Soft soils are well known for their low strength and high compressibility. Several techniques, including reinforcement, are commonly used to increase the strength and decrease the deformation of this kind of soil. This paper presents the results of an investigation into the effects of fiber on the consolidation and shear strength behavior of a clay soil reinforced with nylon fibers. A series of one dimensional consolidation and triaxial tests were conducted on samples of unreinforced and reinforced clay with different percentages of randomly distributed nylon fibers. The results show that the preconsolidation pressure decreases and the coefficient of swelling and compression generally increase with increasing the fiber content. Furthermore, the addition of the fiber leads to a significant increase in shear strength and friction angle of the natural soil.

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Remediation of a soil contaminated with methyl tertiary butyl ether (MTBE) was studied by using the electrokinetic technique. A series of experimental tests were carried out on contaminated soil in an electro-osmotic apparatus at different applied gradients of voltage and time. The tests were conducted with distilled water and ethylenediaminetetra acetic acid (EDTA) solution as electrolyte. During each test the values of pH at anode and cathode reservoirs and also the discharge from cathode were measured. At the end of each test a number of soil samples were extracted from the middle of the soil at different distances from the anode and the removal of contaminant was measured by a gas chromatography apparatus. The results indicate that with EDTA as electrolyte the highest efficiency for removal of MTBE is achieved with 2.0 V/cm gradient and in the duration of 14 days. In addition, EDTA causes the values of pH to increase and decrease in the cathode and anode reservoirs, respectively. It also decreases the effluent and electro-osmotic permeability in comparison with distilled water. Experimental data were analysed by ANOVA and t-test methods. These statistical analyses showed significant difference (at 5% level) between the reference and other tests.

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