冲孔灌注桩孔底岩土体破坏机理及冲锤选型分析

Failure Mechanism Analysis of Rock and Soil in the Bottom of the Impact-cone Concrete Pile and the Selection of the Punching Hammer

通过分析冲孔灌注桩的中空冲击钻头结构和孔底岩土体破坏机理;基于落石冲击力计算相关研究成果,给出了冲锤对井孔底的冲击力计算。基于Mindlin课题基本解通过积分建立环形荷载作用下孔底岩土体力学模型。根据黏土层、砂卵石层、岩层典型地层的物理力学参数和桩孔大小模拟出孔底范围岩土体合理的塑性区边界,分析得出合理的冲锤质量及喇叭头外径;为配置合理的中空冲击钻头提供依据。

By analyzing the structure of the hollowed punching hammer and the failure mechanism of rock and soil in the bottom of the impact-cone concrete pile, based on the calculation on the falling stone impulsive force, the impact of hammer on the bottom of well hole was calculated. The mechanics model of porous subsoil under circular load was established based on the basic solution of the Mindlin problem. Based on the physical and mechanical parameters and pile hole size of typical strata of clay layer, sand ovale layer and rock formation, the reasonable plastic zone boundary of rock and soil in the hole bottom area was simulated.