Abstract: As the Nanjing Jiangbei New District is designated as a state-level new district, the development and construction of Yongjiang new Jiangbei main city has become one of the major projects in Nanjing’s urban development. The Linjiang stratum is a typical Yangtze River floodplain dual structure stratum, with the upper part of 20 m~30 m soft silty soil and the lower part of deeply deposited saturated fine sand, medium coarse sand and gravel sand with artesian high groundwater head, which has a great influence on the deep excavation projects. The high-pressure artesian groundwater is easily inducing the water intrusion hazard in deep excavation projects, which results in great economic losses to owners and the society. Based on a successful case history of mitigating a deep and large excavation intrusion in Jiangbei New District, different emergency treatment methods are adopted according to the different volumes of the intrusions in the excavated area. The mitigation results are summarized to provide technical reference for the similar engineering projects, especially in the Yangtze River floodplain areas.

Key words: Artesian Groundwater, Groundwater Intrusion at Deep Excavation, Double Liquid Grout, Steel Casing Balanced Water Pressure Method, Stepping Artesian Pressure Releasing