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Showing 4 results for Liquid Limit

Nader Shariatmadari , Marzieh Salami, Mehran Karimpour Fard,
Volume 9, Issue 2 (6-2011)

The main task in the design and construction of impermeable liners in landfills is to block the migration of pollutants to the groundwater

systems or to reduce its rate to a reasonable amount. That is why environmental regulations force governments to construct engineered

waste dumps for waste management purposes. These liners are exposed to various types of chemical, biological, and physical processes

and are affected by the leachate which is produced from decomposition of waste materials accompanying methane gas. The leachate

includes a lot of components such as water and different types of salts. For this reason, the geotechnical characteristics of clay liners

which are evaluated in laboratories using distilled water or tap water might be far different from the representative sample of the in-situ

conditions. There are some evidences regarding the effect of these salts on the physical and mechanical properties of clay barriers which

could affect the long-term performance of these liners. Since the main criterion for impermeable bottom liners in landfills is their

hydraulics conductivity, the increase of this parameter could have a considerable environmental impact. This paper embraces the results

of a recent study on the effect of three inorganic salts, NaCl, CaCl2 and MgCl2 on some geotechnical properties of a common used clay

soil in impermeable bottom barrier in Kahrizak landfill, the main waste disposal center of the Tehran Metropolitan. Also the effect of

bentonite content by adding different percentage of this special clay mineral, 10 and 20 percent, on these properties was investigated.

Laboratory tests like liquid limit, compaction, 1D consolidation and free swell tests were performed for this purpose. Results indicated

that all of these salts could have a considerable effect on the geotechnical properties of the mixtures. The main reason of such effects is

the changes which occur in diffuse double layer of clay particles.

J. Nazari Afshar, M. Ghazavi,
Volume 12, Issue 1 (1-2014)

The Stone-column is a useful method for increasing the bearing capacity and reducing settlement of foundation soil. The prediction of accurate ultimate bearing capacity of stone columns is very important in soil improvement techniques. Bulging failure mechanism usually controls the failure mechanism. In this paper, an imaginary retaining wall is used such that it stretches vertically from the stone column edge. A simple analytical method is introduced for estimation of the ultimate bearing capacity of the stone column using Coulomb lateral earth pressure theory. Presented method needs conventional Mohr-coloumb shear strength parameters of the stone column material and the native soil for estimation the ultimate bearing capacity of stone column. The validity of the developed method has been verified using finite element method and test data. Parametric studies have been carried out and effects of contributing parameters such as stone column diameter, column spacing, and the internal friction angle of the stone column material on the ultimate bearing capacity have been investigated.
X. Liu, K. Sheng, J.h. Hua, B.n. Hong, J.j. Zhu,
Volume 13, Issue 3 (12-2015)

In order to improve the utilization of high liquid limit soil, the fundamental properties of high liquid limit soil and its direct utilization method are studied in this paper. This work involves both laboratory and fieldwork experiments. The results show that clay and sandy clay both with high liquid limit can be directly used for the road embankment, and the degree of compaction can be controlled at 88 %. The pack-and-cover method in accordance with Chinese technical specifications is recommended to be operated in the engineering practice. The packed height should be less than 8 meters and the total height of embankment no more than 12 meters in the interests of settlement. From the view of stability, the optimal thickness value of top sealing soil layer and edge sealing soil layer is about 1.5 meter respectively, and the geogrid reinforcement spacing should be about 2.0 meters. In addition, based on Yun-Luo expressway in China filled with high liquid limit soil, the construction techniques and key points of quality control in subgrade with pack-and-cover method are compared and discussed in detail, and the feasibility of these schemes are verified by the experimental results.

Mahdi Karkush, Dhurgham Al-Hamdani,
Volume 15, Issue 3 (5-2017)

The present study focuses on measuring the effects of industrial wastewater disposed from thermal electricity power plant as by-product on the geotechnical properties of sandy soil and applying washing process to remediate the contaminated soil samples and measure the efficiency of washing technique. The disturbed sandy soil samples were obtained from Al-Kufa City located to the southwest of Iraq and the industrial wastewater obtained from Al-Musayib thermal electricity power plant. The intact sandy soil was contaminated in the laboratory with four percentages of industrial wastewater (10, 20, 40 and 100%) calculated according to the weight of dry soil. The industrial wastewater is mixed with distilled water to constitute the solution used in the contamination process of soil through soaking the soil by this solution for 30 days. The study results showed that with increasing the percentages of the contaminant, there was a slight increase in both the liquid limit and particle size, while there was a significant increase in the optimum water content. Nevertheless, a slight decrease was observed in the specific gravity, maximum dry unit weight, and void ratio, while, a considerable decrease was noticed in the angle of the internal friction and coefficient of permeability of soil. The proposed remediation technique “soil washing” is efficient, economical, and time saving when used to remediate sandy soils. After remediation, the results showed an increase in the cohesion, angle of internal friction and maximum dry unit weight. Also, a slight increase was observed in the specific gravity, void ratio and permeability coefficient of remediated soil samples when compared with that of contaminated samples. The removal efficiencies of contaminant from soil were (97.63, 96.79, 96.58, and 93.87%) for the soil samples contaminated with industrial wastewater by (10, 20, 40 and 100%), respectively.

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