针对复合地层下极小半径超大直径盾构隧道施工的技术问题，以珠三角城际轨道交通广州琶洲站至贝岗公园站隧道工程为研究对象，详细阐述盾构掘进的关键施工技术，提出因曲线半径小而掘进轴线向外偏移和掘进引起的地面沉降等问题的解决方法，并且通过分析现场的实时监测数据，揭示了小半径盾构隧道施工时土体竖向及水平位移、孔隙水压力和土压力的变化规律。监测数据表明：在岩层中盾构机的转弯段掘进对地表沉降影响较小；盾构施工对周围土体的影响随距离增大而减小，最大水平位移出现在隧道上方区域；孔隙水压力和土压力的变化趋势有较高的相似性，盾构转弯时对外侧土体影响更大。

Considering the technical issues related to the construction of extremely small radius and ultra large diameter shield tunnels in stratified strata, taking the shield tunnel project of the Pazhou Station to Beigang Park Station section of the Pearl River Delta intercity rail transit in Guangzhou as the research object, key construction technologies of shield excavation were elaborated in detail. Solutions to outward deviation of the excavation axis because of the small curve radius and strata disturbance caused by the excavation were provided. Built upon the analysis of on-site real-time monitoring data, variation patterns of vertical and horizontal displacements, pore water pressure and soil pressure during the construction of the small radius shield tunnel were revealed. Monitoring data shows that the shield excavation of the turning section in rock layers has little impact on surface settlements. The influence of shield tunneling on the surrounding soil decreases with the increasing distance, the maximum horizontal displacements occur in the area above the tunnel. There is a high similarity in the changing trend of pore pressure and soil pressure and the impact on the soil outside the turning is greater when the shield turns.