Real-time and accurate measurement of gas concentration at the borehole
outlet is essential for the intelligent management of gas tunnels. Currently,
tunable diode laser absorption spectroscopy (TDLAS), the widely used technique,
suffers from reduced detection accuracy in the complex environments of gas
tunnels. To overcome this limitation, a TDLAS-based
measurement system is developed by integrating wavelength modulation
spectroscopy with a centroid-weighted Lagrange
interpolation compensation algorithm. The system models and corrects
measurement errors caused by fluctuations in gas composition, ambient pressure,
and temperature at the borehole outlet, thereby improving measurement accuracy
and stability under dynamic conditions. System performance is experimentally
validated using standard gas samples. The main findings are: (1) A gas
concentration inversion model based on the Beer-Lambert
law and HITRAN database parameters is established, identifying absorption line
shape function and line strength as the primary factors influencing measurement
accuracy. The Lorentzian function is found to be more suitable under near-atmospheric pressure and dynamically disturbed conditions. (2) To
compensate for line shift and broadening due to temperature and pressure variations,
a centroid-weighted Lagrange interpolation algorithm is
proposed, achieving accurate gas concentration correction under unsteady-state conditions with high numerical stability and adaptability. (3)
Experimental validation using 0.5% and 4.5% standard gases over a temperature
range of 0 － 40 ℃ demonstrates
that the proposed compensation method maintains measurement errors within 0.5%,
significantly outperforming uncompensated measurements. (4) The developed
system enables high-precision, dynamic monitoring of
single-borehole gas concentrations, exhibits strong
environmental adaptability.
LIU Yong
,
YU Dayang
,
ZHANG Huidong
,
CHEN Changjiang
,
HE An
.
Design and Optimization of a Real-Time Gas Concentration Measurement Model for Gas Tunnel Extraction Boreholes
[J]. Tunnel Construction, 2025
, 45(6)
: 1102
-1111
.
DOI: 10.3973/j.issn.2096-4498.2025.06.005
