Preconditioned IDR(s) iterative solver for non‐symmetric linear system associated with FEM analysis of shallow foundation     

H.H.T. Tran  K.C. Toh  K.K. Phoon 《国际地质力学数值与分析法杂志》2013,37(17):2972-2986

Non‐associated flow rule is essential when the popular Mohr–Coulomb model is used to model nonlinear behavior of soil. The global tangent stiffness matrix in nonlinear finite element analysis becomes non‐symmetric when this non‐associated flow rule is applied. Efficient solution of this large‐scale non‐symmetric linear system is of practical importance. The standard Krylov solver for a non‐symmetric solver is Bi‐CGSTAB. The Induced Dimension Reduction [IDR(s)] solver was proposed in the scientific computing literature relatively recently. Numerical studies of a drained strip footing problem on homogenous soil layer show that IDR(s = 6) is more efficient than Bi‐CGSTAB when the preconditioner is the incomplete factorization with zero fill‐in of global stiffness matrix K_ep (ILU(0)‐K_ep). Iteration time is reduced by 40% by using IDR(s = 6) with ILU(0)‐K_ep. To further reduce computational cost, the global stiffness matrix K_ep is divided into two parts. The first part is the linear elastic stiffness matrix K_e, which is formed only once at the beginning of solution step. The second part is a low‐rank matrix Δ, which is re‐formed at each Newton–Raphson iteration. Numerical studies show that IDR(s = 6) with this ILU(0)‐K_e preconditioner is more time effective than IDR(s = 6) with ILU(0)‐K_ep when the percentage of yielded Gauss points in the mesh is less than 15%. The total computation time is reduced by 60% when all the recommended optimizing methods are used. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Model for degradation‐induced settlements as part of a coupled landfill model          下载免费PDF全文

S. Bente  V. Krase  U. Kowalsky  D. Dinkler 《国际地质力学数值与分析法杂志》2017,41(12):1390-1410

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涡旋诱发重联模型（Ⅰ）——动力学特性   总被引：2，自引：1，他引：2       下载免费PDF全文

刘振兴  濮祖荫 《地球物理学报》1990,33(1):1-11

本文首先从理论上系统地研究了涡旋诱发重联的基本动力学特性.包括:涡旋诱发重联的物理机制;Kelvin-Helmholtz（K-H）不稳定性和撕裂模不稳定性耦合过程;磁流体涡管的基本特性;不同尺度涡旋间的相互作用,动能和磁能间的转化及准稳态时流线、磁力线、等涡度线和等电流密度线的相似性等.用二维MHD数值模拟方法研究了上述一些特性,并与理论分析结论进行了比较.结果表明,模拟结果证实了理论推论.涡旋诱发重联是产生局部磁场重联的重要机制之一,该模型在磁顶区的应用将另文发表.  相似文献   

新丰江水库区1989年11月26日4.5级地震的主要特征     

黄河生  魏柏林等 《华南地震》1991,11(2):68-73

本文总结分析了发生在新丰江水库老震区，距1962年6.1级主震27年的1次4.5级地震的活动和特点，认为此次4.5级地震及其伴生的小震群仍系新丰江水库诱发地震序列的中晚期强余震。  相似文献   

Application of stress-pore pressure coupling theory for porous media to the Xinfengjiang reservoir earthquakes   总被引：1，自引：0，他引：1  

Li-Ying Shen  Bao-Qi Chang 《Pure and Applied Geophysics》1995,145(1):123-137

Theory of the coupling of stress-pore pressure in the saturated, elastic porous media is used in the study of the formation mechanism of the Xinfengjiang reservoir-induced earthquakes. Based on the results, it is believed that compared with the mechanism of additional stress in the vicinity of the reservoir, the mechanism of the coupling of additional stress and pore pressure may be more well-founded for the occurrence of reservoir-induced earthquakes.  相似文献   

Earthquakes in the Czech Republic and Surrounding Regions in 1995–1999     

Zedník  J.  Pospíšil  J.  Růžek  B.  Horálek  J.  Boušková  A.  Jedlička  P.  Skácelová  Z.  Nehybka  V.  Holub  K.  Rušajová  J. 《Studia Geophysica et Geodaetica》2001,45(3):267-282

In the time span from January 1995 to December 1999 the Czech National Seismological Network (CNSN), consisting of ten permanent digital broadband stations, several local networks and two data centers, detected and recorded 9530 regional natural seismic events, 27 greater than magnitude 2. Most of these events were located by the Czech Seismological Service (CSS), and the most prominent of them were analyzed in detail. A large number of quarry blasts were recorded as well but were not included in the analysis. We provide basic information on the configuration of the CNSN and on the way of routine data processing employed by the CSS in this paper. The over-all regional seismicity monitored by the CNSN in 1995–1999 is briefly reviewed. The main results of observations and evaluation of the local (NW-Bohemia/Vogtland, South Bohemia, Sudeten) and induced (Kladno, Píbram, Upper Silesia, Lubin/Poland) seismic activity within this period are presented in a condensed form. Finally, a summary on macroseismic observations on the territory of the Czech Republic in 1995–1999 is also presented.  相似文献   

Locally triggered seismicity in the central Swiss Alps following the large rainfall event of August 2005   总被引：3，自引：0，他引：3  

S. Husen  C. Bachmann  D. Giardini 《Geophysical Journal International》2007,171(3):1126-1134

In 2005 August, an unusual series of 47 earthquakes occurred over a 12-hr period in central Switzerland. The earthquakes occurred at the end of 3-d period of intensive rainfall, with over 300 mm of precipitation. The highest seismicity occurred as two distinct clusters in the region of Muotatal and Riemenstalden, Switzerland, a well-known Karst area that received a particularly large amount of rainfall. The large increase in seismicity, compared to the background, and the short time delay between the onset of the intense rainfall and the seismicity strongly suggest that earthquakes were triggered by rainfall. In our preferred model, an increase in fluid pressure at the surface due to a large amount of rain leads to a local increase in pore fluid pressure at depth. The increase in pore fluid pressure will reduce the shear strength of a porous medium by counteracting normal stress and, at the end, provoke failure. The series of triggered earthquakes in central Switzerland occurred in regions that have been seismically active in the past, showing similar hypocentre locations and magnitudes. This suggests that these earthquakes occurred on existing faults that were critically stressed. We modelled the intense rainfall as a step increase in fluid pressure at the surface that migrates to greater depths following the solution of the one-dimensional diffusion equation in a homogeneous half space. This allowed us to estimate the hydraulic diffusivity by plotting triggered seismicity in a time–depth plot. We found values of hydraulic diffusivity in the range from 0.01 to 0.5 m² s⁻¹ for our study area. These values are in good agreement with previous studies on earthquakes that were triggered by fluids, supporting the idea that the observed earthquake series was triggered by the large amount of rainfall.  相似文献   

浅述次生孔隙的成因   总被引：9，自引：2，他引：9  

李义军 《西北地质》2002,35(1):65-69

生油岩生成的油气，必须运移到储集层中贮存起来，这样油气才可成藏，而岩层的孔隙度是其储集性好坏的重要标志，次生孔隙在此更是有极重要的意义(因为随着岩层的埋深，成岩作用不断在进行，原生孔隙将减少，次生孔隙将在储油方面扮演重要角色)，因此，笔者着重论述次生孔隙的成因及其相关问题。  相似文献   

立交构造与渭河盆地地震活动   总被引：1，自引：0，他引：1       下载免费PDF全文

冯希杰  王平 《地震工程学报》2001,23(2):160-163

分析了鄂尔多斯地块南部和渭河盆地构造的空间分布特征，认为鄂尔多斯地块南部存在3条NW向隆起带，渭河盆地内部存在3个近EW向斜列的次级沉降中心，这些隆起带与次级沉降中心及其间的横向隆起共同组成了立交构造，分析了渭河盆地内部及其周边地区历史地震和现代地震的空间分布，发现立交构造对盆地内地震活动有着较强的控制作用。  相似文献   

Study on the relationship between geothermal exploitation and seismic activity in Xi’an region     

Wu Fu-chun  Song Li-sheng  Zhu Xing-guo  Wang Feng  Jing Bei-ke  Dong Xing-hong  Fang Wei  Zuo Yong-qing 《地震学报(英文版)》2001,14(4):434-439

Based on the analysis of the induced earthquakes in China and abroad, we get some ideas about earthquakes induced by pumping water out of a well or injecting water into a well. The induced earthquakes usually occur near the well, and they are generally small earthquakes. The earthquake sources are shallow, and they belong to the main shock-after shock type of earthquake or the swarm-type of earthquake. The magnitude and the quantity of the induced earthquakes obviously depend on the pressure and the quantity of water pumped or injected. These earthquakes happen as soon as pumping or injecting occurrence, or after ten or twenty days, they may occur at the time of injecting mud or injecting high pressure water when a well is being drilled, or at the time when the ground water is being normally exploited. A large quantity of hot water has been exploited since 1990 in Xi’an, and the quantity of water exploited has been increasing year by year, as a result the groundwater level has been dropping with the water pumped out and the water level is high in summer and low in winter. The earthquakes in Xi’an region belong to the solitary-type and they spread outside Xi’an city where the wells are concentrated but no earthquake happens. The seismic frequency and the energy released have no relation with the quantity of water exploitation or the water level in the well. It is considered that geothermal exploitation does not induce earthquakes in and around Xi’an because of its specially geological condition. Foundation item: Project sponsored by the Landslide Office of Shaanxi Province and Society of Disaster Reduction of Shaanxi Province.  相似文献