摘要:
地下煤火被称为“全球性灾难”,其燃烧不仅会造成煤炭资源的浪费,还会引发严重的环境污染和地质灾害问题。了解煤层燃烧所形成燃空区的形态及其时空演变特征是煤火灭火与灾害防治的基础。将卫星观测数据融入岩层移动数值模拟中,利用热红外遥感和时序合成孔径雷达干涉测量(Interferometric Synthetic Aperture Radar,InSAR)技术反演的地表温度和形变信息作为约束,结合岩层热传导理论与弹塑性力学理论,对地下燃空区三维温度场及其形态的时空演化进行模拟,并在宁夏汝箕沟红梁火区开展应用。结果表明,卫星观测数据可为数值模拟提供更准确的地表参数约束。空间上温度自煤层核心向外逐渐降低,时间上地表和各岩层温度均随煤层燃烧时间逐渐升高。反演中,当岩层弱化系数为0.18时,煤层顶板出现了联通的塑性区域,剖面呈K型,主体受剪切塑性变形影响严重;正演中,当时步达5 400时,地表最大沉降量达149.80 mm,剖面沉降呈波峰状。正、反演两种方法模拟的地下燃空区达到吻合,标准差为4.59 mm,表明该模型能合理地描述地下燃空区的三维形态及其演化特征。研究为揭示地下燃空区时空演化规律提供了新的思路和科学依据,为地下煤火的有效治理提供了理论支撑。
Abstract:
Objectives: Underground coal fires are regarded as a "global disaster," as their combustion not only leads to the waste of coal resources but also causes severe environmental pollution and geological hazards. Understanding the morphology and spatiotemporal evolution of the combustion-affected areas formed by coal seam fires is essential for effective fire suppression and disaster prevention. Methods: We integrate satellite observation data into strata movement numerical simulations. Using surface temperature and deformation information derived from thermal infrared remote sensing and interferometric synthetic aperture radar (InSAR) as constraints, combined with thermodynamic and elastoplastic mechanics theories. We then conducted a numerical simulation to investigate the spatiotemporal evolution of the three-dimensional temperature field and morphology of underground combustion-affected areas. The methodology was applied to the Hongliang Fire Area in Rujigou, Ningxia. Results: The results indicate that satellite observation data provide more accurate surface parameter constraints for numerical simulations. Spatially, the temperature decreases gradually from the coal seam core outward, while temporally, both surface and strata temperatures rise as coal seam combustion progresses. For instance, the time series of temperatures at three characteristic points (Q1-Q3) along the profile reveal that Q1's temperature remains stable at approximately 18 ℃ during the first three months and then increases at an accelerating rate, reaching 27 ℃ after 12 months. At Q2, the temperature rises slowly during the first three months, followed by a linear increase to about 145℃. Q3 experiences a rapid temperature rise, with the rate of increase decelerating over time, reaching around 600 ℃ after one year. In the inversion process, In the inversion process, as the strata weakening coefficient decreases from 1, temperatures above the coal seam rise due to combustion, leading to the formation and continuous expansion of a plastic zone. When the strata weakening coefficient is between 1 and 0.18, no connected plastic zones are observed. However, when the coefficient reaches 0.18, a connected plastic zone appears in the coal seam roof, displaying a K-shaped profile and being significantly impacted by shear plastic deformation. In the forward simulation, the subsidence zone takes on a funnel-shaped deformation pattern, with the magnitude of deformation decreasing outward from the center, which delineates the extent of combustion influence. As the time steps increase, surface subsidence progressively increases. At time step 5 400, the maximum surface subsidence reaches 149.80 mm, with the subsidence profile showing a peak pattern. The forward and inversion simulations of the underground combustion-affected areas align well, with a standard deviation of 4.59 mm, indicating that the model can accurately represent the three-dimensional morphology and evolutionary characteristics of the combustion-affected areas. Conclusions: This study provides a novel approach and scientific basis for uncovering the spatiotemporal evolution patterns of underground combustion-affected areas, offering theoretical support for the effective management of underground coal fires.