The Experts below are selected from a list of 27807 Experts worldwide ranked by ideXlab platform
Shahid Azam - One of the best experts on this subject based on the ideXlab platform.
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study on the geological and engineering aspects of anhydrite gypsum transition in the arabian gulf coastal deposits
Bulletin of Engineering Geology and the Environment, 2007Co-Authors: Shahid AzamAbstract:Evaporitic geology, hot and arid climate, fluctuating relative humidity, and an alkaline environment governed the evolution of sedimentary deposits in the Arabian Gulf coast. Calcium sulphate generally occurs as anhydrite in the unsaturated surface layer of local soil formations. Anhydrite hydrates to gypsum with an associated volume increase of up to 63%, whereas gypsum dehydration results in a reversal back to anhydrite that leads to 39% volume decrease. Swelling and compressibility problems are common in several coastal deposits of the globe. This paper investigates the geological and engineering aspects of anhydrite/gypsum transition in the Arabian Gulf coast. Oedometer test results on Dammam anhydrite were studied in conjunction with morphological assessments at critical volume change stages. Results indicated 10% swelling potential and 295 kPa swelling pressure for hydrating anhydrite. The Compression Index of anhydrite and gypsum were 0.067 and 0.12, respectively, whereas the rebound Index of anhydrite was 0.023.
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study on the geological and engineering aspects of anhydrite gypsum transition in the arabian gulf coastal deposits
Bulletin of Engineering Geology and the Environment, 2007Co-Authors: Shahid AzamAbstract:Evaporitic geology, hot and arid climate, fluctuating relative humidity, and an alkaline environment governed the evolution of sedimentary deposits in the Arabian Gulf coast. Calcium sulphate generally occurs as anhydrite in the unsaturated surface layer of local soil formations. Anhydrite hydrates to gypsum with an associated volume increase of up to 63%, whereas gypsum dehydration results in a reversal back to anhydrite that leads to 39% volume decrease. Swelling and compressibility problems are common in several coastal deposits of the globe. This paper investigates the geological and engineering aspects of anhydrite/gypsum transition in the Arabian Gulf coast. Oedometer test results on Dammam anhydrite were studied in conjunction with morphological assessments at critical volume change stages. Results indicated 10% swelling potential and 295 kPa swelling pressure for hydrating anhydrite. The Compression Index of anhydrite and gypsum were 0.067 and 0.12, respectively, whereas the rebound Index of anhydrite was 0.023.
Lei Huayan - One of the best experts on this subject based on the ideXlab platform.
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secondary consolidation characteristics of soft clay foundation of dredger fill site
Rock and Soil Mechanics, 2015Co-Authors: Lei HuayanAbstract:A series of one-dimensional consolidation tests is conducted on soft clay from dredger fill site of central fishing port area in Tianjin. The relationship among stress, strain and time is obtained; the characteristics of the consolidation and secondary consolidation of dredger fill and natural sedimentary soil are compared, providing theory evidence for the deformation model of soft clay foundation of dredger fill site and the prediction of long-term settlement after construction. It is shown that strain rate has a good linear correlation with double logarithm curve of time for both dredger fill and natural sedimentary soil. After processing, the water content and compressibility of dredger fill is low, while that of natural sedimentary soil remains high. With the increase of consolidation pressure, the coefficient of secondary consolidation of dredger fills changes a little. For natural sedimentary soil, the coefficient of secondary consolidation increases first and then decreases, levels out eventually. The coefficient of secondary consolidation still has a good linear correlation with Compression Index. It keeps a logarithmic downtrend with the increasing of time.
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research on secondary consolidation of clay under different squeezing disturbance
Rock and Soil Mechanics, 2013Co-Authors: Lei HuayanAbstract:Foundation treatment and shield construction disturbance are the causes of squeezing soil which damages the initial structure and state,leads to the disturbance of soil,and changes the property of secondary consolidation.According to the squeezing disturbance of different levels caused by different preloads,a series of step-loading consolidation tests are conducted.The results indicate that,with the increase of preloads,the structure yield stress increases,Compression Index is almost the same when preload is less than structure yield stress,and decreases suddenly when preload is larger than structure yield stress;then it comes to a steady value.The secondary consolidation coefficient increases firstly,then decreases,finally gets to steady with the increase of pressure;and the secondary consolidation coefficient would decrease when disturbance increases;and a computational model for secondary consolidation coefficient is put forward;and the model coincides well according to the several testing data,and does well in predicting,which is useful for the prediction of post-load settlement.
Mohamed Boutouil - One of the best experts on this subject based on the ideXlab platform.
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geotechnical properties of dredged marine sediments treated at high water cement ratio
Geo-marine Letters, 2009Co-Authors: Boubaker Rekik, Mohamed BoutouilAbstract:Cement and lime are widely employed in soil and sediment treatment for an improvement of geotechnical properties, such as an increase in mechanical strength which enables beneficial use in various geotechnical applications. In this study, fine organic-rich dredged harbour sediments of 120% relative water content were treated with dry cement at contents varying between 2% and 10% of bulk sediment wet weight. Tests based on assessments of one-dimensional Compression and Atterberg limits were performed on untreated and cement-treated sediments for various curing periods, as well as grain-size, SEM and X-ray diffraction analyses. The results confirm that increasing the cement content improves the geotechnical properties of these harbour sediments. Already in the early phase of curing (first 3 days of curing), particle size increases while sediment plasticity decreases. Changes in the compressibility behaviour include an increase in apparent preconsolidation pressure, in the Compression Index C c and in the primary consolidation coefficient C v, and a decrease in the secondary Compression Index \( C_\alpha \). This means that the new materials are characterized by a behaviour intermediate between that of fine and that of coarser soils.
Akira Asaoka - One of the best experts on this subject based on the ideXlab platform.
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proposal of a simple method for assessing the susceptibility of naturally deposited clay grounds to large long term settlement due to embankment loading
Soils and Foundations, 2010Co-Authors: Motohiro Inagaki, Mutsumi Tashiro, Masaki Nakano, Akira AsaokaAbstract:A simple method that utilizes the results of laboratory tests has been proposed for determining the susceptibility of soft clay grounds to large residual consolidation settlement due to embankment loading. It was found that there is a possibility of large long-term settlement if the sensitivity and Compression Index ratios of the clay material that constitutes the ground are equal to or more than 8.0 and 1.5, respectively. The Compression Index ratio is defined in this paper as the ratio (Cc/Ccr) of the steepest gradient of the Compression curve of an undisturbed sample to that of the remolded sample. Through the SYS Cam-clay model, an elasto-plastic constitutive model that describes the actions of the soil skeleton structure, it was found that clays with large sensitivity and Compression Index ratios are characterized by initially highly structured soils and that decay/upgradation of the structure can easily occur due to plastic deformation. In addition, by following Schmertmann's graphic method for in-situ Compression curve (1953), this paper proposes a method of deducing the in-situ initial conditions from the results of laboratory consolidation tests on undisturbed samples. These investigations revealed not only that large delayed settlement is facilitated in clays, which have higher degrees of structure and faster rates of structural decay, but also that the Δe method and other simple methods of predicting settlement may underestimate the amount of settlement.
Kang Jingwen - One of the best experts on this subject based on the ideXlab platform.
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properties of secondary consolidation of two types of dredger fill sites
Chinese Journal of Geotechnical Engineering, 2013Co-Authors: Kang JingwenAbstract:By use of the unidirectional oedometer apparatus,a series of 1-D Compression secondary consolidation tests on soil samples in two kinds of dredger fill sites are done.The relationship among stress,strain,void ratio and time is obtained,and the characteristics of the secondary consolidation and its influencing factors are compared.The results show that the secondary consolidation coefficient first increases with the increase of load and then decreases.In contrast,the value in unprocessed site is more than that in processed site.It also increases with the increases of moisture content,and the relationship curve is a concave.It keeps a linear increase with the Compression Index,at the same time,it keeps a logarithmic downtrend with the increasing time.The characteristics of the secondary consolidation are obviously influenced by the height and the drainage condition of soil samples.Based on the results,a simple and practical secondary consolidation coefficient model and deformation forecast method,which are suitable for the characteristics of dredger fill sites,are proposed.Compared with the experimenta;results,the proposed model can be employed to predict the deformation characteristics of the dredger fill sites.