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Study on the influence of freezing temperature and gas pressure on coal frost heaving effect

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Physics of Fluids
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Yanqi Chen
Yanqi Chen
Yanqi Chen
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Wang Zhaofeng at Henan Polytechnic University
Wang Zhaofeng
Shujun Ma
Shujun Ma
Shujun Ma
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Daopeng Fan
Daopeng Fan
Daopeng Fan
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Abstract and Figures

As China's coal mining gradually enters the deep stage, the difficulty of coal and gas outburst prevention and control is increasing. Low-temperature freezing technology has the dual effects of reducing coal seam storage energy and improving coal mass strength and has received widespread attention in the coal mining industry in recent years. When freezing water-bearing coal, frost heave occurs inside the coal mass, which reduces coal mass strength and then affects the application effect of cryogenic outburst prevention technology. In order to investigate the influence mechanism of freezing temperature and gas pressure on the frost heave effect of the coal mass profoundly, the water-bearing gas-containing coal freezing and cooling test was carried out using the self-developed gas-containing coal freezing and cooling test platform. The change rule of the temperature and strain of the coal mass was analyzed during the freezing process. The research results indicate that both freezing temperature and gas pressure impact the frost heave effect of coal. When the freezing temperature is below −10 °C, there is an exponential relationship between the frost heave strain generated by coal and the freezing temperature. When the equilibrium pressure of gas adsorption is less than or equal to 1.5 MPa, there is a linear positive correlation between the frost heave strain generated by coal during the freezing process and the gas pressure. In engineering applications, measures can be taken to reduce the freezing temperature and gas pressure to minimize the amount of coal frost heave strain. However, the freezing temperature should not be lower than −20 °C.
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Study on the influence of freezing temperature
and gas pressure on coal frost heaving effect
Cite as: Phys. Fluids 37, 047120 (2025); doi: 10.1063/5.0268183
Submitted: 28 February 2025 .Accepted: 20 March 2025 .
Published Online: 7 April 2025
Yanqi Chen (陈彦齐),
1
Zhaofeng Wang (王兆丰),
1,2,3,a)
Shujun Ma (马树俊),
1,a)
Daopeng Fan (范道鹏),
1
Yongxin Sun (孙永鑫),
1
and Liguo Wang (王立国)
1,2,3
AFFILIATIONS
1
College of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, China
2
Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization, Henan Polytechnic University,
Jiaozuo 454003, China
3
MOE Engineering Research Center of Coal Mine Disaster Prevention and Emergency Rescue, Henan Polytechnic University,
Jiaozuo 454003, China
a)
Authors to whom correspondence should be addressed: zhaofengw@hpu.edu.cn and mashujun@hpu.edu.cn
ABSTRACT
As China’s coal mining gradually enters the deep stage, the difficulty of coal and gas outburst prevention and control is increasing. Low-
temperature freezing technology has the dual effects of reducing coal seam storage energy and improving coal mass strength and has received
widespread attention in the coal mining industry in recent years. When freezing water-bearing coal, frost heave occurs inside the coal mass,
which reduces coal mass strength and then affects the application effect of cryogenic outburst prevention technology. In order to investigate
the influence mechanism of freezing temperature and gas pressure on the frost heave effect of the coal mass profoundly, the water-bearing
gas-containing coal freezing and cooling test was carried out using the self-developed gas-containing coal freezing and cooling test platform.
The change rule of the temperature and strain of the coal mass was analyzed during the freezing process. The research results indicate that
both freezing temperature and gas pressure impact the frost heave effect of coal. When the freezing temperature is below 10 C, there is an
exponential relationship between the frost heave strain generated by coal and the freezing temperature. When the equilibrium pressure of gas
adsorption is less than or equal to 1.5 MPa, there is a linear positive correlation between the frost heave strain generated by coal during the
freezing process and the gas pressure. In engineering applications, measures can be taken to reduce the freezing temperature and gas pressure
to minimize the amount of coal frost heave strain. However, the freezing temperature should not be lower than 20 C.
Published under an exclusive license by AIP Publishing. https://doi.org/10.1063/5.0268183
I. INTRODUCTION
Coal has long dominated China’s national economy as an essen-
tial energy source and raw chemical material. The current depth of
coal mining is increasing at a rate of 10–25 m annually.
1
With the
gradual increase in mining depth, ensuring the safety of coal mining
operations is facing unprecedented challenges, especially in preventing
and controlling coal and gas outbursts in the geological structure zone,
which is becoming increasingly difficult.
2–4
Cryogenic outburst prevention technology, as a new method for
preventing and controlling coal and gas outbursts in stone gates and
geological structural zones, can not only improve gas adsorption
capacity by reducing coal temperature but also achieve the effect of
reducing gas pressure and gas desorption rate.
5,6
At the same time, a
single freezing of coal can also utilize water to bond and break the coal
to improve its strength and resistance to ground pressure.
7,8
Due to its
characteristics of promoting gas adsorption and improving coal mass
strength, the technology has now received widespread attention in the
industry.
However, liquid water undergoes a liquid–solid phase transition,
leading to a volume increase when its temperature is reduced to
around 0 C. This anomalous feature of water is that it is not a liquid
but a liquid and not a solid. This anomalous characteristic of water will
put the coal mass in the process of freezing and cooling. Not only will
the cold shrinkage phenomenon occur, but it will also produce a frost
heave effect. The reason for the occurrence of the cold shrinkage phe-
nomenon is that the temperature of the coal mass continues to fall in
the freezing temperature process, resulting in shrinkage of the coal
mass skeleton by the thermal expansion and contraction; the coal
matrix particles bond contact more closely, the pore structure is com-
pressed. The cold shrinkage phenomenon enhances the microscopic
Phys. Fluids 37, 047120 (2025); doi: 10.1063/5.0268183 37, 047120-1
Published under an exclusive license by AIP Publishing
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