Abstract: As a new foundation improvement method, the micro grouted piles can achieve the consolidation, grouting and reinforcement improvement of soft soils. It has been widely applied in soft soil areas such as Shanghai and Changshu. Due to the reinforcement factors interact with each other, and the mechanism of pile-soil interaction is complex, the settlement estimation method has not been reported. Based on a trial project of the Changshu Yaopi project, the deformation estimation method of the composite ground, composite foundation with settlement reduction piles and the pile-net composite foundation are used to analyze the total settlement under the upper structure loads. The unimproved natural foundation loading spreading model is used to estimate the total settlement caused by the dewatering effect. The surcharging settlement of the dewatering is estimated based on the Terzaghi consolidation theory. Then the settlement estimation method of the micro grouted pile composite foundation is proposed. On this basis, combined with the typical soil layer conditions, the influence of factors, such as dewatering depth, duration, service load and ratio of the dewatering depth to the service load, on the settlement are analyzed.

Key words: Ground Improvement, Dewatering, PreConsolidation Settlement, Composite Ground, Pile Pattern