The oxidation and spontaneous combustion of water immersion coal threatens the mine safety production after experiencing water evacuation in the underground goaf. The weathering effect creates disparate water content in coal that results in the distinct oxidation process. This paper investigates the immersion coal pore evolution and oxygen adsorption behavior at different water contents from the molecular dynamics perspective. Proximate analysis, ultimate analysis, ¹³C NMR spectrum research, and XPS spectrum were used to construct the macromolecular coal model. There is a double-peak behavior for the water immersion coal porosity and specific surface area. The maximum porosity of water immersion coal was 25.7% and 28.9% arising at 5.9% and 10.2% water content, respectively. The adsorption loading and average oxygen adsorption density both exhibited the rise-decline-rise-decline trend with two remarkable peaks presented at the same site. The two peaks possessed the lowest oxygen adsorption total energy level of − 23.37 and − 21.73 kcal/mol. Temperature rise trial was conducted to evaluate and verify the double-peak characterization of the water immersion coal at the low-temperature oxidation stage. The temperature rising rate versus the heating time of higher water content slowed down at an elevated water bath temperature. There were two maximum immersion coal temperatures, 85.52 and 85.66 °C, with optimum water content of 6.0% and 12.0%, respectively, at the stabilization stage. The obtained achievement of the crucial optimum water content has important theoretical guiding significance for the scientific prevention of the water immersion coal oxidation spontaneous combustion disaster in an underground goaf.

水浸煤在井下采空区抽水后，氧化自燃威胁矿山安全生产。风化作用使煤中的水含量不同，从而导致明显的氧化过程。本文从分子动力学角度研究了不同含水量下浸没煤孔隙演化和氧吸附行为。采用工业分析、元素分析、^{13 C NMR谱研究和XPS谱来构建煤大分子模型。}水浸煤孔隙率和比表面积存在双峰行为。水浸煤的最大孔隙率在含水量5.9%和10.2%时分别为25.7%和28.9%。吸附负荷和平均氧吸附密度均呈现上升-下降-上升-下降的趋势，并在同一位点出现两个显着的峰。这两个峰具有最低的氧吸附总能级，分别为-23.37和-21.73 kcal/mol。通过温升试验来评价和验证水浸煤低温氧化阶段的双峰特性。当水浴温度升高时，较高含水量的升温速率与加热时间的关系变慢。稳定阶段存在两个最高浸煤温度，分别为85.52℃和85.66℃，最佳含水量分别为6.0%和12.0%。关键最佳含水量的取得对于科学防治地下采空区水浸煤氧化自燃灾害具有重要的理论指导意义。