考虑混凝土性质变化灌注桩深部土压力分析

以上海地区埋深较大的暗绿色黏性土为例,选用Burgers模型对该层土体的流变性质进行描述.考虑混凝土性质随时间改变,采用弹性徐变理论分析混凝土变形特征.建立桩周土压力引起的灌注桩径向变形的遗传积分方程,分析桩土接触面位移协调条件,求得桩周径向土压力随时间变化的解析表达式.研究结果表明:埋深较大土体中桩周径向土压力最初大小为混凝土浇筑引起的侧向压力,随着时间推移慢慢增大,最终趋于静止土压力.灌注桩竖向承载力与桩周径向土压力大小有直接关系,合理分析灌注桩桩周径向土压力时效特征对于探讨灌注桩竖向承载力变化机理有重要意义.

Analysis of Deep Earth Pressure Around Cast in place Pile Considering Concrete Property Variation

The rheologic properties of the deeply buried dark green silty clay in Shanghai area are depicted with the Burgers Model.Considering the concrete property variation in solidification,the deformation characteristics of concrete are analyzed with the elastic creep theories.The genetic integral equation of the pile's radial deformation for the reason of the soil pressure around the pile is established.The analytical expression of the time varying horizontal pile soil interaction force is developed through analyzing the condition of the displacement coordinary at the pile soil interface.The research shows that the horizontal soil pressure around the pile,which is initially caused by the pouring process,tends to increasing gradually in deeply buried soil,with the ultimate value being earth pressure at rest.Since the cast-in-place pile's vertical bearing capacity is directly related with the soil pressure around the pile,the time-effect analysis of the soil pressure around filling pile has great significance to the study of the filled pile's vertical bearing capacity variation mechanism.