Experimental Study and Numerical Analysis of Shock Absorption of Pile-type Seismic Surface Wave Barrier
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摘要: 在双层均质土地基条件下,以桩长和桩间距为参数,采用模型试验法和数值分析法研究屏障桩对地震表面波的减震效果。研究结果表明,设置屏障桩可有效减弱地震表面波在土体中的传播,使桩后方减震区域加速度响应明显减弱;屏障桩长度和间距均对地震表面波在土体中的传播影响显著;在桩长试验中,减震率变化同时受桩长和地基土层影响,实际工程中应根据地基中土层分布情况进行桩长设计;在桩间距试验中,减震区域减震率达46%~56%,桩间距宜取约1.5倍桩径。Abstract: In order to study the shock absorption performance of barrier piles for seismic surface waves, this paper adopts two methods: model test and numerical analysis. Under the condition of double-layer homogeneous soil foundation, the two parameters of pile length and pile spacing are taken as variables, and the time domain analysis method is adopted to carry out the vibration test. The dynamic response of the test data in the shock absorption area is analyzed by the index of shock absorption rate. The results show that the barrier pile can effectively weaken the propagation of seismic surface waves in the soil, and the acceleration response in the damping area behind the pile is obviously weakened. The length and spacing of piles have a significant influence on the propagation of surface seismic waves in soil. In the pile length test, the change of damping rate is affected by both the pile length and the foundation soil layer. In practical engineering, the design of pile length should be determined according to the distribution of soil layer in the foundation. In the pile spacing test, the maximum damping rate in the damping area is 46%-56%, and the width of pile spacing should be about 1.5 times of pile diameter.
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Key words:
- Seismic surface wave /
- Pile /
- Model test /
- Numerical analysis /
- Damping rate
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表 1 试验变量
Table 1. Test variables
桩长/m 桩间距/m 桩径/m 0.2 0.10 0.1 0.3 0.15 0.1 0.4 0.20 0.1 0.5 0.25 0.1 0.6 0.30 0.1 表 2 模型试验得到的桩长减震效果
Table 2. Shock absorption effect of pile length obtained from model test
工况 桩长/m 加速度平均值/(m·s−2) 加速度放大系数/% 减震率/% 无桩 — 1.523 100.0 0.0 工况1 0.2 1.238 81.3 18.7 工况2 0.3 0.963 63.2 36.8 工况3 0.4 0.859 56.4 43.6 工况4 0.5 0.797 52.3 47.7 工况5 0.6 0.765 50.2 49.8 表 3 模型试验得到的桩间距减震效果
Table 3. Seismic reduction effect of pile spacing obtained from model test
工况 桩间距/m 加速度平均值/(m·s−2) 加速度放大系数/% 减震率/% 无桩 — 1.523 100.0 0.0 工况1 0.10 0.661 43.4 56.6 工况2 0.15 0.734 48.2 51.8 工况3 0.20 0.963 63.2 36.8 工况4 0.25 1.086 71.3 28.7 工况5 0.30 1.234 81.4 18.6 表 4 有限元材料参数
Table 4. Finite element material parameters
材料 厚度/m 密度/(kg·m−3) 弹性模量/Pa 泊松比 瑞利阻尼系数α 瑞利阻尼系数β 桩 — 2 200 2.2×1010 0.20 0.434 53 0.002 07 黏土层 4.0 1 850 6.0×107 0.25 1.159 02 0.005 50 砂土层 8.0 1 750 8.0×107 0.30 1.150 23 0.005 30 表 5 数值分析得到的桩长减震效果
Table 5. Seismic reduction effect of pile length obtained by numerical analysis
工况 桩长/m 加速度平均值/
(m·s−2)加速度放大
系数/%减震率/% 无桩 — 1.421 100.0 0.0 工况1 2.0 1.186 83.5 16.5 工况2 3.0 1.022 71.9 28.1 工况3 4.0 0.899 63.3 36.7 工况4 5.0 0.817 57.5 42.5 工况5 6.0 0.784 55.2 44.8 表 6 数值分析得到的桩间距减震效果
Table 6. Seismic reduction effect of pile spacing obtained by numerical analysis
工况 桩间距/m 加速度平均值/
(m·s−2)加速度放大
系数/%减震率/% 无桩 — 1.421 100.0 0.0 工况1 1.0 0.769 54.1 45.9 工况2 1.5 0.864 60.8 39.2 工况3 2.0 1.022 71.9 28.1 工况4 2.5 1.091 76.8 23.2 工况5 3.0 1.215 85.5 14.5 -
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