Abstract: This paper presents a case history of the shielded tunnel excavation of Xi’an Metro No. 6 Line undercrossing the historical Xi’an City Wall at Anding Gate. This project was characterized as complicated surface conditions and undercrossing many historical structures. The subsurface soils of City Wall at the gate were reinforced with Sleeve-Value and Pipe grouting method based on the site geological and hydrological conditions. The grouting reinforcement process was numerically simulated by a commercial geotechnical engineering finite element analysis software MIDAS GTS NX. The results indicate that, for the vertical settlement control purposes, the two rows of sleeve pipes with 1.0 meter square spacing was very effective for the reinforcement depths between 2 and 10 meters below the ground surface. The soil improvement is currently under construction, this construction monitoring data will provide a project reference for the similar constructions.

Key words: historical buildings, sleevevalvepipe grouting method, foundation reinforcement, numerical analysis, vertical settlement