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The inherent properties of soft coal seams and their mechanical environment make long boreholes susceptible to issues like collapse, deformation, and blockages. These problems shorten the service life of the boreholes and hinder extraction efficiency. This paper tackles these challenges by analyzing the deformation and damage patterns of long boreholes in soft coal seams. It examines the stress distribution and deformation characteristics around both protected and unprotected boreholes at different burial depths. Additionally, it recommends using screen pipe protection technology to improve gas extraction and mining operations, as demonstrated in Changping Coal Mine. The results show that screen pipe protection substantially improves the stress distribution and deformation stability of coal seam boreholes. The flow attenuation coefficients of two boreholes equipped with protection technology decreased by 48% and 61%. After 50 days of extraction from boreholes with a protection rate exceeding 90%, gas concentration remained above 50%, which is 2.59 times higher than that of unprotected boreholes. This technology effectively addresses the frequent accidents, poor extraction performance, and inefficiency of long boreholes in soft coal seams, ensuring the mine's safe and efficient production. [ABSTRACT FROM AUTHOR]

Context To investigate the impact of moisture on gas adsorption in gas-fat coal, Shanxi gas-fat coal was chosen as the research subject. The Adsorption module within molecular simulation software was utilized to construct gas-fat coal models with moisture contents of 0%, 1.14%, 2.26%, and 3.72%. The results revealed that the isothermal adsorption curves of gas-fat coal under different moisture contents all followed the Langmuir adsorption curve (Type Ι), wherein the Langmuir volume of gas-fat coal was most sensitive to changes in moisture content within the range of 0 to 1.14%. A linear equation was found to better characterize the influence of moisture on gas content in Shanxi gas-fat coal, represented by the formula η = 1/(1 + 1.98078w), where, η represents the moisture impact coefficient; w is the moisture content; 1.98078 is the coefficient of moisture influence of Shanxi gasifier coal. Coupled with changes in the surface free energy of gas-fat coal, the pressure exerted a positive effect on the adsorption of gas on the coal surface, enhancing the adsorption space of methane within gas-fat coal. Methods Using Materials Studio software, the adsorption capacity and adsorption heat of methane were computed at various temperatures (323 K, 333 K, 343 K) and pressures (0.5–8 MPa). Furthermore, a comparative analysis was conducted to assess the applicability of classical linear equations, linear equations, power function equations, and exponential function equations in quantitatively characterizing the influence of moisture. [ABSTRACT FROM AUTHOR]