强夯置换滨海软土成墩效果模型试验研究

强夯置换的碎石墩深度和直径是表征墩型的重要指标，而强夯参数、施工方式是影响墩型的重要因素。研究强夯置换机制对优化强夯置换工艺具有重要意义。依据模型与原型的相似关系比0.05设计了室内模型试验，通过重塑软土形成的模型地基，研究了不同夯击能(0.018、0.027、0.036、0.045kN·m)、不同填料方式(1/4填料、1/3填料、1/2填料、满填料)、不同夯锤锥体角度(0°、30°、60°、70°、80°)3个独立影响因素及其组合变化对成墩形状的影响。结果表明：墩径随置换深度的变化曲线以最大墩径埋深为分界点，其上满足二次多项式分布规律，其下满足线性递减规律。夯击能与置换深度总体上呈正相关关系；锥体角度与置换深度呈负相关关系；锥体角度与夯击能对墩体直径的影响较小；夯坑填料方式对墩体直径的影响显著，与墩体扩径系数呈正相关关系。

Model test on pier formation effect of dynamic replacement in coastal soft soil

The depth and diameter of gravel pier replaced by dynamic replacement are important indicators to characterize the pier shape. While compaction parameter and construction method are important factors to affect the pier shape. It’s very important to study the mechanism of dynamic replacement for optimizing the dynamic replacement process. A laboratory model test was designed based on the similarity ratio(δ=0.05) between model and prototype to study the influence of three independent factors including different ramming energies (0.018、0.027、0.036、0.045kN·m), different packng methods(1/4 packing、1/3 packing、1/2 packing、full packing), different hammer cone angles(0°、30°、60°、70°、80°) and their combined changes on the pier shape through remolding the model foundation formed by soft soil. The results show that the variation curve of pier diameter with replacement depth takes the maximum buried depth of pier diameter as the dividing point. The upper part satisfies quadratic polynomial distribution law, and the lower part satisfies linear decreasing law. The replacement depth is generally positively correlated with the ramming energy, and negatively correlated with the hammer cone angle. The hammer cone angle and the ramming energy have little effect on the diameter of pier, but the method of packing has a significant effect on the pier diameter and has a positive correlation with the expansion coefficient of pier.