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沉桩过程中,PHC管桩内形成的土塞将对桩内壁产生横向胀管作用。建立了PHC管桩土塞胀管作用的力学模型,并进行了定量分析。考虑沉桩扰动影响,将管内土塞分为楔形区和非楔形区,对土塞的一维平衡方程进行了修正。应用圆柱孔扩张理论解释管桩沉桩过程中的挤土效应,对桩外土体进行了弹塑性分析,得到了塑性区半径以及考虑土体初始应力的桩外土侧压力的解析表达式。根据圆环受均布内外压力的拉梅解答,给出了管桩环向破坏的判别准则。通过现场实测对模型进行了验证,对环向箍筋动态应变的测试结果表明,所建立的模型能够定量描述强胀管作用下PHC管桩的环向破坏机制,可用于工程中PHC管桩环向抗拉承载力的验算。
During the pile sinking process, the soil plug formed in the PHC pipe pile will have lateral expansion effect on the inner wall of the pile. The mechanical model of the effect of the plug-in expansion pipe of the PHC pipe pile was established and the quantitative analysis was carried out. Considering the influence of pile disturbance, the soil plug is divided into wedge area and non-wedge area, and the one-dimensional equilibrium equation of earth plug is modified. The cylindrical cavity expansion theory is used to explain the soil compaction effect during pipe pile driving. The elasto-plastic analysis of the soil outside the pile is carried out. The plastic zone radius and analytic expression of soil lateral pressure considering the initial stress of soil mass are obtained. According to Lame’s solution to the ring subjected to uniform internal and external pressures, the criteria for the circumferential damage of pipe pile are given. The model was verified by on-the-spot measurement. The test results of the dynamic strain of the hoop tendon show that the model can quantitatively describe the hoop failure mechanism of the PHC pipe pile under the action of the strong expansion pipe. It can be used in the PHC pipe pile ring Checking of tensile bearing capacity.