Numerical Analysis of Dynamic Response of Two-tiered Modular Reinforced Soil Retaining Wall
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摘要: 针对地震作用下双级加筋土挡墙临界台阶宽度不明、上下阶墙高选取随意,不利于加筋土挡墙推广应用的情况,基于双级模块式加筋土挡墙的振动台试验结果,建立FLAC 3D数值模型,研究了不同台阶宽度(10、20 、30、40、50、60 cm)、不同墙高比(上下阶墙体分别为3/7、4/6、1/1、6/4、7/3)下加筋土挡墙的墙面位移、加速度响应及地震土压力分布情况。结果表明,面板位移随台阶宽度的增加先减小后增大,最小值出现在台阶宽度为50 cm工况中;加速度放大系数沿墙高非线性递增,上阶挡墙在台阶宽度为40 cm和60 cm时出现加速度响应衰减;下阶墙体土压力在台阶宽度为50 cm时数值最小;上下阶挡墙墙高比为4/6时,墙面峰值位移最小;墙高比为6/4时,上阶挡墙的加速度放大系数最大,墙高比为1/1时,下阶挡墙的加速度放大系数最大;墙高比为7/3时,上阶挡墙的地震土压力值最大,墙高比为1/1时,下阶挡墙的地震土压力值最大。综合分析可知,墙高比为1/1时,临界台阶宽度在50 cm附近;当台阶宽度为20 cm时,上下阶墙体高度应有所区别,不宜均分,也不宜差距过大。研究成果可为双级加筋土挡墙工程设计中台阶宽度和上下阶墙高设置提供数据支撑。Abstract: In view of the unclear critical tier width and random height selection of upper and lower walls in two-tiered reinforced soil retaining walls under seismic loads, which hinders their application, a FLAC 3D model was built based on shaking table tests of two-tiered modular reinforced soil retaining walls. It analyzed face displacement, acceleration response, and seismic earth pressure distribution under different tier widths (10, 20, 30, 40, 50, 60 cm) and height ratios (3/7, 4/6, 1/1, 6/4, 7/3). Results revealed that facing displacement first decreased and then increased with tier width, hitting the minimum at 50 cm. The acceleration amplification factor rose nonlinearly with wall height, with attenuation in the upper wall at 40 and 60 cm widths. The lower wall's earth pressure was smallest at a 50 - cm tier width. The peak facing displacement was minimized when the height ratio was 4/6. The upper wall's maximum acceleration amplification occurred at a 6/4 ratio, while the lower wall's was at 1/1. The upper wall's seismic earth pressure was highest at 7/3, and the lower wall's at 1/1. Comprehensive analysis showed a critical tier width near 50 cm at a 1/1 ratio. At a 20 cm tier width, upper and lower wall heights should differ moderately. These findings offer data support for the design of two-tiered reinforced soil retaining walls, aiding in tier width and height configuration.
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表 1 模型相似关系参数
Table 1. Model similarity relation parameters
变量 参数 相似关系 相似常数(原型/模型) 长度 L ${C_{\text{L}}}$ 10 弹模 E ${C_{\text{E}}}$ 1 密度 $\rho $ $ {C}_{\rho }=1 $ 1 应力 $\sigma $ $ {C}_{\sigma }={C}_{E}=1 $ 1 时间 $t$ ${C_{\text{t}}} = C_{\text{L}}^{{\text{0}}{\text{.5}}}$ 3.16 速度 $v$ ${C_{\text{v}}} = C_{\text{L}}^{{\text{0}}{\text{.5}}}$ 3.16 加速度 $a$ ${C_{\text{a}}} = 1$ 1 重力 $g$ ${C_{\text{g}}} = 1$ 1 频率 $\omega $ $ {C}_{\omega }={C}_{L}^{-0.5} $ 0.316 表 2 实体单元材料参数
Table 2. Material parameters of solid element
组成部分 本构 密度/(kg·m−3) 体积模量/Pa 剪切模量/Pa 摩擦角/(°) 黏聚力/Pa 地基土 M-C 1820 6.667×107 3.077×107 41 1×106 回填土 M-C 1820 6.667×107 3.077×107 41 1×103 基础 弹性 2200 1.095×1010 1×1010 — — 面板 弹性 2200 1.095×1010 1×1010 — — 海绵垫 弹性 120 1.1×106 8.35×105 — — 表 3 结构单元材料参数
Table 3. Material parameters of structural units
弹性模量/Pa 泊松比 密度/(kg·m−3) 厚度/m 耦合弹簧的切向刚度/Pa 耦合弹簧的粘聚力/Pa 耦合弹簧的摩擦角/(°) 2.6×109 0.33 300 1×10−3 2×107 1.48×104 32 表 4 接触面单元计算参数
Table 4. Calculation parameters of contact surface element
接触面 法向刚度kn 切向刚度ks 界面摩擦角/(°) 界面黏聚力/Pa 面板-面板 1×109 4×107 36 5.8×104 面板-基础 1×109 4×107 36 5.8 e×104 面板-土体 1×108 1×106 25 2.5×103 -
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