竖向荷载下群桩受力特性研究

The Research on Mechanics Characteristic of Pile Group Foundation under Vertical load

竖向荷载下群桩基础的受力特性较为复杂,尤其是现场试验,由于受到荷载大、费用高、设备复杂等条件的限制,难以普遍开展.通过一定量群桩承载力的现场试验,结合计算机数值仿真分析研究竖向荷载下群桩基础的受力特性,结果表明：群桩整体承载力随桩中心距的增大而增大,但当桩间距S大于5倍桩径后,增大趋势不再显著;群桩中各桩桩顶应力分布很不均匀,但其随桩中心距、上部荷载的增加而逐渐趋于均匀;单桩长径比为20~30时,群桩承载力随桩长的增加而有效增加,超过此范围时,增加桩长,群桩承载力增加效果不明显.

Field static load test of pile group foundation is difficult to carry out because the limitation of funds or equipments. At the same time,the bearing capacity mechanism of pile group foundation and interaction between piles and soil is complex,there are still large gaps between the theory research and practice. In the paper mechanics characteristics of pile group foundation under vertical load were researched by the local testing and computer numerical value. Some solutions were educed that the bearing capacity of pile group foundation will increase while the pile spacing increases,but the trend is very weak while S 5D. The difference of stress between piles in different positions will decrease while the pile spacing increases. The stress distribution on the pile top tends to be uniform with the increase of load. The bearing capacity of pile group can increase as pile length increases,when length-diameter ratio L / D = 20 ~ 30,The bearing capacity of pile group is greater and the expense is lower.