Numerical simulation of mechanical behavior for pile-column supported subgrade over soft ground
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摘要: 以快速拉格朗日有限差分法程序FLAC为平台, 建立软土地区桩柱式路基的数值分析模型, 研究了桩柱式路基的力学行为。分别用桩单元、绳索单元模拟桩柱、筋材, 分析了路基的沉降、侧移、孔压与稳定特性, 及桩柱、筋材的内力分布, 比较了桩柱式路基与传统土石方路基的特点, 对桩柱、筋材、路堤与地基的设计参数对路基沉降和地基侧移的影响进行敏感性分析。分析结果表明, 桩柱式路基表面的最大沉降、差异沉降仅为传统土石方路基的1.48%、1.40%, 地基侧移仅为传统土石方路基的0.88%, 因此, 桩柱式路基力学行为优良。Abstract: Based on FLAC(fast Lagrangian analysis of continua) of 2D explicit finite difference method, a numerical simulation model was established to investigate the mechanical behavior of pile-column-supported subgrade(PCSS) over soft ground.Pile, column and reinforcement geogrid were modeled by using pile elements and cable elements respectively, the surface settlement, ground lateral displacement, pore water pressure, stability of the subgrade were studied, the internal force distributions of pile, column and reinforcement geogrid were analyzed, the characteristics of PCSS and traditional subgrade were compared, and the influences of design parameters for pile, column, embankment, reinforcement geogrid and foundation on subgrade settlement and foundation lateral deformation were studied.Analysis result shows that compared with traditional subgrade, the ratios of the maximum surface settlement, differential settlement of subgrade, the maximum lateral deformation of foundation are 1.48%, 1.40% and 0.88% respectively, so the mechanical behavior of the subgrade is better.
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Key words:
- subgrade engineering /
- PCSS /
- soft ground /
- mechanical behavior
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图 8 Ef、Ec、hc、hf对路基表面沉降的影响
Figure 8. Influence of Ef, Ec, hc and hf on subgrade surface settlement
图 9 Ef、Ec、hc、hf对地基侧向位移的影响
Figure 9. Influence of Ef, Ec, hc and hf on foundation lateral displacement
图 10 桩柱与筋材设计参数对路基表面沉降的影响
Figure 10. Influence of design parameters for pile, column and reinforcement geogrid on subgrade surface settlement
图 11 桩柱与筋材设计参数对地基侧向位移的影响
Figure 11. Influence of pile, column and reinforcement geogrid design parameters on foundation lateral displacement
表 1 土体计算参数
Table 1. Calculation parameters of soils
土层类型 孔隙率n/% 干密度ρ/(kg·m-3) 排水杨氏模量E/MPa 排水泊松比μ 排水粘聚力c/kPa 排水摩擦角φ/(°) 膨胀角ψ/(°) 渗透系数K/(m·d-1) 水平向Kx 竖直向Ky 填土 30 1 600 60 0.30 24 30 0 1.200 0 0.400 0 软粘土 80 582 5 0.45 5 0 0 0.000 3 0.000 1 淤泥质砂 30 1 620 15 0.30 0 32 0 2.400 0 0.800 0 
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表 2 桩单元属性
Table 2. Properties of pile elements
节段 弹性模量/GPa 半径/m 纵向间距/m 单位桩长切向/法向耦合弹簧刚度/(GN·m-1) 切向/法向耦合弹簧粘结强度/(MN·m-1) 切向/法向耦合弹簧摩擦角/(°) 中部 10 0.15 2.5 0/0 0.0/0.0 0/0 顶部与底部 10 0.15 2.5 1/0 2.5/0.0 0/0
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