摘要
河南地区输电线路大量分布在膨胀土地区,膨胀土具有吸水后强度明显降低的特性,可能导致输电线塔基础变形过大甚至失稳,威胁输电线路运行安全。基于膨胀土的强度特点,首先利用现行规范中的方法,计算了膨胀土地基的承载力特征值;然后通过三维有限元数值模拟建立了输电线塔大板基础模型,研究了大板基础膨胀土地基承载力和其破坏模式。模拟结果表明,随着饱和度的增加,膨胀土地基极限抗压承载力降低明显,但降低速率逐渐减小,破坏模式呈现出整体剪切破坏模式。将规范方法与数值模拟结果进行对比,可以初步得到规范法计算得到的膨胀土地基承载力偏保守的结论。
With a vast territory and a huge population in Henan province, it ’ s unavoidable that transmission lines need to be constructed in quantity so as to expand its coverage, in order to improve the qualities of people’s life and promote economic development. The majority of available researches about the foundation of transmission tower are aimed at the cases ol pile foundation, normal soil layer and frozen soil layer, and the method to obtain foundation bearing capacity is usually based on traditional way in relevant criterion. However, with the property that the strength of expansive soil foundation will decline rapidly after the soil absorbs water, the expansive soil foundation will cause great risk to the stability of the transmission towers and the safety of transmission line system. This paper calculates the characteristic value of foundation bearing capacity of unsaturated expansive soil with different saturation tb rough the method provided in current specification, and then analyzes the influence of saturation on the ultimate compressive bearing capacity of lower foundation by establishing a plate foundation using FEM method based on the results obtained from triaxial tests of unsaturated expansive soil. It is concluded that the ultimate compressive bearing capacity decreases obviously with saturation increases and then tend to be stable. What’s more,the failure mode of plate foundation turns out to he general shear failure. Finally, comparing the results calculated from simulations and current specification, it is concluded that it’s conservative to determine the characteristic value of bearing capacity of expansive soil calculated by the method provided in current specification.
作者
刘湘莅
齐道坤
郭新菊
苏征
LIU Xiangli;QI Daokun;GUO Xinju;SU Zheng(State Grid Henan Economic Research Institute, Zhengzhou 450052, China;Department of Geotechnical Engineering,Tongji University, Shanghai 200092, China)
出处
《结构工程师》
北大核心
2019年第2期112-117,共6页
Structural Engineers
基金
国家电网有限公司总部科技项目资助(5217L0160001)
关键词
膨胀土地基
大板基础
数值模拟
地基承载力
expansive soil layer
tower foundation
FEM
bearing capacity of foundation
