竖向荷载作用下根式基础模型试验研究

Model Test Study on Vertical Load Action of Root Foundation

根式桩是一种适用于厚覆盖土层地区的新型桩,能有效提高桩的竖向承载力。然而,针对根式桩竖向承载特性的试验研究相对较少。为了研究其竖向承载特性,利用自制的杠杆加载装置对6种根键位置不同的试桩进行室内试验。通过测量试桩沉降变化,确定桩基承载力;利用土压力盒测定桩底土压力变化,研究荷载在砂土中的变化规律。试验结果表明:相比等截面桩,根键的设置可有效提高桩基承载力,桩基上根键分布位置对桩基承载力效能发挥有显著影响;单层根键试桩在土中应力的传播范围远于等截面试桩,根键为梅花式分布的试桩在土中应力的传播范围远于贯穿式分布的试桩;试桩根键层数的增加或根键位置的变化均会使土中应力传播范围变化。

The root pile is a new type of pile suitable for thick soil areas,which can improve the vertical bearing capacity of the pile.However,there are relatively few experimental studies on the vertical bearing characteristics of root piles.The vertical bearing characteristics are studied,and six kinds of test piles with different root-key positions were tested in laboratory with a self-made lever loading device.The bearing capacity of pile foundation was determined by measuring the settlement of test pile.The earth pressure box was used to measure the pressure change of soil pressure under pile,and the variation law of the load in sandy was studied.The experimental results show that compared with the equal-section piles,the setting of the root-key can effectively improved the bearing capacity of the pile foundation,the location of the root-key on the pile foundation has a significant influence on the bearing capacity of the pile foundation;The stress distribution of the single-layer root-bond test pile in soil is farther than of equal-section test pile,the stress propagation range of staggered root piles in soil is much wider than that of through-distributed test piles;The increase in the number of root-key layers or the change in the position of the root-key will change the stress propagation range in the soil.