Shallow landslides in nearly saturated uncohesive to slightly cohesive soils are triggered by high intensity, short duration rainfall which infiltrates into soil and changes intergranular friction and effective stresses. For this, the especially developed Soil-Water Interaction Modelling System (SWIMS) was used with CL-ML type soils. For simplicity, rainfall intensity and duration were kept constant. Results showed that (1) All 35°slopes were failed by translational failure. For the other (15°, 25°) slopes, no failures were observed; (2) For all slopes, FOS increased with increasing compaction degree and decreased with increasing slope angle; (3) Other parameters, such as soil density, porosity, saturation degree, water contents, and water permeability may also affect shear strength/slope stability, especially for low degrees of saturation (S < 95%), compared to high degrees of saturation (S =, > 95%). (4) A correlation of SWIMS tests observed that average wetting band depths (h obser ), with the calculated wetting band depths from the Lump Equation (h LE ), were poor, as h obser values were much higher than h LE values. Differences increased for very low degrees of saturation (S), compared to S > 95%. This meant that the Lump equation underestimated wetting band depths. Further, if the Lump equation is still considered valid, this would imply either water-permeability increases, porosity decreases or both occur towards full saturation; a process where the last possibility is the most probable occurrence.
Compaction is the one of the most important stages of the storage process in landfills. Well-compacted municipal solid waste (MSW) occupies less volume than an uncompacted MSW sample of the same weight and provides a safer storage area. The composition of MSW changes in between countries and even cities. For that reason, for effective compaction, the composition effect should be investigated. In this study, effects of composition, degradation and energy on the compaction behavior of artificially-prepared and natural fresh and aged MSW samples were determined. Artificial samples were prepared in representative different compositions Europe (E-1), Turkey (T-1) and the USA (U-1) to examine the effect of the composition. In addition to the synthetic MSW samples, natural MSW samples were obtained from the municipal landfill area of Manisa, Turkey. The standard Proctor test results have shown that the highest maximum dry unit weight was observed with the U-1 composition, which has the lowest organic content and the highest metal content. The degradation effect was investigated on the natural samples. The degraded MSW sample (3-4 years) has significantly higher maximum dry unit weight than the fresh natural MSW sample because of its low organic content. According to the results of this study, with respect to the composition effect, the percentage of organic waste is the most important factor on the compaction behavior of MSWs. As paper, organic and plastic contents increase in the MSW composition the γdry-max value decreases and wopt increases. The ash content does it reversely, as such that any increase in γdry-max decreases the wopt value of the MSW.
Soil suction is one of the most important parameters describing soil moisture conditions for unsaturated soils used in landfill liners. However, few studies have been conducted on the suction characteristics of compacted zeolite-bentonite mixtures (ZBMs) and sand-bentonite mixtures (SBMs), which are proposed for use as liner materials. Nevertheless, zeolite is known for its microporous skeleton containing cages and tunnels and it has a great physical affiliation to water uptake. Zeolite and bentonite, in a mixture, are thought to be in competition for water uptake and this may alter the distribution of water content for each soil in the mixture. The present study investigated the suction properties of compacted ZBMs and SBMs for varying mixing ratios and compaction water contents. The soil suction measurement technique chosen was the filter-paper method. The suction characteristics of powdered, granular, and block zeolites, as well as 0, 10, and 20% bentonite in ZBMs and SBMs were measured and compared with each other. Contaminated compacted ZBMs are compared with those of uncontaminated compacted ones at the optimum water content for the 10% and 20% mixtures. The results show that suction capacity of zeolite increases with grain size. As bentonite content increases, both matric and total suction increase for both mixtures. ZBMs have higher matric suction values than SBMs, but not total suction values. Contaminated total suction values are found to be higher than those of uncontaminated samples due to an increase in dissolved ion concentration.
Soil suction is one of the most important parameters for describing the moisture condition and engineering behavior of unsaturated soils. Therefore, changes in suction behavior of soils in the presence of saline waters are important for engineered barriers. The aim of this study was to determine the change in suction and swelling behavior of soils, which were exposed to salt solutions (NaCl, CaCl 2 , natural seawater) with respect to distilled water. The three soil samples were gathered with different mineralogy and plasticity characteristics and tested for determining matric and total suction values and for obtaining free swelling characteristics in the presence of salt solutions. The bentonitic soil sample had the highest total suction value in the presence of seawater. Kaolinitic and zeolitic soil samples had the highest total suction values in the presence of NaCl solution. The highest modified free swell index value of the samples was obtained in the presence of NaCl solution for all the soil samples. No relationship was found between the total suction, matric suction and the modified free swell index value of the tested soils.
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