煤矸石组分与表土质地对充填重构土壤导气率的影响

研究煤矸石组分及表土质地对煤矸石重构土壤导气率的影响,探讨重构土壤这种差异显著的非均质土壤导气内在机理,为进一步研究复杂的非均质土壤导气特性提供理论基础。通过在煤矸石中掺杂不同粒径碎石来改变其组分,并利用3种不同质地的土壤在土柱内进行土壤剖面重构,采用一维瞬态法测量其导气率。结果表明:(1)不同碎石粒径和质量分数对混合基质饱和含水量影响不同,掺杂2~5mm粒径碎石,随着质量分数的增加,饱和含水量逐渐增加,从7.29%增加到12.9%;掺杂5~10mm粒径碎石,饱和含水量随着质量分数的增加先增加后减少,分别为7.28%,8.5%,6.9%。(2)煤矸石的导气率远大于土壤,并且煤矸石的导气率对水分的敏感度随质量含水量的增加而增加,而土壤的导气率对水分变化的敏感度均随质量含水量的增加而降低。(3)碎石的存在为大孔隙的产生创造条件的同时也会减少了土壤通气断面,阻隔空气传输的通道。(4)重构土壤导气率受表土质地和底部填充介质的共同影响,覆土土壤导气率决定了重构土壤的导气率大小,而充填基质导气率决定了充填介质对重构土壤导气率影响的系数(Ska)。Ska与充填介质导气率呈显著相关,可以通过指数函数进行拟合(R2=0.93)。通过充填介质及覆土土壤的导气率可以对重构土壤导气率进行估算,简化了重构土壤导气率的测定过程。

The Effects of Coal Gangue Composition and Surface Soil Texture on the Air Permeability in Reconstruction Soil Filled with Coal Gangue

In order to investigate the mechanism of non-homogeneous soil air permeability in reconstruction soil and provide a theoretical basis for further studies of the characteristics of complex heterogeneous soil, the effects of coal gangue composition and topsoil texture on air permeability of reconstruction soil were studied. The coal gangue was mixed with different particle size gravel to change its composition, the soils were reconstructed by using three different soils in the soil column, and the air permeability was measured by one-dimensional transient method. The results showed that the influence of particle size and mass fraction of different gravel on saturated mass water content of mixed matrix was different. The saturated mass water content was increased gradually from 7.29% to 12.9% with 2~5 mm particle size gravel increasing. The saturated mass water content was increased first and then decreased with the mass fraction increasing of 5~10 mm particle size gravel, which were 7.28%, 8.5% and 6.9% respectively. The air permeability of coal gangue was much larger than that of soil, and the sensitivity of coal gangue to mass water content was increased with the mass water content increasing, while the sensitivity of soil was decreased with the mass water content increasing. The presence of gravel created an advantage for the formation of large pores and reduced the soil ventilation section to block the air transmission channel. The air permeability of reconstruction soil was influenced by topsoil texture and bottom filling matrix. The air permeability of reconstruction soil depended on topsoil permeability, and the air permeability of bottom filling matrix determined the influence coefficient of filling matrix on the air permeability of reconstructed soil (S_ka). S_ka had a significant correlation with the filling matrix permeability, which could be fitted by an exponential function (R²=0.93). The air permeability of reconstructed soil could be estimated by topsoil and filling matrix air permeability, which simplified the air permeability determination process of reconstruction soil.