不同形状夯锤在灰土挤密桩施工中的应用研究

Study on applications of different shape rammers in construction of lime-soil compaction piles

灰土挤密桩被广泛应用于处理黄土地基的湿陷性,其处理效果主要依赖于灰土的夯填质量,实践证明夯填质量除了和夯击能量有关外,还与夯锤的形状有很大关系。文章对三种高度和重量相同但锤头形状不同的夯锤(半球型、椭球型、锥型)的夯填效果进行了对比分析。采用LSDYNA动力分析程序分析了三种落锤以相同高度自由下落时对土体的动力响应。对三种夯锤施工的试桩区进行了复合地基载荷试验,对桩间土和桩体土样的基本物理性质进行了分析。综合动力有限元分析结果和现场试验分析结果发现:椭球型锤贯入效率最高;半球型夯锤夯填效果最好,承载力提高率最大且挤密效果最均匀。

Lime soil compaction piles are widely used to eliminate the collapsibility of loess subgrade, and their treatment effect mainly depends on the ramming and filling quality of lime soil. The engineering practice shows that the ramming and filling quality not only relate to the tamping energy, but also relate to the shape of the rammer. The ramming and filling quality with three kinds of rammers whose height and weight are the same but their head shape are different （ball, ellipsoid, taper） are analyzed. Using LS- DYNA dynamic analysis program, the dynamic response to soil mass with the three kinds of rammers are analyzed when they fall at the same height. In the construction area. the composite foundation loading tests are carried out and the basic physical properties of the soil samples from the soil between piles and from the soil piles are analyzed respectively. Based on the comprehensive dynamic finite element analysis results and the field test results, it is found that the penetration efficiency from the ellipsoid type rammer is the highest, the treatment effect with half spherical rammer is the best, its increase rate of bearing capacity is the largest and the compacting effect is most even.