条带开采煤柱长期稳定性评价及煤柱设计方法

煤柱在地下水、风化作用等多种因素的作用下会发生剥离和尺寸缩减,使煤柱发生渐进性失稳破坏。基于煤柱的渐进性剥离行为和剥离体的堆积特性,建立了煤柱的非均匀剥离模型;分析了煤柱剥离的影响因素、煤柱安全系数与煤柱剥离的关系,建立了条带煤柱长期稳定性评价方法;讨论了采出率、地表沉陷控制和煤柱长期安全系数的协同关系。分析表明:煤柱的剥离与煤的碎胀系数、休止角和采宽采厚比有关,可利用剥离角确定煤柱的极限破坏程度。煤柱的宽高比越大,剥离对其稳定性的影响程度越小。该模型适用于条带煤柱长期稳定性评价。

关闭矿井次生沉陷研究现状及展望

我国关闭矿井数量多范围广,矿井关闭后,停止排水,地下水位上升,受地下水影响,覆岩及地表将再次沉陷,危及关闭矿井上方和周边建构筑物、交通电力通讯等基础设施安全及建设场地稳定性,研究关闭矿井覆岩与地表次生沉陷机理、规律、预测方法具有重要的理论和实用价值。在收集国内外相关文献基础上,结合徐州东西部矿区关闭矿井地面次生沉陷监测实践,系统回顾和分析了关闭矿井地面次生沉陷监测方法、形成机理、时空分布规律及预测方法研究现状和存在的问题。首先,对比研究了常规地面变形监测方法和航天航空测量方法的优缺点,重点总结了合成孔径雷达干涉测量(InSAR)技术应用于关闭矿井地表沉陷监测中的优势及存在的问题;其次,基于国内外大量实测资料,分析总结了关闭矿井覆岩及地表次生沉陷形成机理及时空演化规律,得到了覆岩及地表下沉的主要诱因为采动破裂岩体、覆岩结构及煤(岩)柱在地下水作用下的变形或失稳;覆岩与地表上升的主要诱因为:随着地下水位升高,作用在采动破裂岩体、第四系松散层内的孔隙压力增大,有效应力减小,使其产生弹性恢复变形,膨胀岩体遇水膨胀也可能导致覆岩及地表上升;关闭矿井次生沉陷在时间上可分为5个阶段:①初期稳定阶段;②下沉阶段;③中间稳定阶段;④上升阶段;⑤最终稳定阶段。并分析了不同开采方法、多煤层开采对关闭矿井地表沉陷时空分布规律的影响。在此基础上,基于采动破裂岩体本构关系,分下沉和上升2阶段,分别给出了长壁垮落法、充填开采和柱式开采地表沉陷预测模型。最后指出,关闭矿井覆岩及地表沉陷机理、规律是非常复杂的物理力学过程,涉及地质采矿环境、采动破裂岩体及覆岩结构、本构关系、变形特征、水岩耦合作用、地下水动力效应、膨胀岩体膨胀变形等复杂因素,因此,还需进一步深入研究。

基于改进MT-InSAR的日兰高铁巨野煤田段沉降监测

日兰高铁巨野煤田段农田遍布,合成孔径雷达干涉(InSAR)的时间失相干严重,可用于时序InSAR(MT-InSAR)分析的永久散射体(PS)稀少。将SAR数据限制在失相干影响较弱的10月至次年4月初并联合PS和分布式散射体(DS)有望解决该问题。然而,受限于SAR卫星的重访周期,仅采用10月至次年4月初的SAR影像会导致数据量变少。而当SAR数据较少、相干性较低时,难以准确估计协方差矩阵和相干矩阵,使得现有的DS相位估计方法误差较大。为此,提出了一种基于Fisher信息量的DS相位优化估计算法,利用Fisher信息量调节各干涉对的权重,抑制低相干干涉对的影响。通过模拟数据和真实数据验证了算法的可靠性和可行性。另外,构建了联合PS和DS的小基线(SBAS)干涉处理框架,在增加观测方程的同时保证干涉对的相干质量,从而实现形变信息的稳健估计。利用2020年10月至2021年4月间的Sentinel-1 SAR数据获取了日兰高铁巨野煤田段地表沉降,并结合已有的监测资料分析了地表沉降的成因及时空演化信息。研究结果表明:采用上述方法,能够根据10月至次年4月初的少量SAR数据监测高铁沿线沉降情况;日兰高铁巨野煤田段沿线仍在持续沉降,3 km内的平均形变速率集中在-3.5~-0.5 cm/a,与2015—2019年的观测结果一致,未出现加剧现象;巨野煤田段存在可能由断层活化、深层地下水流失等因素间接造成的更大范围地表沉降,并且沉降靠近高铁侧,这一点需引起注意。

Mechanism of formation of sliding ground fissure in loess hilly areas caused by underground mining

Based on a shallow-buried coal seam covered with thick loose layers in hilly loess areas of western China,we developed a mechanical model for a mining slope with slope stability analysis, and studied the mechanism of formation and development of a sliding ground fissure by the circular sliding slice method.Moreover, we established a prediction model of a sliding fissure based on a mechanical mechanism,and verified its reliability on face 52,304, an engineering example, situated at Daliuta coal mine of Shendong mining area in western China. The results show that the stress state of a mining slope is changed by its gravity and additional stress from the shallow-buried coal seam and gully terrain. The mining slope is found to be most unstable when the ratio of the down-sliding to anti-sliding force is the maximum, causing local fractures and sliding fissures. The predicted angles for the sliding fissure of face 52,304 on both sides of the slope are found to be 64.2° and 82.4°, which are in agreement with the experimental data.

高分辨率遥感影像地物阴影去除算法研究

近几年来,随着遥感技术的快速发展,卫星传感器的空间分辨率在不断地提高,高分辨率遥感影像的应用范围也越来越广,主要包括地形图绘制、变化检测、数字化城市建设等方面。然而,阴影的存在会给高分辨率遥感影像的处理结果带来很多不利影响,如图像匹配、地物的识别与提取等。因此,准确提取高分辨率遥感影像中的建筑物阴影并将其去除掉,是目前遥感影像图像处理方面的一项重要工作。对国内外阴影检测与去除算法系统进行研究,发现现有的算法存在很多局限性,并且处理结果不是很理想,误检率较高。针对这些问题,本文改进了Wallis滤波算法,并基于Matlab进行了结合颜色恒常性理论的阴影去除算法实验研究。通过实验和定量评价,验证了这两种算法较传统的阴影去除算法精度更高。

Study of probability integration method parameter inversion by the genetic algorithm

In order to obtain accurate probability integration method(PIM) parameters for surface movement of multi-panel mining, a genetic algorithm(GA) was used to optimize the parameters. As the measured surface movement is affected by more than one mining panel, traditional PIM parameter inversion model is difficult to ensure the reliability of the results due to the complexity of rock movement. With crossover,mutation and selection operators, GA can perform a global optimization search and has high computation efficiency. Compared with the pattern search algorithm, the fitness function can avoid falling into local minima traps. GA reduces the risk of local minima traps which improves the accuracy and reliability with the mutation mechanism. Application at Xuehu colliery shows that GA can be used to inverse the PIM parameters for multi-panel surface movement observation, and reliable results can be obtained. The research provides a new way for back-analysis of PIM parameters for mining subsidence under complex conditions.

Time series prediction of mining subsidence based on a SVM

In order to study dynamic laws of surface movements over coal mines due to mining activities,a dynamic prediction model of surface movements was established,based on the theory of support vector machines(SVM) and times-series analysis.An engineering application was used to verify the correctness of the model.Measurements from observation stations were analyzed and processed to obtain equal-time interval surface movement data and subjected to tests of stationary,zero means and normality.Then the data were used to train the SVM model.A time series model was established to predict mining subsidence by rational choices of embedding dimensions and SVM parameters.MAPE and WIA were used as indicators to evaluate the accuracy of the model and for generalization performance.In the end,the model was used to predict future surface movements.Data from observation stations in Huaibei coal mining area were used as an example.The results show that the maximum absolute error of subsidence is 9 mm,the maximum relative error 1.5%,the maximum absolute error of displacement 7 mm and the maximum relative error 1.8%.The accuracy and reliability of the model meet the requirements of on-site engineering.The results of the study provide a new approach to investigate the dynamics of surface movements.

A method to calculate displacement factors using SVM

In order to improve the precision of mining subsidence prediction, a mathematical model using Support Vector Machine (SVM) was established to calculate the displacement factor. The study is based on a comprehensive analysis of factors affecting the displacement factor, such as mechanical properties of the cover rock, the ratio of mining depth to seam thickness, dip angle of the coal seam and the thickness of loose layer. Data of 63 typical observation stations were used as a training and testing sample set. A SVM regression model of the displacement factor and the factors affecting it was established with a kernel function, an insensitive loss factor and a properly selected penalty factor. Given an accurate calculation algorithm for testing and analysis, the results show that an SVM regression model can calculate displacement factor precisely and reliable precision can be obtained which meets engineering requirements. The experimental results show that the method to calculation of the displacement factor, based on the SVM method, is feasible. The many factors affecting the displacement factor can be considered with this method. The research provides an efficient and accurate approach for the calculation of displacement in mining subsidence prediction.

Synergistic instability of coal pillar and roof system and filling method based on plate model

The security challenges from room and pillar gobs include land subsidence, spontaneous combustion of coal pillars and mine flood caused by gob water. To explore the instability mechanism of room and pillar gob, we established a mechanical model of elastic plate on elastic foundation in which pillars and hard roofs were considered as continuous Winkler foundations and elastic plates, respectively. The synergetic instability of pillar and roof system was analyzed based on plate bending theory and catastrophe theory. In addition, mechanical conditions and math criterion of roof failure and overall instability of coal pillar and roof system were given. Through analyzing both advantages and disadvantages of some technologies such as induced caving, filling, gob sealing and isolation, we presented a new filling method named box-filling, in view of box foundation theory, to control the disasters of ground collapse, water inrush and mine fire. In a gob's treatment project in Ordos, safety assessment and filling design of a room and pillar gob have been done by the mechanical model. The results show that the gob will collapse when the pillars' average yield band is wider than 0.93 m, and box-filling can control land collapse, mine flood and mine fire economically and efficiently. So it is worth to study further and popularize.

Large-scale deformation monitoring in mining area by D-InSAR and 3D laser scanning technology integration

Large-scale deformation can not be detected by traditional D-InSAR technique because of the limit of its detectable deformation gradient,we propose a method that combines SAR data with point cloud data obtained by 3D laser scanning to improve the gradient of deformation detection.The proposed method takes advantage of high-density of 3D laser scanning point cloud data and its high precision of point positioning after 3D modeling.The specifc process can be described as follows:frst,large-scale deformation points in the interferogram are masked out based on interferometric coherence;second,the interferogram with holes is unwrapped to obtain a deformation map with holes,and last,the holes in the deformation map are flled with point cloud data using inverse distance weighting algorithm,which will achieve seamless connection of monitoring region.We took the embankment dam above working face of a certain mining area in Shandong province as an example to study large-scale deformation in mining area using the proposed method.The results show that the maximum absolute error is 64 mm,relative error of maximum subsidence value is 4.95%,and they are consistent with leveling data of ground observation stations,which confrms the feasibility of this method.The method we presented provides new ways and means for achieving large-scale deformation monitoring by D-InSAR in mining area.

太空采矿发展现状、机遇和挑战

太空资源开发与利用是目前大国博弈的新疆域,也是科技竞争的制高点,承载着未来人类文明可持续发展的希望,更是关乎我国未来发展的一个重大战略问题.本文在详细介绍太空采矿发展现状的基础上,描绘了太空资源开采目标,分析了开发与利用这些目标上所蕴含资源的可能性,认为基于现代技术及空间资源价值,开采近地小行星上的矿产资源是人类发展的大趋势.提出了太空采矿迫切需要开展研究的四个重点方向,分别为太空资源探测、太空采矿智能机器人平台设计与制造、太空资源勘探与采选和太空采矿空间安全与资源原位利用,并构筑了我国太空采矿发展的愿景.

基于InSAR的关闭矿井地表形变监测与分析

为了获取徐州东部矿井关闭后的地表形变,利用10景降轨ENVISAT影像和72景升轨Sentinel-1A影像,基于StaMPS技术通过时间域低通滤波、空间域高通滤波和三维解缠算法获取地表形变.监测结果表明:韩桥矿关闭后地表出现抬升,最大抬升速率为34.4 mm/a;旗山矿关闭后地表先下沉,而后抬升.通过对旗山矿关闭后地表抬升位置与时间分析可知,地下水回升方向为由北向南;对韩桥矿与旗山矿地表形变分析可知,徐州东部矿井关闭后地表形变规律可归纳为受采空区或地下水等因素影响地表先下沉,至相对稳定阶段(或不存在),再到地表抬升.结合韩桥矿地下水位分析可知,矿井关闭后由地下水回升引起的地表抬升存在大约1 a的时间延迟;地表抬升与地下水回升相关性较强,相关系数为0.98.

基于WαSH局部特征的立体影像匹配

针对传统方法对影像畸变敏感,难以用于具有较大变形的立体影像匹配的问题,提出了一种基于加权α形状(WαSH)局部区域特征的匹配方法.该方法采用WαSH特征检测算法提取图像的局部特征,并引入特征区域的二阶矩矩阵对椭圆拟合后的特征进行归一化,获得去除仿射变形的影像块;在归一化后的影像块上采用尺度不变特征变换(SIFT)描述算法提取特征描述向量,并基于最近邻与次近邻距离比率(NNDR)匹配测度进行特征匹配,确定同名特征.选用5组代表性影像进行实验.结果表明:提出的方法对发生较大视点变化、尺度+旋转变化、模糊及JPG压缩的影像均能获得正确率较高的匹配结果,与基于最大稳定极值区域(MSER)的匹配方法相比,匹配正确率及匹配效率更高.

徐州西部关闭矿井地表次生沉陷监测与分析

针对矿井关闭后,覆岩和地表发生沉陷而出现的各种安全问题,该文基于2014年1月17日—2018年1月8日的51景德国X频段陆地合成孔径雷达(TerraSAR-X)卫星影像和斯坦福小基线集技术获取了徐州西部关闭矿井(张小楼矿、夹河矿和庞庄矿)4年地表时序沉陷数据。监测结果表明:观测期内张小楼矿、夹河矿和庞庄矿关闭后地表呈现持续下沉的趋势。其中,张小楼矿和夹河矿关闭后,前8个月内沉降速率依然较快,之后沉降速率减缓,在监测末期地表出现上升;庞庄矿沉降速率总体较为平缓,在监测末期地表也出现上升。综合三个矿井的沉降规律,可将关闭矿井的次生沉陷概括为下沉速度较快阶段,下沉速度放缓阶段和逐渐上升阶段。该研究可为防治关闭矿井次生沉陷灾害和关闭矿井老工业基地综合治理提供参考。

顾及影像稀疏特性的压缩感知超分辨率重建

针对传统压缩感知信号重构仅实现对原始图像的复原和逼近,无法实质性提高影像分辨率问题,该文提出一种非退化的压缩感知超分重构方法:从图像传感器的结构分析数字影像的稀疏特性,进而以插值图像为指导,采用非线性的压缩感知优化重建方法,实现了非退化的单帧图像超分辨率重建。研究表明:该文方法改变了影像采集的过程和途径,弥补了传统压缩感知信号重构无法实质性提高影像分辨率的缺陷,且其重建图像的视觉效果及定量指标均优于传统插值法。

一种空间结构信息的SAR影像直线匹配方法

针对SAR影像受相干斑噪声影响严重,难以直接利用灰度信息对特征直线进行匹配的问题,该文提出了一种基于空间结构信息的特征直线匹配方法。该方法首先根据影像间粗投影变换模型所提供的几何约束,将直线映射至同一坐标系下;然后基于直线双重距离进行匹配。为提高正确率,提出了旋转角一致性检核算法剔除误匹配。最后根据直线的空间特性对匹配直线对进行优化,获得"一对一"的匹配。对多组真实SAR影像进行实验,实验结果表明:该文提出的算法匹配直线对数量多,正确率高,稳定性好,优于L-P算法。