干旱区露天煤矿外排土场重构包气带上层滞水毛细作用机制

The outer drainage field of the open-pit coal mine in arid area reconstructs the mechanism of action of the upper layer of the gas-laden belt

旱区露天矿外排土场土壤结构松散,且含大量块石,土壤孔隙大、渗透性强、保水性差,无法对植物根部进行有效的水分补给。为了提高植物对水分的吸收利用效率,提出重构外排土场土壤包气带,利用土壤毛细作用为植物根部进行水分补给。土壤压实度是影响土壤毛细作用的重要影响因素,为了研究土壤压实度对毛细作用影响规律,以外排土场土壤作为样本,测定最大干密度及最佳含水率,采用竖向毛细管试验,制定3组不同压实度试验方案,分别为90%、93%与96%,采用物理试验对不同压实度下土壤毛细水上升高度及速度进行监测,获得不同压实度下毛细水上升速率及速度变化趋势,依据非饱和土壤动力学,结合毛细试验原理,建立土壤毛细水上升模型,并结合多物理瞬态模拟原理,采用Comsol软件建立同物理模拟相同方案数值模型对物理模拟的毛细水上升高度及速度进行验证。结合3组不同压实度方案,进行了室内植物下部给水种植试验,探究了毛细水作用下利于植物生长的最优土壤压实度。研究结果表明:不同压实度下,土壤毛细水上升速率存在显著差异,压实度与毛细水上升速率成负相关;数值模拟与实测值具有较好的一致性,相同时间内,毛细水上升高度与压实度成反比关系;土壤压实度为93%时,植物长势及存活率均为最优。

In the open-pit mining waste dumps in arid areas,the soil structure is loose and contains a large number of rocks and boulders.The soil pores are large,the permeability is strong,and the water retention capacity is poor,making it difficult to effectively supply water to plant roots.To improve the efficiency of water absorption and utilization by plants,a proposal was made to reconstruct the soil aerated zone of the waste dump and use soil capillary action to supply water to plant roots.Soil compaction is an important factor affecting soil capillary action.To study the influence of soil compaction on capillary action,the maximum dry density and optimal water content of the waste dump soil were determined,and three groups of different compaction test schemes were formulated,which were 90%,93%and 96%,respectively.Physical tests were used to monitor the height and speed of capillary water rise under different compaction degrees.Based on unsaturated soil dynamics and capillary test principles,a model of soil capillary water rise was established,and a numerical model with the same physical simulation scheme was established using comsol software to verify the height and speed of capillary water rise under physical simulation.Indoor planting experiments were conducted with different compaction schemes to explore the optimal soil compaction degree for plant growth under capillary water action.The results showed that there were significant differences in the rate of capillary water rise under different compaction degrees,and the compaction degree was negatively correlated with the rate of capillary water rise.The numerical simulation had good consistency with the measured values,and the height of capillary water rise was inversely proportional to the compaction degree for the same time.When the soil compaction degree was 93%,the plant growth and survival rate were optimal.