Discussion on mechanism of strength deterioration of water immersion coal samples and optimization method of retaining formula for waterproof coal pillars
XU Xiangyu
HUANGFU Mengna
MA Mengting
LI Dongchen
GUO Yongqiang
XU Zhimin
Abstract：The retention of waterproof coal pillar is one of the effective measures to prevent and control the problem of coal mine goaf water damage,in order to consider the influence of long-term water immersion and instability of coal pillar on the safe retention size of waterproof coal pillar,and to further improve the safety of waterproof coal pillar.Taking the North China type coalfield as the background of the study,and based on the simulation of immersion test measured data,the strength damage law of the coal pillar was analyzed when it was immersed in water,and the intrinsic causes of the strength damage and the factors affecting the damage were investigated.The re-sults show that the compressive strength of coal pillars under different immersion environments is reduced with the extension of immer-sion time,and eventually tends to be stable;the relationship between tensile strength and immersion time shows different patterns of change under different immersion conditions,the deionized water immersion conditions are still decreasing and tends to be stable trend,in the high mineralisation of the mine water environment,there is a critical value,and in the breakthrough of the critical value after the trend of decreasing again.The factors affecting the stability of coal pillars include the nature of coal rock body,soaking time,and the hydrochemical characteristics of the soaking solution,among which the soaking time is one of the main influencing factors.Combined with the measured data and the above analyses,the softening factor of coal pillar was introduced to limit the tensile strength in the em-pirical formula from a safer point of view,and the retaining formula of the waterproof coal pillar was amended to:L=0.5KM√3P/RtKp.
Keywords：waterproof coal pillarsoaking teststrength damagewater-rock reactionformula correction
Publication Date：2024-10-28
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：7( 56-62 )