Abstract:

The airtightness of filter cake of Paste HDN when opening the chamber under pressure is analyzed by laboratory test and theoretical calculation. The analytical results show that: (1) The proportion of free water in the filter cake of Paste HDNwith 3day age is about 10%. (2) Under the pressure of 0.292 MPa, 1.7% of the pore size of the filter cake of Paste HDN with 1∶2 of mudwater ratio of improved clay slurry, 1/20 of plasticizer injection amount and 3day of filming age may leak. (3) The are permeation coefficient the filter cake of Paste HDN rangesfrom 10-8 cm3/s to 10-7 cm3/s, which is 2-3 m3/h when converting to tunnel excavation crosssection with diameter of 6m; and the air compressor can fully meet the airsupply requirements.

Key words: Paste HDN, chamber opening under pressure, seepage gas volume, seepage gas coefficient, filter cake airtightness