Unified numerical study of shallow foundation on structured soft clay under unconsolidated and consolidated-undrained loadings     

Santosh Kumar Yadav  Guan-lin Ye  Usama Khalid 《Marine Georesources & Geotechnology》2020,38(4):400-416

Abstract

Based on a new elasto-plastic constitutive model, this paper presents a soil–water coupled numerical prediction of the bearing capacity for shallow foundation constructed on Ballina soft clay for unconsolidated undrained (UU) and consolidated undrained (CU) conditions. This elasto-plastic constitutive Shanghai model has an advantage of describing the mechanical behaviour of over-consolidated and structured soil under different loading and drainage conditions, by using one set of material parameter. In this paper, the Shanghai model used for both UU and CU conditions has the same initial parameters obtained from laboratory test results. The loading conditions and consolidation stages vary based on construction details. The predicted bearing pressure-settlement responses for UU and CU, approves the field observation. The phenomenon of gaining the bearing capacity due to consolidation is captured and explained by the use of soil–water coupled numerical analysis with a new elasto-plastic model. The stress strain behaviour, stress paths and the decay of the structure of elements at different depths presented in this study, reveal the mechanism for the difference between UU and CU conditions to understand the foundation behaviour. Effect of the initial degree of soil structure on the bearing capacity is also addressed. Overall, this approach provides the integrated solution for the shallow foundation design problems under short and long-term loadings.  相似文献   

Individual and combined effects of land use/cover and climate change on Wolf Bay watershed streamflow in southern Alabama          下载免费PDF全文

Ruoyu Wang  Latif Kalin  Wenhui Kuang  Hanqin Tian 《水文研究》2014,28(22):5530-5546

Land use/cover (LULC) and climate change are two main factors affecting watershed hydrology. In this paper, individual and combined impacts of LULC and climate change on hydrologic processes were analysed applying the model Soil and Water Assessment Tool in a coastal Alabama watershed in USA. Temporally and spatially downscaled Global Circulation Model outputs predict a slight increase in precipitation in the study area, which is also projected to experience substantial urban growth in the future. Changes in flow frequency and volume in the 2030s (2016–2040) compared to a baseline period (1984–2008) at daily, monthly and annual time scales were explored. A redistribution of daily streamflow is projected when either climate or LULC change was considered. High flows are predicted to increase, while low flows are expected to decrease. Combined change effect results in a more noticeable and uneven distribution of daily streamflow. Monthly average streamflow and surface runoff are projected to increase in spring and winter, but especially in fall. LULC change does not have a significant effect on monthly average streamflow, but the change affects partitioning of streamflow, causing higher surface runoff and lower baseflow. The combined effect leads to a dramatic increase in monthly average streamflow with a stronger increasing trend in surface runoff and decreasing trend in baseflow. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Equivalent continuum strain calculations based on 3D particle kinematic measurements of sand          下载免费PDF全文

Siavash Amirrahmat  Khalid A. Alshibli  Maha F. Jarrar  Boning Zhang  Richard A. Regueiro 《国际地质力学数值与分析法杂志》2018,42(8):999-1015

Constitutive modeling of granular materials has been a subject of extensive research for many years. While the calculation of the Cauchy stress tensor using the discrete element method has been well established in the literature, the formulation and interpretation of the strain tensor are not as well documented. According to Bagi, 1 researchers mostly adopt well‐known continuum or discrete microstructural approaches to calculate strains within granular materials. However, neither of the 2 approaches can fully capture the behavior of granular materials. They are considered complementary to each other where each has its own strengths and limitations in solving granular‐mechanics problems. Zhang and Regueiro 2 proposed an equivalent continuum approach to calculating finite strain measures at the local level in granular materials subjected to large deformations. They used three‐dimensional discrete element method results to compare the proposed strains measures. This paper presents an experimental application of the Zhang and Regueiro 2 approach using three‐dimensional synchrotron microcomputed tomography images of a sheared Ottawa sand specimen. Invariant Eulerian finite strain measures were calculated for representative element volumes within the specimen. The spatial maps of Eulerian octahedral shear and volumetric strain were used to identify zones of intense shearing within the specimen and compared well with maps of incremental particle translation and rotation for the same specimen. The local Eulerian volumetric strain was compared to the global volumetric strains, which also can be considered as an averaging of all local Eulerian volumetric strains.  相似文献   

Basement structural architecture and hydrocarbon conduit potential of polygonal faults in the Cooper‐Eromanga Basin,Australia          下载免费PDF全文

David Kulikowski  Khalid Amrouch  Dennis Cooke  Michael Edward Gray 《Geophysical Prospecting》2018,66(2):366-396

A thorough and complete understanding of the structural geology and evolution of the Cooper‐Eromanga Basin has been hampered by low‐resolution seismic data that becomes particularly difficult to interpret below the thick Permian coal measures. As a result, researchers are tentative to interpret the basement fault architecture within the basin, which is largely undefined. To provide a better understanding of the basement fault geometry, all available two‐dimensional seismic lines together with 12 three‐dimensional seismic surveys were structurally interpreted with assistance from seismic attribute analysis. The Upper Cretaceous Cadna‐owie Formation and top Permian reflectors were analysed using a common seismic attribute technique (incoherency) that was used to infer the presence of faults that may have otherwise been overlooked. Detailed basement fault maps for each seismic survey were constructed and used in conjunction with two‐dimensional seismic data interpretation to produce a regional basement fault map. Large north‐northeast–south‐southwest‐striking sinistral strike–slip faults were identified within the Patchawarra Trough appearing to splay from the main northeast–southwest‐striking ridge. These sinistral north‐northeast–south‐southwest‐striking faults, together with field‐scale southeast–northwest‐striking dextral strike–slip faults, are optimally oriented to have potentially developed as a conjugated fault set under a south‐southeast–north‐northwest‐oriented strike–slip stress regime. Geomechanical modelling for a regionally extensive system of Cretaceous polygonal faults was performed to calculate the Leakage Factor and Dilation Tendency of individual faults. Faults that extend into Lower Cretaceous oil‐rich reservoirs with strikes of between 060°N and 140°N and a high to near‐vertical dip angle were identified to most likely be acting as conduits for the tertiary migration of hydrocarbons from known Lower Cretaceous hydrocarbon reservoirs into shallow Cretaceous sediments. This research provides valuable information on the regional basement fault architecture and a more detailed exploration target for the Cooper‐Eromanga Basin, which were previously not available in literature.  相似文献   

The Red Sea depositional architecture: insights from 3D modeling     

Khalid A. Almalki  Syed A. Mahmud  Hisham I. Hashem  Oumar A. Loni 《Arabian Journal of Geosciences》2018,11(11):277

More than half a century of geological and exploration studies have taken place in the Red Sea area, and still very limited information is available to the geological community in regard to the lithological distribution and the stratigraphic architecture. In this study, extensive well data was used to build the first lithologic and stratigraphic 3D models of the entire Red Sea to better understand the lithological distribution. The potential models have been constrained by bathymetric and geophysical data. Studied data demonstrate that up to 5 km of sediments were deposited in the Red Sea. It is mainly comprised of limestones, evaporites, and shales. Our models show that the evaporite body represents more than 70% of the Red Sea succession. In particular, the evaporite succession seems to be well developed in the southern region. Salt dome features are present and developed close to the margins. The models suggest that domal formation did not enable thick carbonate accumulation in some parts of the basin but the carbonate generally follows the evaporite trend. The models help to identify the main controls leading to salt diapir by highlighting the distribution of this body and the geometry of geological structures. Syn-rift faulting and rifting has been one of the most prominent structural features. Complex interplay of tectono-stratigraphic events played a significant role in shaping the stratigraphic evolution of the Red Sea basin with multiple evolution phases of paleoenvironment and paleogeographic were recognized based on the models. Our synthesis and interpretation support that moderately deep marine conditions dominated in the Miocene, whereas shallow seas dominated the whole basin during the Plio-Pleistocene period as a result of episodic marine invasion. However, lacustrine environment may have prevailed at the Oligocene time in isolated half grabens.  相似文献   

Synthesis of biochar from sugarcane filter-cake and its impacts on physiological performance of lettuce (<Emphasis Type="Italic">Lettuce sativa</Emphasis>) grown on cadmium contaminated soil     

Anum Sehar  Rukhsanda Aziz  Muhammad Tariq Rafiq  Muhammad Mazhar Hussain  Muhammad Rizwan  Adiba Khan Sehrish  Muhammad Khalid Rafiq  Jalal ud Din  Qaiser Hussain  Mohammad I. Al-Wabel  Shafaqat Ali 《Arabian Journal of Geosciences》2018,11(20):634

Soil contamination with cadmium has become major concern all over the world because of its adverse impacts on ecosystem health and agricultural land. Soil amendment with biochar may have varied effects on physical and chemical properties of soil. The objective of the study was to explore the impact of sugarcane filter-cake biochar on physiological performance and growth of lettuce in an aged soil. Four different doses (0, 1.5%, 3%, and 5%) of biochar were used in the soil and conditioned for 1 month. After this, lettuce seedlings were grown in the soil. The results showed that the biochar treatment improved the fresh and dry biomass of leaves and roots as well as plant height while diminished the bioavailability of cadmium from the soil. As compared to control, biochar significantly enhanced the chlorophyll content in lettuce leaves. Due to the biochar amendment, the oxidative stress decreased in lettuce shoots over the control. As compared to control, concentration of cadmium in lettuce significantly decreased after the application of biochar. It was concluded that biochar could mitigate the toxicity of cadmium in lettuce by altering the biochemical and physiological processes in cadmium contaminated soil.  相似文献   

Seismic stratigraphy of the Mianwali and Bannu depressions,north-western Indus foreland basin     

Farid  Asam  Khalid  Perveiz  Ali  Muhammad Y.  Iqbal  Muhammad Asim  Jadoon  Khan Zaib 《International Journal of Earth Sciences》2018,107(5):1557-1578

International Journal of Earth Sciences - Regional seismic reflection profiles, deep exploratory wells, and outcrop data have been used to study the structure and stratigraphic architecture of the...  相似文献   

Exploring disaster preparedness of students at university in Bangladesh     

Hasan  Md. Khalid  Moriom  Masuma  Shuprio  Shariaj Ibna Mizan  Younos  Tahmina Bintay  Chowdhury  Md. Arif 《Natural Hazards》2022,111(1):817-849

Natural Hazards - Adequate and effective disaster preparedness in each sector is indispensable to abate disaster impacts and intensify disaster resilience in Bangladesh for achieving sustainable...  相似文献   

Petrology and geochemistry of feldspathic impact‐melt breccia Abar al' Uj 012, the first lunar meteorite from Saudi Arabia          下载免费PDF全文

Marianna Mészáros  Beda A. Hofmann  Pierre Lanari  Randy L. Korotev  Edwin Gnos  Nicolas D. Greber  Ingo Leya  Richard C. Greenwood  A. J. Timothy Jull  Khalid Al‐Wagdani  Ayman Mahjoub  Abdulaziz A. Al‐Solami  Siddiq N. Habibullah 《Meteoritics & planetary science》2016,51(10):1830-1848

Abar al' Uj (AaU) 012 is a clast‐rich, vesicular impact‐melt (IM) breccia, composed of lithic and mineral clasts set in a very fine‐grained and well‐crystallized matrix. It is a typical feldspathic lunar meteorite, most likely originating from the lunar farside. Bulk composition (31.0 wt% Al₂O₃, 3.85 wt% FeO) is close to the mean of feldspathic lunar meteorites and Apollo FAN‐suite rocks. The low concentration of incompatible trace elements (0.39 ppm Th, 0.13 ppm U) reflects the absence of a significant KREEP component. Plagioclase is highly anorthitic with a mean of An_96.9Ab_3.0Or_0.1. Bulk rock Mg# is 63 and molar FeO/MnO is 76. The terrestrial age of the meteorite is 33.4 ± 5.2 kyr. AaU 012 contains a ~1.4 × 1.5 mm² exotic clast different from the lithic clast population which is dominated by clasts of anorthosite breccias. Bulk composition and presence of relatively large vesicles indicate that the clast was most probably formed by an impact into a precursor having nonmare igneous origin most likely related to the rare alkali‐suite rocks. The IM clast is mainly composed of clinopyroxenes, contains a significant amount of cristobalite (9.0 vol%), and has a microcrystalline mesostasis. Although the clast shows similarities in texture and modal mineral abundances with some Apollo pigeonite basalts, it has lower FeO and higher SiO₂ than any mare basalt. It also has higher FeO and lower Al₂O₃ than rocks from the FAN‐ or Mg‐suite. Its lower Mg# (59) compared to Mg‐suite rocks also excludes a relationship with these types of lunar material.  相似文献   

A middle–late Ediacaran volcano‐sedimentary record from the eastern Arabian‐Nubian shield     

David Nettle  Galen P. Halverson  Grant M. Cox  Alan S. Collins  Mark Schmitz  James Gehling  Peter R. Johnson  Khalid Kadi 《地学学报》2014,26(2):120-129

The Ediacaran Jibalah Group comprises volcano‐sedimentary successions that filled small fault‐bound basins along the NW–SE‐trending Najd fault system in the eastern Arabian‐Nubian Shield. Like several other Jibalah basins, the Antaq basin contains exquisitely preserved sedimentary structures and felsic tuffs, and hence is an excellent candidate for calibrating late Ediacaran Earth history. Shallow‐marine strata from the upper Jibalah Group (Muraykhah Formation) contain a diversity of load structures and intimately related textured organic (microbial) surfaces, along with a fragment of a structure closely resembling an Ediacaran frond fossil and a possible specimen of Aspidella. Interspersed carbonate beds through the Muraykhah Formation record a positive δ¹³C shift from ?6 to 0‰. U‐Pb zircon geochronology indicates a maximum depositional age of ~570 Ma for the upper Jibalah Group, consistent with previous age estimates. Although this age overlaps with that of the upper Huqf Supergroup in nearby Oman, these sequences were deposited in contrasting tectonic settings on opposite sides of the final suture of the East African Orogen.  相似文献