Effect of digital elevation models on monitoring slope displacements in open-pit mine by differential interferometry synthetic aperture radar

Displacement monitoring in open-pit mines is one of the important tasks for safe management of mining processes.Differential interferometric synthetic aperture radar(DInSAR),mounted on an artificial satellite,has the potential to be a cost-effective method for monitoring surface displacements over extensive areas,such as open-pit mines.DInSAR requires the ground surface elevation data in the process of its analysis as a digital elevation model(DEM).However,since the topography of the ground surface in open-pit mines changes largely due to excavations,measurement errors can occur due to insufficient information on the elevation of mining areas.In this paper,effect of different elevation models on the accuracy of the displacement monitoring results by DInSAR is investigated at a limestone quarry.In addition,validity of the DInSAR results using an appropriate DEM is examined by comparing them with the results obtained by global positioning system(GPS)monitoring conducted for three years at the same limestone quarry.It is found that the uncertainty of DEMs induces large errors in the displacement monitoring results if the baseline length of the satellites between the master and the slave data is longer than a few hundred meters.Comparing the monitoring results of DInSAR and GPS,the root mean square error(RMSE)of the discrepancy between the two sets of results is less than 10 mm if an appropriate DEM,considering the excavation processes,is used.It is proven that DInSAR can be applied for monitoring the displacements of mine slopes with centimeter-level accuracy.

Ground Surface Ruptures and Near-Fault,Large-Scale Displacements Caused by the Wenchuan Ms8.0 Earthquake Derived from Pixel Offset Tracking on Synthetic Aperture Radar Images

The 12 May 2008 Wenchuan Ms8.0 earthquake produced surface displacements along the causative fault, the Yingxiu-Beichuan Fault, which are up to several meters near the fault. Because of the large gradient, satellite synthetic aperture radar （SAR） interferometric data are strongly incoherent; the usual SAR interferometry method does not allow such displacements to be measured. In the present study, we employed another approach, the technique based on pixel offset tracking, to solve this problem. The used image data of six tracks are from the Advanced Land Observing Satellite, Phased Array type L-band Synthetic Aperture Radar （ALOS/PALSAR） dataset of Japan. The results show that the entire surface rupture belt is 238 km long, extending almost linearly in a direction of 42°north-east. It is offset left laterally by a north-west-striking fault at Xiaoyudong, and turns at Gaochuan, where the rupture belt shifts toward the south by 5 km, largely keeping the original trend. In terms of the features of the rupture traces, the rupture belt can be divided into five sections and three types. Among them, the Beichuan-Chaping and Hongkou-Yingxiu sections are relatively complex, with large widths and variable traces along the trend. The Pingtong-Nanba and Qingping-Jingtang sections appear uniform, characterized by straight traces and small widths. West of Yingxiu, the rupture traces are not clear. North of the rupture belt, surface displacements are 2.95 m on average, mostly 2-3.5 m, with 7-9 m the maximum near Beichuan. South of the rupture belt, the average displacement is 1.75 m, dominated by 1-2 m, with 3-4 m at a few sites. In the north, the displacements in the radar line of sight are of subsidence, and in the south, they are uplifted, in accordance with a right-slip motion that moves the northern wall of the fault to the east, and the southern wall to the west, respectively. Along the Guanxian-Jiangyou Fault, there is a uplift zone in the radar line of sight, which is 66 km long, 1.5-6 km wide, and has vertical displacements of approximately 2 m, but no observable rupture traces.

Precise Three-Dimensional Deformation Retrieval in Large and Complex Deformation Areas via Integration of Offset-Based Unwrapping and Improved Multiple-Aperture SAR Interferometry:Application to the 2016 Kumamoto Earthquake

Conventional synthetic aperture radar(SAR)interferometry(InSAR)has been successfully used to precisely measure surface deformation in the line-of-sight(LOS)direction,while multiple-aperture SAR interferometry(MAI)has provided precise surface deformation in the along-track(AT)direction.Integration of the InSAR and MAI methods enables precise measurement of the two-dimensional(2D)deformation from an interferometric pair;recently,the integration of ascending and descending pairs has allowed the observation of precise three-dimensional(3D)deformation.Precise 3D deformation measurement has been applied to better understand geological events such as earthquakes and volcanic eruptions.The surface deformation related to the 2016 Kumamoto earthquake was large and complex near the fault line;hence,precise 3D deformation retrieval had not yet been attempted.The objectives of this study were to①perform a feasibility test of precise 3D deformation retrieval in large and complex deformation areas through the integration of offset-based unwrapped and improved multiple-aperture SAR interferograms and②observe the 3D deformation field related to the 2016 Kumamoto earthquake,even near the fault lines.Two ascending pairs and one descending the Advanced Land Observing Satellite-2(ALOS-2)Phased Array-type L-band Synthetic Aperture Radar-2(PALSAR-2)pair were used for the 3D deformation retrieval.Eleven in situ Global Positioning System(GPS)measurements were used to validate the 3D deformation measurement accuracy.The achieved accuracy was approximately 2.96,3.75,and 2.86 cm in the east,north,and up directions,respectively.The results show the feasibility of precise 3D deformation measured through the integration of the improved methods,even in a case of large and complex deformation.

Ground settlement of Chek Lap Kok Airport,Hong Kong,detected by satellite synthetic aperture radar interferometry

Satellite synthetic aperture radar (SAR) inter-ferometry is used to investigate the slowly accumulating ground settlement at the new Chek Lap Kok Airport in Hong Kong. Most of the land occupied by the airport was reclaimed from the sea and therefore certain ground settlement in the area has been expected. A pair of ERS-2 SAR images spanning nearly a year is used in the study. The high spatial resolution (20 m×20 m) ground settlement map derived indicates that the settlement that occurred in the area over the time period is as large as 50 mm. The SAR measurement results agree with the levelling measurements at some benchmarks in the area to well within 1 cm(rms error),and the overall correlation between the two types of results is 0.89. The paper presents some brief background of inter-ferometric SAR, and outlines the data processing methods and results.

利用InSAR形变反演滑坡滑面运动特征——以汶川县布瓦村滑坡为例

当前滑坡滑面运动特征获取多采用接触式手段,费时费力、成本高昂,且仅能获取稀疏点位滑面运动状态。因此,本文提出一种非接触式滑坡滑面运动特征获取方法,其基本思路是:基于位错理论建立滑坡表面形变与滑面运动间的关系模型,同时引入滑面运动平滑约束条件,最终以InSAR等技术获取的地表形变为约束,反演获得滑面运动特征。本文选择四川省汶川县布瓦村滑坡作为研究对象,以时序InSAR技术获取的滑坡坡面升降轨形变数据为约束,基于发展的理论方法反演获得布瓦村滑坡滑面几何与运动学参数,并结合野外勘查、Lidar观测以及模型残差较好地验证了反演结果的可靠性,其中反演升降轨模型残差仅3.1 mm·a^(-1)和3.4 mm·a^(-1)。反演结果显示,布瓦村滑坡滑面位于坡表以下平均~15.0 m深度处,滑面整体以沿坡向运动为主,最大运动量级达~80 mm·a^(-1),同时在坡体西侧中下部发现微量的垂直坡向运动。本文提出方法可方便、快速的获取空间连续的滑坡滑面运动特征,为滑坡灾害预警和失稳风险评估提供更为直接可靠的科学参考。

基于最优PS点获取方法的矿山工业广场沉降监测

为保障矿山地面和井下工作人员、工业广场周边居民以及运煤系统运行安全,实时监测地表变形情况,提出永久散射体(PS)点的优化获取方法,以提升PS-合成孔径雷达干涉测量(InSAR)技术在沉降监测中的适用性。首先,选择淮北市郊煤矿工业广场煤柱Ⅱ513工作面开采沉陷期间2020年10月31日—2022年8月22日共26景SAR卫星影像,运用PS-InSAR技术确定最优的PS点目标选取方法;然后,基于该方法获取该工作面回采过程中的开采损害保护区地面沉降速率、累计沉降量;最后,基于地面水准点实测数据验证PS-InSAR监测精度并分析研究区地表及建(构)筑物动态沉降情况。结果表明:相干系数和振幅离差指数双阈值法较适应于研究区沉降监测;研究区内可探测到的最大下沉速率为-26.5 mm/a,最大累计下沉值为-53.7 mm;同时,探测到研究区西北部存在岩溶塌陷地质灾害因素;利用水准数据验证精度,均方根误差(RMSE)仅为3.8 mm,决定系数达到0.91。

2023年积石山Ms6.2级地震InSAR同震形变探测与断层滑动分布反演

2023年12月18日,甘肃省临夏回族自治州积石山县发生了Ms6.2级地震,地震灾害损失显著高于同震级地震,查明其同震形变场与断层滑动分布特征,有助于揭示此次地震灾害损失严重的原因。利用Sentinel-1卫星升、降轨雷达影像,采用合成孔径雷达干涉技术获取了本次地震的同震形变场,进而基于Okada弹性位错模型,确定了本次地震的震源参数,并基于分布式滑动模型反演了本次地震断层面上的滑动分布。结果表明,积石山地震为逆冲型地震,升、降轨同震形变场沿视线向最大形变量分别为7.1 cm和7.8 cm,断层最大滑动量为0.31 m,主要集中在地下0~8 km。与2019年6月17日四川长宁Ms 6.0级地震对比发现,长宁地震地表最大形变量为8 cm,断层最大滑动量为0.38 m,均大于积石山地震,推测积石山地震灾害损失严重的主要原因为震区居民房屋相对集中、房屋抗震性能差和黄土区场地地震波放大效应等。

2024年新疆乌什Ms 7.1地震InSAR同震形变探测与断层滑动分布反演

2024年1月23日,新疆维吾尔自治区乌什县发生Ms 7.1地震,快速查明其同震形变场与发震断层滑动特征,有助于科学认识此次地震发震机理。利用Sentinel-1卫星升、降轨雷达影像,采用合成孔径雷达差分干涉测量技术获取了本次地震的同震形变场,进而基于Okada弹性位错模型,确定了本次地震的震源参数,并基于分布式滑动模型反演了本次地震断层面上的滑动分布。结果表明,升、降轨同震形变场沿视线向最大形变量分别为75 cm和48 cm,断层最大滑动量为4.2 m,主要集中在地下3~20 km区域;模型正演结果表明,此次地震在垂直方向最大抬升约53 cm,最大沉降约12 cm;发震断层运动以逆冲为主,兼具少量左旋走滑,根据InSAR结果及地质资料综合判断,本次发震断层为迈丹断裂。

基于时序InSAR技术的中贵天然气管道天水市段沿线滑坡隐患识别与形变分析

中贵天然气管道天水市段沿线地处黄土高原,地貌类型多样、构造活跃、复杂地质条件下发育多种具有隐蔽性和潜伏性的地质灾害,其中滑坡灾害对中贵天然气管道的安全危害极大,因此,对中贵天然气管道天水段沿线滑坡隐患进行有效识别与分析具有重要意义。采用Sentinel-1A升降轨卫星数据,基于时序合成孔径雷达干涉测量(synthetic aperture radar interferometry,InSAR)对中贵天然气天水段沿线滑坡隐患进行了解译识别、现场复核、发育特征与典型滑坡形变分析。研究区共识别17处滑坡隐患点,现场复核最终确定13处,其余4处为人类工程活动区,其中常沟村和磨峪沟村滑坡形变受降雨影响。统计发现研究区管道沿线滑坡多发生在坡度40°~50°,高差400~600 m,东北坡向和距管道100~150 m范围内,且岩土体强度较低,地层以第四系全新统冲洪积层(Q_(4)^(a1+p1))为主。结果表明:联合升降轨的时序InSAR技术可以有效识别管道沿线滑坡隐患,为油气管线的安全运营及今后油气管道选线提供重要的科学依据和参考。

面向时序InSAR的卫星任务规划框架设计

随着国内自主雷达卫星和差分干涉合成孔径雷达技术(D-InSAR)及衍生的时序InSAR技术的发展,以时间序列上重复观测为主的长周期形变监测的应用与日俱增。对遥感卫星地面任务规划系统来说,规划和管理大量有时序关联的重复任务,从而最大限度地满足观测要求,是提升以形变监测为使命的雷达卫星运控效率的关键。在综合考虑雷达差分干涉任务序列性、一致性、周期性特征的基础上,设计了一种面向雷达卫星时序InSAR类型任务的规划框架,旨在规划序列任务时,考虑序列整体特性,进行序列任务组间的冲突检测。基于此方法,对现有的地面任务规划系统进行了优化升级,验证了框架的有效性。结果证明:该方法可快速、自动进行序列任务冲突消解,可为长周期序列任务的规划和管理提供设计参考。

融合可微分渲染的SAR多视角样本增广

合成孔径雷达(SAR)因其全天候、全天时的监测能力在民用和军事领域得到广泛应用。近年来,深度学习已被广泛应用于SAR图像自动解译。然而,由于卫星轨道和观测角度的限制,SAR目标样本面临视角覆盖率不全的问题,这为学习型SAR目标检测识别算法带来了挑战。该文提出一种融合可微分渲染的SAR多视角样本生成方法,结合逆向三维重建和正向渲染技术,通过卷积神经网络(CNN)从少量SAR视角图像中反演目标三维表征,然后利用可微分SAR渲染器(DSR)渲染出更多视角样本,实现样本在角度维的插值。另外,方法的训练过程使用DSR构建目标函数,无需三维真值监督。根据仿真数据的实验结果,该方法能够有效地增加多视角SAR目标图像,并提高小样本条件下典型SAR目标识别率。

基于SBAS-InSAR技术的淮北市地表沉降监测分析

长期高强度的煤炭开采和地下水抽采,导致淮北市地表发生大面积沉降,破坏了耕地以及生态环境,因此对地表沉降监测显得尤为重要。本文通过短基线集合成孔径雷达干涉测量(SBAS-InSAR)方法获取了2020年1月5日到2020年12月30日的淮北市地表年形变速率,并且使用水准数据对监测结果进行了精度验证。结果表明:淮北市沉降存在不均匀现象,年形变速率为-55~42 mm,淮北市地表沉降由地下煤炭资源开采和地下水抽采引起,主要地表沉降由采煤引起。研究结果可为地质灾害预防提供数据参考。

基于实测气象参数的InSAR大气校正及其应用研究

针对传统InSAR技术在监测地表形变时受对流层延迟影响的问题,利用地面实测气象参数和NCEP气象再分析资料建立大气校正模型,对生成的鄞州区干涉图进行对流层延迟校正,获取鄞州区2018~2020年高精度地表形变分布。为分析不同大气校正模型对对流层延迟效应的削弱效果,将监测结果与同期实测水准数据作对比。结果发现,地面气象信息模型、NCEP气象再分析资料模型和未加大气校正的InSAR监测结果的均方根误差RMSE分别为2.78 mm、3.86 mm、5.62 mm,表明利用地面气象信息模型校正大气相位误差具有更高的监测精度,能有效削弱对流层延迟对干涉测量结果的影响。

采煤沉陷区立体化调查监测技术体系研究

采煤沉陷带来耕地受损、生态破坏和地灾隐患等一系列问题,开展采煤沉陷区调查监测,识别沉陷范围、预测沉陷边界、监测沉陷速率,有利于及时掌握沉陷地类、沉陷机理和稳沉状态,为耕地保护、生态修复及灾害防治等工作提供参考。本文通过合成孔径雷达干涉测量(Synthetic Aperture Radar Interferometry,InSAR)、微动勘探实测数据和沉陷区地层相近区域的地面沉降光纤孔监测数据研究皖北某煤矿沉陷区边界和采空区,结果表明:以10 mm为界线,利用InSAR可以快速划定沉降边界;通过微动勘探实测数据发现1000 m深度煤系地层的横波速度比正常地层低25~50 m/s,InSAR结果也显示该区域出现了地面沉降;分析收集到相近区域12组光纤孔监测数据,77.7~200 m深度段地层为主要变形区域,压缩量约为163.77 mm,数据频率能达到分钟级。由此可见,基于InSAR、微动和光纤孔监测三种方法实现多源异构数据耦合,能够在“高潜水位、中厚煤层、千米以深”的采煤沉陷区达到“由表、及里、实时”的立体化调查监测效果,构建立体化调查监测技术体系存在可行性。

Designing and implementation of variance-dependent Goldstein radar interferogram filtering

The variance-dependent Goldstein radar interferogram filter takes into account the information of both interferometric coherence and multilook factors,and can produce very consistent results for interferograms generated under a wide variety of multilook factors and with very different noise level.However,the filter is a bit complicated and its application is still very limited.We present the designing and implementation of the variance-dependent Goldstein radar interferogram filtering,emphasizing on the logic flow,the generation of look-up table,the determination of filtering parameter,and the handling of edge information loss.Experiments with real interferograms are provided to demonstrate the applications of the designed filtering.Comparisons with the result of the coherence-dependent Goldstein filter show that improvements from 18.4% to 36.9% are achieved when the variance-dependent filter is used,and the noisier the interferogram,the greater the improvement.

Temporal decorrelation model for the bistatic SAR interferometry

This paper develops a temporal decorrelation model for the bistatic synthetic aperture radar（BSAR） interferometry. The temporal baseline is one of the important decorrelation sources for the repeat-pass synthetic aperture radar（SAR） interferometry. The study of temporal decorrelation is challenging, especially for the bistatic configuration, since temporal decorrelation is related to the data acquisition geometry. To develop an appropriate theoretical model for BSAR interferometry, the existing models for monostatic SAR cases are extended, and the general BSAR geometry configuration is involved in the derivation. Therefore, the developed temporal decorrelation model can be seen as a general model.The validity of the theoretical model is supported by Monte Carlo simulations. Furthermore, the impacts of the system parameters and BSAR geometry configurations on the temporal decorrelation model are discussed briefly.

ADAPTIVE MODEL-BASED SCATTERING DECOMPOSITION OF POLARIMETRIC SAR INTERFEROMETRY

In this paper,a new decomposition method is proposed to solve the problems that vegetation component is overestimated and is not sensitive to directional scattering features with traditional polarimetric Synthetic Aperture Radar(SAR)decomposition.It uses a Polarimetric Interferometric Similarity Parameter(PISP)calculated from Polarimetric SAR Interferometry(PolInSAR)datasets to the scattering decomposition.The PISP is proposed to reveal the geometric sensitivity of SAR interferometry.It is defined by three optimized mechanisms obtained from PolInSAR datasets,therefore,it not only relates to the coherent scattering mechanism closely,but also sufficiently uses the phase and amplitude information.The PISP of building is high,and forest’s PISP is low.The proposed method uses the PISP as a judge condition to select different vegetation model adaptively.The decomposition results show the proposed method can effectively solve the vegetation ingredients overestimation problem.In addition,it is sensitive to the directional scattering.

顾及InSAR形变特征的斜坡灾害隐患早期识别遥感方法

广东省2020年在册地质灾害隐患点4744处,威胁24.95万人,但近年发生多起重大地质灾害并不在已发现的隐患点库内,全面识别排查潜在隐患仍是当前和今后一段时期防灾减灾重要任务之一。合成孔径雷达干涉测量区域范围大、形变反演灵敏度高,可以弥补传统地面调查及光学遥感技术不足。研究以广州黄埔区为例,采用2019年1月至2022年4月Sentinel-1A长时序雷达数据,综合利用SBAS-InSAR时序形变信息结合地形级实景三维模型解译风险斜坡,识别出研究区崩滑流斜坡变形潜在隐患风险84处,抽取15%比例开展外业调查5处具有显著形变的滑坡崩塌风险,证明该方法具有可行性,并对综合遥感识别地质灾害提出建议。

基于调频连续波的地基干涉合成孔径雷达微形变监测实验平台

地基干涉合成孔径雷达具有测量精度高、测量距离远、全天候等特点,适用于大坝、桥梁的微形变监测。该文搭建了基于调频连续波的干涉合成孔径雷达系统实验平台,通过干涉测量原理构建模型分析回波信号,改进成像及形变监测算法,提高系统监测能力。搭建滑坡位移形变模型,验证系统设计和形变测量方法,实验测量结果与实际移动值相差0.11 mm,误差在规定范围内,满足系统性能要求。

基于永久散射体合成孔径雷达干涉测量技术的地面沉降监测

城市施工建设及地下水开采活动日益频繁,导致城市地面沉降问题日益严重。虽然传统地面沉降监测技术的精度较高,但成本也高。近年来,星载合成孔径雷达干涉测量(InSAR)技术发展起来,已被用于监测大范围地表形变,具有低成本、大面积、高精度等特点。首次采用永久散射体合成孔径雷达干涉测量(PSInSAR)技术,监测上海西南某区域2017—2021年间的地面沉降。结果显示:除一处楼房外,该区域大部分地区未发生沉降,最大沉降速率约−7.10 mm/a,最大沉降量约25.43 mm。采用该技术监测沉降,一方面节省了大量的人力和物力;另一方面,本研究成果对城市地表沉降的科学防治具有重要的参考意义。