为了解决盾构在③1粉砂层掘进后地表沉降难以控制的难题，以宁波地铁1号线西门口站—鼓楼站区间盾构施工为背景，分别从地层力学性质和盾构施工情况进行分析，总结出地表沉降变化规律，得出盾构在③1地层掘进后的突变机制，制定了应对措施，有效地控制了地表沉降，并减小盾构施工风险，归纳了盾构在本地区粉砂层中的施工措施。

It is difficult to bring the ground surface settlement under control when the shield is boring in ③1 silty sand strata. The paper is based on the shield boring of XiGu running tunnel on Line 1 of Ningbo Metro. In the paper, the mechanical properties of the strata and the shield boring are analyzed, the rule of the ground surface settlement is summarized, the mechanism of the abrupt ground surface settlement when the shield is boring in ③1 strata is obtained, and countermeasures are proposed. In the end, the ground surface settlement has been brought under effective control and the risks of shield tunneling have been minimized. Furthermore, the measures to be taken when shield is boring in silty sand strata in this area are summarized. 