地震诱发崩塌滑坡敏感性评价 ——以北川县为例

以汶川地震重灾区四川省北川县为例,对研究区进行崩塌滑坡敏感性评价,并探究地震诱发的崩塌滑坡的分布规律。研究建立研究区崩塌滑坡空间数据库,选取距断裂带距离、坡度、坡型、高差、地层岩性等5个因素作为评价指标,采用层次分析法(Analytic Hierarchy Process,AHP)对指标的权重定量,使用因子加权相加模型对北川县的由地震引发的崩塌滑坡敏感性进行评价。研究发现,距断裂带距离和坡度对崩塌滑坡影响较强。研究结果将北川县划分为崩塌滑坡极度敏感区、高度敏感区、中度敏感区、轻度敏感区和不敏感区五个区域。其中,极度敏感区主要分布在北川县东部的龙门山断裂带上,并沿断裂带延伸,在西部河流两岸也有少量分布,高度敏感和中度敏感区在极敏感区外围辐射分布,轻度敏感区和不敏感区主要分布在研究区的西部地区。     

基于逆向云模型的雷达目标识别

提出了一种基于逆向云模型的雷达目标识别方法。首先,基于模-1距离准则建立了云滴确定度,对高分辨距离像(HRRP)距离单元进行正态逆向云模型建模;然后,定义逆云隶属度表征待测样本属于某个训练类别的概率。对目标模板库中5种飞机高分辨距离像数据的仿真结果表明,该方法具有识别率高、对训练样本量的要求较为宽松和方位角划分不敏感等优点,是一种有效的雷达目标识别方法。     

微观交通仿真模型校正中的参数敏感性分析

为研究交通微观仿真模型中各参数的变动对模拟结果的影响程度,基于敏感度理论,通过对敏感度系数定义,使微观交通仿真模型参数的敏感性具有可比性,并结合各参数敏感度测试散点图对单一交叉口各方向平均行程时间进行敏感性定性分析,最终确定安全距离附加部分、平均停车间距、安全距离折减系数、仿真步长、最大前视距离、安全距离倍数部分等参数为影响行程时间的敏感参数。       

面向大尺度区域分布式水文模型的子流域划分方法改进

子流域划分是构建流域/区域分布式水文模型的基础工作,关系到流域/区域水文模拟和预报精度的好坏。在针对大尺度区域进行子流域划分时,目前普遍使用基于地表径流漫流模型,通过单一集水面积阈值进行河网提取和子流域划分的方法在准确描述研究区的空间范围、确定流域出水口、提取内流区河网等方面存在一定不足。为此,作者对传统子流域划分方法进行改进,面向大尺度区域分布式水文建模提出一套基于流域出水口自动识别和多阈值虚拟河网融合技术的子流域划分方法,该方法包括4大部分,即流域出水口的识别,大、小集水面积阈值的确定,多阈值虚拟河网融合,子流域划分与编码。应用该方法对全国范围内进行了水系提取和子流域划分,共划分子流域25 174个,子流域平均面积381 km2,最大面积5 512 km2,最小面积4 km2,模拟范围与全国水系实际范围的吻合程度达到99.92%。进一步地,将研究结果与全国实测水系和现行流域区划成果进行对比分析,验证了该方法的适用性。该方法高效快速,在准确刻画大尺度区域范围的同时大幅降低了子流域个数,兼顾了模型模拟效率,较好地解决了传统子流域划分方法在大尺度区域分布式水文建模中面临的难题。相关研究可为大尺度区域分布式水文模型构建提供基础支撑,有助于更好地为大面积区尤其是国家宏观层面的水文水资源管理服务。     

RC Z形截面柱抗震性能有限元模拟

基于钢筋混凝土Z形截面柱抗震性能的试验结果,用ANSYS有限元软件对试验试件进行有限元非线性模拟分析.采用分离式钢筋混凝土有限元模型,混凝土单元选用SOLID 65实体单元,钢筋单元选用LINK 180杆单元.用直接建模的方式建立Z形截面柱模型并进行位移加载,对应力云图、滞回曲线、骨架曲线、延性系数和等效黏滞系数等力学性能指标进行分析.研究结果表明:模拟的结果与试验结果吻合良好,采用分离式模型建立的钢筋混凝土有限元模型可以用于RC Z形截面柱抗震性能的研究.     

采用乘性RNN的雷达HRRP目标识别

传统的高分辨距离像识别方法没有考虑时序相关性,且高分辨距离像的方位敏感性导致样本的时序性发生变化.因此,提出一种乘性循环神经网络模型.该算法首先将高分辨距离像样本转化为序列形式,用于考虑距离单元间的相关性;其次,为了缓解方位敏感性导致的高分辨距离像时序变化与参数固定模型不匹配的问题,模型根据输入数据自适应地选择对应的参...     

雷达高分辨距离像分帧新方法

针对雷达高分辨距离像的姿态敏感性问题,提出了一种新的分帧方法.首先分析了距离像频谱幅度的统计特性并假设其服从联合高斯分布,之后使用概率主分量分析模型对各个子帧内频谱幅度建模并用期望最大化算法求取模型参数,最后依次合并Kullback-Leibler距离最小的相邻子帧来完成分帧.实测数据的分帧结果与识别率均表明了该分帧方法的有效性.     

基于GIS和CF模型的2018年日本北海道Mw6.6地震滑坡危险性评价

为了给地震区域的灾后重建和防灾减灾工作提供重要帮助,同时给类似滑坡灾害危险性评价提供参考,开展对2018年日本北海道地震的研究。2018-09-06日本北海道厚真町发生Mw6.6级地震,触发了大量山体滑坡,造成人员伤亡和重大财产损失,引发社会广泛关注。基于0.3 m空间分辨率的Pleiades-1卫星震前震后高清遥感卫星影像进行滑坡目视解译,共圈定12 586处滑坡。选取高程、坡度、坡向、曲率、TPI(坡位指数)、距水系距离、距道路距离、距震中距离、地层岩性9个因子作为滑坡的影响因子。基于GIS平台,应用确定性系数(CF)模型开展北海道地震滑坡危险性评价,评价结果将研究区分为极低危险区、低危险区、中危险区、高危险区、极高危险区五类,得出滑坡危险性评价区划图,并利用ROC曲线对评价结果精度进行检验,正确率为85.3%,表明基于确定性系数模型得出的滑坡危险性评价结果与实际滑坡结果比较吻合。     

基于GIS和信息量法的伊犁黄土滑坡易发性评价

伊犁州位于新疆西北部,黄土分布范围较广,境内降雨丰沛.近年来,随着人类工程活动的增强,黄土滑坡灾害进一步加剧.以新疆伊犁州伊宁县某滑坡密集区域为研究区,在Google Earth平台上采用人工目视方法解译出3424处滑坡.选取高程、坡度、坡向、地形位置指数(TPI)、距道路距离、距河流距离、距断层距离、多年平均降雨量、归一化植被指数(NDVI)共九个滑坡影响因子,运用信息量法进行滑坡易发性评价.将研究区的滑坡易发性分为极低易发区、低易发区、中易发区、高易发区和极高易发区,采用感受性曲线(ROC)对评价结果进行检验.结果 表明:信息量模型训练集和验证集的成功率均在80％以上,信息量模型的评价结果较为理想;高易发区和极高易发区内滑坡数量有2660个,占滑坡总数的77.69％,滑坡面积为2.2 km2,占滑坡总面积的60.27％.基于GI S和信息量法的滑坡易发性评价结果可以为该区域地质灾害防灾减灾工作提供科学依据和可靠参考.     

基于DEM的岷江上游数字流域的离散化

流域地形与土地覆被类型离散化是构建分布式水文模型的关键问题之一，文中通过地形坡向分析技术在栅格DEM基础上生成数字化的流域水系和流域边界，按照流域地形特征将整个流域从空间上划分成多个自然子流域；在每个子流域内部，通过土地利用和土壤分布数字地图的叠加，生成体现单一土地利用类型和土壤类型组合的水文响应单元，并将研究区岷江上游流域离散为31个子流域，136个水文响应单元(HRU)，实现了数字流域的空间离散化，为构建分布式水文模型奠定了基础。研究表明：河道面积阈值的大小决定了离散子流域数目，也决定着水文响应单元的数量，具体流域的阈值需要进行比较分析来确定。     

基于CF法的震后泥石流频发区灾害主控因子研究（研究生论坛）

汶川地震极震区地震引发的大量崩塌、滑坡导致泥石流的孕灾环境发生剧烈变化,震后泥石流灾害十分频发,泥石流的防灾减灾迫在眉睫。本论文以汶川地震极震区都江堰深溪沟流域为研究区,在震后孕灾环境分析的基础上,得出该地区泥石流频发的主控因子为丰富的物源条件和易于灾害发生的地形地貌条件,并采用确定性系数CF法,定量分析了复杂地形地貌条件对泥石流灾害的影响程度,确定了该流域最有利于泥石流灾害发生的高程、坡度和坡向范围;并将研究结果和震后丰富的物源条件进行叠加分析,确定了主控因子共同作用下深溪沟流域泥石流灾害最危险的分布区域。研究结果可以为震后深溪沟流域泥石流灾害频发的成因分析提供依据,对震区的泥石流危险性评价和区划、防灾减灾、灾后恢复重建以及经济建设布局等具有重要的意义。     

A static and dynamic factorscoupled forecasting model of regional rainfall-induced landslides:A case study of Shenzhen

Most rainfall-induced landslide forecasting models focus on the relation between landslides and rainfall,which is one of the dynamic factors,and seldom consider the stacitc factors,such as geological and geograpical factors.Landslide susceptibility,however,is determinded by both static and dynamic factors.This article proposes a static and dynamic factors-coupled forecasting model(SDFCFM) of regional rainfall-induced landslides,which quantitatively considers both the static and dynamic factors that affect l...     

A static and dynamic factors-coupled forecasting model of regional rainfall-induced landslides: A case study of Shenzhen

Most rainfall-induced landslide forecasting models focus on the relation between landslides and rainfall, which is one of the dynamic factors, and seldom consider the stacitc factors, such as geological and geograpical factors. Landslide susceptibility, however, is determinded by both static and dynamic factors. This article proposes a static and dynamic factors-coupled forecasting model (SDFCFM) of regional rainfall-induced landslides, which quantitatively considers both the static and dynamic factors that affect landslides. The generalized additive model (GAM) is applied to coupling both factors to get the landslide susceptibility. In the case study, SDFCFM is applied to forecast the landslide occurrences in Shenzhen during a rainfall process in 2008. Compared with the rainfall logistic regression model, the resulting landslide susceptibility map illustrates that SDFCFM can reduce the forecast redundancy and improve the hit ratio. It is both applicable and practical. The application of SDFCFM in landslide warning and prevention system will improve its efficiency and also cut down the cost of human and matreial resources.     

A static and dynamic factors-coupled forecasting model of regional rainfall-induced landslides: A case study of Shenzhen

Most rainfall-induced landslide forecasting models focus on the relation between landslides and rainfall, which is one of the dynamic factors, and seldom consider the stacitc factors, such as geological and geograpical factors. Landslide susceptibility, however, is determinded by both static and dynamic factors. This article proposes a static and dynamic factors-coupled forecasting model (SDFCFM) of regional rainfall-induced landslides, which quantitatively considers both the static and dynamic factors that affect landslides. The generalized additive model (GAM) is applied to coupling both factors to get the landslide susceptibility. In the case study, SDFCFM is applied to forecast the landslide occurrences in Shenzhen during a rainfall process in 2008. Compared with the rainfall logistic regression model, the resulting landslide susceptibility map illustrates that SDFCFM can reduce the forecast redundancy and improve the hit ratio. It is both applicable and practical. The application of SDFCFM in landslide warning and prevention system will improve its efficiency and also cut down the cost of human and matreial resources.

     

Landslides susceptibility mapping in Guizhou province based on fuzzy theory

The purpose of this study was to assess the susceptibility of landslides around the area of Guizhou province based on fuzzy theory. In first instance, slope, elevation, lithology, proximity to tectonic lines, proximity to drainage and annual precipitation were taken as independent, causal factors in this study. A landslide hazard evaluation factor system was established by classifying these factors into more subclasses according to some rules. Secondly, a trapezoidal fuzzy number weighting (TFNW) approach was used to assess the importance of six causal factors to landslides in an ArcGIS environment. Thirdly, a landslide susceptibility map was created based on a weighted linear combination model. According to this susceptibility map, the study area was classified into four categories of landslide susceptibility: low, moderate, high and very high. Finally, in order to verify the results obtained, the susceptibility map and the landslide inventory map were combined in the GIS. In addition, the weighting procedure showed that TFNW is an efficient method for weighting causal landslide factors.     

崩滑型堰塞坝危险性快速评估研究进展（特约稿）

崩滑型堰塞坝是由地震、降雨、火山喷发等自然因素诱发的崩塌、滑坡堵塞河道所形成的天然土石坝,其在世界范围内广泛分布。崩滑型堰塞坝的形成与溃决具有高突发性、突溃性和强致灾性,会严重威胁所在流域的人民生命财产安全。因此,快速开展堰塞坝危险性评估,对应急抢险救灾具有重要的现实意义。目前对堰塞坝危险性快速评估的研究主要集中在成坝可能性、稳定性、寿命和溃决洪水等四个方面。本文总结了堰塞坝成坝影响因素和成坝快速判别公式,系统阐述了堰塞坝稳定性和寿命的定义、影响因素及快速评估模型,详细归纳分析了堰塞坝溃决模式、溃坝影响因素及坝址与下游河道的洪水快速预测模型。研究表明堰塞坝的形成主要受地形条件,固体物源条件和水源条件的影响;其稳定性、寿命和溃决主要受坝体几何形态,坝体材料、结构和水文特征等方面的影响。根据影响因素所建立的评估模型在一定程度上可以快速估算堰塞坝的稳定性、寿命、溃决流量等参数,但由于信息获取不便等问题,评估结果仍然存在一定的不确定性。在此基础上,本文提出了需要进一步研究的方向：(1) 考虑不同外因（地震、降雨等）条件下滑坡、崩塌启动及运移过程大型模型试验,建立考虑关键影响因素和水土物质相互作用的成坝快速判别模型;(2) 基于物探等手段开展堰塞坝坝体材料和结构参数的快速获取研究;(3) 建立考虑能量转换与耗散的溃坝程度快速评估模型,分析残余坝体致灾危险性;(4) 构建流域堰塞坝溃决洪水演进及水库调蓄减灾分析模型,指导流域水量调度及流域范围内工程建设;(5)开展堰塞坝灾害链对全流域影响的快速动态风险评估,为堰塞坝灾害预测及应急处置提供重要参考依据。     

基于多尺度分割方法的斜坡单元划分及滑坡易发性预测

滑坡易发性预测可以有效预测潜在滑坡的空间位置,是滑坡危险性和风险性评价的基础。由于斜坡单元依据真实地形地貌划分和具有明确的地质特征意义,更多的学者尝试利用斜坡单元进行区域滑坡易发性预测。但是,如何高效准确地划分斜坡单元并考虑其内部环境因子的非均质性是制约斜坡单元应用的关键因素,也是目前研究中的难点。本文以江西省崇义县为例,首先,提取研究区域坡向和山体阴影图作为基础数据,采用多尺度分割（MSS）方法划分斜坡单元,并结合试错法和研究区域历史滑坡形态特征确定MSS方法的最优参数组合。然后,基于斜坡单元提取高程、坡度、剖面曲率等环境因子,分别导入支持向量机（SVM）和逻辑回归（LR）模型,构建Slope-SVM/LR易发性预测模型。通过变化值和标准差表征斜坡单元内部环境因子的非均质性,进而构建Variant Slope-SVM/LR易发性预测模型。最后,采用ROC曲线和频率比精度分析上述模型的预测精度。结果表明：1）当尺度、形状特征权重和紧致度权重参数分别取20、0.8和0.8时,研究区域斜坡单元的划分效果最好;2）Slope-SVM、Variant slope-SVM、Slope-LR和Variant slope-LR模型的ROC精度分别为0.812、0.876、0.818和0.839,相应的频率比精度分别为0.780、0.866、0.792和0.865, 说明Variant slope-SVM/LR模型的预测精度高于Slope-SVM/LR模型。因此,MSS方法可以实现高效准确地自动划分斜坡单元,考虑斜坡单元内部环境因子的非均质性可以提高易发性预测结果的准确性。     

不同分级方法对区域滑坡易发性区划的影响

易发性分区是开展区域地质灾害风险评价的基础步骤，选取合理的分级方法对有效绘制区域滑坡易发性图意义显著，但鲜有研究对比了各易发性分级方法的优缺点，尤其是未能将历史滑坡与预测出的易发性指数相联接。针对该问题，以陕西省延长县为例采用3种机器学习模型计算滑坡易发性指数，即分类和回归树、随机森林和径向基函数；设计了5种易发性分级方法，划分不同的滑坡易发性等级，包括4种常规的基于地理信息系统的分级方法（自然断点、等间隔、分位数和几何间隔），同时考虑了滑坡与易发性指数间的非线性关联性的频率比阈值法。结果表明：3种模型的受试者工作特征（ROC）曲线下面积均大于0.75，但划分的易发性分级图分布模式却存在较大差异，使用几何间隔和分位数法的易发性图能在极高易发区中识别出更多滑坡，但这两种方法划分的极高和高易发区的总面积过大；使用等间隔法和频率比阈值法在极高和高易发区中的滑坡比率更大，说明识别出的滑坡更为集中。本文提出的频率比阈值法用于滑坡易发性分级，能为易发性的准确分区提供思路，为边坡稳定性较差区域的工程选址以及土地利用规划提供科学参考，提高地质安全评估及应急管理能力。     

Application and Validation of a Multi-block Constitutive Model at Landslides of the Wenchuan Earthquake （特约稿）

A multi-block model and a corresponding computer program have been developed which predict the kinematics of landslides. Furthermore, a unique event for studying different models simulating the triggering and movement of landslides is the 2008 Wenchuan earthquake in the mountainous region in Sichuan Province of China, which caused a large number of rapid landslides. The purpose of the paper is two-fold:(a) to propose and incorporate into the multi-block model constitutive relations predicting soil response along slip surfaces, and (b) to apply the multi-block model with the constitutive relations at landslides triggered by the Wenchuan earthquake. The proposed constitutive equations predict the shape of the shear stress-displacement response measured in ring shear tests. In the application, four landslides caused by the Wenchuan earthquake were considered. Only in one of these landslides the shear resistance-displacement response along the slip surface has been measured in laboratory tests. At this landslide, the triggering and movement of the landslide was predicted. In the other landslides, back analyses were performed and it was observed that the multi-block model predicted reasonably well the final configuration of all slides. In addition, as the measured and back-estimated total friction angle of all landslides was less than 18°, and the materials along the slip surface were sandy, it is inferred that some, or all of the slip surface during these slides was sheared in an undrained manner and excess pore pressures generated during sliding played a key role in the triggering and movement of these landslides. Concluding, the paper (A) proposed and validated a multi-block constitutive model which can be applied to predict the triggering and movement of earthquake-induced slides and (B) by analyzing four landslides of the 2008 Wenchuan earthquake, it concludes that some, or all of the slip surface during these slides, was sheared in an undrained manner and excess pore pressures generated during sliding played a key role in the triggering and movement of these landslides.     

Application and Validation of a Multi-block Constitutive Model at Landslides of the Wenchuan Earthquake

A multi-block model and a corresponding computer program have been developed which predict the kinematics of landslides.Furthermore,a unique event for studying different models simulating the triggering and movement of landslides is the 2008Wenchuan earthquake in the mountainous region in Sichuan Province of China,which caused a large number of rapid landslides.The purpose of the paper is two-fold:(a)to propose and incorporate into the multi-block model constitutive relations predicting soil response along slip surfaces,and(b)to apply the multi-block model with the constitutive relations at landslides triggered by the Wenchuan earthquake.The proposed constitutive equations predict the shape of the shear stress-displacement response measured in ring shear tests.In the application,four landslides caused by the Wenchuan earthquake were considered.Only in one of these landslides the shear resistance-displacement response along the slip surface has been measured in laboratory tests.At this landslide,the triggering and movement of the landslide was predicted.In the other landslides,back analyses were performed and it was observed that the multi-block model predicted reasonably well the final configuration of all slides.In addition,as the measured and back-estimated total friction angle of all landslides was less than 180,and the materials along the slip surface were sandy,it is inferred that some,or all of the slip surface during these slides was sheared in an undrained manner and excess pore pressures generated during sliding played a key role in the triggering and movement of these landslides.Concluding,the paper(A)proposed and validated a multi-block constitutive model which can be applied to predict the triggering and movement of earthquake-induced slides and(B)by analyzing four landslides of the 2008 Wenchuan earthquake,it concludes that some,or all of the slip surface during these slides,was sheared in an undrained manner and excess pore pressures generated during sliding played a key role in the triggering and movement of these landslides.