数字滑坡技术及其应用

“数字滑坡”技术,就是以遥感（RS）和空间定位方法为主,结合其他勘探、试验、调查手段获取数字形式的、与地理坐标配准的滑坡基本信息;并利用GIS技术存贮和管理这些数字信息;在此基础上,根据滑坡地学原理进行空间分析,研制各类模型,并服务于滑坡调查、监测、研究、滑坡灾害评价、危险预测、灾情评估、滑坡防治等。通过金龙山三维数字模型,卫星监测易贡滑坡、三峡库区重点城镇滑坡及千将坪滑坡等地的遥感调查说明数字滑坡技术的实际应用。     

地震荷载作用下顺层岩体边坡变形特征分析

应用二维离散元程序UDEC计算了地震荷载作用下边坡的位移,并将计算结果与Newmark法计算结果及震后现场实测值进行了对比。结果表明,Newmark法计算得到的位移值较实测值偏小,离散元计算得到的位移结果较Newmark法更接近于实测值。在此基础上,初步分析了地震荷载作用下坡高、坡角、岩层倾角等因素对顺层岩体边坡位移的影响规律。由分析结果可知,地震荷载下顺层岩体边坡的位移并不随坡高增加而单调增大,在坡高约100 m时位移达到最大值,坡高超高100 m位移反而有所降低;当坡高超高200 m后,位移随坡高的变化幅度不大,顺层岩体边坡的位移随坡角增加而单调增大。随岩层倾角增加边坡位移明显增大;当岩层倾角大于层面内摩擦角时,随着岩层倾角的增大,边坡变形增长幅度明显增大。     

兰临高速公路袁家湾滑坡演化机理

位于兰临高速公路k15+000～k15+500段的袁家湾滑坡系公路修建时开挖高陡边坡所诱发的顺层岩质滑坡,因工程设计和岩体结构等原因,从开挖伊始直到运营期间,该滑坡一直持续滑动而久治不愈,滑坡规模大、危害严重,具有重复性和继承性滑动特征。根据其地质条件、工程特征以及滑动特征和滑动历史,采用工程地质分析、物理模型试验和FLAC3D数值模拟等方法,分析了该滑坡产生的原因、演化机理和过程。     

Evolution of the north flank of Tenerife by recurrent giant landslides

Geomorphologic analysis of submarine and subaerial surface features using a combined topographic/bathymetric digital elevation model coupled with onshore geological and geophysical data constrain the age and geometry of giant landslides affecting the north flank of Tenerife. Shaded relief and contour maps, and topographic profiles of the submarine north flank, permit the identification of two generations of post-shield landslides. Older landslide materials accumulated near the shore (<40-km) and comprise 700 km³ of debris. Thickening towards a prominent axis suggests one major landslide deposit. Younger landslide materials accumulated 40–70 km offshore and comprise the products of three major landslides: the La Orotava landslide complex, the Icod landslide and the East Dorsal landslide complex, each with an onshore scar, a proximal submarine trough, and a distal deposit lobe. Estimated lobe volumes are 80, 80 and 100 km³, respectively. The old post-shield landslide scar is an amphitheatre, 20–25 km wide, partly submarine, now completely filled with younger materials. Age–width relationships for Tenerife's coastal platform plus onshore geological constraints suggest an age of ca. 3 Ma for the old collapse. Young landslides are all less than 560 ka old. The La Orotava and Icod slides involved failures of slabs of subaerial flank to form the subaerial La Orotava and Icod valleys. Offshore, they excavated troughs by sudden loading and basal erosion of older slide debris. The onshore East Dorsal slide also triggered secondary failure of older debris offshore. The slab-like geometry of young failures was controlled by weak layers, deep drainage channels and flank truncation by marine erosion. The (partly) submarine geometry of the older amphitheatre reflects the absence of these features. Relatively low H/L ratios for the young slides are attributed to filling of the slope break at the base of the submarine edifice by old landslide materials, low aspect ratios of the failed slabs and channelling within troughs. Post-shield landslides on Tenerife correlate with major falls in sea level, reflecting increased rates of volcanism and coastal erosion, and reduced support for the flank. Landslide head zones have strongly influenced the pattern of volcanism on Tenerife, providing sites for major volcanic centres.     

Environmental geology in Thailand – programs and strategies

 The paper describes the activities and objectives of the Department of Mineral Resources in the field of environmental geology. This approach is still a comparatively new for Thailand and presently comprises different programs: environmental geology for regional planning, seismic hazards, flooding/landslides, coastal management and geosites conservation. The Environmental Geology Section of the Department is the relevant administrative unit. The technical work and the related documentations focus on rising public awareness and integration of geo-information into land-use planning and land development. Received: 23 April 1999 · Accepted: 8 June 1999     

道真沙坝水库干渠滑坡的治理

本文从治理滑坡的实践出发,探讨并制定了渠道所遇土质滑坡的治理方案,经实施,既经济,效果又好,具有推广实用价值。     

Historical Constraints on Slope Movement Age: a Case Study at Broadway, United Kingdom

The Broadway area of the Cotswolds has been extensively investigated in an attempt to delineate areas of slope instability, including'relict'landslides, which may have been initiated under periglacial climatic conditions. It is, therefore, useful both in terms of the geomorphology and of the understanding of the evolution of the area, to investigate the rates and timing of any reactivation and subsequent movements of landslides in this area. The remains of ridge and furrow cultivation can be seen extensively throughout the Cotswolds. This particular agricultural practice, which documentary evidence suggests dates back to Anglo-Saxon times (approximately 10th century AD), has been disturbed in many places by slope movements. A detailed study of Parish Records and other local his-torical sources has revealed that ridge and furrow cultivation ceased on Parliamentary Enclosure, which in this area, occurred in 1771. Therefore, it is possible to identify patterms of slope movement between these dates. Landslides have been identified by ground mapping and aerial photography, and can be divided into three categories. Firstly, active landslides which are those which have shown evidence of movement during the study period. Secondly, suspended landslides, which show evidence of movement, but have not been observed to move during the study period. In this context, this has been taken to mean landslides, which have shown evidence of movement since 1771. Thirdly, relict landslides which have shown no evidence of movement since 1771 and thus were probably active under a different climatic regime. By incorporating historical data with the geomorphological survey it has been possible to identify areas of potentially difficult ground for engineering geomorphological purposes.     

四川什邡北部山区遥感调查次生地质灾害现状及防治建议

四川汶川发生8．0级强震后,在震中附近山区引发了大量的岩石崩滑、山体滑坡、堰塞湖等次生地质灾害,国土资源部中国地质调查局组织四川、湖北、湖南、陕西、安徽和中国地大的有关专家利用卫星遥感资料,迅速调查次生地质灾害情况,每天上报,供国务院等有关部门决策。本文选择重灾区之一的有代表性的什祁北部山区加以介绍,分析了特殊构造部位与次生地质灾害发生的关系,建立了次生地质灾害遥感解译标志,总结了该区次生地质灾害的主要类型,评价了该区的灾情现状,并提出了合理的防治建议,供同行们切磋。     

地震作用下预应力锚索加固顺层岩坡极限分析

针对地震作用下预应力锚索加固顺层岩坡典型模型,提出了一种地震作用下预应力锚索加固顺层岩坡的极限分析改进方法,该方法考虑了边坡极限状态时锚索的受力变化。基于岩体刚性假设并考虑滑移过程锚索受力变化,结合极限平衡法推导出边坡加固预应力锚索的受力变化公式;地震作用仅考虑地震波传播至滑动面时产生的透射波对边坡稳定性的影响,从功率的角度出发,结合极限分析上限法与强度折减法,考虑预应力锚索受力变化,推导出地震作用下预应力锚索加固顺层岩坡的动安全系数计算理论公式;结合算例,采用考虑与不考虑滑移过程锚索受力变化两种计算方法,分析了在不同入射波波幅、入射角度及滑动面黏聚力、内摩擦角条件下两种方法计算结果的差异。算例结果表明：考虑与不考虑滑移过程锚索受力变化计算方法,计算得出的动安全系数变化规律一致,但考虑滑移过程锚索受力变化的改进计算方法得出的动安全系数动态变化幅度明显更小,反映了锚索的抗震作用效果,可为地震作用下该类型岩坡的预应力锚索加固设计分析提供参考。     

不同降雨条件下黄土高原浅层滑坡危险性预测评价

黄土地区浅层滑坡发育非常广泛,由于其具有分布规律性差、前期变形迹象小、分布范围大、面小点多等特征,目前还无法进行有效预测,因此给黄土地区工程安全带来严重威胁。根据无限边坡模型,结合降雨入渗-土体强度衰减规律和GIS（地理信息系统）技术,构建了不同降雨条件下黄土地区浅层滑坡发育危险性评价模型,并将该评价模型应用到延河一级支流幸福川流域,预测在有效降雨量30、50、100、200 mm条件下,该流域浅层滑坡发育程度,并与当前较为流行的SINMAP模型(地形稳定性模型)进行对比。结果表明：①不稳定和潜在不稳定浅层滑坡主要分布在末级河流的两侧和源头,稳定和较稳定区域主要分布在一级河流河道两侧和塬面上;通过对比分析,SINMAP模型计算的结果与本文建立的模型在降雨强度30 mm时的计算结果较为一致。②在本文建立的模型评价结果中,随着有效降雨量的增加,F_s（稳定性系数）<1.00的不稳定区域所占比例逐渐增加,从30 mm的1.12%到200 mm的4.79%;相反,稳定区域则出现逐渐减少的趋势。③根据已发生灾害点的分布,随着有效降雨量的增加,研究区域已发生的灾害点分布在F_s<1.25的比例明显增加,从30 mm的62%到200 mm的88%,在SINMAP评价模型中,研究区域已发生的灾害点的64%分布在不稳定和潜在不稳定区域内,说明本文所建立的评价模型具有一定的精度。通过与SINMAP评价模型对比,本文建立的模型主要采用基于降雨入渗规律,而SINMAP评价模型主要基于降雨汇流过程,因此在利用过程中应根据区域特征选择利用。