Risk assessment and landslide prevention design using numerical modelling——A case study in Qingliu,China

Numerous Quaternary deposits are existed in the mountainous areas of Southwest China,especially in the transition zone between the QinghaiTibet Plateau and the Sichuan Basin,where strong tectonic movements and frequent climatic changes increase the potential landslides.The possible deformation and failure process of potential landslides and their impacts on the surrounding environment are important research topics.Field investigation and monitoring indicate that the Qingliu landslide in Xiameng town,Li County,Sichuan Province,China has been continuously deforming since August 2020.The deformation zone has a maximum deformation depth of approximately 18.9m,a total area of 54,628 m2,and a volume of 34.0×104 m3,which seriously threatens infrastructure projects and dwellings.As a result,understanding the Qingliu landslide evolution process,assessing the hazard risk,and planning disaster prevention measures are of great significance for reducing disaster loss.In this study,the mass movement process and hazard risk of the Qingliu landslide are evaluated,and the effects of different prevention measures are compared and discussed.By using the depth-integrated method,the mass movement of the Qingliu landslide is analyzed.The numerical simulation results indicate that the maximum velocity of the Qingliu landslide is approximately 37.5 m/s,and the duration of the landslide is approximately 90s.The simulated landslide can eventually form a deposited mass with a maximum deposit thickness of 19.4 m and an area of approximately 60,168.3 m2,thereby blocking the river and burying dwellings.Furthermore,a risk assessment of the Qingliu landslide under different forms of protection measures is also produced and discussed by considering the hazard level and economic vulnerability level of the affected area.Setting three layers of anti-slide piles on the deformation zone to reduce the hazard risk of the Qingliu landslide is a better choice.Our results may be useful for planning prevention measures and improving disaster emergency response systems.

Comparative study of different machine learning models in landslide susceptibility assessment: A case study of Conghua District, Guangzhou, China

Machine learning is currently one of the research hotspots in the field of landslide prediction.To clarify and evaluate the differences in characteristics and prediction effects of different machine learning models,Conghua District,which is the most prone to landslide disasters in Guangzhou,was selected for landslide susceptibility evaluation.The evaluation factors were selected by using correlation analysis and variance expansion factor method.Applying four machine learning methods namely Logistic Regression(LR),Random Forest(RF),Support Vector Machines(SVM),and Extreme Gradient Boosting(XGB),landslide models were constructed.Comparative analysis and evaluation of the model were conducted through statistical indices and receiver operating characteristic(ROC)curves.The results showed that LR,RF,SVM,and XGB models have good predictive performance for landslide susceptibility,with the area under curve(AUC)values of 0.752,0.965,0.996,and 0.998,respectively.XGB model had the highest predictive ability,followed by RF model,SVM model,and LR model.The frequency ratio(FR)accuracy of LR,RF,SVM,and XGB models was 0.775,0.842,0.759,and 0.822,respectively.RF and XGB models were superior to LR and SVM models,indicating that the integrated algorithm has better predictive ability than a single classification algorithm in regional landslide classification problems.

Deformation,structure and potential hazard of a landslide based on InSAR in Banbar county,Xizang(Tibet)

The Tibetan Plateau is characterized by complex geological conditions and a relatively fragile ecological environment.In recent years,there has been continuous development and increased human activity in the Tibetan Plateau region,leading to a rising risk of landslides.The landslide in Banbar County,Xizang(Tibet),have been perturbed by ongoing disturbances from human engineering activities,making it susceptible to instability and displaying distinct features.In this study,small baseline subset synthetic aperture radar interferometry(SBAS-InSAR)technology is used to obtain the Line of Sight(LOS)deformation velocity field in the study area,and then the slope-orientation deformation field of the landslide is obtained according to the spatial geometric relationship between the satellite’s LOS direction and the landslide.Subsequently,the landslide thickness is inverted by applying the mass conservation criterion.The results show that the movement area of the landslide is about 6.57×10^(4)m^(2),and the landslide volume is about 1.45×10^(6)m^(3).The maximum estimated thickness and average thickness of the landslide are 39 m and 22 m,respectively.The thickness estimation results align with the findings from on-site investigation,indicating the applicability of this method to large-scale earth slides.The deformation rate of the landslide exhibits a notable correlation with temperature variations,with rainfall playing a supportive role in the deformation process and displaying a certain lag.Human activities exert the most substantial influence on the spatial heterogeneity of landslide deformation,leading to the direct impact of several prominent deformation areas due to human interventions.Simultaneously,utilizing the long short-term memory(LSTM)model to predict landslide displacement,and the forecast results demonstrate the effectiveness of the LSTM model in predicting landslides that are in a continuous development and movement phase.The landslide is still active,and based on the spatial heterogeneity of landslide deformation,new recommendations have been proposed for the future management of the landslide in order to mitigate potential hazards associated with landslide instability.

Unraveling the hydraulic properties of loess for landslide prediction:A study on variations in loess landslides in Lanzhou,Dingxi,and Tianshui,China

Loess has distinctive characteristics,leading to frequent landslide disasters and posing serious threats to the lives and properties of local re sidents.The involvement of water repre sents a critical factor in inducing loess landslides.This study focuses on three neighboring cities sequentially situated on the Loess Plateau along the direction of aeolian deposition of loess,namely Lanzhou,Dingxi,and Tianshui,which are densely populated and prone to landslide disasters.The variations in hydraulic properties,including water retention capacity and permeability,are investigated through Soil Water Characteristic Curve(SWCC)test and hydraulic conductivity test.The experimental findings revealed that Tianshui loess exhibited the highest water retention capacity,followed by Dingxi loess,while Lanzhou loess demonstrated the lowest water retention capacity.Contrastingly,the results for the saturated permeability coefficient were found to be the opposite:Tianshui loess showed the lowest permeability,whereas Lanzhou loess displayed the highest permeability.These results are supported and analyzed by scanning electron microscopy(SEM)observation.In addition,the water retention capacity is mathematically expressed using the van Genuchten model and extended to predict unsaturated hydraulic properties of loess.The experimental results exhibit a strong accordance with one another and align with the regional distribution patterns of disasters.

Landslide disaster prevention and mitigation through works in Hong Kong

Hong Kong has a high concentration of developments on hilly terrain in close proximity to man-made slopes and natural hillsides.Because of the high seasonal rainfall,these man-made slopes and natural hillsides would pose a risk to the public as manifested by a death toll of 470 people due to landslides since the late 1940s.In 1977,the Government of the Hong Kong SAR embarked on a systematic programme,known as the Landslip Preventive Measure(LPM)Programme,to retroft substandard man-made slopes.From 1977 to 2010,about 4500 substandard government man-made slopes have been upgraded through engineering works.During the period,the Programme had evolved progressively in response to Government’s internal demand for continuous improvement and rising public expectation for slope safety.In 2010,the Government implemented the Landslip Prevention and Mitigation(LPMit)Programme to dovetail with the LPM Programme,with the focus on retroftting the remaining moderate-risk substandard man-made slopes and mitigating systematically the natural terrain landslide risk pursuant to the"react-to-known"hazard principle.This paper presents the evolution of the LPM and LPMit Programmes as well as the insight on landslide prevention and mitigation through engineering works.

Optimal location and effect judgment on drainage tunnels for landslide prevention

An optimal drainage tunnel location determination method for landslide prevention was proposed to solve the existing problems in drainage tunnel construction. Current applications of drainage tunnel systems in China were reviewed and the fimctions of drainage tunnel were categorized as catchment and interception. Numerical simulations were conducted. The results show that both catchment and interception tunnels have variation of the function in the simulation of monolayer model, which shows the reduction of permeability condition in lower layer. The function of catchment can be observed in the deep slope, while the function of interception is observed near groundwater source. By using the slope safety factor and discharge water amount as the objectives of optimal drainage tunnel location, and pore-water pressure in fixed node and section flux as the judgment for construction quality of adjacent drainage tunnel, the design principle of drainage tunnel was introduced. The K103 Landslide was illustrated as an example to determine the optimal drainage tunnel location. The measured drainage tunnel efficiency was evaluated and compared with that from the numerical analyses based on groundwater data. The results validate the present numerical study.

Landslide integrated characteristics and susceptibility assessment in Rongxian county of Guangxi,China

Landslides distribute extensively in Rongxian county, the southeast of Guangxi province, China and pose great threats to this county. At present, hazard management strategy is facing an unprecedented challenge due to lack of a landslide susceptibility map. Therefore, the purpose of this paper was to construct a landslide susceptibility map by adopting three widely used models based on an integrated understanding of landslide’s characteristics.These models include a semi-quantitative method(SQM), information value model(IVM) and logistical regression model(LRM).The primary results show that(1) the county is classified into four susceptive regions, named as very low, low, moderate and high, which covered an area of 13.43%, 32.40%, 31.19% and 22.99% in SQM, 0.86%, 26.82%, 44.11%, and 28.21% in IVM, 9.88%, 17.73%, 46.36% and 26.03% in LRM;(2) landslides are likely to occur within the areas characterized by following obvious aspects: high intensity of human activities, slope angles of 25°～35°, the thickness of weathered soil is larger than 15 m; the lithology is granite, shale and mud rock;(3) the area under the curve of SQM, IVM and LRM is 0.7151, 0.7688 and 0.7362 respectively, and the corresponding success rate is 71.51%, 76.88% and 73.62%. It is concluded that these three models are acceptable because they have an effective capability of susceptibility assessment and can achieve an expected accuracy. In addition, the susceptibility outcome obtained from IVM provides a slightly higher quality than that from SQM, LRM.

金沙江干流巨型滑坡发育特征及其形成机理

金沙江干流穿越地形地貌极为复杂和新构造运动强烈的青藏高原东南缘,流域内发育了大量的巨型滑坡,使得该地区的滑坡灾害十分严重。因此,深入研究金沙江干流滑坡的成因机制对于该区域的防灾减灾具有重要意义。本研究通过搜集前人研究资料和遥感影像分析,对金沙江干流巨型滑坡的形成机制进行了深入探讨。研究发现,金沙江干流巨型滑坡的形成受多种因素的综合影响。首先,地形坡度是影响滑坡形成的重要因素,坡度在25°~40°范围内发生滑坡的概率更高。其次,活动断裂在滑坡形成过程中起到重要作用,断裂带活动会导致岩石变形和破碎,从而增加滑坡发生的可能性。此外,地层岩性也是影响滑坡的重要因素,它影响着岩土体的物理力学特性和岸坡的应力分布特征,导致区域稳定性的差异,增加了滑坡发生的可能。在这些因素中,活动断裂及强震活动在巨型滑坡的形成过程中起到了更为重要的作用。他们可能导致滑坡进一步发展,甚至引发流域堵江、溃坝、洪水等连锁灾害。

Dynamic Effect of Landslides Triggered by Earthquake:A Case Study in Moxi Town of Luding County,China

The dynamic effect is a very important issue widely debated by scholars when studying the genetic and disaster-causing mechanisms of earthquake-triggered landslides.First,the dynamic effect mechanism and phenomena of earthquake-triggered landslides were summarized in this paper.Then,the primary types of dynamic effects were further used to interpret the Mogangling landslide in Moxi Town of Luding County,China.A field investigation,remote sensing,numerical calculation and theoretical analysis were carried out to illustrate the failure mechanism of slope rock masses affected by earthquakes.The interaction between seismic waves and slope rock masses and the induced dynamic effect of slope rock masses were primarily accounted for in the analysis.The slope topography,rock mass weathering and unloading characteristics,river erosion,regional seismogenic structure,and rock mass structure characteristics were also discussed.The results showed that the formation of the Mogangling landslide was mainly related to the high amplification effect of seismic acceleration and back slope effects,interface dynamic stress effects,and double-sided slope effects of seismic waves caused by the catastrophic Ms 7.75 Moxi Earthquake in 1786.The principles for the site and route selection of large-scale infrastructure in the planning stage and the scientific prevention of seismic geological disasters were proposed on the basis of the dynamic effect of earthquake-induced landslides.

江苏省宜兴地区碎石土滑坡地质灾害特征及防治措施研究

针对江苏省宜兴地区典型碎石土滑坡地质灾害,开展了滑坡地质灾害特征分析和防治措施研究。结果表明,碎石土滑坡主要发育于宜兴南部山区山前缓坡地带,自然边坡坡度不大于15°;滑坡体具有上土下岩的二元结构特征,滑坡破坏模式为后退式渐进整体变形破坏的牵引式滑坡,表现为地形改造+降雨诱发;滑坡体轴向水平距离为改造后边坡前缘高差的10.0~12.0倍。采用坡面修整、抗滑桩、回填压脚、挡土墙和截排水沟等综合防治措施可有效消除滑坡地质灾害隐患,坡体水平位移、垂直位移收敛于定值,坡体稳定。

宁镇低山丘陵区降雨型滑坡致灾机理与防治措施研究

宁镇低山丘陵区是突发性滑坡灾害的高易发区和重点防治区。本文以江宁开发区盘山公路降雨型堆积层滑坡为例,根据滑坡灾害调绘和详细勘查,掌握了滑坡的孕灾条件、灾害特征和成因机理。利用Geo-Studio和理正岩土软件定量分析了不同工况下滑坡稳定性和拟设支挡结构受力特征。结果表明:滑坡正处在蠕动变形阶段,罕遇强降雨和人为切坡扰动是诱发滑坡的主要因素,滑坡在天然、降雨和地震工况皆处于不稳定状态,并求取滑坡推力设计值和拟设抗滑桩桩身内力及分布。提出了以抗滑桩板墙+拱形锚杆格构+系统截排水为主的综合治理方案,为宁镇地区同类型滑坡灾害防治提供参考。

硬质岩滑坡深大抗滑桩一体化旋挖成孔技术及应用

硬质岩深大抗滑桩桩孔成孔效率是滑坡灾害防治的难点问题之一。选取川西南典型复杂山区硬质岩滑坡抗滑桩成孔为研究对象,系统分析了裂隙弱发育深部硬质玄武岩地层抗滑桩传统工艺成孔存在的问题,对此设计了9种组合旋挖成孔工艺方案进行现场试桩试验,从钻进效率、技术及经济可行性等方面进行了分析论证。现场试验及分析结果表明:采用“大扭矩截齿筒钻旋挖+扩孔直径差0.4 m”分级扩孔一体化成孔技术在硬质岩地层中钻进效率较高、钻具损耗较低、成本较低,验证了硬质岩抗滑桩高效旋挖分级扩孔技术的可行性和高效性,对比现有人工成孔、冲击钻成孔、旋挖一次成孔等工艺,从安全、效率、成本等方面均得到了极大提升。该技术成功应用于白鹤滩迁建集镇后缘滑坡桩基施工,每延米综合耗时1.43 h,较改进前旋挖一次成孔效率提升3倍,成本降低了60%。该技术为复杂地质条件下水敏型、震敏型硬质岩滑坡抗滑桩快速成孔施工提供了高效、可行的技术方案。

滑坡防治措施的总体分析及实例应用研究

为切实掌握滑坡灾害的防治措施,该文结合滑坡工程实际,首先对滑坡灾害防治措施进行总体分析,再进一步进行了实例应用研究。分析结果表明:滑坡防治措施主要包括减轻或消除水威胁、设置抗滑措施及土体改善措施,且结合工程实际,本文实例的防治措施设计为“抗滑桩+挡土墙+截排水措施”。

高陡滑坡失稳机制及防治研究

赫章县七家湾气象站滑坡属于中型推移式滑坡,横宽为200 m,纵长为90 m,主滑向为336°,滑坡平均厚度为10 m,体积为180000 m^(3)。本文结合滑坡区自然环境特征,分析滑坡发育特征和变形特征,明确滑坡失稳机制,然后开展滑坡稳定性评价,提出滑坡防治方案,最终消除地质灾害风险。

Analysis of debris flow control effect and hazard assessment in Xinqiao Gully,Wenchuan M_(s)8.0 earthquake area based on numerical simulation

Xinqiao Gully is located in the area of the 2008 Wenchuan M_(s)8.0 earthquake in Sichuan province,China.Based on the investigation of the 2023"6-26"Xinqiao Gully debris flow event,this study assessed the effectiveness of the debris flow control project and evaluated the debris flow hazards.Through field investigation and numerical simulation methods,the indicators of flow intensity reduction rate and storage capacity fullness were proposed to quantify the effectiveness of the engineering measures in the debris flow event.The simulation results show that the debris flow control project reduced the flow intensity by41.05%to 64.61%.The storage capacity of the dam decreases gradually from upstream to the mouth of the gully,thus effectively intercepting and controlling the debris flow.By evaluating the debris flow of different recurrence intervals,further measures are recommended for managing debris flow events.

来宾市兴宾区某滑坡地质灾害特征及防治方法探讨

研究区位于来宾市兴宾区某初级中学东南侧,已发生浅层土质牵引式滑坡一处,采取应急处治措施后,暂时防止了滑坡体再次发生滑动,但该滑坡体西侧有一处更大的潜在滑坡体,目前虽处于基本稳定状态,但是在降雨等不良地质条件下,随时可能发生滑坡地质灾害。文章根据现场调查,选取“锚拉抗滑桩+挡板+截排水”的滑坡综合治理方案,可以兼顾周边基础用地的需求。通过滑坡治理,既保护了人们的生命财产安全,又带来了稳定的社会环境,肯定了地质灾害治理的必要性。

黄土铁路路堤滑坡破坏机制与防治技术研究

2021年7月20日,河南省遭遇极端暴雨,诱发大量路基水害。通过对路基水害开展现场调查,查明了水害发生区间内区域地形地貌及水文地质条件,提出了黄土路堤滑坡破坏模式,并结合数值模拟分析路堤滑坡的破坏机制。运用多次分段控制注浆钢花管的防治技术对路堤边坡进行整治,采用挖探调查、高密度电法的手段探究钢花管加固黄土路堤的注浆效果,并结合数值模拟分析注浆加固前后黄土路堤边坡的稳定性。研究结果表明:(1)路堤滑坡不同于路堤浅表层溜坍的坡面病害,是一种严重的坡体病害,常由于坡脚地形低洼,降水在路堤边坡坡脚或下部汇集,浸泡软化路堤边坡,引起边坡岩土抗剪强度不足导致滑坡;(2)数值模拟结果表明坡脚积水深度对路堤边坡的竖向应力场无明显影响,对积水侧边坡的水平应力场与位移场影响显著;随着积水深度增大,路堤边坡最大剪应变的最值增大,稳定系数减小;(3)挖探调查与高密度电法探测结果表明钢花管注浆技术在黄土地层劈裂注浆效果良好,黄土边坡内部孔隙被水泥浆体充填,隔绝了坡体内部的流水通道,抑制坡体内部受水侵蚀;(4)钢花管注浆加固后数值模拟结果表明,整治加固后路堤稳定性显著提升。研究成果为铁路系统工务部门的水害防治工作提供参考。

滑坡稳定性分析及防治设计研究

针对土体强度参数的不确定性,文中提出了一种理论加数值的滑坡稳定性分析方法,结合可靠性法结果和定量法,并采用原位地质试验,综合确定土体强度参数的合理值。为了评估边坡稳定性,分别采用上限法和强度折减法进行极限分析和有限元模拟。研究表明,应力和应变主要集中在边坡的坡趾和顶部,为此提出了采用格构式锚杆挡墙、滑坡桩和裂缝填充等对策,以降低滑坡破坏的风险,基于有限元分析结果,验证了建议的可行性和有效性。

德钦县楚巴崩塌特征分析及防治措施研究

对澜沧江左岸楚巴崩塌斜坡区的地质环境条件进行了详细调查,采用地质测绘、山地工程及试验分析等方法,分析了此次崩塌的危岩体、基座及堆积等发育特征。通过定性分析和数学计算,对各危岩体的稳定性进行了综合评价,查清了危岩破坏模式和威胁范围,针对风险较高的危岩,结合工程实施条件,提出了“拦石墙+拦石网+人工清危+主动防护网”的方案进行防治,对楚巴崩塌发育特征进行分析并研究防治措施,为该类崩塌的避险与工程治理提供设计参考。

滑坡稳定性分析及防治必要性评价

文中以滑坡勘察成果为基础,先通过传递系数法开展滑坡稳定性评价,并利用P×C法进行滑坡防治必要性评价。分析结果表明,通过滑坡稳定性计算,2-2’剖面的稳定性相对最差,其次是3-3’和1-1’剖面,且暴雨工况的稳定性相对最差,属欠稳定-基本稳定状态,其余地震工况、天然工况多属基本稳定状态或稳定状态,即不利工况条件下存在较大的失稳可能。同时,经滑坡防治必要性评价,滑坡整体防治必要性得分为80.27,对应防治必要性等级为Ⅲ级,说明滑坡整体稳定性较差。最后,两类分析结果均表明滑坡防治具有明显的必要性,有必要尽快开展防治处理,确保区内居民生命财产安全。