新建盾构隧道下穿既有地铁线路施工时会引发交汇段地表沉降叠加，对既有地铁线路运营安全产生威胁。文章以深圳地铁9号线梅村—上梅林区间盾构施工为例，针对盾构在近始发端头下穿施工时存在的建压困难、沉降控制难度大、施工安全风险高等难题，采用了始发段钢套筒保压、克泥效充填盾构间隙、辅助注浆纠偏、风险分区管理、自动化实时监测以及理论分析等综合技术措施及管理手段，顺利通过了既有地铁线路下穿段。%The construction of a new shield tunnel passing under the existing metro line often causes a superimposi⁃tion of surface settlement at the intersection area, which threatens the operating safety of the existing line. Based on shield tunnel construction from the Meicun station to the Shangmeilin station of Shenzhen Metro Line 9, this paper addresses the problems of earth-pressure build-up, settlement control and construction safety risks involved with the construction of an underpass adjacent to the shield launching end by using comprehensive technical construc⁃tion measures and management means. These include:pressure maintenance using a steel sleeve at launching sec⁃tion, shield gap filling by the clay shock method, auxiliary grouting rectification, risk-zoning management, automat⁃ic real-time monitoring and theoretical analysis. These measures help to ensure the smooth construction of a shield tunnel under an existing metro line.
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