عنوان مقاله [English]
Consolidation and stability of soil is influenced by the presence of minerals in the soil and it is especially related to its moisture and this is a prevalent difficulty in the construction of irrigation and drainage networks. In this research, the effect of natural gypsum on the properties of soil in the location of constructing network was studied. In order to achieve answers which comply with the conditions of operation, samples were prepared from the construction site, where they contain natural gypsum in soil. Samples were selected, based on a weighted combination of soil and natural gypsum, with percentages of 1%, 4%, 10% and 15% and by conducting standard chemical tests to determine the percentage of gypsum and some general properties of soil. In order to assess the rate of dissolution, consolidation test was also conducted and in this process EC was measured for a month in output water samples extracting from the process of replacing distilled water, in a one-day period and under the stresses of 1, 4 and 8 kg/cm^2 in the consolidation device. The results showed that by increasing the amount of gypsum, plasticity index and dry density of soil samples have decreased, but permeability and settlement rates have increased. Since in the calculation of settlement of gypsum-containing soils, in the addition to the percentage of gypsum, parameters such as volumetric compression ratio and stress are effective as well; so, these factors have been investigated in this research a formula has been suggested by considering these factors.