To determine the law of gas migration in the process
of tunnel excavation in a highgas area of complex coal strata, a
thermalhydrologicalmechanical
(THM) coupling model of gas permeability based on the mechanism of multiple
physical fields is derived. The characteristics of gas migration over time are
discussed. The results show the following. (1) The gas pressure decreasing
speed decreases with increasing distance from the tunnel face, and the gas
decreasing speed is highest at the tunnel face. The pressure field reaches a
new balance after 20 hours, and the greater the distance from the tunnel face,
the more time is needed for gas pressure to reach a new balance. (2) The
porosity of the rock mass shows a decreasing trend overall. The rock mass
porosity clearly decreases in 10 hours, and the decreasing amplitude decreases
and time for balance increases with increasing distance from the tunnel face.
(3) When the coal seam has not been excavated, the gas pressure ahead of the
tunnel face is relatively low, and the gas pressure decreases rapidly in 15
hours; the gas pressure varies at different distances from the tunnel face, and
it reaches a new balance after 40 hours.
YANG Benwei
,
CHEN Xiang
,
LIN Zhi
,
YANG Hongyun
,
ZHENG Enshu
,
ZHAO Tianwei
. Research on Gas Migration Law in a Fractured Rock Mass
under Coupling Action of Multiple Physical Fields[J]. Tunnel Construction, 2021
, 41(3)
: 388
-395
.
DOI: 10.3973/j.issn.2096-4498.2021.03.006
