Abstract：Abstract: Research purposes: This paper presents a case of the slurry shield of Beijing underground straight rail transit line. Aiming at mud preparation and mud membrane formation for large - diameter sli^rry shields driving in sandy cobble ground in Beijing，laboratory tests were conducted to examine the influence factors of sli^rry characters. Moreover，mud seepage discharge，pore water pressure，impermeability of mud membrane，and distance of sli^rry infiltration，were used for analyzing and evaluating of tlie effect of experimental mud fluids. Research conclusions:(1 ) It is feasilDle to adopt polyacrylamide， mixed metal hydroxide in combination witli sodium carboxy methyl cellulose as mud additive. (2) The prepared HPRT had a significant effect on face stability and dregs transportation，while the formation time of mud membrane was not immediately obvious. (3) The "Type 3" mud fluid of oil field in north China，which was the optimal mud type for slurry shields driving in sandy cobble ground in Beijing， was conductive to plugging formation porous，reducing filtration of water. In addition，the anti - permeability of prepared mud membrane was obviously preferable. (4) The research results can provide a valuable reference for t!ie engineering construction of similar slurry shields driving in sandy cobble ground.
2017, Vol. 34 
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