大直径扩底灌注桩抗压承载力试验研究

Experimental Study on Compressive Bearing Capacity of Large Diameter Cast⁃in⁃place Under⁃reamed Pile

目前对于大直径深长扩底灌注桩的现场试验研究还较少,其荷载传递形式还没有较多的数据支持。通过对砂土中大直径灌注桩和大直径扩底灌注桩现场静载试验结果进行分析和比较,研究了砂土层中大直径灌注桩和扩底桩的承载特性和荷载传递机理。研究结果表明,等直径桩和扩底桩的受力形式是先激活上部桩侧摩阻力,再激活下部桩侧摩阻力和桩端阻力,并且扩底桩不仅使桩身抗压承载力增大、桩顶沉降量减小,还使桩身受力结构形式得到调整,使桩身侧摩阻力、桩端侧摩阻力和桩端阻力都有明显提高,使桩身各部位摩阻力充分发挥作用。

At present,there are few field test studies on large⁃diameter deep and long belled cast⁃in⁃place pile,and there is no more data support for its load transfer form.By analyzing and comparing the field static load test results of large⁃diameter cast⁃in⁃place pile and large⁃diameter belled cast⁃in⁃place pile in sandy soil,the bearing characteristics and load transfer mechanism of large⁃diameter cast⁃in⁃place pile and belled pile in sandy soil are studied.The results show that the stress form of equal diameter pile and belled pile is to activate the upper pile side friction first,and then activate the lower pile side friction and pile end resistance.Belled pile not only increases the compressive bearing capacity of pile body and reduces the settlement of pile top,but also adjusts the stress structure form of pile body,and significantly improves the pile side friction,pile end side friction and pile end resistance,makes the friction resistance of each part of the pile body play a full role.