EHP桩复合地基承载特性现场载荷试验研究

Field Load Test on Axial Capacity of a New Composite Pile

EHP桩(Environmental Homogeneous Plastic Pile)是一边成孔一边全置换浇筑充填形成物理力学性质可控可调的新型环保均质塑性桩体,以解决传统水泥土搅拌桩存在的桩体不均匀、桩身不连续和桩体强度偏低等问题。为探究EHP单桩及复合地基的承载性能,对水泥掺量为8%、10%、13%的EHP桩及复合地基进行了现场静载荷试验,并与传统水泥土搅拌桩承载性能进行对比。结果表明:单桩及复合地基均未加载到破坏,荷载-沉降曲线均为缓变形,最大荷载下累计沉降量随水泥掺量的增加而呈幂函数关系下降;相同水泥掺量时,EHP桩及复合地基的抵抗变形能力均优于传统水泥土搅拌桩,在保证加固效果时,可减少水泥用量;EHP单桩和复合地基承载力能够满足设计要求,具有良好的经济性和应用前景。

The Environmental Homogeneous Plastic(EHP)pile is a new cement-soil mixing pile type with the controlled physical and mechanical properties.The pile is installed by injecting the environmentally friendly homogeneous plastic materials into the borehole.The new material for the pile has the advantages over the soil-cement mixed columns that usually have the issues of non-uniform,discontinued column shafts and low shaft strength.The field static plate loading tests were performed on composite soil and piles mixed with three different cement contents:8%,10%and 13%and the test results were compared with the conventional composite ground formed by the conventional soil-cement mixing columns.The results show that neither the single pile nor the composite foundation is loaded to failure,and the load settlement curveshave gradual deformation pattern.The cumulative settlement under the maximum load decreases with the increase of the cement content as a power function.At the same cement content,the deformation resistance of the EHP pile and composite foundation is better than that of the conventional soil-cement mixing columns,and the cement ratio can be reduced when the improvement effect is evident.The axial bearing capacity of EHP single piles and the composite foundations can meet the design requirements as well as cost effective for the project.