Abstract: Shield tunneling is one of the popular construction methods for tunnels in soft ground in urban area. However, accidents often occur in shield launching and arriving due to the stability problem of the end soil. The unstability of the end soil is a main risk in shield launching and arrival. Relevant engineering data and study results are summarized and analyzed in the paper. Conclusions drawn are as follows: 1) An end soil reinforcement database is proposed for shield launching and arrival, and automatic selection of the end soil reinforcement methods is realized. 2) Analysis and judgment are made on the stability of each soil layer on basis of the characteristics and parameters of the soil strata, considering the water condition and the nonwater condition. 3) A judgment method for the comprehensive stability of the end soil in shield launching and arrival is proposed, on basis of analysis and judgment on the stability of each soil layer.

Key words: shield tunneling, launching and arrival, reinforcement method, stability