Research On Construction Technology Of Ultra-Shallow Three-hole Neighborhood Tunnel Across Railway Main Line

With the vigorous development of various infrastructure, interaction of proximity engineering construction became more serious. New diversion tunnel across the railway became an inevitable way, how to ensure the safety of construction and railway operators is a new topic. Tianjin main canal of south-to-north water transfer first stage project which overlapped Beijing-Kowloon Railway was taken as background, in order to analyze surface subsidence control technology, choose excavation methods, ensure construction sequence, analyze dynamic response of train load and mechanical behavior of construction, choose construction assistive measures which were related to the project numerical simulation was used. The following conclusions:(1) By comparing two steps and four step construction method to determine the four steps aside core soil excavation and horizontal cross brace assistive technology measures;(2) by analyzing surface subsidence, initial support displacement, plastic zones and initial support structural stress of different conditions, considering economy, convenience and schedule requirements, determine the construction method of side drift leading 20 m then the center drift;(3) dynamic response of roadbed and lining structure under train loads was revealed;(4) By comparing without tube curtain and reinforcement,only tube curtain and tube curtain +reinforcement+ horizontal support,implementation effect of tube curtain support was studied;(5) Mechanical behavior of construction for the deformation control measures used in three-hole neighborhood tunnels was studied,then key control positions in each steps were ensured.