Abstract: The use of lateral shieldlaunching technology for a doubletrack tunnel in a main metro line without trenches that will allow doubletrack shield launching and simultaneous driving in a complex environment is discussed by taking the NiujieJinrongjie section of Beijing metro line 19 as an example. Based on an analysis of the control conditions of shield laterallaunching technology, a compositemined singlechannel structure that combines a largespan pilebeamarch shieldlaunching crosspassage, an premined section, and a grounding section is studied. A system for independent doubletrack shield launching and simultaneous driving is established, and a technical scheme for lateral launching of the shield that has a flexible layout, occupies a limited amount of land, and is associated with a controllable environmental safety risk is developed. In addition, based on key technical factors such as the construction sequence for the composite structure, the mining excavation method, advance support measures, stratum reinforcement measures, etc.〖KG-*3〗, a stratumstructure numerical simulation model that can be used to predict and analyze the structural and environmental risks of the composite singlechannel structure and to verify the safety and feasibility of the technical scheme is established.

Key words: lateral launching of double , track shield tunnel, mined single , channel with composite structure, environmental risk forecast