Modelling and calculating lateral pressure of expansive soil-EPS inclusion-retaining wall system
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摘要: 采用ABAQUS有限元热力耦合模块,以热膨胀类比膨胀土增湿膨胀,对膨胀土–EPS缓冲层–挡墙体系进行了数值模拟,研究了EPS缓冲层与墙体和膨胀土间的界面摩擦、墙后膨胀土的宽度、EPS块体间隙等因素对EPS缓冲层减压性能的影响。结果表明：①膨胀土–EPS缓冲层之间、挡墙–EPS缓冲层之间的界面摩擦力使作用在挡墙上的侧压力产生重分布,进而显著影响挡墙的倾覆力矩,但对水平推力影响很小；②墙后膨胀土宽度越宽,作用在膨胀土–EPS缓冲层–挡墙上的侧压力越大。当膨胀土宽度超过挡墙高度的2倍时,墙后侧压力不再明显增加；③组成EPS缓冲层的EPS块体间的间隙不影响挡墙上的侧压力分布。结合数值模拟结果,对膨胀土–EPS缓冲层–挡墙体系的工作机理进行了分析,提出了挡墙侧压力的计算模型。以重力式挡墙为例,说明了该计算模型在膨胀土–EPS缓冲层–挡墙体系设计中的应用,为EPS用于膨胀土挡墙缓冲减压的工程设计提供参考。Abstract: The thermal fields and thermal expansion are used to simulate the moisture fields and swelling of expansive soils upon wetting in this study. The thermal-mechanical coupled finite element analysis is employed to simulate the "expansive soil-EPS inclusion-retaining wall" system using ABAQUS. The following influences are analyzed: (1) the interface friction among the EPS, the wall and the expansive soil; (2) the width of the expansive soil, and (3) the gap between the EPS blocks. The numerical results indicate that the lateral pressure on the retaining wall increases as the width of the expansive soil increases until the width exceeds two times the height of the retaining wall. The interface friction induces redistribution of the lateral pressure on the wall and affects of the overturning moment on the wall. The gaps between the EPS blocks do not affect the lateral pressure on the wall. The interaction mechanisms between expansive soil, EPS inclusion and retaining wall are explored based on the numerical results, and a model for calculating the lateral pressure on the "expansive soil-EPS inclusion-retaining wall" is proposed. The design method for the "expansive soil-EPS inclusion-retaining wall" is illustrated by taking the gravity retaining wall as an example.
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Keywords:
- expansive soil /
- EPS /
- retaining wall /
- lateral pressure /
- numerical analysis
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图 2 膨胀土-EPS缓冲层单元体模型
Figure 2. Elemental specimen of expansive soil-EPS inclusion system
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图 5 膨胀土计算宽度对挡墙上的侧压力的影响
Figure 5. Influences of width of expansive soil on lateral pressure
表 1 数值模拟中采用的参数
Table 1 Parameters used in numerical simulation
含水率 弹性模量/MPa 黏聚力/kPa 内摩擦角/(°) 泊松比 增湿膨胀系数 w0=17% 22.8 117 28.5 0.19 0.024 wsat=30% 8.1 20 9.7 0.19 0.024 
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表 2 不同界面摩擦工况下挡墙的受力情况
Table 2 Influences of interface friction
工况 界面摩擦系数 水平推力/kN 倾覆力矩/(kN·m) 1 0 122 441 2 0.5 121 380 3 0.8 120 376
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