عنوان مقاله [English]
Nowadays, improving problematic soils is considered as one of the geotechnical engineering challenges. Since the problematic soils have a secondary origin that are the results of chemical weathering, they have a wide range of dispersive characteristics. One of these types of soils is clay that causes many problems in the engineering project. These problems are related to their specifications, such as week strength, settlement, and dispersivity problems. One of the treatment methods of the mentioned problems is chemical soil stabilization. In this study, by adding nano-silica to a kind of clay in the city of Karaj (west of Tehran), the strength behavior of this type of soil was investigated. For this purpose, having conducted index and identification tests
on the natural soil, we added nano-silica to the studied soil with 0.5, 1, 2, 3, 4, and 5 percent. Then, the direct shear, unconfined compressive strength, and consolidation tests were conducted on these soils. Moreover, imaging was captured by scanning electron microscopy (SEM) to evaluate and compare the textural features of the soil, before and after the stabilization process. The results show that adding nano-silica up to 2 percent leads to uniaxial compression strength enhancement, the shear strength parameters (including cohesion and internal friction angle), and reduction of the compressibility and swelling coefficients of the studied soil. In this study, it is clearly indicated that the technique of soil stabilized with nano-silica is a very effective method of ground improvement, which improves the shear strength, the unconfined compression strength, and the consolidation parameters of soil; consequently, it enhances the stability of structures, such as foundation and roadbed. With the development of the construction technology, this improvement technique can be considered as a practical method for improvement of strength behavior of clay in many fields of geotechnical engineering.