A Parametric Study on Stability of Open Excavations in Alluvial Soils of Lahore District, Pakistan     

Muhammad Irfan  Aziz Akbar  Mubashir Aziz  Ammad Hassan Khan 《Geotechnical and Geological Engineering》2013,31(2):729-738

Rapid urbanization and expansion of metropolitans in the developing world is pressing the need of tall structures with multiple basements. In several such projects, open land is available around excavation site and unsupported deep excavations by maintaining appropriate side slopes offer economical solution. In this research, subsoil stratigraphy of Lahore district was established to be comprising of a top clay stratum 1.5–8 m thick, followed by a sand layer. Considering subsoil data from several geotechnical investigation reports, the effect of four key parameters viz., cohesion of clay layer, friction angle of sand layer, thickness of clay layer at the top and slope inclination of underlying sand layer on safety factor of open excavations was studied. Six hundred twenty-five slope stability analyses were conducted by considering different geometries and soil properties. Based on the results of these analyses, a regression model was suggested to estimate safety factor of open excavations in similar stratigraphy which would be useful in feasibility studies and preliminary design of deep excavations. It was established that the clay layer cohesion was the most dominant contributor to safety factor.  相似文献   

A family of well behaved charge analogues of Durgapal’s perfect fluid exact solution in general relativity     

Mohammad Hassan Murad  Saba Fatema 《Astrophysics and Space Science》2013,343(2):587-597

This paper presents a new family of interior solutions of Einstein–Maxwell field equations in general relativity for a static spherically symmetric distribution of a charged perfect fluid with a particular form of charge distribution. This solution gives us wide range of parameter, K, for which the solution is well behaved hence, suitable for modeling of superdense star. For this solution the gravitational mass of a star is maximized with all degree of suitability by assuming the surface density equal to normal nuclear density, ρ _nm=2.5×10¹⁷ kg?m^?3. By this model we obtain the mass of the Crab pulsar, M _Crab, 1.36M _⊙ and radius 13.21 km, constraining the moment of inertia >?1.61×10³⁸ kg?m² for the conservative estimate of Crab nebula mass 2M _⊙. And M _Crab=1.96M _⊙ with radius R _Crab=14.38 km constraining the moment of inertia >?3.04×10³⁸ kg?m² for the newest estimate of Crab nebula mass, 4.6M _⊙. These results are quite well in agreement with the possible values of mass and radius of Crab pulsar. Besides this, our model yields moments of inertia for PSR J0737-3039A and PSR J0737-3039B, I _A =1.4285×10³⁸ kg?m² and I _B =1.3647×10³⁸ kg?m² respectively. It has been observed that under well behaved conditions this class of solutions gives us the overall maximum gravitational mass of super dense object, M _G(max)=4.7487M _⊙ with radius $R_{M_{\max}}=15.24~\mathrm{km}$ , surface redshift 0.9878, charge 7.47×10²⁰ C, and central density 4.31ρ _nm.  相似文献   

Environmental impact assessment on water quality deterioration caused by the decreased Ganges outflow and saline water intrusion in south-western Bangladesh   总被引：3，自引：0，他引：3  

Md. Mokhlesur Rahman  Muhammad Qumrul Hassan  Mohammad Saiful Islam  S. Z. K. M. Shamsad 《Environmental Geology》2000,40(1-2):31-40

 This paper deals with an environmental impact assessment of low water flow in the river Ganges during a dry period at the Khulna and Mongla port areas in south-western Bangladesh. Large-scale surface water withdrawal in India after commissioning the Farakka Barrage causes a drastic fall in the Ganges low-flow condition within the Bangladesh territory during every dry period. The average lowest discharge in the Ganges is 552 m³/s, which is about 73% less than that in the pre-Farakka time. This has caused the deterioration of both surface and groundwater quality of the study area. Salinity is the principal cause of water quality degradation in the area. Present observation shows that the surface water of the area is sulphate-chloride dominated, which signifies high salinity whereas the groundwater is categorized as of medium to high salinity. To maintain the Rupsa River's maximum salinity below 1000 μS/cm the discharge in the Ganges should be ∼1500 m³/s, whereas that at Garai basin is ∼10 m³/s. If this present situation continues it will be a crippling blow to the environment of the area in the long term. An integrated multidisciplinary approach to hydrogeological research is urgently required to salvage the area from further deterioration. Received: 9 August 1999 · Accepted: 8 March 2000  相似文献   

Flood hydrograph simulation in ungaged basins: modeling linear–nonlinear storage-discharge relationships in a semiarid mountain region     

Hassan Rezaei-Sadr 《自然地理学》2019,40(1):52-70

For the purpose of flood mitigation in a mountain region, this study aims to evaluate the degree of nonlinearity in the hydrologic storage-discharge relationship. The study area includes a mesoscale catchment, its headwater subcatchment, and its large-scale parent basin in the Zagros mountain region of southwestern Iran. Rainfall events are divided into two variable classes, Low Temporal (LT) and High Temporal (HT), based on their heterogeneity across time. For Low Temporal rainfall events, the mesoscale catchment and its headwater subcatchment show strong nonlinear behavior, but their responses tend to be less nonlinear for High Temporal rainfall events. Meanwhile, for High Temporal events, soil moisture has a dominant role in catchment response. On the other hand, a different perspective is drawn for the larger basin because a strong nonlinear response is obtained for all events regardless of temporal heterogeneities and soil moisture conditions, emphasizing the filtering effect of catchment extent on the rainfall–runoff process.  相似文献   

Modelling the effects of climatic and hydrological regime changes on the sediment dynamics of the Fraser River Basin,British Columbia,Canada     

Kai Tsuruta  Marwan A. Hassan  Simon D. Donner  Younes Alila 《水文研究》2019,33(2):244-260

Future sediment dynamics may be affected by changing climates or hydrological regimes because of the close link between hydrology and sediment erosion, deposition, and transport. Previously, investigations of these potential changes have been constrained by a combination of limited observational data, hydrological drivers, and appropriate mechanistic models. Additionally, there is often ambiguity regarding how to disentangle the impacts of climate and hydrology from direct human factors such as reservoirs and land‐use change, which often exert more control over sediment dynamics. In this study, we utilize a recently developed, large‐scale, distributed, mechanistic sediment transport model to project future sediment erosion, deposition, and transportation within the Fraser River Basin in British Columbia, Canada—a basin with historical water flux and sediment load observations and limited anthropogenic influences upstream of its delta. The sediment model is driven by synthetic land‐surface hydrology derived from Scenarios A1B, A2, and B1 of the Special Report on Emissions Scenarios, which were provided by the Pacific Climate Impacts Consortium. Resulting simulations of water flux and sediment load from 1965 to 1994 are first validated against observational data then compared with future projections. Future projections show an overall increase in annual hillslope erosion and in‐channel transportation, a shift towards earlier spring peak erosion and transportation, and longer persistence of the sediment signal through the year. These shifts in timing and annual yield may have deleterious effects on spawning sockeye salmon and are insufficient to counteract future coastal retreat caused by sea‐level rise.  相似文献   

Jewish settlement and its economic impact on the West Bank, 1967–1987     

Hassan Abdul Kadir Saleh Prof. 《GeoJournal》1990,21(4):337-348

This paper focuses on the process of Jewish settlement in the West Bank and its economic consequences in the period from 1967 to the outbreak of the Intifada late in 1987. It attempts to show that this process is the practical application of Israeli objectives which are based on expansion and occupation of neighbouring Arab lands, facilitated by the fashioning of a dual or bifurcate economy there.After the war of June 1967, Israeli occupation authorities started to draw up plans with a view to settling Jews in the West Bank. There has been an increase in the numbers of settlements and settlers, estimated at 122 and 52,000 respectively in 1987. The pattern of settlement distribution is randomly dispersed, although it is concentrated in a region located to the NW of Jerusalem. The settlement began in the Jordan valley and extended gradually westward in the highlands.Jewish settlement has affected economic development of the West Bank, where there were many constraints on Arab agriculture and industry. Inequality is evident between settlers and Palestinians in an economy that has been structurally bifurcated: although settlers represent about 3% of total population of the West Bank, their economic activity constitutes at least 35% of the GDP of the West Bank.  相似文献   

The Earth systems and Earth science informatics     

Hassan A. Babaie 《Earth Science Informatics》2008,1(1):1-2

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Kinematic significance of fold- and fault-related fracture systems in the Zagros mountains, southern Iran     

Katayoun Mobasher  Hassan A. Babaie   《Tectonophysics》2008,451(1-4):156-169

Initiation and formation of folds and the Kazerun high-angle fault zone, in the Zagros fold-and-thrust belt, were related to the continuing SW–NE oriented contraction that probably initiated in the Late Cretaceous, and intensified, starting in Miocene, when the Arabian and Eurasian plates collided. The contraction that led to folding and thrusting of the Phanerozoic sequence in the belt has led to the strike–slip reactivation of basement faults that formed during the Precambrian. Two major systems of fractures have developed, under the same regional state of contraction, during the folding and strike–slip faulting processes. Folding led to the formation of a system of fold-related fractures that comprises four sets of fractures, which include an axial and a cross-axial set that trend parallel and perpendicular to the confining fold axial trace, respectively, and two oblique sets that trend at moderate angles to the axial trace. Slip along high-angle, strike–slip faults formed a system of fractures in the damage zone of the faults (e.g., Kazerun), and deformed folds that existed in the shear zone by rotating their axial plane. This fault-related fracture system is made of five sets of fractures, which include the two sets of Riedel shear fractures (R and R′), P- and Y-shear fractures, and an extensional set.

Remote sensing analysis of both fracture systems, in a GIS environment, reveals a related kinematic history for folding outside of the Kazerun shear zone and faulting and deformation (fracturing and rotation of folds) within the Kazerun fault zone. Rotation of the folds and formation of the five sets of the fault-related fractures in the Kazerun shear zone are consistent with a dextral motion along the fault. The mean trends of the shortening directions, independently calculated for the fold- and fault-related fracture systems, are remarkably close (N53 ± 4°E and N50 ± 5°E, respectively), and are perpendicular to the general NW–SE trend of the Zagros fold-and-thrust belt. Although segments of the Kazerun fault are variably oriented within a narrow range, the angular relationships between sets of fault-related fractures and these segments remain constant.  相似文献   

Magmatic unmixing in spinel from late Precambrian concentrically-zoned mafic–ultramafic intrusions, Eastern Desert, Egypt     

Ahmed Hassan Ahmed  Hassan Mohamed Helmy  Shoji Arai  Masako Yoshikawa 《Lithos》2008,104(1-4):85-98

Spinel is widespread in the ultramafic core rocks of zoned late Precambrian mafic–ultramafic complexes from the Eastern Desert of Egypt. These complexes; Gabbro Akarem, Genina Gharbia and Abu Hamamid are Precambrian analogues of Alaskan-type complexes, they are not metamorphosed although weakly altered. Each intrusion is composed of a predotite core enveloped by pyroxenites and gabbros at the margin. Silicate mineralogy and chemistry suggest formation by crystal fractionation from a hydrous magma. Relatively high Cr₂O₃ contents are recorded in pyroxenes (up to 1.1 wt.%) and amphiboles (up to 1.4 wt.%) from the three plutons. The chrome spinel crystallized at different stages of melt evolution; as early cumulus inclusions in olivine, inclusions in pyroxenes and amphiboles and late-magmatic intercumulus phase. The intercumulus chrome spinel is homogenous with narrow-range of chemical composition, mainly Fe³⁺-rich spinel. Spinel inclusions in clinopyroxene and amphibole reveal a wide range of Al (27–44 wt.% Al₂O₃) and Mg (6–13 wt.% MgO) contents and are commonly zoned. The different chemistries of those spinels reflect various stages of melt evolution and re-equilibration with the host minerals. The early cumulus chrome spinel reveals a complex unmixing structures and compositions. Three types of unmixed spinels are recognized; crystallographically oriented, irregular and complete separation. Unmixing products are Al-rich (Type I) and Fe³⁺-rich (Type II) spinels with an extensive solid solution between the two end members. The compositions of the unmixed spinels define a miscibility gap with respect to Cr–Al–Fe³⁺, extending from the Fe³⁺–Al join towards the Cr corner. Spinel unmixing occurs in response to cooling and the increase in oxidation state. The chemistry and grain size of the initial spinel and the cooling rate control the type of unmixing and the chemistry of the final products. Causes of spinel unmixing during late-magmatic stage are analogous to those in metamorphosed complexes. The chemistry of the unmixed spinels is completely different from the initial spinel composition and is not useful in petrogenetic interpretations. Spinels from oxidized magmas are likely to re-equilibrate during cooling and are not good tools for genetic considerations.  相似文献   

Virtual rate and mean distance of travel of individual clasts in gravel-bed channels     

Marwan A. Hassan  Michael Church  Philip J. Ashworth 《地球表面变化过程与地形》1992,17(6):617-627

Travel distances in gravel-bed rivers of tagged particles of various sizes are related to excess stream power estimated for peak discharge. Mean distance of movement, irrespective of grain size, is weakly correlated with stream power, especially near the threshold of movement. There may be several reasons for the weak correlation, including variable effects of bed structure, varying magnitudes of sediment mobilizing events and sampling problems. Grain size itself is of marginal significance. The virtual rate of travel calculated using total time for which the flow is larger than that needed to initiate clast movement also bears a weak relation to the excess stream power over the period. Better results are obtained by relating the virtual rate of travel to the first peak of the flow event only. This implies that the initial seeding of the tagged particles dominates the observations. Nonetheless, an underlying general relation is indicated by the data, which are derived from a wide range of flow regime types.  相似文献