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Hanifi Canakci 《Environmental Geology》2007,53(4):915-922
This paper focuses on an investigation of the possible causes for the collapse of limestone caves in Gaziantep, Turkey. The
city contains a lot of man-made caves, at a shallow depth, of various width and length. These caves were mainly excavated
to provide work or storage space. As the city has been growing fast with increased population, many structures were constructed
over these caves. Recently, two caves collapsed and five houses were damaged. These caves are all made of limestone and it
was observed after the collapse that the limestone was saturated with water due to sewer pipe leakage and surface water. Tests
were carried out on the limestone and it was determined that the compressive strength of limestone decreases by about 50%
and the tensile strength decreased by about 80% when saturated with water. It was concluded that the reduced strength of the
limestone combined with additional loads due to the factors mentioned above seem to be the main reason for these collapses. 相似文献
2.
Hanifi Missoum Mostefa Belkhatir Karim Bendani Mustapha Maliki 《Geotechnical and Geological Engineering》2013,31(1):279-296
In a number of recent case studies, the liquefaction of silty sands has been reported. To investigate the undrained shear and deformation behaviour of Chlef sand–silt mixtures, a series of monotonic and stress-controlled cyclic triaxial tests were conducted on sand encountered at the site. The aim of this laboratory investigation is to study the influence of silt contents, expressed by means of the equivalent void ratio on undrained residual shear strength of loose, medium dense and dense sand–silt mixtures under monotonic loading and liquefaction potential under cyclic loading. After an earthquake event, the prediction of the post-liquefaction strength is becoming a challenging task in order to ensure the stability of different types of earth structures. Thus, the choice of the appropriate undrained residual shear strength of silty sandy soils that are prone to liquefaction to be used in engineering practice design should be established. To achieve this, a series of undrained triaxial tests were conducted on reconstituted saturated silty sand samples with different fines contents ranging from 0 to 40 %. In all tests, the confining pressure was held constant at 100 kPa. From the experimental results obtained, it is clear that the global void ratio cannot be used as a state parameter and may not characterize the actual behaviour of the soil as well. The equivalent void ratio expressing the fine particles participation in soil strength is then introduced. A linear relationship between the undrained shear residual shear strength and the equivalent void ratio has been obtained for the studied range of the fines contents. Cyclic test results confirm that the increase in the equivalent void ratio and the fines content accelerates the liquefaction phenomenon for the studied stress ratio and the liquefaction resistance decreases with the increase in either the equivalent void ratio or the loading amplitude level. These cyclic tests results confirm the obtained monotonic tests results. 相似文献
3.
Hadjadj Fatima Zohra Laredj Nadia Maliki Mustapha Missoum Hanifi 《Geotechnical and Geological Engineering》2022,40(8):4159-4170
Geotechnical and Geological Engineering - The improvement of salt affected lands is a major environmental challenge in arid and semi arid regions all over the world. Electrokinetic treatment is one... 相似文献
4.
Greenhouse gas emissions, energy security and sustainability are three of the greatest contemporary global challenges to mankind today. The Sino-German Group of scientists have composed a special issue, which is a collection of diverse quality scientific works, that will try to elucidate the current developments in CO2 geologic sequestration research to reduce greenhouse emission including measures to monitor surface leakage, groundwater quality and the integrity of caprock, while ensuring a sufficient supply of clean energy. 相似文献
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During the last mid-century, the Chlef area was strongly affected by two earthquakes. From the geological context, there were numerous ejections onto the ground level of great masses of sandy soils and large displacements of various forms of some building foundations. These damages are due to soil liquefaction problem. This loss of shear strength can be attributed to many factors. History of recent cases indicates that sand deposited with silt content is much more liquefiable than clean sand. Therefore, a deep understanding of silty sand behavior is needed for the liquefaction assessment of silty sandy soils. Moreover, during seismic shaking, the post-liquefaction behavior of silty sand and, consequently, the stability of structures founded on liquefied soil depend on the steady-state shear strength of soil. The objective of this laboratory investigation is to show the effect of silt contents and the relative density on the mechanical behavior of such soils in monotonic loading. In this context, a series of undrained triaxial tests were performed on reconstituted saturated silty sand samples with different fines content ranging from 0% to 40%. In all tests, the confining pressure was held constant to 100 kPa. The fines content and the global void ratio are expressed by means of the equivalent void ratio. Linear correlations relating the undrained residual shear strength of loose, medium dense, and dense (D r?=?12%, 50%, and 90% before consolidation) sand–silt mixtures to the equivalent void ratio are obtained. The concept of the equivalent void ratio will then be used as a key parameter to express the dilatancy behavior of both clean and silty sand soils. Moreover, from the experimental results obtained, it is clear that the global void ratio cannot be used as a state parameter and may not represent the actual behavior of the soil as well. 相似文献
6.
Nadia Laredj Hanifi Missoum Karim Bendani Mustapha Maliki 《Arabian Journal of Geosciences》2011,5(5):935-942
Knowledge of transport processes of heat and moisture in soils of arid zones is vital to understanding the environmental and economic impacts of many activities: agriculture, waste disposal, geoenvironmental practices and earth sciences. Through extensive review and study on the different aspects of coupled transfer processes in swelling porous media, a general mathematical model for coupled heat, moisture, air flow and deformation problems in clayey soils is proposed in a consistent and unified manner. The model is characterized by the presence of a deformable solid matrix filled with two fluid phases (liquid water and air). In the proposed model, both pore water and air transfers are assumed to be governed by the generalized Darcy’s law. Fully coupled, non-linear partial differential equations are established and then solved by using a Galerkin weighted residual approach in space domain and an implicit integrating scheme in time domain. The obtained model has been finally validated by means of some case tests for the prediction of the thermo-hydro-mechanical behaviour of unsaturated swelling soils. The calculated relative errors between experimental and numerical results are 3% for temperature and 7% for stresses. Consequently, the developed numerical model predicts satisfactory results, compared to experimental test measures. The model is applicable to two-dimensional problems with various initial and boundary conditions; non-linear soil parameters can be easily included in this model. 相似文献
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In this study, the dissolution of magnesite particles in aqueous lactic acid solutions was investigated in a batch reactor employing the parameters of stirring speed, particle size, temperature and acid concentration. The shrinking core model was evaluated to determine the effect of particle size, temperature and concentration. It was also found that the stirring speed did not change the dissolution. Consequently, it was determined that the dissolution rate is controlled by surface chemical reaction. The activation energy of the process was determined to be 50.3 kJ mol− 1. 相似文献
8.
Recent developments in the application of x-ray micro-tomography in laboratory geomechanics have allowed all the individual
grains of sand in a test sample to be seen and identified uniquely in 3D. Combining such imaging capabilities with experiments
carried out “in situ” within an imaging set-up has led to the possibility of directly observing the mechanisms of deformation
as they happen. The challenge has thus become extracting pertinent, quantified information from these rich time-lapse 3D images
to elucidate the mechanics at play. This paper presents a new approach (ID-Track) for the quantification of individual grain
kinematics (displacements and rotations) of large quantities of sand grains (tens of thousands) in a test sample undergoing
loading. With ID-Track, grains are tracked between images based on some geometrical feature(s) that allow their unique identification
and matching between images. This differs from Digital Image Correlation (DIC), which makes measurements by recognising patterns
between images. Since ID-Track does not use the image of a grain for tracking, it is significantly faster than DIC. The technique
is detailed in the paper, and is shown to be fast and simple, giving good measurements of displacements, but suffering in
the measurement of rotations when compared with Discrete DIC. Subsequently, results are presented from successful applications
of ID-track to triaxial tests on two quite different sands: the angular Hostun sand and the rounded Caicos Ooids. This reveals
details on the performance of the technique for different grain shapes and insight into the differences in the grain-scale
mechanisms occurring in these two sands as they exhibit strain localisation under triaxial loading. 相似文献
9.
Miloud Sardou Said Maouche Bendehiba Sabeur Hanifi Missoum 《Arabian Journal of Geosciences》2018,11(10):229
The historical records show that the Northwestern Algeria has experienced more than 130 floods, which were sometimes catastrophic. They caused more than 1000 deaths and significant damage. In this work, we try to reconstruct the most devastating and deadly historical flood that occurred on November 26 and 27, 1927. This event is interesting to discuss disaster scenario because of its extent and impacts and the availability of data. For this purpose, we used historical press reports, scientific papers, and archival reports. This work allowed the reconstruction of the hydroclimatic situation during the flood and the regional scale impacts. It presents also the catastrophic flooding of the Ain Sefra river at Mostaganem and that of El Hammam river, as well as the Fergoug dam breaking at Mohammadia. The main factor triggering these floods was the heavy rainfall. Other factors have increased the damage such as the occupation of high-risk areas and the human failure. This event caused 430 killed persons, more than 1200 disaster victims, and around one billion francs losses. These effects evidence the high vulnerability of the Northwestern Algeria to the occurrence of floods. For that, if a similar event occurs in the future, it can be extremely negative. 相似文献
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