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采用考虑结构性损伤的四折线应变软化模型,针对管桩沉桩过程中产生的挤土效应,得出改进的柱形孔扩张理论解,并与已有模型进行对比分析,结果表明,简化的四折线模型与软土的典型压缩曲线最为接近,提出了四折线模型中各直线段和相应参数的确定方法。采用Mohr-Coulomb屈服准则和相关联流动法则,提出了桩周不同区域内土体的应力、应变计算公式,给出了极限软化半径、极限破坏半径和极限扩张压力的计算方法。结合工程实例,通过对比分析发现,四折线模型的位移计算值与实测值最为接近,能更好地符合管桩挤土效应的实际情况。
A four-line strain softening model considering the structural damage is adopted. According to the squeezing effect of pipe pile during pile driving, an improved theoretical solution of cylindrical cavity expansion is obtained and compared with the existing model. The results show that the simplified The typical compression curves of the four-fold model and the soft soil are the closest to each other, and the method of determining each straight-line segment and corresponding parameters in the four-fold model is proposed. Based on the Mohr-Coulomb yield criterion and the associated flow rule, the formulas of stress and strain for soils in different regions of the pile are proposed, and the calculation methods of the limit softening radius, the ultimate failure radius and the ultimate expansion pressure are given. With the engineering example, through the comparative analysis, it is found that the calculated displacement of the fourth-line model is closest to the measured value, which can better meet the actual situation of the squeezing effect of pipe pile.