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181.
Frictionless contact formulation for dynamic analysis of nonlinear saturated porous media based on the mortar method 下载免费PDF全文
A finite element algorithm for frictionless contact problems in a two‐phase saturated porous medium, considering finite deformation and inertia effects, has been formulated and implemented in a finite element programme. The mechanical behaviour of the saturated porous medium is predicted using mixture theory, which models the dynamic advection of fluids through a fully saturated porous solid matrix. The resulting mixed formulation predicts all field variables including the solid displacement, pore fluid pressure and Darcy velocity of the pore fluid. The contact constraints arising from the requirement for continuity of the contact traction, as well as the fluid flow across the contact interface, are enforced using a penalty approach that is regularised with an augmented Lagrangian method. The contact formulation is based on a mortar segment‐to‐segment scheme that allows the interpolation functions of the contact elements to be of order N. The main thrust of this paper is therefore how to deal with contact interfaces in problems that involve both dynamics and consolidation and possibly large deformations of porous media. The numerical algorithm is first verified using several illustrative examples. This algorithm is then employed to solve a pipe‐seabed interaction problem, involving large deformations and dynamic effects, and the results of the analysis are also compared with those obtained using a node‐to‐segment contact algorithm. The results of this study indicate that the proposed method is able to solve the highly nonlinear problem of dynamic soil–structure interaction when coupled with pore water pressures and Darcy velocity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
182.
183.
Sanaz Salati Frank J.A. van Ruitenbeek Freek D. van der Meer Majid Hashemi Tangestani Harald van der Werff 《International Journal of Applied Earth Observation and Geoinformation》2011
Lithological boundaries provide information useful for activities such as mineral and hydrocarbon exploration, water resource surveys, and natural hazard evaluation. Automated detection of lithological boundaries reduces bias inherent in expert interpretation of boundaries and thus improves the reliability of lithological mapping. The Rotation Variant Template Matching (RTM) algorithm was applied to ASTER imagery to detect pre-defined lithological boundaries. Templates incorporating the mineral combinations gypsum–calcite and calcite–illite were designed to detect boundaries between evaporites, marly limestone, and sandstone. The RTM algorithm successfully detected lithological boundaries by rotating the templates over the ASTER imagery. The accuracy of the detected boundaries was spatially assessed using fuzzy set theory. Boundaries from a published geological map and boundaries interpreted from a stereo pair of aerial photos by five experts were used as references for assessing the accuracy. A confidence region unifying spatial errors was defined for the geological map and stereo-pair interpretation to provide boundary zones from these references. The correspondence between detected boundaries and the boundary zones of the aerial photo was better than between detected boundaries and boundary zones of the geological map. 相似文献
184.
Amirali Mostafavi Moghadam Abbas Ghalandarzadeh Majid Moradi Ikuo Towhata Pouria Hajialikhani 《Bulletin of Earthquake Engineering》2011,9(4):1259-1288
This research is to study the efficiency of displacement reducer fuses, installed behind the caisson quay walls for controlling
the dynamic backfill thrust and minimizing the displacement, settlement and tilting of the walls. For this purpose, two types
of fuses, Displacement Reducer Panels (DRP) and Displacement Reducer Elements (DRE), were constructed and installed behind
the wall. The DRPs were constructed by hollow Polypropylene sheets to reproduce elastoplastic and plastic mechanical behaviors.
The DREs were cylindrical stainless-steel dampers, working upon friction mechanism that can reproduce perfect plastic behavior.
Here, two series of shaking table 1-g tests were performed with DRP and DRE applications. In this regard, different mechanical
behaviors and capacities were considered for fuses against demand thrusts of backfill in order to compare the mitigation tests
with no-mitigation cases. Harmonic base motions with constant amplitude and constant frequency were used in the model test.
The foundation soil and the backfill soil were constructed with the relative densities of 85 and 25%, respectively, to reproduce
non-liquefiable base layer and loose backfill situations in the model, respectively. The results showed remarkable reduction
in kinetic energy, dynamic backfill thrust and consequently seaward movement, settlement and inclination of the caisson quay
wall in case of using fuses with plastic behaviors behind the wall. 相似文献
185.
Ade Faisal Taksiah A. Majid Fauziah Ahmad Felix Tongkul Syafrina Mayang Sari 《Natural Hazards》2011,59(1):237-269
The seismic hazard assessment of a site that lies in the low seismic region affected by the future existence of a large dam
has been given less attention in many studies. Moreover, this condition is not addressed directly in the current seismic codes.
This paper explains the importance of such information in mitigating the seismic hazard properly. Ulu Padas Area in Northern
Borneo is used as an example for a case study of a site classified as a low seismic region. It is located close to the border
of Malaysia, Brunei Darussalam, and Indonesia and may have a large dam in the future as the region lies in hilly geography
with river flow. This study conducts probabilistic and deterministic seismic hazard analyses, and reservoir-triggered seismicity
of a site affected by the future existence of a large dam. The result shows that the spectrum acceleration of the maximum
design earthquake for the investigated site in the Ulu Padas Area in Northern Borneo is taken from the reservoir-triggered
seismicity earthquake at short periods and from the current condition at longer periods. 相似文献
186.
This paper presents the results of a study on the variation of Re in the Sar Cheshmeh porphyry copper‐molybdenum deposit in Iran. The Re content was determined in monomineralic molybdenite separates from veinlets and from molybdenum milled floatation concentrates. Mineralogical data and chemical analyses indicate two generations of veinlet molybdenites in the Sar Cheshmeh deposit. The first generation (molybdenite I), which contains low Re, is found as intergrowth with quartz in silicified rocks with low total sulfide content, and the second generation (molybdenite II), which contains high Re, is found in veinlets with low quartz content. There is a positive correlation between the elevation of molybdenite deposition and Re content. Decrease in the temperature and pH of the hydrothermal fluids are effective for the accumulation Re in molybdenite. X‐ray diffraction study of 14 molybdenite samples indicate that the molybdenites are of the 2H polytype. 相似文献
187.
A new approach to plane failure of rock slope stability based on water flow velocity in discontinuities for the Latian dam reservoir landslide 总被引:2,自引:2,他引:0
The stability of slopes is always of great concern in the field of rock engineering. The geometry and orientation of pre-existing
discontinuities show a larger impact on the behavior of slopes that is often used to describe the measurement of the steepness,
incline, gradient, or grade of a straight line. One of the structurally controlled modes of failure in jointed rock slopes
is plane failure. There are numerous analytical methods for the rock slope stability including limit equilibrium, stress analysis
and stereographic methods. The limiting equilibrium methods for slopes under various conditions against plane failure have
been previously proposed by several investigators. However, these methods do not involve water pressure on sliding surfaces
assessments due to water velocity and have not yet been validated by case study results. This paper has tried to explore the
effects of forces due to water pressure on discontinuity surfaces in plane failure through applying the improved equations.
It has studied the effect of water flow velocity on sliding surfaces in safety factor, as well. New equations for considering
water velocity (fluid dynamics) are presented. To check the validity of the suggested equations, safety factor for a case
study has been determined. Results show that velocity of water flow had significant effect on the amount of safety factor.
Also, the suggested equations have higher validity rate compared to the current equations. 相似文献
188.
Municipal solid waste compost and cattle manure are used as organic fertilizers in agriculture and horticulture. These wastes, however, may also have some negative effects on the agricultural environment. This study investigates the effects of municipal solid waste compost of Kerman (MSC) and cattle manure (CM) on availability of the heavy metal in calcareous soil (extractable with EDTA) in greenhouse conditions. The MSC and CM were mixed thoroughly with soil at rates of 0%, 2%, and 4% of dry matter. After 90 days of incubation, the soil samples were analyzed. Addition of levels of each two organic wastes into soil significantly decreased the soil pH and increased the soil EC as compared with control (unamended soil).The available contents (EDTA-extractable) of Cd, Pb, Cu, Zn, and Cu in the soil samples were increased because of each two organic treatments applied. The heavy metal contents in the soil samples amended with MSC were more than CM. The heavy metal contents of organic wastes were well below the maximum allowed by USEPA. It is recommended that in Iran, the legal maximum permissible limit for heavy elements in organic wastes must be determined. 相似文献
189.
The Cheshmeh Hafez epithermal base metal deposit is located in Troud-Chah Shirin mountain range in the Alborz magmatic belt of northern Iran. In this area, the Eocene volcanism and associated mineralization are controlled by NW-SE trending Anjilo and Troud major faults. Geological units are composed of porphyritic andesite, andesitic basalt, dacite, rhyodacite, trachyandesite and basalt, which are typically high-K igneous rocks transitional to shoshonites. Alteration in Cheshmeh Hafez area comprise of propylilitization, sericitization, argillization and silicification. Mineralization consists of three stages. Stage 1, quartz, carbonate with early pyrite I and chalcopyrite assemblages. Stage 2, the main stage of sulfide deposition, comprises early euhedral galena I followed by galena II and sphalerite, then galena III, chalcopyrite, tetrahedrite, pyrite II, bornite and digenite. Stage 3 involves the deposition of quartz and calcite barren veins with minor pyrite. The average assays from 12 channel samples of Cheshmeh Hafez veins are 0.15 g/t Au, 3.23 g/t Ag, 4.47 wt % Pb, 2.64 wt % Cu, and 1.73 wt % Zn. Fluid inclusion homogenization temperatures (Th) in quartz fall within the range of 140°-280°C with salinities ranging from 4.7 to 18 wt. % NaCl equivalent. Comparison of Th versus ice melting (Tmice) values indicates fluid dilution. 相似文献
190.
Bahram Malekmohammadi Majid Ramezani Mehrian Hamid Reza Jafari 《Hydrogeology Journal》2012,20(7):1393-1405
One of the most important water-resources management strategies for arid lands is managed aquifer recharge (MAR). In establishing a MAR scheme, site selection is the prime prerequisite that can be assisted by geographic information system (GIS) tools. One of the most important uncertainties in the site-selection process using GIS is finite ranges or intervals resulting from data classification. In order to reduce these uncertainties, a novel method has been developed involving the integration of multi-criteria decision making (MCDM), GIS, and a fuzzy inference system (FIS). The Shemil-Ashkara plain in the Hormozgan Province of Iran was selected as the case study; slope, geology, groundwater depth, potential for runoff, land use, and groundwater electrical conductivity have been considered as site-selection factors. By defining fuzzy membership functions for the input layers and the output layer, and by constructing fuzzy rules, a FIS has been developed. Comparison of the results produced by the proposed method and the traditional simple additive weighted (SAW) method shows that the proposed method yields more precise results. In conclusion, fuzzy-set theory can be an effective method to overcome associated uncertainties in classification of geographic information data. 相似文献