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将柱孔周围土体中的应力分布分为弹性区和塑性区,在弹性区中采用小变形理论,在塑性区中采用大变形理论和统一强度准则。根据柱孔扩张问题排水条件时的应力平衡方程、应力和应变连续的边界条件,推导出考虑土体剪胀、大变形、排水条件和中主应力等因素的柱孔扩张问题塑性区半径和极限扩孔压力的理论解答,同时也获得了弹塑性区中的应力和应变场分布规律。理论计算结果与现场实测结果较为接近,初步说明该理论具有一定的工程应用价值。对比分析表明:扩孔压力和塑性区半径受土体剪胀的影响要比b值显著。
The stress distribution in the soil around the column hole is divided into elastic zone and plastic zone, small deformation theory is used in elastic zone, large deformation theory and unified strength criterion are adopted in plastic zone. According to the stress balance equation and the continuous stress and strain boundary conditions for the drainage condition of column hole expansion, the radius and the limit of the plastic zone expansion are derived considering the dilatancy, large deformation, drainage conditions and intermediate principal stress Theoretical solution to the pressure of expanding the hole and the distribution of stress and strain field in the elastic-plastic zone are also obtained. The result of theoretical calculation is close to the field measurement, which shows that the theory has a certain engineering application value. The comparative analysis shows that the expansion pressure and the radius of plastic zone are more affected by soil dilatancy than b.