路堤下粉喷桩复合地基的设计方法探讨

Disscussion on design method of DJM-pile compound grounds for enbankment

通过有限元计算,讨论了采用粉喷桩处理饱和黄土与淤泥质土所形成的复合地基,在柔性基础作用下,基础刚度及复合地基中的桩体对复合地基承载力的影响。结果表明:减小基础刚度有利于桩间土体承载力的发挥;桩体对饱和黄土承载力的影响程度大于对淤泥质土体承载力的影响程度。最后依据实测及有限元分析结果,在原有刚性基础下粉喷桩复合地基承载力计算公式的基础上,增加了基础刚度影响系数与桩间土体承载力提高系数,给出了各影响系数的建议取值范围,并在实际工程中得到了成功应用。

Through FEM calculations, this paper discusses the influence of foundation rigidity and pile shafts on the bearing capacity of the composite ground of saturated loess and mucky soil with deep mixing cement piles under a flexible foundation. The results indicate that reducing foundation rigidity is beneficial to the beating capacity of the soil between the piles, and that the degree of influence of pile shafts on the beating capacity of saturated loess is larger than that of mucky soil. Finally, on the basis of the formula to calculate the bearing capacity of compound grounds reinforced with deep jet cement piles under a rigid foundation, two coefficients-foundation rigidity coefficient and soil beating capacity coefficient are proposed according to the in-situ testing results and FEM calculation results; mean while, the value ranges of those new affecting coefficients are suggested. The formula proposed in this paper have been successfully applied in real projects.