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柱孔扩张理论广泛用于旁压试验机制分析、沉桩挤土效应等岩土工程问题中。基于经典的Vesic孔扩张理论,采用能够考虑中主应力效应的广义SMP屈服准则,并结合有限应变理论对均质土体中柱孔扩张问题进行分析,根据应力路径假设提出确定塑性区平均体应变的解析步骤。通过大量变参数计算给出具有不同刚度指标r I、泊松比和内摩擦角的土中柱孔扩张极限状态下的塑性区平均体应变、孔扩张半径比和孔扩张系数。分析结果表明,r I、、越大,塑性区平均体应变越小,塑性区半径比越大,孔扩张系数越大;随着r I增加,的变化对孔扩张系数的影响更显著。同时,将结果与基于Mohr-Coulomb准则的孔扩张解答进行比较,探讨不同土性参数时中主应力效应对孔扩张系数的影响。文中分析方法及给出的考虑中主应力效应的柱孔扩张系数表可为原位试验分析及桩侧摩阻力估算提供参考。
The theory of column hole expansion is widely used in the geotechnical engineering problems such as the analysis of the mechanism of the pressure test, the pile squeezing effect and so on. Based on the classical Vesic pore expansion theory, the generalized SMP yield criterion considering the effect of intermediate principal stress and the finite strain theory are used to analyze the expansion of column bore in homogeneous soil. According to the stress path assumption, the average body strain The analytical steps. A large number of variable parameters are used to calculate the average body strain, the ratio of hole expansion radius and the hole expansion coefficient in plastic zone under the expansion limit of soil column holes with different stiffness indexes r I, Poisson’s ratio and internal friction angle. The results show that the larger the r I ,, the smaller the average body strain of the plastic zone, the larger the plastic zone radius ratio, the larger the pore expansion coefficient; the more the r I increases, the more pronounced the pore expansion coefficient. At the same time, the results are compared with pore expansion solutions based on the Mohr-Coulomb criterion to investigate the effect of the main stress effect on pore expansion coefficient under different soil parameters. The method of analysis and the table of dilatancy coefficient of column hole considering the effect of principal stress given in this paper can provide reference for in-situ test analysis and estimation of friction on pile side.