Abstract:

aking the key construction technology for the large diameter slurry shield tunneling in waterrich sandy gravel strata in Beijing rail underground transit line as an example, the author analyzes the key technologies such as type selection of shield machines, reinforcement of strata for shield launching, boring parameter control, slurry treatment and cutting tool replacing under hyperbaric conditions. The conclusions drawn are as follows: 1) The optimization of the cutter head and the boring parameters is studied and rational boring parameters and cutting tool arrangement are determined, which minimizes the wearing of the cutting tools and the influence on the environment and ensures the construction safety; 2) The settlement is fully monitored and the monitoring results are timely fed back, which ensures the construction safety; 3) The airtightness during the cutting tool replacement under hyperbaric conditions in sandy gravel strata is ensured, which minimizes the influence on the surrounding environment and residents; A hollow pile is installed to facilitate the cutting tool replacement so as to avoid hyperbaric operations, which minimizes the hyperbaric operation risks; 4) Carbide cutting tools are used, which improves the percussionresistant capability and wearresistant capability of the cutting tools and the surrounding scraping tools; the disc cutters break the strata effectively, which minimizes the abnormal failure of the cutting tools and ensures the successful boring.

Key words: busy urban area, waterrich sandy gravel strata, large diameter slurry shield, tunnel construction