水文保留曲面下草原露天矿内排土场地貌近自然重塑

Reshaping of near-natural landform of the internal dump in the grassland open-pit mine based on HPCS

露天开采作为草原矿区开采的重要方式,采排复过程中形成的“梯田式”内排土场传统地貌面临占地面积大、景观破碎、水土侵蚀等问题。基于自然的解决方案(NbS)可以自然地貌为师,具有融合矿区原始景观的独特优势。为构建与周边自然地貌相融合的内排土场地貌,在现有工艺和团队已有成果上,提出一种采排复一体情景下,基于水文保留曲面(HPCS)的内排土场近自然地貌重塑模型,以新疆黑山露天矿内排土场为例,构建HPCS下近自然设计地貌(NNDL_HPCS)为实验组,地表调整曲面下近自然设计地貌(NNDL_SAS)、原始自然地貌(PNL)和传统设计地貌(TDL)3者为对照组,结合GIS空间分析软件与CLiDE演化模型,模拟并评价NNDL_HPCS在地貌融合、土方调配与土壤抗水蚀3方面的改良效果,结果表明:地貌设计上,基于HPCS的内排土场近自然地貌重塑模型可依据预设采复周期下采复子区采前地表、矿层顶板和矿层底板3者的数字高程数据(DEM),自动求解复填可用土方量,获取复填子区地表高程设计结果;地貌融合上,NNDL_HPCS较NNDL_SAS和TDL视觉上更接近于PNL,其相对PNL的高程总方差较后两者分别低50.37%和37.92%,且其自然水文保留率较后两者分别高出2.85%和8.53%;土方调配上,NNDL_HPCS土方运移成本小幅增加,其土方平均运距分别较NNDL_SAS和TDL分别高出约4.99%和5.05%;土壤抗水蚀上,NNDL_HPCS较NNDL_SAS 10 a可减少约55%的表土水蚀总量,较TDL减少约72.6%,可显著提高内排土场表土抗水蚀能力。

Open-pit mining is an important mining method in China’s grassland mining areas.However,the traditional landform of“terraced field”inner dump formed in the process of mining and dumping is faced with problems such as large land area,landscape fragmentation and soil erosion.The nature-based solution(NbS)is based on the natural landscape and has the unique advantage of integrating the original landscape of the mine.Based on the existing technologies and team achievements,in order to build the inner dump landform that is integrated with the surrounding natural topography,a near-natural landform reshaping model of the inner dump was proposed based on a hydrological preserved curved surface(HPCS).In this paper,the Heishan open-pit mine in Xinjiang was selected to construct a near-natural design landform with HPCS(NNDL_HPCS)as the experimental group,and the NNDL with surface adjustment surface(NNDL_SAS),pristine natural landform(PNL)and traditional design landform(TDL)were used as the control group.Combined with the GIS and CLiDE model,the improvement effects of the NNDL_HPCS on geomorphic fusion,earthwork allocation and soil water erosion resistance were simulated and evaluated.The results showed that:Based on the HPCS near-natural landform reshaping model of the inner dump,the DEM of the pre-mining surface,the roof and floor of the mining sub-area under the preset mining cycle was used to automatically solve the available earthwork for filling and obtained the surface design elevation of the filling sub-area.In terms of geomorphic fusion,the NNDL_HPCS was closer to the PNL than that of the NNDL_SAS and the TDL.The total variance of the NNDL_HPCS relative to the PNL was 50.37%and 37.92%lower than that of the NNDL_SAS and the TDL,and the natural hydrological retention rate was 2.85%and 8.53%higher than that of the NNDL_SAS and the TDL,respectively.In terms of earthwork allocation,the average earthwork distance of the NNDL_HPCS was 4.99%and 5.05%higher than that of the NNDL_SAS and the TDL respectively.In terms of soil water erosion resistance,the NNDL_HPCS can reduce water erosion by 55%compared with the NNDL_SAS and 72.6%compared with the TDL in 10 years,which can significantly improve the water erosion resistance of inner dump topsoil.