The stability of air pressure in shield chamber during
tunneling under "air pressure mode" and chamber opening under
pressure should be guaranteed. Hence, the air pressure loose zones in 4 areas
of soil in front of cutterhead, soil around the excavation gap, grouting area
in shield tail and screw conveyor are analyzed, the Krabbe formula is improved,
and based on which a semiempirical and semitheoretical calculation method of air loss Q is proposed by considering the permeability coefficient, earth
chamber pressure and soil variation. The calculation method is applied to
practical engineering, and the following conclusions are drawn by sensitivity
analysis of the crosssection with the largest air
loss: (1) There is a quadratic positive correlation between chamber pressure
and air pressure loss, and the increase in air pressure within the scope of the
project will result in a certain volumn of air loss. (2) The crosssection with the largest volumn of air loss locates in formation
abrupt change area, and by carrying out sensitivity analysis on this crosssection, the power of air compressor equipped on shield can be
reasonably judged.
YANG Zhiyong
,
YANG Xing
,
QI Weiqiang
,
JIANG Yusheng
,
AN Hongbin
. Calculation and Influencing Factors of Air Loss in
Shield Chamber[J]. Tunnel Construction, 2020
, 40(8)
: 1147
-1153
.
DOI: 10.3973/j.issn.2096-4498.2020.08.006
