大型石化 CFG 桩复合地基三维有限差分模拟

摘要

CFG piles are more and more widely used in foundation treatment engineering.Currently,soft-soil foundation treatment in large petrochemical project is very complex.In such condition,one 3D finite difference model was built.The stress and deformation behaviors of CFG composite foundation under different pile spacing condition were analyzed in detail.The effect of soft soil interlayer was also investigated.Based on the effect a-nalysis of reinforcement depth,the critical reinforcement depth of different foundation size was obtained.Be-sides,variable rigidity leveling of composite foundation was carried out by variable pile length or spacing meth-od.Some conclusions have been drawn.The relationship between foundation settlement or settlement difference and loading is linear type.CFG pile of the 1 /3 diameter zone outside two sides can be optimized by variable pile length or spacing method.When soil among CFG piles is not reinforced,the pile spacing should not be larger than 6d.If the burial depth of soft soil interlayer is large than 10 m,the effect can be ignored.the critical rein-forcement depth of different foundation size is about 6 m.The foundation settlement or settlement difference can be controlled by variable pile length or spacing method,and suitable method should be chosen for geotechnical and engineering condition.%针对大型石化工程软土地基处理的复杂性，建立了 CFG 复合地基的三维有限差分模型，详细分析了不同桩间距下复合地基受力和变形特性，探讨了软土夹层对复合地基的影响，在桩间土加固深度影响分析的基础上，获得了不同基础尺寸的临界加固深度。此外，通过变桩长和变桩距方法，对复合地基进行了变刚度调平。研究表明：基础沉降和差异沉降与荷载成线性关系，基础两侧约1／3直径范围内 CFG 桩可采用变桩长或变桩距方法优化；桩间土体不加固时，桩间距不宜大于6d；软土夹层埋深10 m 以上，其对CFG 复合桩基的影响基本可忽略；不同基础尺寸下临界加固深度约为6 m；变桩长或桩距方法均能控制基础沉降和差异，但需根据工程条件和实际地质情况合理选用。