Analysis of a rock slide stabilized with a toe-berm: a case study in British Columbia, Canada

Practical experience has shown that slope movement can be controlled by the placement of a berm near the toe of the moving mass. During construction of the Revelstoke project (British Columbia, Canada), excavation of a large highway rock cut triggered movement of a 250,000 m³ rock slide. A 15,000 m³ toe-berm was used as a temporary measure to control the displacements of the slide and allow permanent remedial measures to be completed. The rock slide was extensively investigated and monitored. The Sarma limit equilibrium method and the three-dimensional distinct element program, 3DEC were used to investigate the stabilizing effect of the toe-berm on the slope deformations. In addition, 3DEC was used to investigate the effect of internal discontinuities on slope displacements. The numerical model responded in a manner that is in general agreement with field observations and supported the observations that a small toe-berm can be an effective remedial measure in controlling slope displacements.     

三维离散单元法及其在滑坡分析中的应用

介绍了三维离散单元法的基本原理,编制了相应的C语言程序,并对具体的滑坡实例进行了模拟,发现计算结果与已有研究成果较为一致,表明三维离散单元法是一种可以动态模拟山地滑坡行为的比较适宜的数值方法。     

结构性砂土力学特性三维离散元分析

利用离散元法对结构性砂土的三轴试验进行了三维数值模拟并对其宏观特性进行了分析。首先将考虑胶结尺寸(宽度和厚度)的三维胶结接触模型导入离散元软件PFC3D中,对结构性砂土数值试样进行三轴试验数值模拟;然后对比分析离散元模拟与室内试验结果;最后从宏观力学角度对试验结果进行了分析。离散元模拟结果表明:结构性砂土与无胶结松散砂土表现不同,其在低围压时表现出应变软化和体积剪胀特征,并随胶结含量的增加或围压的减少而愈发显著,在高围压时则呈应变硬化和体积剪缩现象;低平均应力时,随胶结含量的增加,试样峰值内摩擦角、黏聚力以及内摩擦角均增加,其中黏聚力增加较为明显,随着平均应力的增加,峰值强度包线逐渐趋向于无胶结土。     

兰加拉学院图书馆及教学楼

项目地点:加拿大温哥华项目类型:院校公共项目开工日期:2005年6月该项目获2005年豪瑞可持续建筑大奖赛北美地区提名奖     

石碑塬滑坡地震动力及液化有限元分析

介绍了石碑塬滑坡是1920年海原地震所形成的巨型低角度浅层地震滑坡,运用大型岩土分析软件Geostudio,对滑坡进行了地震动力及液化分析,对研究该滑坡的形成机理有一定的借鉴意义。     

Arsenic in the Meager Creek hot springs environment, British Columbia, Canada.

Levels of arsenic in water from Meager Creek hot springs, British Columbia, Canada, were found to be naturally elevated. Biota including microbial mats, green algae, sedge, cedar, fleabane, monkey flower, moss, mushrooms and lichens, that were expected to be impacted by the water, were analyzed for total levels of arsenic and for arsenic species. The major arsenic species extracted from all samples were arsenate and arsenite, which are toxic forms of arsenic. Additionally, small amounts of arsenosugars X and XI were detected in microbial mats and green algae, implying that cyanobacteria/bacteria, and possibly green algae are capable of synthesizing arsenosugars from arsenate. Low to trace amounts of arsenosugars X and XI were detected in lichens and the fungus Tarzetta cupularis. A large fraction (on average, greater than 50%) of arsenic was not extracted by using methanol/water (1:1) and the chemical and toxicological significance of this arsenic remains unknown.     

The Aso-Bridge coseismic landslide: a numerical investigation of failure and runout behavior using finite and discrete element methods

The complex coseismic process of the Aso-Bridge landslide during the main shock of the 2016 Kumamoto Earthquake was investigated. Finite element analysis and discrete element analysis considering vertical seismic accelerations (VSA) were conducted to explore the salient features of the prefailure mechanism and postfailure kinematic process of the coseismic landslide associated with the initiation time and kinematic runout behavior, respectively. Two seismic input conditions, one involving only horizontal seismic accelerations (HSA), and the other accounting for both HSA and VSA, were used to assess the influence of VSA from the prefailure to postfailure regimes. First, satisfactory agreement between the study and the published results in terms of landslide initiation time was obtained. As revealed by the rapid change of source displacement (RCSD), VSA did not alter landslide initiation time; however, it significantly increased the RCSD approximately 2-fold, which provided a clear initiation time. At landslide initiation, the estimated average velocities in a vertical direction increased approximately 16-fold (from −0.011 to −0.174 m/s) by accounting for VSA. Second, the results suggested that VSA had a trivial influence on runout behavior in the postfailure regime, given that such behavior was dominated by the collision and free fall during the sliding as well as the terrain features. With an average velocity of 21.34 m/s, the sliding source ultimately reached the riverbank within 21 s. The paper demonstrates that a combination of FEA and DEA can be used to investigate the coseismic process of the Aso-Bridge landslide and lead to satisfactory agreement with the event. Our comprehensive analysis provides insight into the role of VSA in earthquake-induced landslides.

     

Responsible cruise tourism and regeneration: the case of Nanaimo,British Columbia,Canada

Cruise ship tourism continues to grow faster than other tourism sectors globally, with increasing potential benefits for cruise destinations, which seek to boost tourism revenue for instance by developing passenger terminals and associated infrastructure. However, there is a growing awareness of the need for ‘responsible cruise tourism’ in view of the costs of cruise ship tourism to host communities. The case of Nanaimo in British Columbia, Canada, illustrates these issues in terms of the management of cruise ship tourism and associated socio-economic benefits and costs, with implications for policy and practice in other contexts.     

Origins and implications of drinking water odours in lakes and reservoirs of British Columbia, Canada

The relationship between commonly measured limnological parameters and odours was examined in 16 reservoirs and lakes used as sources for drinking water and three reference lakes. Odour analysis was conducted using flavour profile analysis (FPA) and, on select lakes, gas chromatography ion-trap mass spectrometry (GC-ITMS) for target compounds. Total phosphorus (TP) was the best single predictor of FPA intensity and multiple regression models accounted for 37-39% of intensity variance in the epilimnion and metalimnion, respectively. Earthy odours were more prevalent in reservoirs and lakes with higher TP, whereas decomposing vegetation and green vegetation+grassy odours almost exclusively occurred when TP was lower (<13 microg P/L). Only geosmin was identified with GC-ITMS, and it was found to occur in lakes and reservoirs of higher trophic status (e.g. more algal biomass). Infrequent episodic events in the Greater Victoria's principal reservoir (e.g. algal blooms) have previously been linked with taste and odour problems in their tap water. However, analysis of odours under the conditions of this study (i.e. no strong odour episodes in the source reservoir) suggest that typical odours prevalent in tap water originating from Sooke Lake Reservoir are derived from treatment processes or the distribution system, not directly from the reservoir. This study demonstrates the utility of employing relatively simple and established methods to better understand management issues of a drinking water system.     

加拿大不列颠哥伦比亚省“知道—实践—理解”课程模式及其启示

加拿大不列颠哥伦比亚省将"培养有教养的公民"作为新一轮课程改革的新教育目的与理念,并构建了"知道—实践—理解(Know-Do-Understand)"课程模式。其中,知道(Know)指向学生对课程内容的了解,实践(Do)强调学生对课程能力的实践,理解(Understand)则关注学生对大概念的理解,三者联动,为培养有教养的公民输送知识基础、能力基础、思想基础。"知道—实践—理解"课程模式为我国基础教育课程改革提供了启示:我国亟待在新时代教育根本任务和课程方案及标准之间搭建"课程理论桥梁";在各门课程之间搭建"课程理论桥梁";建构我国基础教育课程改革的学理。     

Some elements comprising particulate matter during summer in waters of various environments in British Columbia, Canada

Multi-elemental traces comprising particulate matter in natural water collected during summer in 1978 and 1979 from British Columbia, Canada, were analyzed by α-particle excited X-ray fluorometry. Common elements from all waters examined were Si, Cl, Ca and Fe. The similarity of their distribution in different aquatic environments was statistically analyzed. They were distributed homogeneously in the marine environment but heterogeneously in the freshwater environments. No heavy metals concerned with the environmental standards were detected for all waters examined.     

Discrete element modelling and scenario prediction of failure,movement and energy dissipation of a potential landslide under a seismic loading

Bulletin of Engineering Geology and the Environment - Simulation of the process of landslide occurrence, including deformation and failure, material movement and energy dissipation of slopes, can...     

加拿大不列颠哥伦比亚大学材料科学与工程专业本科培养计划的分析

分析了加拿大不列颠哥伦比亚大学材料科学与工程专业本科生的培养计划,通过对其材料工程系的课程设置、学业方向、部分课程大纲和教学情况比较分析发现,该校在课程设置上偏向于传统金属材料,但同时也开拓了新的研究方向和课程方向;在专业基础课的设置方面,注重讲授基础知识及其在材料研发中的应用。该校按照材料大类的思路对本科生进行培养,对中国材料科学与工程专业本科生的培养及课程体系的优化具有很好的借鉴作用。     

求解非均匀无限地基相互作用力的有限元时域阻尼抽取法

由于无限地基的动力效应较难确定,结构-地基的动力相互作用主要局限于频域分析,从而限制了非线性分析应用。阻尼抽取法(DSEM)通过在有限域内施以附加人工阻尼再移频抽取的办法可以有效地模拟非均匀无限粘弹性介质的动力特性,在结构-无限地基动力相互作用分析中有较好的应用前景。在此基础上,本文提出了DSEM进行结构-地基交界面相互作用力-位移时域分析的有限元逐步积分形式算法,并给出了具体实现公式,可以更好地适应工程有限元计算及与结构-地基相互作用程序结合的需要。最后,以实例形式论述了该方法良好的精度及实现中各个关键因素的影响。     

以国际化发展促内涵建设——加拿大不列颠哥伦比亚大学发展模式探析

加拿大不列颠哥伦比亚大学凭借完备的校院两级国际化发展战略,在破解校院发展难题、提升人才培养质量和巩固其世界一流大学排名等方面成功地建立了以"国际化发展促内涵建设"的模式,其经验值得中国高校借鉴。     

Rats! What triggers us to control for rodents? Rodenticide user survey in British Columbia,Canada

Anticoagulant rodenticides (ARs) are used worldwide to suppress rodent populations. Owing to the highly toxic and persistent properties of ARs, farmland predators are increasingly being documented with residues in their systems. Our objective was to evaluate the usage of ARs in Delta, the main region where raptor carcasses have been collected for AR residue testing in British Columbia. We found that farmers most frequently engaged in rodent control (95%). Hobby farmers and residential owners only engaged in rodent control if rodents had been seen or had damaged their property. Products containing brodifacoum were most frequently applied (32%), which was also the most commonly found AR in raptors sampled in the region. Unintended misuse (17%) stemmed from a lack of understanding about the differences in toxicity of products. Our survey demonstrates the need for more information for land-owners regarding correct AR application and safe disposal of poisoned rodents.     

GPGPU-parallelised hybrid finite-discrete element modelling of rock chipping and fragmentation process in mechanical cutting

Mechanical cutting provides one of the most flexible and environmentally friendly excavation methods.It has attracted numerous efforts to model the rock chipping and fragmentation process,especially using the explicit finite element method(FEM) and bonded particle model(BPM),in order to improve cutting efficiency.This study investigates the application of a general-purpose graphic-processing-unit parallelised hybrid finite-discrete element method(FDEM) which enjoys the advantages of both explicit FEM and BPM,in modelling the rock chipping and fragmentation process in the rock scratch test of mechanical rock cutting.The input parameters of FDEM are determined through a calibration procedure of modelling conventional Brazilian tensile and uniaxial compressive tests of limestone,A series of scratch tests with various cutting velocities,cutter rake angles and cutting depths is then modelled using FDEM with calibrated input parameters.A few cycles of cutter/rock interactions,including their engagement and detachment process,are modelled for each case,which is conducted for the first time to the best knowledge of the authors,thanks to the general purpose graphic processing units(GPGPU) parallelisation.The failure mechanism,cutting force,chipping morphology and effect of various factors on them are discussed on the basis of the modelled results.Finally,it is concluded that GPGPU-parallelised FDEM provides a powerful tool to further study rock cutting and improve cutting efficiencies since it can explicitly capture different fracture mechanisms contributing to the rock chipping as well as chip formation and the separation process in mechanical cutting.Moreover,it is concluded that chipping is mostly owed to the mix-mode Ⅰ-Ⅱ fracture in all cases although mode Ⅱ cracks and mode Ⅰ cracks are the dominant failures in rock cutting with shallow and deep cutting depths,respectively.The chip morphology is found to be a function of cutter velocdty,cutting depth and cutter rake angle.     

岩土材料的离散元分析

采用离散元软件PFC3D和超颗粒单元进行岩石破碎研究．对球形岩石颗粒的单轴压缩状态和力链分布进行了分析．获得了岩石颗粒在初始状态,压缩状态的球颗粒分布形态和力链轨迹和岩石破碎的迹线分布。这种方法直观有效的分析了岩石破碎的过程．且通过有限元分析达到两相验证的结果．为深入研究岩土材料的离散特性提供了参考与支持。     

Simulating dynamic processes and hypermobility mechanisms of the Wenjiagou rock avalanche triggered by the 2008 Wenchuan earthquake using discrete element modelling

The discrete element method is well suited for simulating the cracks and subsequent large displacements of catastrophic landslides or rock avalanches, and is therefore a useful tool for analysing their complicated dynamic processes and hypermobility mechanisms. In this study, particle flow code was used to investigate the dynamic processes and hypermobility mechanisms of the Wenjiagou rock avalanche triggered by the 2008 Wenchuan earthquake. Characterization of the avalanche dynamics was achieved using a model comprising four stages: failure rupture, projectile motion, granular debris flow, and debris mass accumulation. The results show that collision on the valley floor was the main factor causing the fragmentation of the Wenjiagou rock avalanche. The upper and front edge of the landslide body were the most likely to move over a long distance. The results also show that friction was the main source of energy dissipation during the entirety of the avalanche movement. The high gravitational potential energy of the avalanche was the basis of the high mobility. In addition, because of their effects on energy dissipation, the low basal friction coefficient, favourable block movement, and topographical conditions played key roles in the rapid, long-runout Wenjiagou avalanche process.