西部典型高寒露天矿区开采岩土变形规律与损伤传导机理

Deformation law and damage conduction mechanism of rock and soil in typical high-cold open-pit mining area in the western regions

  • 摘要: “一带一路” 沿线西部高寒及生态脆弱矿区是我国煤炭露天开发主产区,但高强度露天开采和剧烈环境变化使岩体损伤机理复杂,岩土变形与边坡控制难度大,导致矿区生境损伤退化严重。为揭示露天开采岩土变形规律与传导机理,以新疆准东地区3个露天矿区10座大型露天煤矿为研究靶区,选取41景SentineL-1A雷达影像数据和13个月矿山月度外排量,基于小基线集差分干涉测量技术(SBAS-InSAR),结合时序气象因子的Pearson相关性分析,研究了开采扰动区岩土变形发育特征,分析了不同变形区开采扰动距离与时序变形规律,探讨了变形区分布与采排空间分布及外排堆载的相关关系,并对开采岩土变形传导机理进行分析。研究表明:准东地区露天开采岩土扰动分布具有明显的空间异质性,内外排土场、同侧呈垂直分布或无外排土场分布的端帮边坡、同侧外排土场错位平行分布的端帮边坡的3种边坡岩土体分别呈现出沉降、沉降和隆起的典型变形模式。开采扰动岩土变形距离呈现明显的有界性,准东地区端帮沉降与隆起变形扰动距离分别位于17051392 m内。开采扰动岩体沉降变形具有显著的温度时效性,冻结期和融化期温度与变形呈中等相关或强相关,沉降变形区分别表现出稳定性与突变性。沉降区在工作帮及内排土场三维支挡的约束变形作用下呈现出“马鞍形”分布规律,隆起区分布与外排土场分布密切相关,隆起变形量与外排堆载量具有强相关关系(相关系数rxy > 0.82)。基于卸荷回弹变形与外排堆载的边坡隆起变形影响关系,构建了基于开采卸荷的端帮边坡外排土场非对称堆载模型,揭示堆载应力传导过程并提出修正排土场基底承载力公式,明确了堆载引起局部隆起的弹性地基梁效应,基于该效应,提出考虑外排土场传递附加应力后的边坡稳定性计算公式,揭示了基于基底硬岩传导层的边坡弹性地基梁隆起传导机理。研究成果为西部高寒露天矿区开采损伤的精准分析、生态减损型开采技术的研发提供了理论与数据支撑。

     

    Abstract: The western cold areas and ecologically fragile mining areas along the Belt and Road are the main zones for China's open-pit coal mining. Yet, due to the complicated rock mass damage mechanism from intensive open-pit mining and drastic environmental changes, coupled with the great difficulty in controlling rock-soil deformation and slope stability, these mining areas are suffering from severe damage and degradation of the mining environment. To elucidate the deformation patterns and transmission mechanisms of rock and soil under open-pit mining, three open-pit mining areas in the Junggar Coalfield of Xinjiang were selected, and ten large-scale open-pit coal mines were targeted. Using 41 scenes of Sentinel-1A radar imagery and 13 months of monthly external dumping data from the mines, the study applied the Small Baseline Subset Differential Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique and conducted Pearson correlation analysis with temporal meteorological factors. The research examined the characteristics of rock-soil deformation in mining disturbance zones, analyzed the spatial-temporal deformation patterns and disturbance distances of different deformation zones, explored the correlation between deformation zone distribution and mining-spoil spatial layout as well as external discharge loading, and investigated the transmission mechanism of mining-induced rock-soil deformation. The results indicate that the spatial dis-tribution of rock-soil disturbances caused by open-pit mining in the Zhundong region exhibits significant heterogeneity. Three typical deformation patterns are observed in slope rock-soil masses: settlement and uplift in inner and external spoil dumps; end slopes with either vertical distribution of external spoil dumps or no external spoil dumps; and end slopes with offset parallel distribution of external spoil dumps. The disturbance distance of mining-induced rock-soil deformation demonstrates a clear bounded nature, with settlement and settlement-uplift deformation in the Zhundong region confined within 1705 m and 1392 m, respectively. The subsidence deformation of rock masses under mining disturbances exhibits significant temperature-dependent temporal effects, showing moderate or strong correlations between deformation and temperature during freezing and thawing periods, with subsidence deformation zones manifesting stability and abrupt changes, respectively. Under the constrained deformation effect of three-dimensional support from the working slope and inner dump, the settlement zone exhibits a “saddle-shaped” distribution. The distribution of bulge zones is closely related to external dumps, with bulge deformation volume showing a strong correlation with external discharge loading (correlation coefficient rxy > 0.82). Based on the influence relationship between unloading rebound deformation and bulge deformation induced by external discharge loading, an asym-metric loading model for external spoil dumps on end slopes under mining-induced unloading conditions was constructed. The stress transmission process of surcharge was revealed, and a modified bearing capacity formula for spoil dump foundations was proposed. The elastic foundation beam effect of local bulge caused by surcharge was clarified, Based on this effect, a slope stability calculation formula considering the additional stresses transferred from the external waste dump is proposed, and the bulge transmission mechanism of the elastic foundation beam on slopes was elucidated, based on substrate hard rock conduction layer. The findings provide theoretical and data support for the precise analysis of mining-induced damage and the development of eco-friendly mining technologies in high-altitude open-pit mining areas in western China.

     

/

返回文章
返回