黄土地基中微型抗压与抗拔桩对比试验研究

Experimental Study of Micro Compression and Uplift Pile in Loess Foundation

微型抗拔桩是西北黄土地区光伏电站的一种典型锚固基础,为研究微型桩在抗压与抗拔条件下位移与受力性状的异同,在黄土地基进行了不同尺寸的抗压桩与抗拔桩的单桩竖向静载试验。试验结果表明:相同荷载作用下,抗拔桩的桩顶位移和位移增长速率均大于抗压桩,考虑桩顶上拔量得出的极限承载力低于按规范进行试验得出的结果,因此,在确定抗拔桩的极限承载力时应考虑桩顶上拔量;两种试桩桩身轴力随埋深分布曲线相似,即存在一个向下传递的过程;抗拔桩桩身中上部侧阻达到极限后会随着荷载的增加出现减小的趋势;抗拔桩桩端侧阻存在弱化现象,抗压桩桩端侧阻则存在强化现象。研究结果对黄土地区光伏电站微型抗拔桩锚固基础的设计与施工具有重要的参考意义。

Mini pile is a typical anchorage foundation of photovoltaic power station in northwest loess region. Vertical compressive and uplift static load test on mini-piles in which the piles is in different sizes were carried out in loess foundation to research the differences of displacement and bearing capacity when a single pile is under the condition of compression and uplifting. The results indicated that under the same load,the uplift piles displacement and its rising rate were greater than those of compressive piles. Bearing capacity of uplift piles according to displacement is lower than that according to technical code. As a result,the displacement of uplift piles should be taken into consideration to determine the bearing capacity. The axial force distribution of uplift pile is similar to that of compressive pile. The top could bear main load when the load is small; with the increasing of load,the load which the top of pile body could bear soon reach the limit,and main load transfer to the medium and bottom. Lateral friction of top and medium of uplift pile which is reach limit would decrease with the increase of load. The lateral friction of bottom of the uplift pile shows the weakening effect and the compressive pile shows the strengthening effect. The results can provide important reference to the design and construction of micro uplift pile in photovoltaic power station in the loess area.