Frictionless contact formulation for dynamic analysis of nonlinear saturated porous media based on the mortar method          下载免费PDF全文

Hassan Sabetamal  Majid Nazem  Scott W. Sloan  John P. Carter 《国际地质力学数值与分析法杂志》2016,40(1):25-61

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   

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  

Morteza AHMADI  Majid ESLAMI 《山地科学学报》2011,8(2):124-130

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   

Lithological mapping and fuzzy set theory: Automated extraction of lithological boundary from ASTER imagery by template matching and spatial accuracy assessment     

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   

Displacement reducer fuses for improving seismic performance of caisson quay walls     

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   

Influence of large dam on seismic hazard in low seismic region of Ulu Padas Area,Northern Borneo     

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   

Variation of Rhenium Contents in Molybdenites from the Sar Cheshmeh Porphyry Cu‐Mo Deposit in Iran     

Balandeh AMINZADEH  Jamshid SHAHABPOUR  Majid MAGHAMI 《Resource Geology》2011,61(3):290-295

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   

A review of socio-economic and nutritional issues of Bihari Camp Dwellers in Bangladesh: a micro study     

Rosie Majid Ahsan Dr.  Shahnaz Huq Hussain 《GeoJournal》1990,20(3):285-291

The living conditions of the Bihari camp dwellers of Bangladesh are an embarrassment to the country's social environment. An investigation was made about the socio-economic condition of the Biharis living in the Khalishpur camp, Khulna. A comparison has been made between the Biharis and equivalent Bengali slum dwellers in Khalishpur. The data were collected from primary sources. A 10% systematic sampling was undertaken to collect a total of 150 Bihari households and through a 20% systematic sampling 150 Bengali households were surveyed by questionnaires. Data analysed both qualitatively and quantitatively indicate that the Biharis are leading an extremely substandard life when food consumption, medical expenditure, schooling, income and employment pattern were considered. The condition as prevalent in the camp has led to a high rate of infectious diseases which is likely to aggrevate creating environmental hazards. The country then may face serious social problems which should be prevented through gearing up the process of repatriation and through encouraging community participation in improving their economic and social environment.The study was sponsored by CONCERN a voluntary Irish Organization in Bangladesh.  相似文献   

Spatiotemporal analysis of photo contribution patterns to Panoramio and Flickr     

Majid Alivand  Hartwig H. Hochmair 《制图学和地理信息科学》2017,44(2):170-184

ABSTRACT

Photo-sharing services provide a rich resource of crowdsourced spatial data consisting of georeferenced imagery and metadata. Shared photos can provide valuable information for a variety of applications and geospatial analysis tasks, such as identifying tourist hot spots or traveled routes. Understanding the spatiotemporal patterns of photo contributions will allow analysts to assess the suitability of these data for related analysis tasks. Using California as a study area, this paper analyzes various aspects of photo contribution patterns of Panoramio and Flickr. It identifies areas where annual photo contributions are still growing and areas that undergo a decline in annual contributions. Multiple regression is used to identify which environmental correlates are associated with an increase in photo-sharing activities. Furthermore, panel data of annual contributions between 2006 and 2013 for California subcounties will be used in a regression model to demonstrate that there is a positive feedback effect between Panoramio and Flickr photo contributions, but no neighborhood effect. The results of this paper provide insight into the data quality of crowdsourced image collections. These collections are commonly used for geospatial applications, including tourist information services and the computation of scenic routes.  相似文献   

Heavy metal accumulation in soil after application of organic wastes     

Majid Fekri  Soheila Kaveh 《Arabian Journal of Geosciences》2013,6(2):463-467

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   

SEFIDROOD RIVER SUB-WATERSHED-DAM-ESTUARY AND DEGRADATION MODEL： A HOLISTIC APPROACH IN IRAN     

ForoodAZARIDEHKORDI MajidFMAKHDOUM NobukazuNAKAGOSHI 《中国地理科学(英文版)》2003,13(4):328-333

The major concern of this article is to address the shortcoming and outgoing effects of the human activities on the landscape patterns and their consequences in the Sefidrood River watershed in Iran. A flow of data includes three inputs; each of them belongs to one part of three zones of a fluvial system. The three parts of the Sefidrood River fluvial system include Zone 1, a sub-watershed as degradation modeling site, Zone 2, Sefidrood Dam asdam site, and Zone 3, 17kin away from the Sefidrood River path to the Caspian Sea as ending point site. The degra-dation model in the Zone 1 provides a suitable mean for decision support system to decrease the human impacts oneach small district. The maximum number for degradation coefficient belongs to the small district with the highest physiographic density, relatively cumulative activities, and a lower figure for the habitat vulnerability. The human degradation impact were not limited to the upstream. The investigation to the Sefidrood Dam and ending point of the Sefidrood River depicts that sedimentation continues as a significant visual impact in the Sefidrood Dam reservoir and the estuary.  相似文献