Spatio‐temporal tracer variability in the glacier melt end‐member — How does it affect hydrograph separation results?          下载免费PDF全文

Jan Schmieder  Jakob Garvelmann  Thomas Marke  Ulrich Strasser 《水文研究》2018,32(12):1828-1843

Geochemical and isotopic tracers were often used in mixing models to estimate glacier melt contributions to streamflow, whereas the spatio‐temporal variability in the glacier melt tracer signature and its influence on tracer‐based hydrograph separation results received less attention. We present novel tracer data from a high‐elevation catchment (17 km², glacierized area: 34%) in the Oetztal Alps (Austria) and investigated the spatial, as well as the subdaily to monthly tracer variability of supraglacial meltwater and the temporal tracer variability of winter baseflow to infer groundwater dynamics. The streamflow tracer variability during winter baseflow conditions was small, and the glacier melt tracer variation was higher, especially at the end of the ablation period. We applied a three‐component mixing model with electrical conductivity and oxygen‐18. Hydrograph separation (groundwater, glacier melt, and rain) was performed for 6 single glacier melt‐induced days (i.e., 6 events) during the ablation period 2016 (July to September). Median fractions (±uncertainty) of groundwater, glacier melt, and rain for the events were estimated at 49±2%, 35±11%, and 16±11%, respectively. Minimum and maximum glacier melt fractions at the subdaily scale ranged between 2±5% and 76±11%, respectively. A sensitivity analysis showed that the intraseasonal glacier melt tracer variability had a marked effect on the estimated glacier melt contribution during events with large glacier melt fractions of streamflow. Intra‐daily and spatial variation of the glacier melt tracer signature played a negligible role in applying the mixing model. The results of this study (a) show the necessity to apply a multiple sampling approach in order to characterize the glacier melt end‐member and (b) reveal the importance of groundwater and rainfall–runoff dynamics in catchments with a glacial flow regime.  相似文献   

筒型桩靴在饱和砂土中的贯入阻力研究          下载免费PDF全文

吴曲楠  刘润  张海洋  王宇飞 《地震工程学报》2018,40(6):1183-1190

桩靴贯入阻力的准确预测是自升式钻井平台安全作业的前提。通过小比尺模型试验,研究饱和砂土中桩靴贯入速度对筒型桩靴插桩性能的影响,并基于地基承载力理论提出筒型桩靴贯入阻力的计算方法,进而采用CEL有限元方法模拟筒型桩靴的贯入过程,并与试验结果进行比较。研究发现:当模型试验中桩靴贯入速度在0.1～0.3mm/s时,桩靴的贯入可看作是准静态过程,此时贯入阻力变化不大,采用基于地基承载力理论中的Hansen公式和Vesic公式可较为准确地计算出对应某一深度的贯入阻力;CEL有限元方法可有效模拟筒型桩靴的贯入过程,当桩靴的贯入速度为0.1～0.3mm/s时,数值模拟结果与试验结果吻合较好。  相似文献   

基于ARIO模型的震后重建施工现场安全管理方法          下载免费PDF全文

顾连胜 《地震工程学报》2018,40(6):1350-1355

为提高受灾地区重建安全性，提出基于ARIO模型的震后重建施工现场安全管理方法。在将建筑设计影响因素划分为直接因素与间接因素的基础上，将ARIO模型引入震后重建施工现场安全管理中，利用其分析施工过程中各产业技术与该地区经济的联系，在考虑经济因素的基础上实现震后施工现场安全管理。设计并构建施工初期数据采集系统、施工前安全管理系统、施工过程中安全管理系统，将ARIO与VR结合，使各系统运行时施工人员能够在虚拟漫游中以第一视角完成虚拟施工，掌握整个工期、流程、所用设备等有关信息，并由辅助专家作出相应指导，实现震后重建施工现场安全系统化管理。提出施工安全辅助建议，以完善灾后重建安全管理方法。实验结果表明，该方法运行后安全系数大于当前方法，其科学性和鲁棒性较强。  相似文献   

震后建筑进度BIM估计模型改进   总被引：1，自引：0，他引：1       下载免费PDF全文

武炜  崔邯龙  张丽丽 《地震工程学报》2018,40(4):841-847

传统震后建筑进度BIM估计模型,未考虑精益管理对建筑施工的影响,造成建筑成本浪费较多,影响后期建筑施工进度。本文构建基于BIM和精益管理的震后建筑进度评估模型,根据模型细分震后建筑进度评估过程,在此基础上根据BIM实施三维算量,采用进度计划编制子模型获取各分项工程量,确定建筑施工的主要进度计划,实现对建筑进度计划的编制;通过虚拟施工和现实施工两条主线,利用进度控制子模型实现对施工状态的模拟和精益管理。以此为基础,进行挣值分析比较计划施工成本、实际施工成本和挣值曲线,获取震后建筑的施工进度与成本情况。实验结果说明,本文构建的模型可对震后建筑进度和工程成本进行精准估计,能够减少成本浪费。  相似文献   

建筑用玻化微珠保温混凝土剪力墙抗震结构设计          下载免费PDF全文

朱保华  韩丽婷 《地震工程学报》2018,40(5):963-968

传统方法主要通过导热系数低的材料和增加墙体厚度来达到抗震效果。该方法不仅浪费能源而且抗震性能较差,因此对建筑用玻化微珠保温混凝土剪力墙抗震结构进行设计,构建玻化微珠保温混凝土本构模型,获得与抗震结构相关的理论数据。根据所获取的数据,选择板壳单元SHELL63作为玻化微珠保温混凝土剪力墙抗震结构单元。依据抗震结构材料参数以及抗震结构单元,采用ANSYS软件模拟构建玻化微珠保温混凝土剪力墙抗震结构。分析实验结果可知,所设计建筑节能抗震结构的抗震性能较好,实际运用价值高。  相似文献   

Spatial patterns and driving mechanisms of mid‐Holocene hydroclimate in western North America          下载免费PDF全文

Nicholas Wayne Hermann  Jessica Leigh Oster  Daniel Enrique Ibarra 《第四纪科学杂志》2018,33(4):421-434

  相似文献   

Implementation of a coupled plastic damage distinct lattice spring model for dynamic crack propagation in geomaterials          下载免费PDF全文

Chao Jiang  Gao‐Feng Zhao 《国际地质力学数值与分析法杂志》2018,42(4):674-693

This paper studies dynamic crack propagation by employing the distinct lattice spring model (DLSM) and 3‐dimensional (3D) printing technique. A damage‐plasticity model was developed and implemented in a 2D DLSM. Applicability of the damage‐plasticity DLSM was verified against analytical elastic solutions and experimental results for crack propagation. As a physical analogy, dynamic fracturing tests were conducted on 3D printed specimens using the split Hopkinson pressure bar. The dynamic stress intensity factors were recorded, and crack paths were captured by a high‐speed camera. A parametric study was conducted to find the influences of the parameters on cracking behaviors, including initial and peak fracture toughness, crack speed, and crack patterns. Finally, selection of parameters for the damage‐plasticity model was determined through the comparison of numerical predictions and the experimentally observed cracking features.  相似文献   

弧形海岸裂流的数值模拟研究   总被引：3，自引：0，他引：3  

汪鸿  朱首贤  李训强  张文静  聂屿 《海洋学报(英文版)》2018,37(3):21-30

弧形海岸波浪产生的裂流严重危害人类活动，但是目前对其特征缺乏充分认识。本文对Haller物理模型实验和三亚大东海的数值模拟表明FUNWAVE模式具有较好的裂流模拟能力。基于该模式进行了多种弧形海岸条件的裂流数值模拟，给出裂流的一些特征：（1）海岸弯曲度增大，裂流增强；（2）海岸坡度对裂流有比较大的影响，太陡或太平缓的海岸不利于形成裂流；（3）海岸尺寸减小，裂流减弱；（4）波高和波周期增大，裂流增强，但是对于某些海岸而言，0.4m波高可能就存在危害比较大的裂流。  相似文献   

Sharks caught in the KwaZulu-Natal bather protection programme,South Africa. 14. The smooth hammerhead shark Sphyrna zygaena (Linnaeus)     

ML Dicken  H Winker  MJ Smale  G Cliff 《African Journal of Marine Science》2018,40(2):157-174

The current study provides long-term catch-rate, biological and feeding data for smooth hammerhead sharks, Sphyrna zygaena, caught in South Africa’s KwaZulu-Natal bather protection programme. In total, 2 512 S. zygaena were caught in net installations between 1978 and 2014, and 72 S. zygaena were caught on drumlines between 2007 and 2014. There was no significant log-linear year trend in the net catch rate over time (slope = 0.0054, t = 1.808, p = 0.07). However, there was a significant temporal increase in mean size of the captured sharks (slope = 0.0012, t = 3.502, p < 0.001). A quasi-Poisson generalised additive mixed model showed that increasing latitude, winter months, colder sea temperatures and the deployment of drumlines all had a significant positive effect on the catch rate of sharks in nets. The size frequency of the catch was unimodal, with significantly more females caught in the nets and more males on the drumlines. The majority (93.1%) of all sharks caught were immature and measured between 80 and 120 cm precaudal length. Teleosts and cephalopods dominated the sharks’ diet in terms of all dietary indices. The prey species consumed indicate that immature S. zygaena are feeding primarily within the pelagic zone of shallow coastal habitats.  相似文献   

Review on the study of topographic effect on seismic ground motion          下载免费PDF全文

Hong Zhou 《地震科学（英文版）》2018,31(2):110-116

Topographic effect study is a very important research topic in seismology, seismic engineering,earthquake engineering, engineering earthquake construction and engineering seismology. This paper focuses on its present development status. Post-earthquake investigation has found that the existence of topography caused more serious earthquake damage. The actual seismographs also recorded the topographic amplification effect of 6 to 7 times and even more than 10 times. Numerical simulation is an important technique to study topographic effect, which complements the lack of observed records. However researches on 3-D topographic effect are not enough and need to be studied deeper. To find the main influence factors and the quantitative relationship between topography and ground motion are required very urgently. Obviously the achievements not only can be applied in the earthquake resistant design, but also can provide the quantitative pre-earthquake disaster prediction and quantitative post-earthquake disaster evaluation.  相似文献