强震山区滑坡发育分布的地形地质控制作用研究

1933年叠溪M_w 7.5级地震在松坪沟强震区触发了大量岩质滑坡。为系统描述这些滑坡的地形和地质控制作用,通过遥感、激光雷达(LiDAR)、无人机(UAV),以及人工地面调查共编录208个滑坡,其中滑坡面积0.1 km~2的大型滑坡48个;选择系列指标(滑坡类型、数量及数量占比、面积及面积占比、点核密度及面积赋权核密度)分析滑坡位置的地形(坡向、高程、地形起伏和坡度)和地质(坡体结构和岩性组合)特征。结果表明:(1)滑坡集中分布在斜坡坡度为50°～60°、地形起伏370 m、高程2 000～3 000 m范围。(2)河谷(娃儿堡—较场区段)的左岸(反向坡3%)与右岸坡体结构(反向坡41%)差异较大。左岸滑坡占比(85%)高于右岸(15%),平面和楔形体滑坡数量占比可达81%,不发育倾倒体,而右岸倾倒体数量占比可达38%,岩崩和碎屑流在左右两岸占比相当,分别为9%与12%。(3)大于60%的平面和楔形体滑坡主要分布在杂谷脑组、侏倭组和C+P组厚–巨厚层砂岩夹薄层千枚岩、板岩地质单元,大于70%的岩崩和碎屑流主要分布在新都桥组和波茨沟组薄层板岩与千枚岩互层的地质单元。(4)厚层地质单元滑坡面积最大达7.89 km~2,平均值为薄层地质单元的7倍。进一步认为,坡体结构与岩性组合共同控制了滑坡发育数量、类型与规模,与松坪沟快速地壳抬升及河流侵蚀相关的大高差、大起伏、大梯度河谷地形为滑坡分布范围和聚集提供了有利地形条件。研究成果可为强震山区滑坡识别和预测提供地形和地质依据。     

西南地区传统村落空间分布特征及影响因素研究

我国西南地区独特的自然和人文环境造就了数量众多的"中国传统村落",为了深入了解西南地区传统村落的分布状况和成因,文章利用地理信息系统分析软件(ArcGIS),对西南地区不同时间截面的传统村落空间分布特征进行分析。同时结合空间统计分析软件(GeoDa)及地理探测器工具,综合多种影响指标,对西南地区传统村落空间分布的成因进行解析。结果表明:(1)西南地区的传统村落具有明显的地域空间分布不平衡性,不同时期的传统村落空间分布表现出明显的集聚分布态势,且聚集核心一直保持不变。在整体空间结构上,西南地区传统村落呈"单核聚集—单核多点网状布局"的空间结构发展模式。(2)通过分析多项指标因子对西南地区传统村落空间分布的影响程度,发现自然因素中的海拔高程、地形起伏度对传统村落空间分布的影响最大,地形起伏度较大、地面崎岖的中高海拔山区传统村落分布最集中。相比而言,人文因素对西南地区传统村落的空间分布影响较小。在乡村振兴的时代大背景下,西南地区传统村落的保护与利用将具有重要的现实意义。     

北京二环内历史城区民宿空间分布及影响因素研究

文章着重于旅游住宿层面,主要研究位于二环以内老城区的民宿产业因受到区域内旅游资源的分配和其他相关因素的影响,所形成的空间分布模式。文章利用地理信息系统等技术工具,通过核密度和多距离空间聚类分析,深入研究北京二环内历史城区民宿的空间分布特征及影响因素。研究表明,北京二环内民宿分布主要呈现四周环绕中央的沙漏型带状分布和小区域集聚大区域分散的空间分布模式。总体民宿和细分民宿在空间分布上具有明显的尺度依赖性,且城市型民宿和传统胡同院落型民宿的空间分布特征具有差异性。     

巢湖凤凰山滑坡形成机制和稳定性分析

1　前　　言 滑坡是山区和丘陵地区常见的地质灾害 ,其发育常常与区域岩土分布有关 ,如我国西北地区的黄土滑坡 ,西南地区和皖南山区的层状岩体或片状变质岩的滑坡 ,长江中下游地区的膨胀土滑坡以及华南地区风化岩体的滑坡[1,2 ] 。随着经济建设的发展和环境地质条件的恶化 ,近年来我国滑坡地质灾害越来越严重 ,滑坡地质灾害引起了人们的广泛重视。地球内力造成地形起伏 ,而外力则对地形进行夷平 ,现代地形是地球内、外营力长期作用、塑造的结果。在自然条件下 ,组成斜坡的岩土体强度与重力及各种地质营力长期互相作用、互为消长 ,随着边坡岩土体的逐渐夷平、固结 ,边坡内部应力调整 ,岩土体强度提高和植被发育     

"5·12"汶川地震崩塌滑坡危险性评价——以都汶公路沿线为例

选择地震极重灾区(都汶公路沿线)作为研究区域,利用遥感影像解译和野外调查数据,采用信息量方法,分析地震崩塌滑坡对影响因子的敏感性,结合GIS技术评价地震崩塌滑坡的危险性.研究表明,都汶公路沿线最利于地震崩塌滑坡的条件为:(1) 坡度:大于35°;(2) 坡向:E,ES和S坡向;(3) 坡面粗糙度:大于1.15;(4) 距断层距离:5～20 km;(5) 土地利用类型:林地、灌木林地和疏林地;(6) 地层岩性:元古代闪长岩、元古代斜长花岗岩、元古界玄武岩、安山岩、石炭系灰岩、泥灰岩和志留系灰绿色千枚岩及石灰岩,尤其是元古界玄武岩和安山岩.利用信息量综合因子叠加技术,对研究区域崩塌滑坡体进行危险性评价,并将其分为极高度危险区、高度危险区、中度危险区、轻度危险区以及基本无危险区.危险性评价结果表明:研究区域大部分处于中度危险区、高度危险区、极高度危险区,三者面积占总面积的70.34%,其中极高度危险区占到总面积的19.15%,范围较大,在公路修复和重新规划建设中应加强预防这些区域发生崩塌滑坡;基本无危险区范围较小,仅占总面积的11.81%;在分布特征上,极高度危险区和高度危险区主要分布在映秀至草坡河段上,草坡河至汶川段大部分处于轻度危险区及以下.研究结果可为震后公路恢复、重建及灾区重建提供科学指导与技术支持.     

镇康县滑坡易发性评价模型对比研究

准确的滑坡易发性评价结果是滑坡风险评价的关键,对防灾减灾意义重大.为了提高滑坡易发性评价精度,基于地理信息系统(GIS)平台,将镇康县境内150个滑坡灾害点转换为栅格数据作为评价样本,选取高程、坡度、坡向、起伏度、地形曲率、剖面曲率、地层、断层、年均降雨量、河流、土地利用类型、道路12项评价因子,并通过独立性检验,构建...     

GIS支持下基于层次分析法的汶川地震区滑坡易发性评价

 2008年5月12日14时28分,四川汶川发生了Ms8.0级大地震,地震诱发了数以万计的滑坡灾害。在大约48 678 km2的区域内,采用震后遥感影像解译并结合野外调查的方法,共解译出48 007个滑坡。应用GIS技术,建立了汶川地震诱发滑坡灾害及相关地形、地质空间数据库,分析了断层、岩性、高程、坡度、坡向、河流、公路等7个因素与滑坡分布的关系,应用滑坡面积百分比这一标准来分别衡量每个因素中各个级别对滑坡的影响程度;然后使用层次分析法对这7个参数进行权重分析;在GIS平台下对这些参数进行综合分析,通过分析结果将研究区内滑坡按易发程度分为极高易发区、高易发区、中易发区、低易发区与极低易发区5类,极高易发区与高易发区面积约8 211 km2,占研究区总面积的16.9%;最后,使用汶川地震滑坡数据库对研究结果进行检验,检验曲线表明分区效果良好,其中极高易发区与高易发区内实际发生滑坡面积为430 km2,占滑坡总面积的60.5%。     

上海农村居民点用地布局与演变特征分析

分析上海农村居民点用地总量与人均指标的空间布局及演变特征,辨识农村居民点空间分布与发展规律,为农村居民点空间发展战略与规划编制提供依据。研究方法:规范研究法、聚集度指数法、回归分析法、空间热力图分析法。研究结果:农村居民点规模小布局分散、道路河流指向性明显;农村居民点规模、全域聚集度、耕地聚集度、非农人口分布、人均用地指标分布均呈现圈层布局特征;郊区农村居民点用地大部分规模不变。研究结论:亟需编制多层级村庄规划;近郊以及西南部区域是上海农村居民点聚集度高和非农人口比例高的区域,应是宅基地城镇化的重点区域;远郊人均用地指标高,应是农村保护保留整治更新的重点区域;上海居民点用地减量化政策亟待突破。     

挤密桩在郑西客运专线湿陷性黄土地基处理中的应用

1黄土地基处理的原则郑州至西安客运专线,全长458.8 km(含郑州、西安枢纽配套工程)。主要经过山前平原、冲积平原、河流一、二级阶地和丘陵低山区等不同的工程地质地貌单元,沿线黄土分布广泛,约占线路总长的90%左右,其中绝大部分黄土为湿陷性黄土,因此,在工程设计中,对黄土的地     

街道结构特征及其与土地利用分布的关系——以天津市典型区域为例#br#

以空间句法理论为指导,以街道中心度指数表示街道网络结构特征,利用相关性和回归方法分析其与土地利用建设强度和功能混合度分布的关系,进而提出二者的协同分布策略,为空间利用效率提升提供依据。通过对天津市两个典型区域的研究发现,街道中心度指数与土地利用分布具有相关性,但在不同的街道结构特征下,相关性大小、影响方向及主导指数等方面存在差异,服务于城市的土地利用倾向分布于大尺度范围内中心度较高的街道,而服务于附近居民的土地利用倾向分布于小尺度范围内中心度较高的街道。因此,建议在进行土地利用布局时,应从不同尺度考察该区域的可达性、通过性的分布模式,判断其对不同范围内人流和车流的吸引力,以提高土地利用布局与该区域在不同尺度空间区位的耦合度,提升土地利用效率和地区活力。     

River eutrophication: irrigated vs. non-irrigated agriculture through different spatial scales

The main objective of this study was to determine how spatial scale may affect the results when relating land use to nutrient enrichment of rivers and, secondly, to investigate which agricultural practices are more responsible for river eutrophication in the study area. Agriculture was split into three subclasses (irrigated, non-irrigated and low-impact agriculture) which were correlated to stream nutrient concentration on four spatial scales: large scale (drainage area of total subcatchment and 100 m wide subcatchment corridors) and local scale (5 and 1 km radius buffers). Nitrate, ammonium and orthophosphate concentrations and land use composition (agriculture, urban and forest) were measured at 130 river reaches in south-central Spain during the 2001-2009 period. Results suggested that different spatial scales may lead to different conclusions. Spatial autocorrelation and the inadequate representation of some land uses produced unreal results on large scales. Conversely, local scales did not show data autocorrelation and agriculture subclasses were well represented. The local scale of 1 km buffer was the most appropriate to detect river eutrophication in central Spanish rivers, with irrigated cropland as the main cause of river pollution by nitrate. As regards river management, a threshold of 50% irrigated cropland within a 1 km radius buffer has been obtained using breakpoint regression analysis. This means that no more than 50% of irrigation croplands should be allowed near river banks in order to avoid river eutrophication. Finally, a methodological approach is proposed to choose the appropriate spatial scale when studying river eutrophication caused by diffuse pollution like agriculture.     

Landslide distribution and size versus relative relief (Shaanxi Province,China)

The present study aims to investigate the distribution and size of landslides in relation to relative relief. For this, a landslide inventory map of the area was developed from the interpretation of satellite images and detailed field survey. From this we could map 331 landslides in Ningqing County (Shaanxi Province). By using GIS and statistical approaches, we studied the coupling between landslide size distribution and relative relief. From this the control of relative relief on the rollover effect of the size distribution of landslides is obtained. The result shows that the landslide frequency-relative relief distribution is unimodal, with majority of landslides occurring in areas with relative reliefs in between 300 and 400. The relative number density of landslides decreased with the increase in the relative relief; on the contrary, the average area, average length and average width of landslide increased with the increase in relative relief. The percentage of large-scale landslide increased with the increase of relative relief or vice versa. In addition, the cumulative frequency-area distributions of these landslides empirically agree well with a power-law relation with an exponent of 1.776 above a certain size threshold. Below this value, it exhibited an obvious rollover effect. Further analysis has shown that landslide cumulative frequency-area curve is strongly influenced by relative relief. The rollover effect is more obvious with the increase of relative relief. The exponent of power law correlation gradually increased from 0.993 to 1.872 with increasing relative relief.     

地震作用下黄土滑坡加速度深度放大效应及震后变形模式研究

基于相似比理论,设计并完成了典型黄土滑坡物理模型试验,采用先进的离心机振动台技术,实现水平+垂直振动,研究黄土滑坡的地震动放大效应及变形模式,并配合有限差分数值模拟方法相互验证。结果表明：沿滑坡体浅表层加速度放大作用具有明显的趋表效应,水平向和垂向加速度放大效应呈非线性增加,且水平向大于垂向;在滑坡体的滑动面附近加速度放大作用呈现出岩性结构效应;随高程增加加速度响应逐渐增大,表现出高程效应,滑坡后壁放大作用明显。随入射地震波强度的增加,滑坡体内部关键部位加速度放大作用基本是先增大后减小的趋势。强震作用下黄土滑坡的破坏形式为：滑坡后壁形成拉裂隙并逐渐扩展,滑坡后壁发生崩塌,滑体略有下挫,形成拉槽,坡体中部鼓胀,坡脚有大量崩积物。研究结果为探讨地震作用下黄土滑坡的加速度放大效应和变形破坏情况,以期为天水地区黄土滑坡的地震稳定性评价和抗震设计提供参考。     

区域滑坡空间预测方法研究及结果分析

区域滑坡空间预测是通过分析滑坡在区域空间分布的丛集性及规律性,圈定出滑坡相对危险性区域。通过MAPGIS软件平台及其二次开发的滑坡灾害分析系统,采用半定量和定量两种方法对浙江省永嘉县区域滑坡进行了预测。半定量方法采用反映历史滑坡强度的袭扰系数和滑坡易发程度指数来评价,编制了危险性预测分区图;定量化方法采用信息量模型来评价,采用规则网格作为预测单元,运用该模型对永嘉县区域滑坡进行了空间定量预测,并依信息量法的结果编制了该区的危险性划决预测分区图,为政府部门进行土地规策、避免在滑坡易发区进行大规模土地开发和工程建设提供了科学依据。同时通过两种方法的预测结果,对比分析了滑坡的形成和各影响因素的关系,为滑坡的有效防治提供了参考。     

黄土滑坡典型工程地质问题分析

黄土滑坡是西北地区最为严重的地质灾害。随着西部经济的发展及工程活动的加强,黄土滑坡成为近年工程地质研究的热点问题。黄土滑坡后缘地裂缝发育,具有高陡的后壁以及演化特征。泾阳南塬自1976年大面积农业灌溉以来,发生了27处50余起黄土层内滑坡。2005年～2007年6月,对南塬黄土滑坡进行了多次现场调查和滑坡特征测量,获得了详实的野外资料。在现场工作的基础上,初步分析了地下水位上升诱发高速远程滑坡机制、塬边地裂缝成因机制、滑坡高陡后壁成因机制及其稳定性评价方法及黄土滑坡演化机制与演化平衡等当前黄土滑坡研究亟待解决的工程地质问题。     

Mapping the susceptibility of rainfall and earthquake triggered landslides along China–Nepal highways

The 2015 Gorkha earthquake (Mw?=?7.8) caused significant earthquake triggered landslides (ETL) in a landscape that is heavily intervened by rainfall triggered landslides (RTL). China’s Belt and Road Initiative plan to boost South-Asian regional trade and mobility through two key highway corridors, i.e. 1) Longmu–Rasuwa–Kathmandu (LRK) and 2) Nyalam–Tatopani–Kathmandu (NTK) route, that dissect the Himalayas through this geologically unstable region. To understand the spatial characteristics and susceptibility of these ETL and RTL, we delineate the landslides by means of time variant satellite imageries, assess their spatial distribution and model their susceptibilities along the highway slopes. We use a coupled frequency ratio (FR) – analytical hierarchy process (AHP) model by considering nine landslide determinants, e.g. geomorphic type (slope, aspect, curvature, elevation), hydrologic type (erosive potential of gullies, i.e. stream power index and distance to streams), normalized difference vegetation index, lithology and civil structure type (i.e. distance to roads). The results demonstrate that elevation and slope predominantly control both these landslide occurrences. The model predicts locations of ETL with higher accuracy than RTL. On comparison, NTK was safer with 133.5 km² of high RTL or ETL (or both) landslide susceptible areas, whereas LRK has 216.04 km². For mapping the extent of these landslides, we constricted it to the slope units of highways to reduce the computational effort, but this technique successfully achieved an acceptable threefold average model prediction rate of 82.75% in ETL and 77.9% in RTL. These landslide susceptibility maps and route comparisons would provide guidance towards further planning, monitoring, and implementing landslide risk mitigation measures for the governments.

     

Enhancing the accuracy of rainfall-induced landslide prediction along mountain roads with a GIS-based random forest classifier

Along mountain roads, rainfall-triggered landslides are typical disasters that cause significant human casualties. Thus, to establish effective mitigation measures, it would be very useful were government agencies and practicing land-use planners to have the capability to make an accurate landslide evaluation. Here, we propose a machine learning methodology for the spatial prediction of rainfall-induced landslides along mountain roads which is based on a random forest classifier (RFC) and a GIS-based dataset. The RFC is used as a supervised learning technique to generalize the classification boundary that separates the input information of ten landslide conditioning factors (slope, aspect, relief amplitude, toposhape, topographic wetness index, distance to roads, distance to rivers, lithology, distance to faults, and rainfall) into two distinctive class labels: ‘landslide’ and ‘non-landslide’. Experimental results with a cross validation process and sensitivity analysis on the RFC model parameters reveal that the proposed model achieves a superior prediction accuracy with an area under the curve  of 0.92. The RFC significantly outperforms other benchmarking methods, including discriminant analysis, logistic regression, artificial neural networks, relevance vector machines, and support vector machines. Based on our experimental outcome and comparative analysis, we strongly recommend the RFC as a very capable tool for spatial modeling of rainfall-induced landslides.

     

黄土滑坡工程地质问题分析研究

近年来,黄土滑坡成为我国西北地区最为严重的地质灾害之一。随着工程活动的加强,黄土滑坡成为近年地质研究的热点问题。2012年在对麟游县一后侧山体滑坡进行了多次现场调查和滑坡特征测量后获得了详细的野外勘察资料。基于现场工作,初步分析了降雨、地下水、地震等导致滑坡机制,通过工程实例,归纳出有效地黄土滑坡治理方案。     

Investigation into the triggering mechanism of loess landslides in the south Jingyang platform,Shaanxi province

Loess landslide incidents have resulted in significant economic losses and human casualties in Northwest China. To investigate the triggering mechanism of such loess landslides in the south Jingyang platform, Shaanxi province, an area which is subject to loess landslides, we performed a series of field measurements for loess landslide LD37 and also undertook laboratory. Comparisons between the field measurements of LD37 and the results of the constant shear drained (CSD) triaxial test indicate that the seepage from irrigation-water infiltration triggered the loess landslides in the study area where the initiation of the local sliding surfaces was linked to gentle stratum erosion and their subsequent development was because of excessive stratum erosion. The development of slow–rapid strain cycles in the ε–p′ plot from the CSD triaxial test results indicates that loess landslides are a feature of progressive failure of the loess slope. Preventive measures to reduce irrigation-water infiltration into loess slopes should be taken to prevent similar incidents from recurring in the future.

     

卡拉水电站边坡稳定及对坝址选择影响分析研究

 卡拉水电站位于雅砻江中游河段四川省凉山州境内,初拟装机1 080 MW。电站所处河段主要为砂板岩构成的纵向河谷,两岸岩层软硬相间,冲沟发育,物理地质作用强烈。在16 km河段内发育了9个大型或特大型滑坡体,总体积约772.05×106 m3。由于近坝址区山势陡峭、水流湍急、河道狭窄,滑坡体规模巨大,一旦失稳,将造成水库淤积或河道堵塞,并危及大坝及其他电站枢纽建筑物的安全,滑坡体的稳定性及其影响成为坝址选址的控制性因素。在环境地质背景研究基础上,对滑坡体稳定性进行宏观判断;通过极限平衡分析方法对典型滑坡体进行稳定计算;在滑坡体破坏规模分析、滑坡涌浪计算的基础上,分析滑坡体失稳后可能造成的工程影响,并按照“先避让、后处理”的原则,在综合考虑水能利用、电站建设条件等因素的基础上,对卡拉水电站坝址选择及下阶段的工作提出了初步意见和建议。