Theoretical simulation of the evolution of methane hydrates in the case of Northern South China Sea since the last glacial maximum     

Lihua Liu  Haibing Shao  Shaoying Fu  Nengyou Wu 《Environmental Earth Sciences》2016,75(7):596

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Analysis of the THM behaviour in a clay-based engineered barrier system (EBS): modelling of the HE-E experiment (Mont Terri URL)     

Xuerui Wang  Hua Shao  Jürgen Hesser  Olaf Kolditz 《Environmental Earth Sciences》2016,75(20):1350

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Rotation Center and Horizontal Bearing Capacity of the Bucket Foundation in Soft Ground     

Xiaowei Tang  Xiwen Zhang  Qi Shao  Zhenqing Li 《Marine Georesources & Geotechnology》2016,34(6):594-601

In the last 20 years, the bucket foundation has been developed as a new type of offshore platform structure. Because of its short period of application to engineering practices, the theoretical decision on the rotation center and horizontal bearing capacity of the bucket foundation has yet to be agreed. A limit analysis method is used to determine the updated rotation center position and horizontal bearing capacity to evaluate the failure mechanisms of the bucket foundations. The results are compared with numerical simulation and experiments, and also with other theoretical methods. The proposed method can satisfactorily consider the engineering conditions and the result is accurate in determining the rotation center and horizontal bearing capacity.  相似文献   

Analysis of phenotypic and genetic parameters for growthrelated traits in the half smooth tongue sole, <Emphasis Type="Italic">Cynoglossus semilaevis</Emphasis>     

刘峰  李仰真  杜民  邵长伟  陈松林 《中国海洋湖沼学报》2016,34(1):163-169

Phenotypic and genetic parameters for growth-related traits in the half-smooth tongue sole, Cynoglossus semilaevis, were estimated in 22 full-sib families produced by normal and neo-male breeding stocks. As phenotypic males with female genotypes, neo-males are harmful in C. semilaevis aquaculture because they reduce overall production. The present study evaluated the difference in the growth-related traits: total length (TL), body weight (BW) and square root of body weight (SQ_BW) at the age of 570 days between normal and neo-male offspring (neo-males used as male parents). The difference in the proportion of females between normal and neo-male offspring was also assessed. Based on the linear mixed model, restricted maximum likelihood (REML) and best linear unbiased prediction (BLUP) were used to estimate various (co)variance components and estimated breeding values (EBVs) of growth-related traits. As a result, all the mean values of the three studied traits were significantly larger in normal offspring than in neo-male offspring. Additionally, the female proportion was significantly larger in normal offspring than in neo-male offspring. Heritability was 0.128±0.066 2 for TL, 0.128±0.065 5 for BW and 0.132±0.062 9 for SQ_BW, all of which were low level heritabilities. The correlation coefficients of EBVs and phenotypic values of the target traits were 0.516 for TL, 0.524 for BW and 0.506 for SQ_BW, all of which were highly significant (P <0.01). Genetic correlations among TL, BW and SQ_BW were positive high (0.921–0.969) and higher than those of phenotype (0.711–0.748), both of which had low standard errors (0.063–0.123 for genotype, and 0.010–0.018 for phenotype). Compared with normal offspring, neo-male offspring have lower breeding values for each studied trait through EBVs comparison. Therefore, neo-male offspring should not be used as broodstock in a C. semilaevis breeding programs.  相似文献   

西藏乌鲁穷含铜磁铁矿床的发现及地质特征   总被引：2，自引：2，他引：0       下载免费PDF全文

杨绍  李德威  陈桂凡  李华亮  张硕  周涛 《中国地质》2018,45(6):1214-1227

继尼雄、弗野、材玛等铁矿床的发现之后,新一轮1：5万区域地质调查又在班公湖-怒江成矿带西段乌鲁穷地区发现了较大规模的含铜磁铁矿矿床。野外路线调查、剖面实测和大比例尺填图表明,乌鲁穷磁铁矿形成于南羌塘南缘中-晚侏罗世中酸性岩体与上三叠统日干配错群二组（T₃R²）碳酸盐岩外接触带中,矿体受后期近南北向高角度正断层改造,成矿作用表现出多期次、多阶段特征。通过对矿体邻近的石英闪长岩、二长花岗岩和控矿断层中同构造碳酸盐脉进行锆石LA-ICP-MS U-Pb同位素测年,获得石英闪长岩、二长花岗岩成岩年龄分别为：（161.3±0.72）Ma、（157.5±1.7）Ma,并获得同构造碳酸盐脉热液锆石年龄为（84.2±1.1）Ma。结合前人研究和1：5万地质调查成果,认为乌鲁穷含铜磁铁矿在中-晚侏罗世（157.5~161.3 Ma）班公湖-怒江洋北向俯冲过程中初步富集成矿,形成矽卡岩型含铜磁铁矿矿床,矿体在晚白垩世（84.2 Ma）陆内伸展过程中再次富集;提出班公湖地区在晚白垩世中期存在一期横跨缝合带的陆内伸展成矿事件,成矿作用与班公湖-怒江洋闭合后地幔软流圈底辟及其相关的地壳线性热隆伸展是一个机理关联的系统。  相似文献   

Comparison of single- and dual-permeability models in simulating the unsaturated hydro-mechanical behavior in a rainfall-triggered landslide     

Wei Shao  Zongji Yang  Junjun Ni  Ye Su  Wen Nie  Xieyao Ma 《Landslides》2018,15(12):2449-2464

Landslide-prone slopes in earthquake-affected areas commonly feature heterogeneity and high permeability due to the presence of cracks and fissures that were caused by ground shaking. Landslide reactivation in heterogeneous slope may be affected by preferential flow that was commonly occurred under heavy rainfall. Current hydro-mechanical models that are based on a single-permeability model consider soil as a homogeneous continuum, which, however, cannot explicitly represent the hydraulic properties of heterogeneous soil. The present study adopted a dual-permeability model, using two Darcy-Richards equations to simulate the infiltration processes in both matrix and preferential flow domains. The hydrological results were integrated with an infinite slope stability approach, attempting to investigate the hydro-mechanical behavior. A coarse-textured unstable slope in an earthquake-affected area was chosen for conducting artificial rainfall experiment, and in the experiment slope, failure was triggered several times under heavy rainfall. The simulated hydro-mechanical results of both single- and dual-permeability model were compared with the measurements, including soil moisture content, pore water pressure, and slope stability conditions. Under high-intensity rainfall, the measured soil moisture and pore water pressure at 1-m depth showed faster hydrological response than its simulations, which can be regarded as a typical evidence of preferential flow. We found the dual-permeability model substantially improved the quantification of hydro-mechanical processes. Such improvement could assist in obtaining more reliable landslide-triggering predication. In the light of the implementation of a dual-permeability model for slope stability analysis, a more flexible and robust early warning system for shallow landslides hazard in coarse-textured slopes could be provided.  相似文献   

Characterization of the mechanical properties of a claystone by nano-indentation and homogenization     

Fan Zhang  Hanqun Guo  Dawei Hu  Jian-Fu Shao 《Acta Geotechnica》2018,13(6):1395-1404

Based on the analyses of mineralogical compositions by X-ray diffraction and microstructure by optical microscopy, the Young’ modulus and hardness of a claystone were characterized by the nano-indentation technique and homogenization method. Three distinct microstructural zones are identified in the claystone: clay matrix, a composite matrix of clay and small mineral grains and imbedded quartz grains. The elastic modulus and hardness of different zones were determined by nano-indentation testing. Based on the statistical analysis of nano-indentation results, the spatial mappings and frequency distributions of elastic modulus and hardness of the different zones were obtained. The elastic moduli of main constituent phases of the claystone are then estimated from the nano-indentation tests. These values were further used for the determination of the macroscopic elastic modulus of the claystone using two different homogenization schemes: the dilute scheme and Mori–Tanaka scheme. The predicted values by the homogenization schemes are compared with experimental data obtained from conventional uniaxial compression tests.  相似文献   

Up-to-date urban rainstorm intensity formulas considering spatial diversity in China     

Danna Shao  Guang-sheng Liu 《Environmental Earth Sciences》2018,77(14):541

With accelerating urbanization in China, urban waterlogging has had a serious impact on urban sustainable development and citizen welfare. Simple urban rainstorm intensity formulas with a monotonous frequency distribution type cannot meet the practical needs of urban drainage planning and design. This study focuses on the development of urban rainstorm intensity formulas based on spatial diversity in China. Using the annual maximum sampling method, rainstorm data of 607 cities throughout China were collected into a database, with a total of 24,933 rainfall samples (annual observations) under various specified precipitation durations. The database was used to verify that integrating the Pearson III and Gumbel distributions would constitute an optimal theoretical distribution type, owing to its small error and increased fitting precision. Modification and coordination of four important parameters in the rainstorm intensity formula were done using a digital elevation model, which improved the accuracy of the formula. In addition, precipitation distributions in China were treated from the perspective of topographic features to validate the calculations from up-to-date formulas. Accuracy assessment was accomplished using a national code (GB-50014-2006), GIS-based isograms, and authoritative results from the Hydrological Bureau of the Ministry of Water Resources. This work provides a comprehensive foundation for the establishment of an up-to-date rainstorm intensity formula for China, which can be used widely in different cities.  相似文献   

我国干热岩资源分布及勘探:进展与启示   总被引：3，自引：0，他引：3  

蔺文静  王贵玲  邵景力  甘浩男  谭现锋 《地质学报》2021,95(5):1366-1381

干热岩是地热资源的重要赋存形式之一,是未来地热开发的主攻方向.我国干热岩勘查工作近年来进展迅速,先后在不同地区发现了优质的干热岩资源,取得了我国干热岩资源勘查突破,但同时也存在不少勘查失败的案例.本文在分析高放射性产热型、沉积盆地型、近代火山型和强烈构造活动带型等四种类型干热岩成因模式的基础上,结合我国的地质构造背景、地热地质条件,对未来我国干热岩资源重点勘查方向及靶区进行了论述,并重点针对目前不同类型区干热岩资源勘探工程进行了梳理,简要分析了不同勘探区的选址依据、勘探过程、地温场分布及特征、前景预测等,并初步进行了经验总结,希望对我国未来干热岩资源勘查及开发工作起到借鉴作用.  相似文献   

2018年全球重大天气气候事件及其成因   总被引：5，自引：3，他引：2  

孙劭  李多  王遵娅  王国复  柯宗建 《气象》2019,45(4):533-542

2018年全球主要温室气体浓度继续攀升,地表温度相比工业化前水平偏高0.99℃,为有观测记录以来的历史第四高值。全球冰川总量连续31年减少,南北极海冰范围全年处于历史低位。全球海洋表面温度较常年显著偏高,海平面继续加速上升,海洋热含量创历史新高,海洋酸化的影响日益加剧。年内,世界各地发生了许多重大天气气候事件,包括北半球异常活跃的热带气旋季、欧洲夏季持续性高温干燥天气、印度西南部的特大洪灾、澳洲东部严重旱情、欧美多地的低温暴雪以及全球多地的森林大火和强对流天气,造成了严重的人口伤亡和社会经济损失。本文系统性总结了2018年全球重大天气气候事件及其影响,并重点分析了印度近百年来最严重洪灾和美国东海岸爆发性低温雨雪冰冻两个典型气候事件的形成原因。分析表明,夏季南亚季风强度偏强、控制时间偏长,8月在南亚季风槽西部位置偏北、索马里越赤道急流偏强的共同作用下,南印度洋及阿拉伯海上空的水汽大量向印度地区输送,持续性的强降水天气引发了该地区近百年以来最严重的洪灾;1月上旬,在耦合的急流结构、强烈的海洋温度梯度以及气旋外围气温偏高的共同作用下,冬季风暴格雷森在短时间内爆发性加强,造成美国东海岸出现气温骤降、强风暴雪等剧烈天气现象。  相似文献