后压浆灌注桩极限承载力分析

Analysis on Ultimate Bearing Capacity of Post-grouting Cast-in-place Pile

对后压浆灌注桩的极限承载力进行了分类讨论,其可能的破坏模式主要有桩体破坏、桩底土体冲剪破坏模式,针对两种破坏模式分别提出了简单合理的极限承载力计算模型。针对以往土体强度采用摩尔-库仑准则的弊端,不能合理地考虑不同应力罗德角下主应力对强度值的贡献,而采用SMP准则则可合理地考虑不同应力罗德角下主应力对强度值的贡献,使土体在三维应力下的破坏状态更趋于实际情况。针对桩底土体采用SMP强度准则利用圆弧滑动面与虚功率原理,分析了压浆体与土体的相互作用,结合SMP强度准则推导得到了后压浆浆体承载力的计算式,为分析后压浆土体的承载力提供了一个新的理论模型,所提的承载力计算式可合理地用于三维应力状态下后压浆土体的预测分析。

The paper discusses the ultimate bearing capacity of post-grouting cast-in-place pile in classes, wherein the possible failure modes are pile damage and punching shear failure of soil mass at pile bottom. In connection with these two modes, the simple and reasonable models calculating ultimate bearing capacity are proposed respectively. Against the deficiency of previous soil mass strength calculation by Mohr-Coulomb criterion with the contribution of main stress under different Lode angles to the strength not to be considered rationally, however by SMP criterion with this consideration to be done to a rational extent, the failure status of the soil mass under three-dimensional stress could go to the actual situation. Against the soil mass at the pile bottom, with SMP strength criterion and by the principles of circular slip surface and fictitious power, the interaction between the slurry and the soil mass is analyzed and the formula calculating bearing capacity of the slurry is derived, which offer a new theoretical mode for analysis of bearing capacity of post-grouting based soil mass. This formula could be used to analyze the prediction of post-grouting based soil mass under three- dimensional stress reasonably.