Spatial prediction of highway slope disasters based on convolution neural networks

In order to clarify the spatial differentiations of highway slope disasters (HSDs) in Boshan District, spatial prediction was carried out based on ECG-CNN with the support of GIS. Spatial prediction factors of HSDs were selected, and the stabilities of the 147 highway slopes in Boshan District were determined. The spatial prediction model of HSDs was established by ECG-CNN, and the spatial susceptibility map of HSDs in Boshan District was plotted. Influences of the prediction factor combinations and the drill sample and verification sample combinations on the prediction success rates were verified. The results show that low susceptible areas, medium susceptible areas and high susceptible areas account for 56.92%, 28.46% and 14.62% of the total areas of Boshan District, respectively. Some sections of Binlai Expressway, G205, G309, S210 and S307, pass through high susceptible areas. The surface cutting depth has a small impact on the prediction success rate, while the elevation and gradient have great impacts on the prediction success rate. When the drill samples are small, network drill’s maturity has a great impact on the prediction success rate, while when there are many drill samples, the model’s logical structure itself has a large impact on the prediction success rate.

     

Towards a science of past disasters

It is widely recognised that natural disasters emerge in the interplay between extreme geophysical events and the human communities affected by them. Whilst detailed natural scientific knowledge of a given event is critical in understanding its impacts, an equally thorough understanding of the affected communities, their economies, ecologies, religious structures, and how all of these have developed over time is arguably as important. Many extreme events leave methodologically convenient traces in the geological and archaeological records in the form of discrete stratigraphic layers often associated with both accurate and precise dates. This paper focuses on volcanic eruptions and draws on matched case studies to illustrate the usefulness of a two-step, quasi case–control comparative method for examining vulnerability and impacts in the near- and far-fields of these eruptions. Although issues of data resolution often plague the study of past disasters, these limitations are counterbalanced by the access to unique long-term information on societies and their material expressions of livelihood, as well as a similarly long-term perspective on the critical magnitude/frequency relationship of the geophysical trigger(s) in question. By drawing together aspects of contemporary Disaster Risk Reduction research, archaeology, and volcanology, this paper sketches out a methodological roadmap for a science of past disasters that aims to be relevant for not only understanding vulnerabilities and impacts in the deep past, but for also better understanding vulnerability in the present.     

东南沿海台风暴雨型单体斜坡灾害风险评价——以泰顺仕阳北坡为例

在东南沿海地区每年汛期由台风暴雨诱发的坡积层滑坡灾害事故众多,给当地人民生命财产安全造成巨大威胁。斜坡单体风险评价是地质灾害治理与防控的重点、难点。在野外调查、工程地质钻探及岩土体力学测试的基础上,以仕阳镇仕阳北坡为例,结合气象资料分析了不同降雨条件下斜坡的稳定性;采用蒙特卡洛方法计算了斜坡安全系数的统计特性;基于斜坡破坏概率研究了承灾体的易损性,并定量计算了不同降雨条件下建筑物及人员的风险值。结果表明：随着降雨强度的增加,滑坡发生概率随之增加,其风险值也逐渐增加,特大暴雨工况风险最大,其人员风险为94人/年,经济风险为1.41亿元/年。研究结果对东南沿海地区该类滑坡的防治工程有重要的参考意义,可为该类滑坡的防灾减灾决策提供建议。     

Reservoir assessment using non-invasive geophysical techniques

This paper describes the use of three geophysical techniques to detect potential seepage that could jeopardise the integrity of reservoir embankments, could induce partial or total collapse and pose a risk to the population nearby. A fast-scanning geophysical technique using two dipole electromagnetic (EM) profile apparatus GEM2 provided the first step to detect the weakest points on the selected dams in order to proceed to a more detailed analysis and visualisation of the soil erosion (fissuring or piping) using electrical resistivity tomography (ERT). Finally, self-potential surveys were carried out to relate to the EM and ERT anomalies that could be pathways for seepage and changes of the water displacement inside the embankment. The three geophysical techniques used were evaluated in one case study of reservoir in a location relevant to flooding issues in Czech Republic. A risk approach based on the geophysical results was undertaken for the reservoir embankment. The three techniques together were compared for the same problematic section and confirmed seepage by showing similar results. Conclusions were also drawn on the efficiency of using these three techniques as a package to give a comprehensive non-invasive assessment to be used as common practice by local authorities and environment agencies whereby remedial action could be recommended to protect assets and civilians.     

基于ISM的公路突发地质灾害应急机制构建

公路突发地质灾害应急机制是保障人民生命财产安全和降低灾害破坏程度的有效手段,为了科学、合理地构建公路突发地质灾害应急机制,运用系统工程理论,采用结构解释模型(ISM)方法确认并分析了应急机制构成的主要要素及其相互影响关系,建立了多层递阶解释结构模型。应用该模型,对应急机制体系进行了分析,将相关要素进行了分级,并分析了要素之间的纵向和横向关系。构成公路突发地质灾害应急机制的8个要素被划分成5个层次。应急预案是应急机制构建的综合成果,对减灾和防止次生灾害的发生起着直接的作用;而应急预案能否发挥其应有的作用,还受到后勤保障和实施速度的影响;会商机制可以有效的保证后勤保障和实施速度;险情监测、安全隐患检查、灾害调查又为会商的顺利进行提供了大量的资料和数据;而信息机制又是这些要素的基础。要素间的相互关系被清晰的揭示,为公路应急机制体系的建设和完善提供了科学依据。     

路堑边坡工程的动态仿真分析

高速公路建设中不可避免地会遇到各种结构类型的斜坡,其稳定性状况在很大程度上决定了工程的投资和工期。因此,研究其工程适宜性具有较大现实意义。从影响路堑边坡稳定性的各种因素出发,应用岩体力学理论和数值模拟技术研究边坡开挖过程中的变形破坏特征,分析地下水、时效特性和工程措施优化等对边坡稳定性的影响,对边坡信息化设计和施工具有一定指导意义。研究表明,路堑边坡岩体的变形破坏特征符合卸荷岩体力学行为,在最优坡度设计基础上,应当及时进行加固。     

A classification system for the assessment of slope stability of terrains along highway routes in Jordan

 The establishment of comprehensive development plans, in general, and the proper selection of highway routes, in particular, require an assessment of landslides or instability hazards in the project sites. The frequent landslides that occurred along the routes of major highways in Jordan, and particularly along the Amman-Na'ur-Dead Sea highway and Irbid-Jerash-Amman highway, have substantially increased the cost of construction and caused a considerable delay in the completion of work. The study of many landslides that occurred in the last 25 years along the highway routes and in the sites of some major civil engineering projects in Jordan has led to the recognition of major factors that affect the stability of slopes, and thus the safety and economics of these projects. The geological formation, structural features, topographic characteristics, geometry, and climatic conditions were adopted as the basis for the classification of terrains in terms of their stability. Each factor has been assigned a rating to indicate its relative contribution to the overall stability according to engineering judgment and past experience. The areas have been classified into 5 groups according to their total stability rate. The simplicity, comprehensiveness, and accuracy are the main characteristics of the proposed classification. Its significance stems from its helpfulness as a guide to the geotechnical and highway engineers in assessing the overall stability of the alternative routes of proposed highway projects. Received: 3 December 1996 · Accepted: 29 April 1997     

黄土地区公路边坡降雨失稳预报研究

为了研究黄土地区公路边坡降雨失稳灾害的预测预警方法,通过现场调查和理论分析,研究了黄土地区公路边坡降雨灾害危险性初步判别的标准;在分析公路边坡稳定性主要影响因素(边坡结构、边坡形态和植被特征)的基础上,提出了黄土地区公路边坡标准坡型的模型;以标准边坡坡型为基准,根据边坡失稳资料和降雨数据,建立了公路边坡抗灾能力评分表和评分标准。由此提出了适合于陕北黄土地区(包括砂黄土地区和典型黄土地区)公路边坡降雨灾害预测预警的抗灾雨量法,可以针对某个具体的黄土地区公路边坡的降雨灾害进行工点失稳预报。工程应用表明抗灾雨量法可操作性较好。     

应力监测在公路岩质边坡中的应用研究

针对山区高速公路岩质边坡数量大、失稳难以及时预警的问题,提出对边坡支护锚杆进行应力监测的方式以评价其稳定性。以广陕高速改扩建工程沿线的一处典型岩质边坡为例,采用FLAC3D软件对岩质边坡的开挖支护过程进行模拟,利用强度折减法分析随岩体强度降低过程中支护锚杆的轴力变化规律,确定应力监测预警值,并结合现场试验结果对边坡安全状况进行评价。研究结果表明,试验边坡监测位置应以泥岩结构面处为主,应力监测预警是一个整体的预警系统,监测点位任一处达到预警值均应提出预警。监测结果显示,应力监测在120 d时出现明显变化,而位移变化则较为滞后,在167 d后才出现明显变化;综合应力与位移监测的结果可以得出,试验边坡处于安全运营状态,所提出的应力监测评价公路岩质边坡的稳定性具有可行性。     

路基边坡的植物防护方法

针对目前公路边坡防护的现状及发展趋势,较系统地介绍了多种路基边坡植物防护方法,并指出了公路路基边坡植物防护方法中需要进一步研究和解决的问题。      

Toward a rapid probabilistic seismic vulnerability assessment using satellite and ground-based remote sensing

Natural hazards such as earthquakes threaten millions of people all around the world. In a few decades, most of these people will live in fast-growing, inter-connected urban environments. Assessing risk will, therefore, be an increasingly difficult task that will require new, multidisciplinary approaches to be tackled properly. We propose a novel approach based on different imaging technologies and a Bayesian information integration scheme to characterize exposure and vulnerability models, which are among the key components of seismic risk assessment.     

用改进的DDA方法模拟公路隧道的稳定性

用改进的非连续变形分析(DDA)方法对某公路隧道进行了稳定性分析。采用有限元网格生成方法--行波法,在计算区域内自动生成三角形的DDA块体。块体的边界分为真实节理和虚拟节理,虚拟节理的强度取岩体的真实强度。另外,计算中还考虑了预应力锚杆对隧道围岩的加固作用。将计算得到的隧道拱顶、边墙的位移与现场监测结果进行了对比,两者基本吻合,说明改进的DDA方法在地下隧道的稳定性分析方面具有应有前景。     

A multidisciplinary approach for the investigation of a rock spreading on an urban slope

Landslides are very complex processes controlled by multiple factors. The knowledge and characterization of these factors is essential for a comprehensive understanding of the mechanisms and kinematics of the instabilities and for an efficient design of corrective measures. The aim of this work is to combine traditional geological and geotechnical techniques with geophysical, remote sensing and forensic techniques for obtaining a whole picture of an active lateral spreading affecting the Finestrat municipality in Alicante, SE Spain. Geomorphological, geotechnical and geophysical techniques (i.e. ground penetrating radar and refraction seismic) have provided essential information about the geometry, structure and petro-physical properties of the slope. A Terrestrial Laser Scanner was used for recognizing the most important sets of discontinuities affecting the rock mass and to evaluate the activity of the landslide slope. Complementarily, a forensic analysis of the building damage completed the available datasets, yielding very useful kinematic information of the landslide. Finally, a sensitivity analysis of the stability of the rock slope has been performed considering both block toppling and block sliding models. Therefore, the multisource analysis performed in this work has allowed the identification and characterization of a complex lateral spreading, highlighting its effectiveness for a comprehensive understanding of this type of landslide.     

水位下降卸荷诱发库岸边坡快速失稳机理分析

本文以某工程现场岩质边坡为例，采用与传统裂隙水压力分布不同的水压力分布方式和边坡裂隙中可能发生的水锤效应相耦合，分析研究了岩质边坡发生滑动的机理及稳定性。研究表明，本文所采用的水压力分布方式较为符合边坡中的水压力分布实际情况，可以给出一个较为合理的稳定系数。当考虑水锤效应时，岩质边坡的稳定系数大大降低，说明水锤效应加剧了边坡破坏失稳的过程。本文所采用的水压力分布方式与边坡裂隙中的水锤效应相耦合的计算方法，在边坡稳定性分析中具有参考意义。     

Bayesian techniques for seismic hazard assessment using imprecise data

Some Bayesian methods of dealing with inaccurate or vague data are introduced in the framework of seismic hazard assessment. Inaccurate data affected by heterogeneous errors are modeled by a probability distribution instead of the usual value plus a random error representation; these data are generically called imprecise. The earthquake size and the number of events in a certain time are modeled as imprecise data. Imprecise data allow us to introduce into the estimation procedures the uncertainty inherent in the inaccuracy and heterogeneity of the measuring systems from which the data were obtained. The problem of estimating the parameter of a Poisson process is shown to be feasible by the use of Bayesian techniques and imprecise data. This background technique can be applied to a general problem of seismic hazard estimation. Initially, data in a regional earthquake catalog are assumed imprecise both in size and location (i.e errors in the epicenter or spreading over a given source). By means of scattered attenuation laws, the regional catalog can be translated into a so-called site catalog of imprecise events. The site catalog is then used to estimate return periods or occurrence probabilities, taking into account all sources of uncertainty. Special attention is paid to priors in the Bayesian estimation. They can be used to introduce additional information as well as scattered frequency-size laws for local events. A simple example is presented to illustrate the capabilities of this methodology.     

Drought risk assessment using remote sensing and GIS techniques

Beginning with a discussion of drought definitions, this review paper attempts to provide a review of fundamental concepts of drought, classification of droughts, drought indices, and the role of remote sensing and geographic information systems for drought evaluation. Owing to the rise in water demand and looming climate change, recent years have witnessed much focus on global drought scenarios. As a natural hazard, drought is best characterized by multiple climatological and hydrological parameters. An understanding of the relationships between these two sets of parameters is necessary to develop measures for mitigating the impacts of droughts. Droughts are recognized as an environmental disaster and have attracted the attention of environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural scientists. Temperatures; high winds; low relative humidity; and timing and characteristics of rains, including distribution of rainy days during crop growing seasons, intensity, and duration of rain, and onset and termination, play a significant role in the occurrence of droughts. In contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas, a drought is a temporary aberration. Often, there is confusion between a heat wave and a drought, and the distinction is emphasized between heat wave and drought, noting that a typical time scale associated with a heat wave is on the order of a week, while a drought may persist for months or even years. The combination of a heat wave and a drought has dire socio-economic consequences. Drought risk is a product of a region’s exposure to the natural hazard and its vulnerability to extended periods of water shortage. If nations and regions are to make progress in reducing the serious consequences of drought, they must improve their understanding of the hazard and the factors that influence vulnerability. It is critical for drought-prone regions to better understand their drought climatology (i.e., the probability of drought at different levels of intensity and duration) and establish comprehensive and integrated drought information system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snow pack, reservoir and lake levels, ground water levels, and stream flow. All drought-prone nations should develop national drought policies and preparedness plans that place emphasis on risk management rather than following the traditional approach of crisis management, where the emphasis is on reactive, emergency response measures. Crisis management decreases self-reliance and increases dependence on government and donors.     

Ground stability assessment using geophysics and field observation techniques

Inspection of ground stability is necessary to ensure the suitability of an area for engineering and environmental applications. In a certain area, a combination of measurement of cracks and seismic refraction method can provide a better knowledge of the future behavior of the area in terms of its stability. In this reconnaissance study, seismic refraction method and continuous measurements of crack displacement were conducted to detect the stability of an area that lies on the downstream side of the Mosul dam, and to establish its possible mechanisms of failure. The study shows two types of instability, namely, fall and sliding, and these were due to heavy rainfall, springs, and spillway operation.     

玛尔挡改线公路高边坡稳定性分析及生态治理

通过对玛尔挡改线公路高边坡工程地质及水文地质条件调绘探查、岩层节理裂隙统计,采用赤平极射投影法对边坡进行稳定性分析。分析结果显示,高边坡整体处于稳定状态,但如果不采取防护措施,边坡岩土层经过长期的风化剥蚀,边坡局部会逐渐趋于欠稳定状态。根据该地区气候、环境及以往经验,提出采用锚拉式混凝土挡墙结合柔性防护网的生态防护措施对边坡进行防护,实施效果良好。