Time‐scale analysis in unsaturated porous media under external wave loads     

Heng Xiao  Yin Lu Young  Jean H. Prévost 《国际地质力学数值与分析法杂志》2010,34(18):1935-1959

Extreme waves caused by tsunamis and storm surges can lead to soil failures in the near‐shore region, which may have severe impact on coastal environments and communities. Multiphase flows in deformable porous media involve several coupled processes and multiple time scales, which are challenging for numerical simulations. The objective of this study is to investigate the roles of the various processes and their interactions in multiphase flows in unsaturated soils under external wave loading, via theoretical time‐scale analysis and numerical simulations. A coupled geomechanics–multiphase flow model based on conservation laws is used. Theoretical analysis based on coupled and decoupled models demonstrates that transient and steady‐state responses are governed by pore pressure diffusion and saturation front propagation, respectively, and that the two processes are essentially decoupled. Numerical simulations suggest that the compressibility of the pore fluids and the deformation of the soil skeleton are important when the transient responses of the media are of concern, while the steady‐state responses are not sensitive to these factors. The responses obtained from the fully coupled numerical simulations are explained by a simplified time‐scale analysis based on coupled and decoupled models. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

The Sixth All-Russia Conference on the Study of the Quaternary “Fundamental Problems of the Quaternary: Results and Trends of Further Research”     

Yu. A. Lavrushin  V. S. Volkova  I. V. Khazina 《Stratigraphy and Geological Correlation》2010,18(4):464-466

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Evaluating the spatiotemporal variations of water budget across China over 1951–2006 using IBIS model     

Qiuan Zhu  Hong Jiang  Xiaohua Wei  Changhui Peng  Xiuqing Fang  Shirong Liu  Guomo Zhou  Shuquan Yu  Weiming Ju 《水文研究》2010,24(4):429-445

The Integrated Biosphere Simulator is used to evaluate the spatial and temporal patterns of the crucial hydrological variables [run‐off and actual evapotranspiration (AET)] of the water balance across China for the period 1951–2006 including a precipitation analysis. Results suggest three major findings. First, simulated run‐off captured 85% of the spatial variability and 80% of the temporal variability for 85 hydrological gauges across China. The mean relative errors were within 20% for 66% of the studied stations and within 30% for 86% of the stations. The Nash–Sutcliffe coefficients indicated that the quantity pattern of run‐off was also captured acceptably except for some watersheds in southwestern and northwestern China. The possible reasons for underestimation of run‐off in the Tibetan plateau include underestimation of precipitation and uncertainties in other meteorological data due to complex topography, and simplified representations of the soil depth attribute and snow processes in the model. Second, simulated AET matched reasonably with estimated values calculated as the residual of precipitation and run‐off for watersheds controlled by the hydrological gauges. Finally, trend analysis based on the Mann–Kendall method indicated that significant increasing and decreasing patterns in precipitation appeared in the northwest part of China and the Yellow River region, respectively. Significant increasing and decreasing trends in AET were detected in the Southwest region and the Yangtze River region, respectively. In addition, the Southwest region, northern China (including the Heilongjiang, Liaohe, and Haihe Basins), and the Yellow River Basin showed significant decreasing trends in run‐off, and the Zhemin hydrological region showed a significant increasing trend. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

荆江河道GPS与全站仪边长及方向改化     

陈于  胡友健  陈刚  潘雄 《地理空间信息》2010,8(2):49-51

在区域范围较大的工程测量中,需对方向和边长观测值作归化改正和投影改正,但这一点常被许多测绘工作者忽略,因而造成不能对工程测量的结果加以正确的处理,甚至怀疑观测精度不够,还需加以复测,这给工程的进度造成了不良影响。以在荆江河段河道演变监测控制测量中对方向和边长观测值作归化改正和投影改正为例,阐述了边长及方向归化改正的具体方法及改化过程,通过改化计算,同时也说明全站仪导线边长测量成果经改化后能满足后续工程勘测精度的要求。  相似文献   

A coupled model for prediction of settlement and gas flow in MSW landfills     

L. Yu  F. Batlle  A. Lloret 《国际地质力学数值与分析法杂志》2010,34(11):1169-1190

Prediction of long‐term settlement and control of gas pollution to the environment are two principle concerns during the management of municipal solid waste (MSW) landfills. The behavior of settlement and gas flow in MSW landfills is complicated due to the combined effect of mechanical deformation of the solid skeleton and continuous biodegradation of the waste. A one‐dimensional settlement and gas flow model is presented in this paper, which is capable of predicting time evolution of settlement as well as temporal and spatial distribution of gas pressure within multi‐layered landfills under a variety of operating scenarios. The analytical solution to the novel model is evaluated with numerical simulation and field measurements. The resulting efficiency and accuracy highlight the capability of the proposed model to reproduce the settlement behavior and gas flow in MSW landfills. The influences of operating conditions and waste properties on settlement and gas pressure are examined for typical MSW landfills. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Optimization of approaches for simulation of the chemical composition of river water     

M. Yu. Semenov  V. A. Snytko 《Doklady Earth Sciences》2013,453(2):1288-1291

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Tests and applications of an approach to absorbing reflected waves towards incident boundary     

张洪生  王炎  许春辉  商辉  于小伟 《中国海洋工程》2013,27(6):703-718

If the upstream boundary conditions are prescribed based on the incident wave only, the time-dependent numerical models cannot effectively simulate the wave field when the physical or spurious reflected waves become significant. This paper describes carefully an approach to specifying the incident wave boundary conditions combined with a set sponge layer to absorb the reflected waves towards the incident boundary. Incorporated into a time-dependent numerical model, whose governing equations are the Boussinesq-type ones, the effectiveness of the approach is studied in detail. The general boundary conditions, describing the down-wave boundary conditions are also generalized to the case of random waves. The numerical model is in detail examined. The test cases include both the normal one-dimensional incident regular or random waves and the two-dimensional oblique incident regular waves. The calculated results show that the present approach is effective on damping the reflected waves towards the incident wave boundary.  相似文献   

The influence of dam and lakes on the Yangtze River streamflow: long‐range correlation and complexity analyses     

Qiang Zhang  Yu Zhou  Vijay P. Singh  Xiaohong Chen 《水文研究》2012,26(3):436-444

Employing long‐range correlation, complexity features and clustering, this study investigated the influence of dam and lake‐river systems on the Yangtze River flow. The impact of the Gezhouba Dam and the lake systems on streamflow was evaluated by analysing daily streamflow records at the Cuntan, the Yichang and the Datong station. Results indicated no evident influence of the Gezhouba Dam on streamflow changes. Distinct differences in scaling behaviour, long‐range correlation and clustering of streamflow at the Datong station when compared with those at the Cuntan and Yichang stations undoubtedly showed the influence of water storage and the buffering effect of the lake systems between the Datong station and other two hydrological stations on streamflow in the lower Yangtze River basin. Decreased regularity, enhanced long‐range correlation and increased clustering of streamflow in the lower Yangtze River basin due to the effect of water storage of the lake systems were corroborated. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

灰色最小二乘支持向量机在滑坡变形预测中的应用     

李潇 《测绘通报》2010,(6)

结合灰色系统思想与最小二乘支持向量机构成灰色最小二乘支持向量机,根据目前灰色模型与最小二乘支持向量机结合的方法,提出并联型、串联型和残差型三种预测模型的结构.将上述三种灰色最小二乘支持向量机模型用于对三峡库区石佛寺滑坡垂直位移进行预测,模型精度和预测结果比较理想,优于单一预测模型.试验表明:灰色最小二乘支持向量机可提高预测精度,用于滑坡变形预测是有效可行的.  相似文献   

Geochemical study on oil-cracked gases and kerogen-cracked gases (II)—Discrimination methods between oil-cracked gases and kerogen-cracked gases     

Huang  GuangHui  Zhang  Min  Hu  GuoYi  Xiao  ZhongYao 《中国科学:地球科学(英文版)》2010,52(1):10-18

In the processes of discrimination between oil-cracked gases and kerogen-cracked gases, Behar and Pinzgofer et al.’s results were adopted in the former researches, in which the ratio of C₂/C₃ is basically a constant while the ratio of C₁/C₂ gradually increases in the course of primary cracking of kerogen. Otherwise in the course of secondary cracking of oil, the ratio of C₂/C₃ increases rapidly while C₁/C₂ keeps relatively stable. Our study on analogue experiment shows that, whether it is oil or kerogen, in its process of gas generating by cracking, the ratios of C₂/C₃, C₁/C₂ or C₁/C₃ will all be increased with the growth of thermal conditions. In comparison, the ratio of C₂/C₃, which is affected by genetic type to some comparatively less extent, mainly responds to the maturity of gases, while the value of C₂/C₃ is about 2, and that of C₂/iC₄ is about 10, and the corresponding value of R _o is about 1.5%–1.6%. The influence of gas source on C₂/C₃ is less than that of gas maturity, otherwise C₁/C₂ (or C₁/C₃) is obviously affected by cracking matrices. The ratios of C₁/C₂, C₁/C₃ of oil-cracked gases are less than that of kerogen-cracked gases, under the condition that the ratios of C₂/C₃ are similar in value, so are the value of dryness indexes. There exists wide diffidence between this view and the former discrimination method in theory. The analysis of the spot sample indicates that we can apply the above basic view to dealing efficiently with the problem of the discrimination between oil-cracked gas and kerogen-cracked gas.

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