桩体复合地基重复加卸载过程中侧向约束桩土压力特性实验研究

An Experimental Study of Soil Pressure Characteristics of Laterally Constraint Pile When Pile Composite Foundation Loading and Unloading Repeated

侧向约束桩土压力问题比较复杂。采用室内模型实验研究桩体复合地基重复加卸载过程中侧向约束桩土压力特性。结果表明：①荷载作用下,桩侧土压力在桩上部呈直角三角形分布,中部有一个最大值,下部呈直角梯形分布,整体上呈抛物线分布。②重复加、卸载过程中,下部的桩侧土压力增（降）幅最小,上部次之,中部最大。③首次加载阶段,峰值出现在0.11-0.33 H处,有下移趋势。重复加载阶段,峰值位置有上移趋势;重复卸载阶段,峰值位置有下移趋势,变化范围在0.55-0.33 H处。④重复加、卸载到相同荷载时,桩侧土压力随加、卸载次数增加而减小;分布曲线的抛物线线型和峰值位置不变。

The problem of soil pressure for lateral constraint pile is more complicated. Soil pressure characteristics of laterally constraint pile were studied by experiment when pile composite foundation loading and unloading repeated. The study results are shown as follows： （1）Under the load,the soil pressure in the upper part of the lateral constraint pile is a right angle triangle distribution and right angle trapezoidal distribution in the lower part and parabolic distribution on the whole. There is a maximum value in the middle. （2）During repeated loading and unloading process,the lower part of the pile＇s lateral soil pressure increase（ drop） the smallest,the second in the upper part,the largest in the middle. （3）For the first loading stage,the peak appears in the 0. 11 - 0. 33 H,and there is a downward trend. Repeated loading stage,the peak position has the upward trend,repeated unloading stage,the peak position has a downward trend,the peak changes in the range of 0. 55 - 0. 33 H. （4） Repeated loading or unloading to the same load,the pile ＇s lateral soil pressure reduces with the increase of the number of loading or unloa-ding. Parabolic curve and peak position of the distribution curve have not changed.