Simulation of soil water and salt movement in mining ground fissure zone based on HYDRUS

Coal mining brings rapid economic development and also results in a series of ecological and environmental problems. Among them,the ground fissures produced by coal mining subsidence are the most intuitive one. They are widely distributed,destructive to land,and impacting on the growth of surrounding plants. The impact is severe. The sa- linity of the western mine water is relatively high,and secondary salinization is easy to occur. The water and salt migra- tion in the fracture zone has a potential impact on plant growth in the area. In order to study the effect of mining ground fissures on the water and salt transport in soil,this paper used simulated fissure experiments in the laboratory to study the artificial simulation of soil water and salt distribution in the ground fissure area under the different soil salt solubility conditions features. In addition,the numerical simulation software HYDRUS 2D was applied to establish the soil water and salt transport model under the condition of mining ground fissures. The simulation was carried out by using the simulation to compare the measured values with the simulated values. The research results show that HYDRUS simulation values and measured values show the same rules,which meet the accuracy requirements,indica- ting that HYDRUS can better simulate the water and salt migration in the fracture area. In the 56-day simulation test, the soil water content in the cracked area showed a rapid decline period in the first 3 weeks,a moderate-speed decline period in 4 to 5 weeks,and a stable period after 5 weeks. The closer to the ground fissure,the faster the soil water con- tent decreases. The ground fissures can reduce the surrounding soil moisture content and accelerate the loss of soil wa- ter. For ground fissures with 20 cm steps,the impact range is about 45 cm away from the fissures. The soil salt move- ment trend in the ground fissure area is basically consistent with the water trend,following the law of salt moving with water movement. This research has certain reference value and scientific significance for the ecological management of coal mining subsidence areas.