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Effect of Treated Waste Water on the Behavior of Unsaturated Soil
Abstract
Many tests have been carried out on Karak clay to explore the unsaturated shear strength and volume change characteristics. The specimens have been prepared with and without treated contaminated water. A specific experimental programme has been planned and completed on a range of degree of saturation. The shear strength test and swelling test results with distilled water have been compared with the presence of contamination in Karak clay. The test results show that there is not too much difference between the unsaturated shear strength tests on specimens without and with contaminated water in Karak clay. Also, the use of treated water will not increase or decrease the swelling. The results obtained from this study are expected to be of benefit and practical use for carrying out stability analysis of structures like embankments and foundations supported by clay particularly in a country that suffers from water shortage like Jordan. However, experimental evidence to support this study is still limited.
Bu çalışmada, Isparta ve civarında bulunan dört farklı endüstriyel atıksuyun iki farklı kil zeminin bazı mühendislik özelliklerine olan etkileri araştırılmıştır. Bu amaçla kıvam limitleri, standart kompaksiyon ve sabit hacimli şişme deneyleri musluk suyu kullanılarak yapılmıştır. Daha sonra aynı deneyler dört farklı endüstriyel atıksu kullanılarak tekrar yapılmıştır. Yapılan deneylere göre killerin kıvam limitlerinin, kompaksiyon parametrelerinin ve şişme basıncı değerinin kullanılan atıksularla değiştiği görülmüştür. Atıksular kullanıldığında her iki zemin türü için de, maksimum kuru birim hacim ağırlığın arttığı, likit limitin, plastik limitin, plastisite indisinin, optimum su muhtevasının ve şişme basıncının azaldığı görülmüştür. Endüstriyel atıksuların özelliklerinin her gün değişiklik göstermesi sebebiyle deney sonuçlarının değerlendirilmesinde daha fazla deney sonucuna ihtiyaç olduğu göz önünde tutulmalıdır.
The influence of compaction pressure, compaction water content and type of compaction (static or dynamic) on subsequent soil behaviour during wetting and isotropic loading has been investigated by conducting controlled-suction tests on samples of unsaturated compacted speswhite kaolin. The results are interpreted within the context of an elastoplastic framework for unsaturated soils, to examine which compaction-induced effects can be explained simply by variation in the initial state of the soil and which require that soils produced by different compaction procedures are modelled as fundamentally different materials. The compaction pressure influences initial state, by affecting the initial position of the yield surface, but it also influences, to a limited degree, the positions of the normal compression lines for different values of suction. The compaction water content influences the initial suction, but also has a significant influence (greater than does compaction pressure) on the positions of the normal compression lines. A change from static to dynamic compaction has no significant effect on subsequent behaviour.
The influence of pore-water suction on the strength of a porous material is that it contributes a compressive load which increases the shear strength. When the material is unsaturated, the normal load or effective stress is due, in part to the continuous water at measured suction in unemptied pores, and in part to isolated bodies in nominally emptied pores at suctions approximating to the suction at emptying.
When the material is draining from saturation, the effective stress σ is
where S is the fraction of saturation, α is the fraction of the initial water content drained at the maximum suction, Psd is the prevailing pore water suction, and Psd is a suction passed through in reaching pSd at which the reduction of S is dS. When the material is rewetting, the relationship becomes
where psw is now the prevailing suction during wetting and f is a distribution function of the degree of saturation such that
δS is the fractional saturation removed in the suction range δsd at sd and regained in the suction range δsw at sw. msd is the maximum suction attained.
The effective stress is revealed experimentally by unconfined compression tests on samples with imposed pore water suctions, and the dependence on this suction confirms reasonably that which is predicted by the theoretical formulas.