جستجوی مقالات مرتبط با کلیدواژه « Soil stabilization » در نشریات گروه « مهندسی معدن »

Improvement of problematic soils, as an inevitable issue, has an important role in the construction projects. Adding some additive materials to the soil, has been considered as one of the effective procedure in improving characteristics behavior of soils. In this study, the effect of polypropylene fibers and nano-SiO2 in combination with clay was investigated, as a novel method, in order to refining mechanical properties of the soil. The purpose of this research is to investigate the effect of nano-SiO2 and polypropylene fibers on the properties of low plasticity clay by applying Unconfined Compression Test. Three different mixtures of the proportion of polypropylene fibers(0.25 %, 0.5%, and 1% of dry weight of clayey soil) and nano-SiO2 (0.5%, 0.75%, and 1% of dry weight of clayey soil) has been used. The results of this study show that adding the mixture of polypropylene fibers and nano-SiO2 into the clay soils, leads to 4.69% and 4.17% increment of unconfined compressive strength and modulus of elasticity, respectively, in comparison to the untreated clay. Also adding nano-SiO2 to the soil, causes more failure of samples occur respect to the case in in which the soil is getting mixed with fiber, though by increasing the amount of fibers, the failure mechanism of refined samples changes, thus the failure strain increases.

Dispersive soils are among the most important problematic soils in earth structures, especially earth dam projects. Lime and aluminum sulfate are common and traditional additives for stabilization of dispersive soils due to the proper replacement of calcium or aluminum ions instead of sodium ions. Considering the progress of nanotechnology and using its in soil improvement, in this study, nano-sized aluminum oxide powder was used to improve dispersive soil. Five different nano material ratios (0, 0.2, 0.4, 0.8 and 1% by weight of dry clay) were mixed with a dispersive clay and four different lime contents (0, 2, 4 and 6% by weight of dry clay) and the dispersion potential of mixtures are obtained from double hydrometer test. The results show that increasing nano Al2O3 greatly reduced the percentage of dispersion. Adding 1% nano-Al2O3 in dispersive clay has diminished 64% the potential of dispersion. In samples with containing 2% lime, only 0.2% of the nano material has been able to place the soil in non-dispersive category.

The stabilization and improvement of the soil is a branch of geotechnical engineering by which improve the engineering and geotechnical characteristic (same as strength, ductility and bearing capacity) of the problematic soils. In this study, Micronized Calcium Carbonate and a Polymer named as Poly Vinyl Acetate as the two types of additives were used to stabilize the silty sand soil, and their effects on modulus of elasticity were studied. For this purpose, after performance the index tests, the Micronized Calcium Carbonate and Poly Vinyl Acetate with different percentages of 1, 2, 3 and 4 were added to the soil and with curing times of 1, 7, 14 and 28 days, uniaxial compressive strength were done on stabilized samples. Then elastic modulus of soil in different conditions (different additives percentage and curing time) were determined. Besides, SEM (Scanning Electron Microscopy) imaging were performed on the three soil to investigate the structural characteristic changes of each sample before and after the stabilizing samples. According to the tests results, in general increasing the additives to a certain percentage in a constant curing time, results in the enhancement of the elastic modulus of the soil and by increasing curing time at a constant percentage of additives, elastic modulus will increase significantly. The results show that the effect of Poly Vinyl Acetate on the enhancement of the elastic modulus of silty-sand soil is more than the Micronized powder of Calcium Carbonate