低频地质雷达新技术在滑坡勘查中的试验研究

滑坡地质灾害在我国西北、西南广泛分布,传统的滑坡调查是采用地面调查结合钻探、槽探、坑探等方法进行.采用高性价比的地球物理手段进行滑坡勘查,对查清滑坡结构、探索其成灾机理和地质灾害评估及预警有重要意义.本文研究目的旨在探索研究低频地质雷达方法在滑坡勘查中的应用效果,为地质灾害调查提供实用技术手段.通过理论分析和野外试验,建立了滑坡正演模型,得出了滑坡典型电磁波传播特征,并在西北和西南几处滑坡上开展了野外试验,分析了黄土滑坡和基岩滑坡的雷达剖面特征,给出了地球物理解释.试验结果表明:低频地质雷达技术能够划分滑坡地层结构,对滑面深度和滑床形态准确刻画,对落水洞位置准确定位,这充分证实地质雷达是一种实用有效的地质灾害调查与评价技术手段.     

综合物探方法在滑坡地质勘探中的应用研究

综合物探方法在滑坡等地质灾害的勘探中发挥着重要的技术作用。这里以河南省某地滑坡勘探为例,利用高密度电阻率法和地质雷达法等综合物探方法,分析两种物探方法的技术原理、联合解释,并结合地质钻探、地质调查等资料,查明该场地滑坡体的分布情况。结果表明,综合物探方法能有效地减少物探的多解性,提高成果解释精度,其综合物探解释成果与地质情况较为吻合,显示出综合物探方法在滑坡等地质灾害勘探中的重要作用。最后,对综合物探方法及综合解释进行了简要的总结和展望。      

兰州市九州石峡口滑坡形成机制与稳定性分析

基于滑坡区地质环境,通过区域地质调查、大比例尺平面图测绘、滑坡微地貌和变形破坏特征测量、扫描电镜(SEM)分析滑带土微观结构等手段,对兰州市九州石峡口滑坡的特征和形成机制进行了系统研究.结果表明,该滑坡具有显著的分级分块滑动特性,降雨、不合理的人工绿化灌溉及滑坡区高陡的地形是诱发该滑坡复活的主要因素.采用多种极限平衡计算方法并结合滑坡所处的地质环境评价该滑坡在天然、降雨、地震以及降雨和地震耦合作用下的稳定性,为该滑坡的治理提供理论指导.     

昌马断裂带地震滑坡的基本特征

根据详细的野外地质调查和滑坡探槽资料，讨论了昌马断裂带地震滑坡形成的地质环境与内部结构特征。     

地震作用下陈庄黄土-泥岩接触面滑坡失稳机理及稳定性研究

以甘肃礼县陈庄黄土-泥岩接触面滑坡为研究对象,在对该滑坡的地震地质环境、基本特征等调查的基础上,运用数值分析对陈庄黄土-泥岩接触面滑坡在各人工计算场地基岩地震动时程作用下的失稳机理及稳定性进行动态模拟研究。结果表明,陈庄滑坡在地震诱发下变形破坏模式为受拉和受剪的复合破坏模式。失稳机理过程可概括为：地震作用→底部岩体受张拉→潜在滑面主滑段上部剪应力增大→剪应变集中带出现→剪应变集中带延伸扩展贯通→滑坡失稳;滑坡稳定性方面,随着输入地震动的增大,陈庄黄土-泥岩接触面滑坡稳定性降低,其中在50年超越概率2%的基岩地震动时程作用下滑坡处于不稳定状态。     

地震诱发滑坡的危险性分析与预测

结合地震滑坡的特点和相关文献研究,介绍了地震力的分析方法、地震滑坡的机理、地震危险性分析的方法、地震活动性参数的确定方法以及场点地震危险性概率计算原则。将两种地震诱发滑坡预测结果进行对比,分析结果表明,地震滑坡危险区主要集中在中国西部地区（川、滇、甘、陕、新疆等省区）及中国台湾地区,随预测年限的增加场地的地震滑坡危险性也随之增高,地震崩塌滑坡的危险区域明显加大。     

四川德阳地区龙风水库西岸滑坡稳定性分析及防治

本文在对四川德阳地区龙风水库西岸滑坡的地质地貌条件及变形迹象进行深入调查的基础上,对该滑坡的主要成因及稳定性进行了分析与评价,并有针对性地提出了工程防治方案。研究表明,疏松透水的土层、较强的降雨以及人类耕作活动是导致滑坡发生的主要因素。在天然状态下该滑坡稳定或基本稳定;在天然＋地震状态下,该滑坡欠稳定或不稳定;在连续高强度降雨状态下,该滑坡不稳定。故采取截、排水及抗滑桩等工程措施是防治该滑坡的有效方案。     

降雨型滑坡时空预报新方法

地质条件和降雨是引起重庆地区山体滑坡的两个最主要条件. 文中在分析降雨型滑坡形成条件的基础上, 提出了将地质条件和降雨因素进行分级叠合的降雨型滑坡时空预报新方法. 首先, 利用多因素相互作用关系矩阵, 对某个地区或者某个边坡所在位置的地质条件进行半定量的评价和分级. 然后, 根据日最大降雨量和降雨过程的总降雨量, 对该地区降雨的严重程度进行分级. 最后将“地质条件影响因子”和“降雨影响因子”进行分级叠合, 得到了“滑坡易滑程度判别因子”, 并据此将滑坡按照其易滑度分为滑坡极易发生、滑坡易发生、滑坡不易发生和滑坡基本不发生4级. 通过对某个地区的一些危险边坡进行地质勘察, 结合比较准确的天气预报, 可以对该地区的降雨型滑坡进行较为准确的时空预测预报. 以鸡扒子滑坡为例, 验证了利用“双因素”分级叠合方法进行降雨型滑坡时空预报的可靠性和可行性.     

乌鲁木齐头屯河上游1999年8月滑坡成因分析

引言1 999年 8月 1 7日新疆头屯河上游庙尔沟一带发生滑坡 ,滑坡体长 70 0 m,宽 3 0 0 m多 ,滑向 1 5 0°。滑坡舌推挤到庙尔沟—昌吉公路西北边缘 ,对交通造成威胁。文中我们对滑坡的结构、成因进行了分析研究。图 1　滑坡区地质示意图( 1)第四系　 ( 2 )第三系　 ( 3)白垩系　 ( 4)侏罗系　 ( 5 )三叠系( 6 )二叠系　 ( 7)石炭系　 ( 8)断层　 ( 9)滑坡Fig.1　 Geological sketch of the landslide area1　滑坡区的区域地质条件从大地构造角度看 ,滑坡位于北天山乌鲁木齐山前凹陷。在地貌上滑坡区是头屯河侵蚀区 ,河流切割深度1 0 0 m,发…     

湖北省三峡库区秭归县头道河Ⅱ号滑坡特征及稳定性评价

针对湖北省三峡库区秭归县头道河Ⅱ号滑坡现状条件下的明显变形迹象,本文对该滑坡进行了综合的分析和研究,详细介绍了该滑坡的地质背景及滑坡特征。采用剩余推理法,对滑坡体在各种不同工况下的稳定性作了科学分析,并对滑坡体在三峡水库蓄水以后的稳定性作了合理评价。结果表明,滑坡体在目前状态下基本稳定,三峡水库蓄水以后,将对滑坡体稳定性产生较大影响,极有可能导致滑坡体失稳,据此结合工程实际提出了一些可行的防治措施及建议。     

GPR reflection characteristics and depositional models of mud volcanic sediments—Wushanting mud volcano field, southwestern Taiwan

Ground penetrating radar (GPR) survey was conducted in the Wushanting mud volcano field (Yanchao, Kaohsiung) using a 500 MHz antennae, which allowed high-resolution imaging of subsurface structures. Seven GPR reflection characteristics are recognized. Sigmoid GPR reflection patterns resulted from a recent mud lobe deposited above an underlying older mud lobe front. Contorted GPR facies resulted from recent mud flow which encountered obstacles. Subparallel reflections resulted from mud volcano deposits of limited flowability, low velocity and gentle gradient. Hummocky reflection patterns are formed by interfingering of recent mud lobes building onto low land. Disrupted GPR facies were due to lateral breaks of continuity from mud cracks, which, according to field observation, can provide channels for erosion and form deeper erosion gullies. GPR time slices of different depths are rendered as a three-dimensional model. Approximately orbicular GPR reflection characteristics can indicate arcuate stacked mud lobe fronts of different periods. Some depositional models to explain GPR reflection characteristics can be founded upon observations of recent sedimentary phenomena. The models of this study may be applied to paleoenvironments and the depositional evolution of mud volcanoes in similar geological settings.     

GPR reflection characteristics and depositional models of mud volcanic sediments—Wushanting mud volcano field,southwestern Taiwan

Ground penetrating radar (GPR) survey was conducted in the Wushanting mud volcano field (Yanchao, Kaohsiung) using a 500 MHz antennae, which allowed high-resolution imaging of subsurface structures. Seven GPR reflection characteristics are recognized. Sigmoid GPR reflection patterns resulted from a recent mud lobe deposited above an underlying older mud lobe front. Contorted GPR facies resulted from recent mud flow which encountered obstacles. Subparallel reflections resulted from mud volcano deposits of limited flowability, low velocity and gentle gradient. Hummocky reflection patterns are formed by interfingering of recent mud lobes building onto low land. Disrupted GPR facies were due to lateral breaks of continuity from mud cracks, which, according to field observation, can provide channels for erosion and form deeper erosion gullies. GPR time slices of different depths are rendered as a three-dimensional model. Approximately orbicular GPR reflection characteristics can indicate arcuate stacked mud lobe fronts of different periods. Some depositional models to explain GPR reflection characteristics can be founded upon observations of recent sedimentary phenomena. The models of this study may be applied to paleoenvironments and the depositional evolution of mud volcanoes in similar geological settings.     

Combining Electrical Resistivity Tomography and Ground Penetrating Radar to study geological structuring of karst Unsaturated Zone

This paper highlights the efficiency and complementarity of a light package of geophysical techniques to study the structure of karst Unsaturated Zone (UZ) in typical Mediterranean environment where soil cover is thin or absent. Both selected techniques, 2D Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT), are widely used in environmental studies and their application is accessible for a lot of scientists/engineers. However, GPR or ERT alone is not able to provide an enhanced characterization of geological features in karst media. In the present study, GPR results supply a near surface high resolution imaging and thus can provide relevant geological information such as stratifications and fractures. Despite the quality of the results GPR's investigation depth remains limited to around 12 m. Apparent and inverted resistivity provided by ERT surveys shows strong lateral and vertical variations. These variations can inform about general geological structuring and feature orientation. ERT is able to prospect down to 40 m but it's a low resolution integrative technique. In the study area the investigated limestone is a commonly electrical resistive formation (more than 2000 Ω.m). However deeper than 5–7 m, the ERT profiles reveal several zones of moderate resistivity (around 900 Ω.m). In these zones a stratification change corresponding to slanted bedding is clearly identified by GPR results. The combination of both GPR and ERT results can allow a well-established geological interpretation. These moderate resistivity zones with slanted beddings can explain the presence of a perennial water flow point 35 m below the surface of the studied site within the underground gallery of the Low-Noise Underground Laboratory (LSBB).     

The use of GPR for characterizing underground weathered profiles in the sub-humid tropics

Ground penetrating radar (GPR) has been used as a tool to access information about ground subsurface features. Such information is very important for different types of studies, varying from those related to archeological research to those studying geological elements of bedrock. More recently, however, GPR has been increasingly applied to environmental studies, especially for soil research. This paper presents the results of an application of GPR for the study of weathered profiles. GPR was used to discover the degree of trustworthiness of the information on the ground subsurface through the interpretation of the results of the radar sections as well as the data collected from boreholes, which reached until 21 m. The results show a relatively high degree of details obtained by GPR, indicating the possibility of speeding up ground subsurface surveys related to geomorphological, geological, and pedological studies.     

THE DELINEATION OF THREE-DIMENSIONAL SHALLOW GEOMETRY OF ACTIVE FAULT BASED ON TLS AND GPR: A CASE STUDY OF AN NORMAL FAULT ON THE NORTH MARGIN OF MAOYABA BASIN IN LITANG,WESTERN SICHUAN PROVINCE

It is crucial to reveal the surface traces and activity of active faults by obtaining high-precision microtopography and three-dimensional shallow geometry. However, limited by the traditional geological investigation methods in the field and geological condition factors, the measurement method on microtopography and shallow geometry of active fault is badly insufficient. In this study, the TLS and GPR are firstly used comprehensively to delineate the microtopography and shallow geometry of the normal fault scarp on the north margin of Maoyaba Basin in Litang. Firstly, the vertical displacements of two landforms produced by the latest two periods of normal faulting and the two-dimensional GPR profiles are obtained separately. Secondly, the three-dimensional measurement method of active fault based on TLS and GPR is preliminarily established. On this basis, three-dimensional model of fault scarp and three-dimensional images of subsurface geometry are also obtained. These data all reveal a graben structure at normal fault scarps. Thirdly, the fusion and interpretation of three-dimensional data from the surface and subsurface are realized. The study results show:1)the vertical displacements of the T₁ and T₂ terraces by the normal fault movement is 1.4m and 5.7m, the GPR profile shows a typical fault structure and indicates the existence of small graben structure with a maximum width of about 40m in the shallow layer, which further proves that it is a normal fault. 2)the shallow geometry of the normal fault scarp can be more graphically displayed by the three-dimensional radar images, and it also makes the geometry structure of the fault more comprehensive. The precise location and strike of faults F₁ and F₂ on the horizontal surface are also determined in the three-dimensional radar images, which further proves the existence of small graben structure, indicating the extensional deformation characteristics in the subsurface of the fault scarps. Furthermore, the distribution of small graben structure on the surface and subsurface is defined more precisely. 3)the integrated display of microgeomorphology and shallow geometry of normal fault scarp is realized based on the three-dimensional point cloud and GPR data. The fusion of the point cloud and GPR data has obvious advantages, for the spatial structure, morphological and spectral features from the point cloud can improve the recognition and interpretation accuracy of GPR images. The interpreted results of the GPR profiles could minimize the transformation of the surface topography by the external environment at the most extent, restore the original geomorphology, relocate the position and trend of faults on the surface and constrain the width of deformation zones under the surface, the geological structure, and the fault dislocation, etc. In a word, the TLS and GPR can quickly and efficiently provide the spatial data with multi-level and multi-visual for non-destructive inspection of the microgeomorphology and shallow structure for the active fault in a wide range, and for the detection of active fault in the complex geological environments, and it is helpful to improve the accuracy and understanding of the investigation and research on microtopography and shallow geometry of active faults. What's more, it also offers important data and method for more comprehensive identification and understanding of the distribution, deformation features, the behaviors of active faults and multi-period paleoseismicity. Therefore, to continuously explore and improve this method will significantly enhance and expand the practicability and application prospects of the method in the quantitative and elaborate studies of active faults.     

LANDSLIDE POTENTIALITY OF THE TSENGWEN RESERVOIR WATERSHED,TAIWAN,CHINA

To recognize the geographical characteristics of the landslide areas will be helpful for the watershed management in the reservoir watershed.According to the quantitative analysis,we'll take different scores and weighting for the potential parameters of the landslide areas in the Tsengwen reservoir watershed,and in the meanwhile,we'll extract the different factors,including the slope,aspect,altitude,soil and geological textures etc.,and the results shown as maximum one-day rainfall,ratio of forests and average relief is the most affecting parameters on the potential risk map of landslide areas.     

LANDSLIDE POTENTIALITY OF THE TSENGWEN RESERVOIR WATERSHED, TAIWAN

To recognize the geographical characteristics of the landslide areas will be helpful for the watershedmanagement in the reservoir watershed. According to the quantitative analysis, we'll take differentscores and weighting for the potential parameters of the landslide areas in the Tsengwen reservoirwatershed, and in the meanwhile, we'll extract the different factors, including the slope, aspect,altitude, soil and geological textures etc., and the results shown as maximum one--day rainfall, ratio offorests and average relief is the most affecting parameters on the potential risk map of landslide areas.     

Slope movements in the Flysch Carpathians of Eastern Czech Republic triggered by extreme rainfalls in 1997: a case study

The severe rainfalls in Northern and Central Moravia and Eastern Bohemia in July 1997, triggered slope movements recorded particularly in the flysch-type rocks of Northern and Eastern Czech Republic. The basis of the diversified woodland and agricultural landscape of the Western Carpathians is the highland and mountain erosion–denudation and structure-denudation relief, which consists of flysch rock complexes. The geomorphological and geological setting is predisposed to extensive slope deformations––especially landslides. Slope movements play an important role in topography modelling and cause great direct and indirect damages in the countryside as well. Slope deformations of different intensity and aerial extent control the character of relief on the local or regional scale. Significant changes of land use may result from the slope movements, especially when the reclamation of the slope deformations are not undertaken. Landslides themselves have a great impact on the water regime of the landscape and consequently on the development of ecosystems. That is why they are often considered to be a significant biodiversity factor. It is also necessary to pay attention to the opposite effect since the land use (dispersed woody patches, landscape mosaic) is to a certain extent influencing the development and progress of the slope deformations. Based on the order we focused our geological investigations on the area in which the slope movements began to develop to such an extent that human lives and properties were considerably endangered. The total damages from activated landslides reached about 40 million USD. The landslide research differs in individual localities and their topical situations and is accompanied by a stability assessment of the locality and a proposal of rescue measures. An alternative solution should consist of an assessment of necessary changes in the area plans of affected villages, prospects of their future habitability, and displacements of engineering networks and roads.     

综合地质预报技术在岩溶区隧道施工中的应用

通过对地质分析法、地质雷达、红外探测,超前水平钻孔等超前地质预报技术在某隧道中岩溶预报中的应用研究,对比分析几种地质预报技术的特点,得到由多种预报手段综合而成的预报系统的实用性以及在指导施工方面的作用优于单一地质预报方法的结论,并对照实际开挖情况提出针对岩溶地质条件的施工建议.     

三维探地雷达技术在道路塌陷空洞探测中的应用

道路塌陷空洞一直是威胁交通安全运行的重要隐患,对道路塌陷空洞的探测方法进行研究具有重大的现实意义。研究工作通过实例探讨三维探地雷达（GPR）对道路塌陷区进行探测的方法技术及其应用效果。为查明道路塌陷空洞的空间分布特征,在塌陷区布设了共23条测线,1.0 m×0.5 m的三维测网并进行数据采集;通过对雷达数据进行处理,获得不同测线、不同方向的三维雷达剖面。结合地质情况对上述图件进行综合分析与解释,准确地查明塌陷空洞的位置、埋深及发育程度;经开挖验证,解译结果可靠。工程实践表明,三维探地雷达技术可以快速、高效地应用于道路塌陷探测中,其探测结果可为塌陷区后续施工以及安全防治提供参考。