摘要
目的研究压桩时桩周软土的微观结构变化规律,揭示静压沉桩挤土效应的实质及其随时间的变化特征.方法采用水平向压缩试验模拟静压桩挤土过程,将微结构的变化过程划分为两个阶段,即前期振荡阶段和后期趋稳阶段,借助扫描电镜记录挤土过程中软土微观结构变化进行土的微观结构定量参数分析.结果得出软土微结构在压缩固结过程中随时间的变化规律.在前期阶段,从沉桩开始到1～2 h,桩周土体各项微结构指标变化复杂而剧烈,超静孔隙水压极高,在横向挤压力的作用下很容易发生变形和位移,土体应力传递速度快,挤土效应极为显著.而后期阶段,孔隙水压力已大幅度消散,土结构调整进入相对稳定的变化阶段,这期间再沉相临桩,挤土效应会大大减弱.结论软土地基沉桩挤土效应具有明显的微结构时效特征.模拟试验结果对实际工程中采取有效措施减少或避免挤土效应具有指导意义.
The simulating experiment has been adopted for pile soil compaction effect based on soil compression test in horizontal direction,and the microstructure changes of soil has been recorded by means of scanning electron microscope.The change law of microstructure with time in the compression process of soil is obtained by microstructure quantitative parameter analysis of soil.The change process of microstructure is classified as two different stages.The early stage,from 1-2 hours after the completion of pile driving a-round the pile of soil micro-structure of the complex and dramatic changes in indicators,ultra-high pore pressure in the lateral extrusion under pressure are prone to deformation and displacement of soil stress transfer speed,soil compaction effect was significant.The late stage,the pore water pressure has been substantially cleared,soil structural adjustment to the attendant changes in the stability phase,which during the adjacent piles,soil compaction effect will be greatly reduced.The simulation experiment results have guiding signifi-cance for preventing pile soil compaction effect.
出处
《沈阳建筑大学学报（自然科学版）》
CAS
北大核心
2010年第3期423-427,共5页
Journal of Shenyang Jianzhu University：Natural Science
基金
天津市自然科学基金项目(06YFJMJC05700)
关键词
静压桩
挤土效应
扫描电镜
微结构参数
时效特征
jacked pile
pile soil compaction effect
scanning electron microscope
micro-structure parameter
aging characteristic
