Predictive uncertainty of peak outflow relations for landslides dam breach     

Chao Dang  Nana Chu  Yu Ding 《Environmental Earth Sciences》2014,72(11):4265-4271

Risk assessment development considering the failure of landslide dams often requires the estimation of peak outflow through the breach. The empirical equations based on data from case studies tend to be the first direct approach. This paper conducted an uncertainty analysis when these empirical relations were utilized to predict the peak outflow of a breached landslide dam. The results suggest that the relations derived from manmade dams or embankments typically overestimate the peak outflow about 1/5 to 3/4 of an order of magnitude; and the relations derived from the database of landslide dams have much smaller mean prediction errors and also exhibit broad uncertainty bands. Application of the uncertainly analysis was illustrated by the Tangjiashan landslide dammed lake, formed during 2008 Wenchuan earthquake. In addition, the predicted results from Eq. 1 deduced herein were considered to be the reliable estimate of peak outflow through the breach of landslide dam.  相似文献   

土壤硝酸盐氮的空间变异特征及影响因素分析     

张玉玲  司超群  陈志宇  初文磊  陈在星  王璜 《吉林大学学报(地球科学版)》2018,48(1):241-251

为了掌握土壤中硝酸盐氮的空间变异性规律,为硝酸盐污染土壤控制与修复提供依据,以东北某农业灌区为例,利用地质统计方法进行土壤硝酸盐氮的空间变异特征及影响因素分析。研究结果表明：土壤硝酸盐氮的空间变异性显著,变异系数达到82.88%以上。第一层土壤硝酸盐氮在南北向空间上存在严格的自相关性,空间变异的结构性成分比例较高;第二、三层位土壤硝酸盐氮空间变化接近分形布朗运动;第四层位土壤硝酸盐氮在各方向上都具有较高的随机性。总体土壤硝酸盐氮质量分数由西向东逐渐递减,在浑河中下游以及细河附近土壤硝酸盐氮质量分数偏高。不同影响因素对于硝酸盐氮的空间变异特征影响不一致：土壤硝酸盐氮质量分数与有机质质量分数的空间分布趋势一致;不同土壤类型中,水田环境中土壤硝酸盐氮随着深度线性递减,而其他类型土壤中硝酸盐氮质量分数在表层向下递减后有一个回升现象,这与它们各自所处的环境特点有关,而地表壤土和砂土富含硝酸盐。  相似文献   

内蒙古杭锦旗气田区地下水化学特征及其形成机制     

吴初  武雄  钱程  朱阁 《现代地质》2017,31(3):629

对内蒙古杭锦旗气田区浅层地下水运用Piper三线图、Gibbs图、氯碱指数图等方法进行水化学特征及其形成作用分析研究,结果表明：杭锦旗气田区浅层地下水具有较高的矿化度,偏碱性,硬度较大,枯水期TDS浓度和总硬度高于丰水期;研究区浅层地下水化学组分在小范围内具有一定的空间变异性,地下水阳离子以Na+、Ca2+为主,阴离子以HCO3-为主,水化学类型主要有HCO3 Ca型、HCO3 Na型和SO4·Cl Na型;研究区浅层地下水化学组分来源于碳酸盐矿物、硅铝酸盐矿物和蒸发岩的风化溶解,且丰水期和枯水期水化学组分有微弱变化,地下水化学特征的形成以岩石风化溶解作用为主。  相似文献   

Simplified methods to analyze geosynthetic mattress resting on deformable foundation soil     

Wei Guo  Hailei Kou  Bo Zhou  Jian Chu 《Marine Georesources & Geotechnology》2017,35(3):339-345

A special case of geosynthetic tubes is the geosynthetic mattress characterized by its larger width-to-height ratio and higher lateral-force-resisting capacity. When the geosynthetic mattresses are adopted for dike or breakwater construction in coastal engineering projects, they are often laid on deformable foundation soil. The induced ground settlement will influence the cross-sections and tensile forces of the geosynthetic mattresses. Two analytical methods, called the Winkler foundation method and the e–log p method, are proposed in this paper to analyze the geosynthetic mattresses resting on deformable foundation soil. For the Winkler foundation method, the subgrade soil is assumed as a Winkler elastic foundation represented by the modulus of subgrade reaction, K_f. For the e–log p method, the 1D consolidation relationship (e–log p curve) is adopted to describe the behavior of the subgrade soil within which the distribution of vertical surcharge is calculated using Boussinesq equation. The numerical analyses using FLAC are also conducted to evaluate the accuracy of the proposed methods. The differences between the analytical and numerical solutions are also discussed. It is found from this paper that the proposed e–log p method is more suitable than the Winkler foundation method for the calculation of the geosynthetic mattress resting on deformable foundation soil.  相似文献   

基于电磁驱动的滑坡模型水分迁移理论及试验研究     

周昌  胡新丽  徐楚  王强  徐迎 《岩土力学》2018,39(9):3347-3354

加快模型试验中水的渗流速率对库岸滑坡研究意义重大。考虑滑坡渗流特性,基于电磁驱动原理,在滑坡模型中施加相互垂直的电场、磁场,推导出孔隙水受力公式,根据电渗固结理论,推导水分迁移速率v与电压Ve、磁场强度B的关系式,进而获得时间相似比,实现了通过电磁场强度来控制滑坡模型水分迁移速率,改进模型试验,为研究库水位升降对滑坡的影响提供条件。通过试验进行验证：电磁场对水分迁移速度的影响具有显著效果,且电压大小对模型的稳定渗流场影响较小。说明在不改变模型材料参数的条件下,改变磁场强度和电压可获得任意孔隙水的渗流速度,为研究库水位波动条件下的滑坡演化机制奠定基础。  相似文献   

水库型滑坡模型试验相似材料的研制及应用     

徐楚  胡新丽  何春灿  徐迎  周昌 《岩土力学》2018,39(11):4287-4293

相似材料的研制是滑坡模型试验的关键。在相似材料的研究基础上,通过大量的配比试验,结合模糊综合评价法对不同配比材料的相似性进行比较,研制出同时模拟物理力学性能相似和渗流作用相似的水库型滑坡相似材料,这种材料由标准砂、滑体土、膨润土和水溶液混合而成。同时通过库水作用下滑坡模型试验评价该材料的相似效果,记录水位升降过程中坡内的孔隙水压力变化、渗流变化、滑面形态及裂缝形成发展过程。试验结果表明,库水对岩土体物理力学性质的弱化和坡内指向临空面的渗透压力是滑坡产生的主要诱发因素;水库型滑坡的破坏模式为有多级滑面的牵引式破坏;试验观测的浸润线与理论计算结果基本吻合。该相似材料的物理力学性能和渗流效果均能达到试验相似要求,模拟库水作用下滑坡变形破坏过程的效果良好,是一种比较理想的水库型滑坡模型相似材料。研究结果为进一步开展大型水库型滑坡模型试验提供了科学依据。  相似文献   

Anti-Phase Relationship Between the East Asian Winter Monsoon and Summer Monsoon During the Holocene?     

Qian Ge  Zuo Xue  Zhigang Yao  Zhengchen Zang  Fengyou Chu 《中国海洋大学学报(英文版)》2017,16(2):175-183

The relationship between the East Asian winter monsoon (EAWM) and East Asian summer monsoon (EASM) during the Holocene is complicated and remains controversial. In this study, analysis of grain size and benthic foraminiferal oxygen isotope, as well as accelerator mass spectrometry ¹⁴C dating was performed on a sediment core retrieved from the newly revealed muddy deposit on the northern South China Sea continental shelf. The history of the EAWM and EASM were reconstructed for the last 8200 a BP. Further analysis in conjunction with previously published paleo-climate proxies revealed that the relationship between the EAWM and EASM during the Holocene is more complex than a simple and strict anti-phase one-both negative and positive correlations were identified. The EAWM and EASM are negatively correlated around 7500, 4800, 4200, 3200, and 300 a BP (cooling periods), while positively correlated around 7100, 3700, and 2100 a BP (warm periods). In particular, both the EAWM and EASM intensified during the three positive correlation periods. However, we also found that the relationship between these two sub-monsoons is anti-phase during the final phase of particularly hot periods like Holocene Optimum and Medieval warm period. The possible impact from variations of solar irradiance on the relationship between the EAWM and EASM was also discussed.  相似文献   

A Coastal Air-Ocean Coupled System (CAOCS) Evaluated Using an Airborne Expendable Bathythermograph (AXBT) Data Set     

Peter C. Chu  Shihua Lu  Yuchun Chen 《Journal of Oceanography》1999,55(4):543-558

A coastal atmosphere-ocean coupled system (CAOCS) is developed with Princeton Ocean Model (POM) as the oceanic component, and with National Center for Atmospheric Research (NCAR) regional climate model (RegCM2) as the atmospheric component. The model domain (98.84°–121.16°E, 3.06°S–25.07°N) covers the whole SCS and surrounding land and islands. The surface fluxes of water, heat (excluding solar radiation), and momentum are applied synchronously with opposite signs in the atmosphere and ocean. Flux adjustments are not used. The CAOCS model was verified using an intensive airborne expendable bathythermograph (AXBT) survey between 14–25 May 1995 over the majority of the SCS down to about 300-m depth.  相似文献   

介绍一种测量溶解氧的微型光纤传感器   总被引：2，自引：0，他引：2  

褚柳宁 《海洋技术学报》1999,18(2):49-55

本文介绍了一种根据动态荧光猝灭原理而设计的微型光纤溶解氧传感器（氧微光极）,讨论了氧微光极的结构设计、工作原理、技术特点及试验应用情况。该系统具有良好的测量特性,是适合于水环境应用的理想工具  相似文献   

1971年以来珠穆朗玛峰地区气候变化     

杨续超  张镱锂  张玮  YAN Yuping  WANG Zhaofeng  DING Mingjun  CHU Duo 《地理学报(英文版)》2006,16(3):326-336

Global climate change has profound influence on natural ecosystem and socioeconomic system and is a focus which governments, scientific societies as well as common people of various countries have paid much attention to. Observations indicate that there i…  相似文献