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干旱区露天矿外排土场隔水层重构材料试验研究

Experimental study on reconstruction material of impervious layer in open-pit mine external dump in arid area

  • 摘要: 新疆煤炭资源储量巨大,具备开发建设大型露天煤矿的条件与优势,但由于新疆干旱区气候特点,造成露天开采对生态环境影响和破坏范围广、程度高,开展干旱区露天矿生态修复具有重大实际意义。由于排土场物料松散、孔隙度大、渗透性大,对干旱区排土场生态修复提出严峻挑战。为解决我国西部干旱区露天煤矿生态修复过程中水资源的紧缺问题,提高干旱区露天矿生态修复效果,基于材料强度和渗透率双重技术目标,探究重构露天矿外排土场隔水层材料配比,以不同材料配比方案利用室内渗透性试验及单轴抗压强度开展相关研究。采用XRD衍射试验、单轴抗压试验与变水头渗透试验确定了不同配比试件的材料主要成分、单轴抗压强度与渗透率并研究了重构隔水层的材料配比参数。试验结果表明:固化剂掺比增加2%时,试件抗压强度提高22%,但增加趋势随着固化剂掺比超过8%时开始降低,固化剂掺比从8%增加至10%时,试件的抗压强度仅增加6%。随着粉煤灰掺比的增加其渗透率逐渐减小,粉煤灰掺比每增加2%可使渗透率降低28%。固化剂掺比量对试件抗压强度的影响程度大于粉煤灰掺比对其的影响程度,且对于渗透率而言,粉煤灰掺比的影响程度更高。粉煤灰掺比固定时,固化剂掺比与试件的单轴抗压强度呈正相关。固化剂掺比一定时,粉煤灰掺比增加其单轴抗压强度也在增大。

     

    Abstract: Xinjiang has huge reserves of coal resources and has the conditions and advantages to develop and construct large-scale open-pit coal mines. However, due to the climate characteristics of Xinjiang’s arid areas, open-pit mining has a wide range and high degree of impact on the ecological environment and damage. It is of great practical significance to carry out ecological restoration of open-pit mines in arid areas. Due to the loose materials, high porosity and permeability of the waste dump, the ecological restoration of the waste dump in arid areas is a serious challenge. In order to solve the shortage of water resources in the ecological restoration process of open-pit coal mines in the arid areas of western China, improve the ecological restoration effect of open-pit coal mines in the arid areas, based on the dual technical objectives of material strength and permeability, explore and reconstruct the material ratio of the impervious layer of the open-pit mine external dump, carry out relevant research with different material ratio schemes using indoor permeability test and uniaxial compressive strength. The main composition, uniaxial compressive strength and permeability of the materials with different proportions were determined by XRD diffraction test, uniaxial compression test and variable head permeability test, and the material proportioning parameters of the reconstructed aquiclude were studied. The test results show that the compressive strength of the specimen increases by 22% when the curing agent ratio increases by 2%, but the increasing trend starts to decrease when the curing agent ratio exceeds 8%. When the curing agent ratio increases from 8% to 10%, the compressive strength of the specimen increases by only 6%. With the increase of fly ash content, its permeability decreases gradually. Every 2% increase of fly ash content can reduce the permeability of 28%. The following rules are obtained: the influence of the content of curing agent on the compressive strength of the specimen is greater than that of the fly ash content, and the influence of the fly ash content on the permeability is higher. When the fly ash content is fixed, the curing agent content is positively correlated with the uniaxial compressive strength of the specimen. When the ratio of curing agent is fixed, the uniaxial compressive strength of fly ash increases with the increase of the ratio.

     

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