Some numerical issues using element‐free Galerkin mesh‐less method for coupled hydro‐mechanical problems     

Mohammad Norouz Oliaei  Kenichi Soga  Ali Pak 《国际地质力学数值与分析法杂志》2009,33(7):915-938

A new formulation of the element‐free Galerkin (EFG) method is developed for solving coupled hydro‐mechanical problems. The numerical approach is based on solving the two governing partial differential equations of equilibrium and continuity of pore water simultaneously. Spatial variables in the weak form, i.e. displacement increment and pore water pressure increment, are discretized using the same EFG shape functions. An incremental constrained Galerkin weak form is used to create the discrete system equations and a fully implicit scheme is used for discretization in the time domain. Implementation of essential boundary conditions is based on a penalty method. Numerical stability of the developed formulation is examined in order to achieve appropriate accuracy of the EFG solution for coupled hydro‐mechanical problems. Examples are studied and compared with closed‐form or finite element method solutions to demonstrate the validity of the developed model and its capabilities. The results indicate that the EFG method is capable of handling coupled problems in saturated porous media and can predict well both the soil deformation and variation of pore water pressure over time. Some guidelines are proposed to guarantee the accuracy of the EFG solution for coupled hydro‐mechanical problems. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Early Permian ammonoids from the Kaeng Krachan Group of the Phatthalung-Hat Yai area, southern peninsular Thailand   总被引：1，自引：1，他引：1  

Masayuki Fujikawa  Katsumi Ueno  Apsorn Sardsud  Wirote Saengsrichan  Yoshihito Kamata  Ken-ichiro Hisada 《Journal of Asian Earth Sciences》2005,24(6):739

An Early Permian small ammonoid fauna consisting of Neocrimites sp., Agathiceras suessi Gemmellaro, A. girtyi Böse, Agathiceras? sp., and Miklukhoceras sp. was found in nodules of a fine sandstone bed exposed in the Phatthalung-Hat Yai area of southern peninsular Thailand. The ammonoid-bearing bed belongs stratigraphically to the uppermost part of the Kaeng Krachan Group, which is essentially a clastic-dominant, Late Carboniferous (?) to Early Permian stratigraphic unit, widely distributed in western and peninsular Thailand. This ammonoid fauna is considered to be of Bolorian (Kungurian) age and includes Agathiceras girtyi Böse, which is described for the first time from Thailand. The present discovery of Bolorian ammonoids suggests that the uppermost part of the Kaeng Krachan Group is slightly younger than previously considered and around the latest Early Permian. This further implies that the continental margin environment of the Sibumasu Block drastically changed at around Bolorian time from a cool, clastic-dominant shelf condition to a temperate to subtropical, carbonate platform due to rapid northward drift after middle Artinskian rifting.  相似文献   

Tectonic evolution along the northernmost border of the Philippine Sea plate since about 1 Ma     

Tanio Ito  Kenichi Kano  Yo Uesugi  Kazuo Kosaka  Tatsuro Chiba 《Tectonophysics》1989,160(1-4):305-326

Recent structural, tephrochronologic and magnetostratigraphic studies conducted along the northernmost border of the Philippine Sea (PHS) plate enable us to reconstruct the precise tectonic evolution along the convergent boundary between the PHS plate and the Northeast Japan (NEJ) plate or the North American (NAM) plate since about 1 Ma. The authors of the present study split the tectonic evolution into five stages and present the characteristics of each stage. A plate tectonic interpretation is proposed, based upon the tectonic evolution, with special reference to the mode of convergent motion. In brief, our interpretations are as follows: the relative motion between the PHS and the NEJ plates was not recognized geologically within the area studied from about 1.0 to 0.9 Ma (Stage 1), suggesting either none or small influence from the coupling between the two plates during that period of time. Convergence between the PHS and the NEJ plates was possibly in N-S direction from 0.9 to 0.5 Ma (Stage II), and probably north-northwestward since 0.5 Ma (Stages III to V). The mode of the convergent motion was that of buoyant subduction in Stages II and III. The mode changed gradually from buoyant subduction during Stage IV to collision in Stage V (0.07 Ma to the present).  相似文献   

Nankai Trough and Zenisu Ridge: a deep-sea submersible survey     

Xavier Le Pichon  Toshimishi Iiyama  Jacques Boulgue  Jacques Charvet  Michel Faure  Kenichi Kano  Siegfried Lallemant  Hakuyu Okada  Claude Rangin  Asahiko Taira  Tetsuro Urabe  Seiya Uyeda 《Earth and Planetary Science Letters》1987,83(1-4)

Eight submersible dives between 3000 and 4200 m water depth were made off southern Japan in the eastern Nankai subduction zone. Benthic communities associated with chemosynthetic processes were discovered along the 800 m wide active tectonic zone, at the toe of the accretionary prism. A benthic community was also discovered along a zone of active compression, at the foot of Zenisu Ridge, 30 km south of Nankai Trough. Temperature measurements within the sediments below the benthic communities confirm that upward motion of interstitial water occurs there. Studies of water samples indicate advection of methane and light hydrocarbons. Specimens of the benthic community have been shown to have included in their shells carbonate resulting from methane consumption. Thus the benthic communities are related to overpressure-driven fluid advection along tectonic zones with active surface deformation. A 300 m high active scarp at the toe of the accretionary prism is related to relative motion in a 280° direction which is close to the 305° average direction of subduction in this area. The dives establish further that compressive deformation is presently occurring at the foot of Zenisu Ridge. The previous interpretation of the Zenisu Ridge as a zone of recent north-south intraplate shortening, 40 km south of the Nankai Trench, is confirmed. We conclude that tectonic evolution might well lead to future detachment of the Zenisu Ridge and overthrusting of this large piece of oceanic crust over the continental margin. Such a process might be an efficient one to emplace ophiolites over continents.  相似文献   

The effects of precipitation schemes and horizontal resolution on the major rainband in typhoon Flo (1990) predicted by the MRI mesoscale nonhydrostatic model   总被引：2，自引：0，他引：2  

A. Murata  K. Saito  M. Ueno 《Meteorology and Atmospheric Physics》2003,82(1-4):55-73

Summary ?This paper describes a numerical study of the major spiral rainband in typhoon Flo (1990) using the Meteorological Research Institute Mesoscale Nonhydrostatic Model (MRI-NHM). The effects of precipitation schemes and horizontal resolution on the representation of the simulated rainband are discussed. Dynamic and thermodynamic structures of the simulated major rainband to the north of the storm center are well represented in the model with a 5 km horizontal resolution. The structures are consistent with observational results reported for other tropical cyclones. Among the realistic features are: a cold pool and convergence on the inner side of the band; convergence above low-level inflow layers; and the outward slope of the updraft with height. The band is caused by the motion of the storm through its surroundings where horizontal wind has vertical shear. The simulation of the structure and precipitation pattern associated with the major rainband depends on the precipitation scheme rather than the horizontal resolution. The band appears more realistic when using explicit cloud microphysics as a precipitation scheme, rather than moist convective adjustment. This result is attributable to the difference in scheme triggering. In the simulation with moist convective adjustment, the elimination of vertical instability in low-level atmosphere is excessive, suppressing band formation. The overall structure of the band is also more realistic in the simulation using explicit cloud microphysics, because a cold pool exists in the lower layers and the vertical axis of upward flow tilts outward. This result suggests that prediction will partly depend on variables associated with cloud microphysics, such as the mixing ratio of cloud water. The horizontal grid distance, which varied between 5 and 20 km, quantitatively influenced the rainfall amount, although the large-scale band structure remained unchanged. The rainfall amount increased as the grid interval was reduced from 20 to 10-km but decreased as the interval was further reduced from 10 to 5 km. Received March 20, 2001; revised August 20, 2001  相似文献   

Mineralogical and Genetical Aspects of the Doyashiki Kuroko Deposits, Hokuroku Basin, Japan     

Satoshi Kitazono  Hirotomo Ueno 《Resource Geology》2003,53(2):143-153

Abstract. A detail investigation of ore and gangue minerals was performed on the Doyashiki Kuroko deposits, Hokuroku basin, Japan for the first time. Main ore minerals are sphalerite, galena, pyrite, chalcopyrite, tetrahedrite-tennantite and digen-ite. Small amounts of enargite, wittichenite, electrum, covellite, bornite, marcasite and hematite are also observed. Quartz, barite and gypsum are common gangue minerals. Homogenization temperatures and salinities of fluid inclusions in quartz, sphalerite and barite range from 190 to 240C and 3.0 to 5.5 wt% NaCl equivalent, respectively. The FeS contents of sphalerite and Ag contents of electrum were 0.12 to 0.18 mol %, 39.0 to 39.6 atom %, respectively. The chemical composition of digenite as a primary mineral shows high sulfur contents.
These data indicate that ore fluid responsible for digenite and associated ore minerals was characterized by a range of high sulfur fugacity with a moderate formation temperature. This is concordant with the mineral assemblage of bornite-pyrite and chalcopyrite, which shows high sulfur fugacity conditions. It seems that the mineralization closely associated with acidic volcanism has occurred around 13 Ma of Middle Miocene on the seafloor at the depth of about 1500 m.  相似文献   

K-Ar Ages of Tin-Polymetallic Mineralization in the Oruro Mining District, Central Bolivian Tin Belt   总被引：2，自引：0，他引：2  

Asahiko Sugaki    Nobutaka Shimada  Hirotomo Ueno  Shimpei Kano 《Resource Geology》2003,53(4):273-282

Abstract. K-Ar age determinations were carried out on vein- and rock-forming minerals from five vein-type tin-polymetallic ore deposits of the Oruro mining district in the central part of the Bolivian tin belt. The sericite from vein selvedges and an altered host rock provides good estimates of the ages of hypogene mineralization, and supergene alunite and jarosite provide ages for erosional and weathering episodes. It is concluded that hypogene mineralization in the Oruro mining district took place during the early to middle Miocene: 15.8±0.8 Ma at San José, 20.1±l.l Ma at Morococala, 20.5±1.0 Ma at Avicaya, and 19.6±1.0 Ma at Llallagua. Fine grained supergene alunite (δ³⁴S = -10.1 960) and jarosite yield K-Ar ages of 6.7±0.7 Ma at Avicaya and 3.9±0.7 Ma at Bolivar, respectively, suggesting that erosion and chemical weathering were active at those times.  相似文献   

A Cauchy problem for Milne's integral equation with a pincherle-goursat kernel     

S. Ueno 《Astrophysics and Space Science》1976,44(1):151-158

In a series of our preceding papers (cf. Bellman and Ueno, 1971a, 1971b, 1972a, 1972b, 1972c; Ueno 1972), with the aid of invariant imbedding technique, we transformed the two point boundary value problem for integral equations into the initial-value problem. In this paper, extending the procedure to the Milne's integral equation, whose kernel is expanded into a double Fourier cosine series, we show how to find a Cauchy system for the required solution of Milne's integral equation and the Fredholm resolvent. The obtained integro-differential equations are reduced to large system of ordinary differential equations with known initial conditions. Then, they are suitable for the numerical computation of the solution by the modern high-speed computer.  相似文献   

Scattering and transmission matrices of partially polarized radiation in a Rayleigh atmosphere bounded by a specular reflector     

S. Ueno 《Astrophysics and Space Science》1974,30(1):27-34

In a manner similar to that given in a preceding paper (cf. Castiet al., 1970), in this paper we show how to get a Cauchy system for the scattering and transmission matrices of the azimuth-independent term of partially polarized light in accordance with Rayleigh scattering in a homogeneous atmosphere bounded by a specular reflector. This set of integro-differential equations for the scattering and transmission matrices is suitable for numerical computation by high-speed digital computer.  相似文献   

Preliminary Examinations of the Ore-forming Process by Fluid Mixing – a Test of MIX99     

Kenichi HOSHINO  Yuki YAMAMOTO  Xiangping GU  Su Young LEE  Makoto WATANABE 《Resource Geology》2000,50(3):185-190

Abstract: Possible ore deposition by fluid mixing was preliminarily examined using MIX 99, a FORTRAN program developed for simulating water-rock interactions. We consider mixing of two fluids, the low f_O2 and high temperature source fluid and the high f_O2 and low temperature seawater. Oxygen fugacity of a mixed fluid formed by titration of seawater into the source fluid gradually decreases with decreasing temperature (model A). Sequential precipitation of ore-forming minerals was examined in this model. On the other hand, simultaneous precipitation of the minerals could be followed by simulation of instantaneous overall mixing of the two fluids (model B). Results of simulation of the both models revealed that a temporal sequence of mineralization observed in the Karuizawa mine, NE Japan, can be formed by model A, while model B is suitable for the mineralization of an active chimney found in the Rainbow hydrothermal area of the Mid-Atlantic Ridge.  相似文献