深厚软土地基上充灌袋围埝下沉计算研究

采用大型充灌袋在深厚软土地基上建造围埝具有节约材料、降低造价、方便施工等优势，因此，在围海造陆中得到了广泛地应用。软弱地基由于承载力不足，且常处于流塑状态，故充灌袋围埝建造时会挤出淤泥而沉入软土中。随着下沉深度增加，围埝两侧的边载也随之增加，围埝基底也逐渐落在承载力较高的土层上，当围埝的重量与地基承载力相等时，围埝停止下沉，达到极限平衡状态。确定围埝达到设计标高时的下沉深度和充灌袋的用量是充灌袋围埝设计的核心问题。利用土体极限平衡理论并考虑隆起淤泥对承载力的影响，推导出充灌袋围埝挤淤深度的计算公式，并通过挤淤的模型试验和现场工程的监测数据来验证公式的合理性和适用性。此研究成果可供充灌袋围埝挤淤深度的设计及相关工程以参考。

A method for caculating penetration of geo-tubes dike resting on deep soft foundation soils

Due to the advantages of the low cost and construction convenience, the geo-tubes are widely used in reclamation projects to build dikes on thick soft soil foundation. As the bearing capacity of soft foundation soil isn’t high enough,and usually the soil is in plastic flow state, the geo-tubes will penetrate into the foundation soils by squeezing out soft soil when geo-tubes dike is built on soft soils. With increasing penetration, the bilateral load applied on geo-tube dike become bigger. When the basal of geo-tube dike lands on the deep soil layers with higher bearing capacity, the weight of the dike approaches the bearing capacity of foundation soil, the penetration will stop, at this time, the soil attains limiting equilibrium condition. In the actual project, it is crucial to estimate the specified penetration at the design stage of constructing a geo-tube dike, and determine the quantity of the geo-tubes. Based on the limit equilibrium concept, in which the weight of dike and the bearing capacity of the foundation soil are balanced, a formula for caculating penetration depth of geo-tubes is deduced by considering the effect of the soil upheaval on the bearing capacity. The rationality and applicability of the formula is validated by model test results and the observed data from practical construction projects. The results can provide reference for the design of penetration of geo-tubes dike.