Geotechnical Characteristics of Anhydrite/Gypsum Transformation in the Middle Miocene Evaporites, Red Sea Coast, Egypt (original) (raw)
Related papers
2012
Several studies were conducted to specify the characteristics of the swelling behavior. The swelling ratio and the swelling pressure are valuable to civil engineers and practioners especially in the phases of design and calculation. Really, the evaluation of these parameters, until now, is not unified. It is proposed, in this paper, to review some qualitative and quantitative methods of expansive green clay of Gzenaya in Tangier (Morocco). Test procedures, evoked and based on the oedometer apparatus, are analyzed to show their direct influence on soil behavior during swelling. Particular attention is bore to the influence of the conditions of loading and saturation on the values of the swelling parameters and its kinetics of swelling. The opportunity is offered to highlight other parametric conditions which interfere, seriously, in test conditions, in particular, the combination "initial water content-dry density" of the soil and its amount of fine size particles (smaller ...
Swelling properties of clays, a major risk factor for the infrastructure projects
UNIVESITARIA SIMPRO 2021 May 27-28, 2021, Petrosani, Romania., 2021
Swelling and shrinking properties refers to significant positive or negative variations of volumes due to absorbtion or dessication of water in fine soils under natural or anthropic regime of moisture. These physical phenomena are worldwide spread and had important engineering consequences with associates cost of damages of several billion annually in all climate areas. In spite of the fact that these geotechnical properties are studied for more than eight decades, the particularities of these peculiar relations between water, mineral composition and geomechanical behavior are still unrevealed entirely. In Romania, swell/shrink soils are reported in all regions at different depths, but rarely related to geotechnical engineering accidents such as slope slides or road failures. This work presents some obvious relations between the hydrogeological structure, the presence of "large swell/shrink soils", their mineralogical composition and geomechanical properties and the ubiquitous landslides on Peri Carpathians Hills. Large infrastructure projects offer the opportunities to put into evidence the swelling properties of Upper Pliocene-Lower Pleistocene deposits, which supports the Holocene alluvial deposits of Argeş River. Analyzed samples allow us to define some basic correlations between plasticity index, colloidal fraction, dry density, swelling pressures or free swelling and mineralogical composition.
Swelling pressure of natural and modified smectite-bearing clay raw materials
Physicochemical Problems of Mineral Processing, 2015
Smectite clays, due to their barrier properties and swelling ability, are often applied for waterproofing purposes. A proper value of swelling pressure is one of the parameters, which must be met by the fillers used in hybrid waterproofing materials. The authors determined the swelling pressure of selected clay raw materials in their natural state and after chemical modification. This parameter was measured by the Komine method, as this procedure is more accurate than the standard edometric method. The authors introduced some changes in the method. The samples represent Krakowiec clays (Miocene) and a Triassic clay, collected in active pits of building clays, which are widely exploited in south Poland. The content of the smectite group minerals, determined from the sorption of methylene blue and copper(II) triethylenetetramine, ranges between 15 and 35%. Further characteristics of the clays were obtained with X-ray diffraction, chemical analyses (calcium carbonate content including)...
Triggering swelling potential of anhydrite clay rocks by brittle failure processes
Understanding the potential influence of brittle failure on swelling processes is motivated by the remarkable short and long-term heaving problems associated with tunnels constructed in anhydrite rich rock types (Gipskeuper) in Switzerland and elsewhere. Brittle failure behavior is hypothesized to be a key factor to explain the remarkable extension of water conductive zones around the excavations. In order to verify this hypothesis and to demonstrate the potential effect of brittle ground behavior on water pathway development and thus swelling, a numerical study based on ground data from several projects in Switzerland was initiated. The results obtained in the study demonstrate that brittle, extensional fractures beneath the invert of tunnels provide a remarkable and in many ways critical trigger of the swelling potential of anhydrite clay rocks.
Characterization of the High Swelling Green Clay in the Vicinity of Amman Area
The Open Civil Engineering Journal, 2021
Introduction: Jordan is awarded huge areas in the north and western part of the country in which brown and green clay is dominant. This research focuses on the problems and behaviour of the green clay only. The main problem of the green clay is its high swelling pressure which is the main cause of excessive settlement and wall cracks in buildings, especially during the wet season. Methods: This study aims to investigate the engineering properties and behaviour of the green clay deposits in the Amman area, which will serve as a guide for both geotechnical and structural engineers when preparing the foundation design. Results: Based on the consolidation test, the investigated green clay showed high swelling pressure of 3.11 kg/cm2, liquid limit (LL) of 73%, plasticity index (PI) of 40%, the shrinkage limit (SL) of 12%, and liquidity index (LI) of 0.125. The moisture content at saturation is 35.14%, while the natural moisture content is 28%, dry density is 1407 kg/m3, cohesion (C) is 0...
Swelling of Clay Minerals and Its Impact on Permeability
2014
Formation damage has been described as any irreversible alteration, i.e. decrease of permeability, of the hydrocarbon reservoir rock after wellbore operations, which may have a serious economic impact upon the productivity of the reservoir. The presence of clays minerals is often considered as a major cause of formation damage. Thus, clay behavior in porous media needs to be taken into account when evaluating the potential productive capacity of hydrocarbon reservoir sandstones. Since the main mechanisms of permeability reduction, such as fine migration and clay swelling, occur at the pore-scale, in this study we couple permeability experiments with X-ray μ-computed tomography (μ-CT) to visualize and quantify clay behavior in porous media. The selected porous media were packed columns (diameter, d = 1.27 cm, average length, L=6.4 cm) of soda lime beads and quartz grains. Various amounts of swelling (montmorillonite) and non-swelling (kaolinite) clays were added as coatings on beads and quartz. The amount of clay in the samples varied from 1.38 to 5.5wt.% in montmorillonite-coated samples and from 2.0 to 6.84wt.% in kaolinite-coated samples. Permeability measurements were performed on each sample to investigate the impact of clay content and grain size on permeability reduction as a result of clay swelling. Permeability changes were monitored as a function of time. Visualization of coated bead and grains columns by μ-CT provided quantitative information on morphological changes of clay grains/coatings among dry and water-saturated samples. All claycoated samples showed 10-40% decrease in permeability as compared to uncoated samples (K/K o = 0.6-0.9). In general, the higher the clay content was, the larger permeability reduction was observed. Permeability remained constant within an error after 4 hours of flow experiment in montmorillonite samples. In contrast, permeability of kaolinite samples oscillated with time, possibly due to fine migration. A 39% volume increase of montmorillonite particles was observed by μ-CT immediately after the sample was saturated with water, i.e. swelling occurred almost instantaneously after water-clay contact. However, no further changes in volume were observed after 4 hours of flow. Kaolinite-coated samples showed a 15% volume increase of clay particles, which was attributed to the hydration of clay pellets by water. The calculated porosity reduction associated with clay swelling ranged from 0.4-1.7% including both montmorillonite-and kaolinite-coated samples. This decrease in porosity was estimated to cause only a 2-5% reduction in permeability, primarily due to the high initial porosity and permeability of the selected samples. This study presents a base line to estimate changes in permeability as a result of clay swelling for variable clay content, grain size, and porosity. v
The Impact of Hydric Swelling on the Mechanical Behavior of Egyptian Helwan Limestone
Periodica Polytechnica Civil Engineering, 2020
This study was concerned at a limestone quarry located southeast of Helwan city, Egypt, in order to investigate the effect of hydric swelling on the geomechanical aspects of limestone rocks. The Volume of Egyptian limestones change due to the presence of clay minerals (swelling/shrinking). These changes in volume induced by changing environmental conditions, high temperature and fluctuation of the relative humidity, causes accelerated physical deterioration of limestone. The rainfall is infrequent, and it is usual for the area to have no precipitation for successive months. There is a remarkable variability in daily temperature between summer and winter. The hot and arid environment that controls the geological development can affect the engineering behavior of local sedimentary stones. Petrographic investigation by scanning electron microscopy (SEM) of Helwan limestone (biomicritic limestone) revealed the existence of smectite and glauconite within the stone. The clay fraction extracted from Helwan limestone is equal to 10 % by weight. The analysis of oriented clay mounts by X-ray diffraction (XRD) confirmed the dominance of smectite in the clay fraction. To study the effect of the clay content on the mechanical behavior of Helwan limestone, hydric swelling tests were performed at first by using a displacement sensor, afterwards, the effect of a sequence of wetting/ drying cycles on the stone strength was determined by the unconfined compressive strength (UCS) test. Results confirmed that the strength loss of the limestone is directly proportional to the degree of swelling of the clay, as expected. This highlights the importance of this parameter for selecting stones in new construction or for replacing purposes, and for establishing preventive measurements to minimize this damage in historic buildings.
MATEC Web of Conferences, 2014
The swelling phenomenon appears seriously when changing the soil-moisture conditions. The swelling pressure induced by the expansive soil can causes unfavourable problems or instability for the civil structures. So, understanding the soil behavior is considered a valuable work for engineers and consultants in the geotechnical and civil engineering sectors. In reality, the assessment of the swelling pressure of expansive soil depends, first of all, of test conditions related to the change of soil-moisture, as it happens, the influence of the combination "loading-start wetting" and also the unloading process after saturation. To this end, we establish an experimental study on the green clay of Tangier to evaluate the swelling pressure by using oedometer apparatus. Secondly, attention is bore to the combination "initial water content-dry density", another factor related to the change of the soil-moisture, to show the influence of initial state condition on the swelling pressure.