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Abstract When slurry shield tunneling，slurry pressure can?t be set easily under complex conditions，such as channel erosion of the riverbed. If it wasn?t dealt with carefully，slurry fracturing or even slurry eruption would happen，which had negative effect on project security or led to project accident. In order to observe slurry fracturing propagation phenomenon and analyze its mechanism，in-situ slurry fracturing apparatus was made for the first time and in-situ tests were carried out. Based on these，a slurry fracturing propagation model was established；and a calculation method for upper limitation value of slurry pressure set to prevent slurry fracturing was given. The results suggest that mechanical properties of slurry fracturing propagation are not only related to stratum properties，but also related to the chosen slurry properties. When properties of stratum can?t be changed easily，increasing slurry bulk density and viscosity is beneficial to prevent slurry fracturing propagation during tunnel excavation. The phenomenon of slurry pressure reduction after slurry fracturing is beneficial to prevent slurry fracturing propagation. The slurry pressure should not be increased hurriedly after it becomes lower because of slurry fracturing；otherwise，not only the slurry pressure couldn?t be added，but also it leads to slurry fracture stretch more quickly，which speed up slurry eruption. Anti-fracturing ability of slurry and stratum would mostly become smaller and smaller during slurry fracturing propagation. Therefore，the first step to prevent slurry eruption is to prevent slurry fracturing；and the upper value of slurry pressure should be limited.
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Received: 24 October 2012
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2013, Vol. 32 
