筋箍碎石桩复合地基极限承载力计算

Calculation of ultimate bearing capacity of composite foundation with geosynthetic encased stone columns

基于弹性力学与弹塑性土力学理论,本文分析了受荷时碎石桩桩体的空间应力应变分布,在Brauns法基础上综合考虑筋材及桩侧土体围限力,桩土自重及桩土接触面剪切力对桩体承载力影响,根据极限平衡理论,推导出筋箍碎石桩极限承载力计算公式。引入现场试验与某工程实例,将本文计算与其他方法计算结果进行对比,对于普通碎石的计算结果两者较为接近,对于筋箍碎石桩,本文方法所得计算结果较实测值更为接近,这表明本文方法可为工程实践提供参考,最后在算例基础上,分别讨论了桩土接触面的剪切力、桩径、筋材强度对筋箍碎石桩极限承载力的影响。

According to the soil mechanics theory and elastic-plastic mechanics theory, the distribution of the stresses and strain of stone column is analyzed in this paper. Through improving the Brauns method, the combined effects of the horizontal confined force of the geosynthetic and soil, the self weight of the soil and column and the friction on the interface between the soil and column on the bearing capacity of the geosynthetic encased stone columns are considered. The formula for calculating the ultimate bearing capacity of the geosynthetic encased column is deduced with the ultimate equilibrium method. Practical calculation and comparison with the measured values and the results of other exiting method indicate that for the common stone columns, the results from the two methods are both close to the measured values, but for the geosynthetic encased stone columns, the method proposed in this paper has higher calculation accuracy. The comparative results indicate that the method proposed can be a reference for design and calculation of the geosynthetic encased stone columns. Based on the practice example, the influence of the friction angle of soil-column, the diameter of column and the tensile strength of geosynthetie on the ultimate bearing capacity of stone columns are discussed respectively.