B/D L/D OA
    (hHcrit)
    AB
    (Hcrit < hHu)
    BC
    (h>Hu)
    Arles 3.60 0.78 0.14 >0.6 0.16
    Cubzac A 3.10 0.71 0.36 1.00
    Cubzac B 2.30 0.36 0.20 1.00 0.18
    Kalix 0.80 0.25 0.31 1.00
    King's Lynn 3.20 1.20 0.19 1.00
    Koda 3.70 0.42 0.25 0.85 0.32
    Portsmouth 2.30 1.30 0.10 0.42
    Ruper A 3.00 1.00 0.13 0.80
    St-Alban B 0.88 0.36 0.20 0.90 0.15
    St-Alban C 1.17 0.60 0.10 0.85 0.08
    Tickton 5.40 1.30 0.24 1.00
      L为路堤边坡横向宽度(m); Hcrit为路堤临界高度(m); Hu为路堤极限高度(m)
    下载: 导出CSV

    表  2  地基土分层参数

    Table  2.   Layered parameters of foundation soil

    土名 层厚/m 物理状态 水理特征 强度指标 压缩指标 SPT-N/击 CPT-qc/MPa [fa0]/kPa qik/kPa
    w/% e WL IP IL cu/kPa φu/(°) a1-2/MPa-1 Es/MPa
    淤泥质黏土① 13 50.6 1.406 43.94 19.6 1.34 10 3.19 1.29 1.96 1~2 0.25 50
    粉质黏土②1 2 23.3 0.647 35.40 13.3 0.09 38 12.4 0.16 10.08 200 50
    粉土②2 >15 28.5 0.766 24.684 10.6 1.36 0.11 16.50 10 (1800) 35
      ()数据为土层撞断承载力标准值qb
    下载: 导出CSV

    表  3  PC疏桩D/400补偿软土地基设计参数

    Table  3.   Design parameters of scattered pile(PC, D/400)as compensation to soft soil foundation

    路基 疏桩
    路段性质 路基h/m 预压土hp/m 标准值pk/kPa 桩长L/m 嵌入深度hd/m 间距s/m(置换率) 桩帽bc/mc(置换率)
    连接段 7 2.0 180 28 15 2.5(0.020) 1.3(0.270)
    过渡段 5 1.4 128 24 11 3.1(0.013) 1.5(0.234)
      ()内数据为对应的平面置换率
    下载: 导出CSV

    表  4  疏桩补偿软土协力设计验算

    Table  4.   Cooperative design checking of scattered pile as compensation to soft soil

    验算 被动区软土稳定 软土地基承载力 PC疏桩承载力/kN
    断面 ηgcr/3Su0 Qkcr/kN ηgcr/5Su0 Qkcr/kN 容许承载力Rpk 轴心抗压设计值Nd
    连接段 0.16 890.63 0.50 560.46 842 > 1475
    过渡段 0.28 824.29 0.37 682.73 692
    下载: 导出CSV
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出版历程
  • 收稿日期:  2020-02-07
  • 修回日期:  2020-07-04
  • 刊出日期:  2021-02-01

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