Analysis of the microseismicity characteristics in landslide dam failure flume tests: implications for early warning and dynamics inversion

Landslides - Determining the premonitory and dynamic characteristics of landslide dam failures can provide an early warning as well the identification of the evolution of the failure process, and...     

Rainfall thresholds for landslide early warning system in Nakhon Si Thammarat

Transient seepage in unsaturated soil slope is one of the significant triggering factors in rainfall-induced landslides. Rainfall infiltration leads to the decrease in stabilizing effect because of increased positive pore-water pressures. SEEP/W and SLOPE/W used in this study have been widely employed to describe frameworks for understanding transient seepage in soil slope, and to perform slope stability analyses, respectively. The study area is in Sichon District in Nakhon Si Thammarat Province, southern Thailand. A landslide there was investigated by modeling the process of rainfall infiltration under positive and negative pore-water pressures and their effects on slope stability. GIS (Geographic Information System) and geotechnical laboratory results were used as input parameters. The van Genuchten’s soil water characteristic curve and unsaturated permeability function were used to estimate surface infiltration rates. An average rainfall was derived from 30-year monthly rainfall data between 1981 and 2011 in this area reported by the Thailand Royal Irrigation Department. For transient condition, finite element analysis in SEEP/W was employed to model fluctuations in pore-water pressure during a rainfall, using the computed water infiltration rates as surface boundary conditions. SLOPE/W employing Bishop simplified method was then carried out to compute their factors of safety, and antecedent precipitation indices (API) calculated. Heterogeneous slope at the site became unstable at an average critical API (API_cr) of 380 mm, agreeing well with the actual value of 388 mm.     

坡地地质灾害的减灾策略——以降雨预警基准为例

降雨是诱发坡地地质灾害的重要原因,因此掌握降雨的趋势与分布规律,可有效地用于坡地灾害预警,但由于降雨预测精度、灾害资料统计的不足与坡地地质条件的不确定性,实际应用降雨预警基准仍存在许多困难。通过分析台风诱发坡地地质灾害的降雨特性,来说明降雨预警基准在防灾减灾工作上应用的条件与限制。结果表明,对于不同类型之坡地灾害与降雨分布特性,需采用不同的雨量预警基准。唯有通过岩土力学、工程地质学与气象学的整合研究,才能有效提高降雨预警基准预测的准确率,因此各学科的整合是未来防灾减灾研究工作的发展趋势。     

An acoustic emission landslide early warning system for communities in low-income and middle-income countries

Early warning systems for slope instability are needed to alert users of accelerating slope deformation behaviour, enable evacuation of vulnerable people, and conduct timely repair and maintenance of critical infrastructure. Communities exposed to landslide risk in low- and middle-income countries seldom currently instrument and monitor slopes to provide a warning of instability because existing techniques are complex and prohibitively expensive. Research and field trials have demonstrated conclusively that acoustic emission (AE) monitoring can be an effective approach to detect accelerating slope movements and to subsequently communicate warnings to users. The objective of this study was to develop and assess a simple, robust, low-cost AE monitoring system to warn of incipient landslides, which can be widely deployed and operated by communities globally to help protect vulnerable people. This paper describes a novel AE measurement sensor that has been designed and developed with the cost constrained to a few hundred dollars (US). Results are presented from physical model experiments that demonstrate performance of the AE system in measuring accelerating deformation behaviour, with quantifiable relationships between AE and displacement rates. Exceedance of a pre-determined trigger level of AE can be used to communicate an alarm to users in order to alert them of a slope failure. Use of this EWS approach by communities worldwide would reduce the number of fatalities caused by landslides.     

贵州兴义滑坡特征及过程预警研究

本文以新源县喀拉海依苏滑坡隐患体为研究案例,采用COMSOL Multiphysics数值模拟有限元软件,建立了基于非饱和渗流理论与Mohr-Coulomb准则的滑坡稳定性计算模型。根据数值模拟结果得到研究区滑坡体原始应力分布与初始孔隙压力的分布情况、在降雨入渗条件下的内部应力、有效塑性应变、塑性区、含水率、潜在滑移面等的分布情况,并计算得到滑坡体在降雨入渗条件下的安全系数。根据模型计算,滑坡体在不同降雨入渗工况下的安全系数随降雨量的增大而减小,滑坡体在连续降雨5天的临界阈值为218.82 mm,根据安全系数的变化可得到滑坡体临界降雨阈值。该论文提供了一种强度折减安全系数计算降雨型黄土滑坡降雨阈值的数值模拟方法,研究结果为西北地区降雨型黄土滑坡失稳破坏的临界降雨阈值研究提供了一种有效的研究手段。     

Spatially distributed rainfall information and its potential for regional landslide early warning systems

Hydrological extreme events pose an imminent risk to society and economics. In this paper, various aspects of hydrological hazards in Russia are analysed at different scales of risk assessment. It is shown that the number of hydrological and meteorological hazards in Russia has been growing every year. The frequency of economic losses associated with extreme low flow in this century has increased by factor five compared to the last decade of the previous century. With regard to floods, an interesting spatial patter can be observed. On the one hand, the number of floods in the Asian part of the country has increased, whereas on the other hand, the number and intensity of floods in estuarine areas in the European part of Russia have significantly reduced since the middle of the twentieth century, especially in the 2000s. This decrease can be attributed to runoff flooding in the mouths of regulated rivers, with an effective system of flood and ice jam protection. The analysis shows that there is an 8–12-year periodicity in the number of flood occurrences and that flood surges have intensified over the last 110 years, especially on the European territory of Russia. An integrated index that accounts for flood hazards and socio-economic vulnerability was calculated for each region of Russia. A classification of flood risk was also developed, taking into account more than 20 hydrological and social–economic characteristics. Based on these characteristics, hazard and vulnerability maps for entire Russia were generated which can be used for water management and the development of future water resources plans.     

滑坡变形高精度智能化监测预警技术研究与实践

根据滑坡的勘察评价、治理工程设计、工程施工、防治效果评价、灾害预警等工作阶段,对变形监测成果的高精度要求,分析了滑坡变形监测的现状以及成果精度、数据可靠性等方面存在的问题,深入研究了高精度、智能化滑坡变形监测的技术方案,并在多个大型复杂滑坡和特殊高陡边坡监测中进行了实践应用。解决了常规滑坡监测难以获得高精度变形成果的问题,为滑坡变形评价、灾害监测预警等提供高效、可靠、高精度的监测数据,提出了很好的工作方案。     

Spatially distributed rainfall information and its potential for regional landslide early warning systems

Crucial to most landslide early warning system (EWS) is the precise prediction of rainfall in space and time. Researchers are aware of the importance of the spatial variability of rainfall in landslide studies. Commonly, however, it is neglected by implementing simplified approaches (e.g. representative rain gauges for an entire area). With spatially differentiated rainfall information, real-time comparison with rainfall thresholds or the implementation in process-based approaches might form the basis for improved landslide warnings. This study suggests an automated workflow from the hourly, web-based collection of rain gauge data to the generation of spatially differentiated rainfall predictions based on deterministic and geostatistical methods. With kriging usually being a labour-intensive, manual task, a simplified variogram modelling routine was applied for the automated processing of up-to-date point information data. Validation showed quite satisfactory results, yet it also revealed the drawbacks that are associated with univariate geostatistical interpolation techniques which solely rely on rain gauges (e.g. smoothing of data, difficulties in resolving small-scale, highly intermittent rainfall). In the perspective, the potential use of citizen scientific data is highlighted for the improvement of studies on landslide EWS.     

基于表面位移的公路滑坡监测预警研究

公路滑坡是常见的地质灾害,但对运营期公路边坡进行长期监测并成功预警的实例却很少。主要原因是公路边坡点多、线长、规模小、缺乏详细的地质勘探资料、监测费用高、预警难度大。利用拉索触发式位移计对滑坡表面位移进行监测,精度可达1 mm,通过电信的GPRS公网实时传送到远程监控中心,全程自动化,且费用低。同时,利用有限元商用软件 PLAXIS的强度折减模块和塑性分析模块对不同参数组合进行计算,在缺乏滑坡岩土体强度参数、渗透系数、土-水特征曲线等资料的情况下,建立滑坡安全系数与表面监测位移的关系, 从而通过表面位移量的变化进行阶段式预警,并制定相应的预防措施。提出的方法已在湘西某高速公路滑坡获得应用。     

降雨诱发区域性滑坡预报预警方法研究

论文以四川省雅安市雨城区为研究区,将逻辑回归模型引入区域降雨型滑坡预警预报,建立了同时考虑降雨强度和降雨过程的降雨临界值表达式.在滑坡危险性区划的基础上,研究提出了区域降雨型滑坡预警预报指标,包括临界值降雨指数R和滑坡发生指数L,并利用20台自动遥测雨量计和地质灾害群测群防网络,采用历史记录雨量和预报雨量,建立了区域降雨型滑坡预报预警体系.     

Integration of a limit-equilibrium model into a landslide early warning system

Landslides are a significant hazard in many parts of the world and exhibit a high, and often underestimated, damage potential. Deploying landslide early warning systems is one risk management strategy that, amongst others, can be used to protect local communities. In geotechnical applications, slope stability models play an important role in predicting slope behaviour as a result of external influences; however, they are only rarely incorporated into landslide early warning systems. In this study, the physically based slope stability model CHASM (Combined Hydrology and Stability Model) was initially applied to a reactivated landslide in the Swabian Alb to assess stability conditions and was subsequently integrated into a prototype of a semi-automated landslide early warning system. The results of the CHASM application demonstrate that for several potential shear surfaces the Factor of Safety is relatively low, and subsequent rainfall events could cause instability. To integrate and automate CHASM within an early warning system, international geospatial standards were employed to ensure the interoperability of system components and the transferability of the implemented system as a whole. The CHASM algorithm is automatically run as a web processing service, utilising fixed, predetermined input data, and variable input data including hydrological monitoring data and quantitative rainfall forecasts. Once pre-defined modelling or monitoring thresholds are exceeded, a web notification service distributes SMS and email messages to relevant experts, who then determine whether to issue an early warning to local and regional stakeholders, as well as providing appropriate action advice. This study successfully demonstrated the potential of this new approach to landslide early warning. To move from demonstration to active issuance of early warnings demands the future acquisition of high-quality data on mechanical properties and distributed pore water pressure regimes.     

r.massmov: an open-source landslide model for dynamic early warning systems

This paper illustrates the main characteristics of the newly developed landslide model r.massmov, which is based on the shallow water equations, and is capable of simulating the landslide propagation over complex topographies. The model is the result of the reimplementation of the MassMov2D into the free and open-source GRASS GIS with a series of enhancements aiming at allowing its possible integration into innovative early warning monitoring systems and specifically into Web processing services. These improvements, finalized at significantly reducing computational times, include the introduction of a new automatic stopping criterion, fluidization process algorithm, and the parallel computing. Moreover, the results of multi-spatial resolution analysis conducted on a real case study located in the southern Switzerland are presented. In particular, this analysis, composed by a sensitivity analysis and calibration process, allowed to evaluate the model capabilities in simulating the phenomenon at different input data resolution. The results illustrate that the introduced modifications lead to important reductions in the computational time (more than 90 % faster) and that, using the lower dataset resolution capable of guaranteeing reliable results, the model can be run in about 1 s instead of the 3.5 h required by previous model with not optimized dataset resolution. Aside, the results of the research are a series of new GRASS GIS modules for conducting sensitivity analysis and for calibration. The latter integrates the automated calibration program “UCODE” with any GRASS raster module. Finally, the research workflow presented in this paper illustrates a best practice in applying r.massmov in real case applications.     

基于专家评分模型和GIS的滑坡预警分析开发研究

利用层次分析法,结合专家评分模型,构建了滑坡预警评价指标体系。在GIS技术的支持下,开发出滑坡预警分析系统。采用该系统不但能预测滑坡灾害的空间发展趋势,而且还可反映出某一时段内其发生发展态势。文中以河北省太行山地区为例,利用该系统,实现了该区的滑坡预警评价分析。其结果与实地滑坡分布规律存在很好的一致性。     

基于数字滑坡技术的暴雨滑坡、泥石流预警、监测模型研究

中国学者在暴雨滑坡、泥石流预测预报研究领域取得的成果为采用数字滑坡技术进行暴雨滑坡、泥石流预警、监测模型研究提供了宝贵的基础,应用数字滑坡技术建立暴雨滑坡、泥石流预测模型的原则是：（1）必须在滑坡、泥石流形成条件理论指导下;（2）应了解研究区地质环境及滑坡、泥石流特征;（3）就基于数字滑坡技术而言,只能选取遥感方法可能...     

Comparing methods for determining landslide early warning thresholds: potential use of non-triggering rainfall for locations with scarce landslide data availability

Landslides - Rainfall intensity-duration landslide-triggering thresholds have become widespread for the development of landslide early warning systems. Thresholds can be in principle determined...     

速度倒数法滑坡预警模型流变试验研究

滑坡失稳的预测预报研究是地质工程领域中的一项重要课题,准确地确定预测预报理论模型的参数是实际应用中的难点。在实际滑坡监测中通常可以观察到位移曲线呈现阶梯形,这些阶梯形位移变化点就是滑坡的变形突变点。为研究滑坡变形突变点的变形特征,进行了不同荷载作用下的天然试样以及不同荷载、不同含水率作用下的浸水试样的流变试验,得到了累计位移-时间曲线以及变形速度-时间曲线。依据秦四清的锁固段理论以及速度倒数法滑坡预警模型对试验结果进行分析。研究结果表明：荷载和含水率的变化对模型参数没有影响,模型参数是关于材料属性的函数;变形过程中突变点的变形特征与破坏时的变形特征相似,并且速度倒数法预警模型在突变点和破坏点确定的模型参数基本一致。因此,滑坡监测曲线中早期位移突变点确定的模型参数可以用于确定滑坡破坏时的预警模型。     

某滑坡土体土-水特征曲线试验研究

利用能够控制基质吸力的4联式非饱和土直剪仪,对清江流域古树包滑坡滑带土体进行了不同固结应力条件下土-水特征试验,得出了土-水特征曲线并进行了函数拟合。结合土-水特征曲线拟合函数,经过数学推导确定了函数中各个参数的物理意义,建立了能够同时反映固结应力、基质吸力和含水率之间关系的函数表达式,弥补了其他方法不能考虑固结应力的缺陷,对补充和发展土-水特征曲线试验和理论具有重要意义。     

滑坡灾害预测预报分类

有人主张滑坡灾害的空间和时间预测预报应是并存的,即脱离时间预测预报的空间预测是不可取的。但也有人认为两者可以相互独立而又互为补充。事实上,空间预测是时间预测预报的先决条件,只有在明确了预测的对象之后,方可有目的地开展滑坡灾害的时间预测预报。因而,一般地讲,滑坡灾害空间和时间预测具有先后序次关系。但从减灾的角度考虑,二者又具有相对的独立性。即可以在时间预测之外进行空间预测。目前对滑坡灾害预测预报分类的系统研究不多,所开展的预测预报事例报导基本上属于个例研究。论文将滑坡灾害预测预报分为空间和时间2大类,并进一步将空间预测划分成区域空间预测、地段空间预测和场地空间预测;将时间预测预报划分成长期时间预测、短期时间预测和临滑时间预测预报。文章针对滑坡灾害时间预测预报的特点,对预测预报的信息源进行了分析和分类。并对不同的工程阶段所要预测的滑坡灾害问题进行了分类归纳。