عنوان مقاله [English]
The necessity of using suitable methods of soil stabilization is of great importance, regarding the increasing growth of population. Soil stabilization by microbiological sedimentation of calcium carbonate is an appropriate method, which has been recently evaluated all around the world, and is known as a method compatible with the environment used in some places of the world. There are two methods of remediation of sandy soils by use of microorganisms. The first method is based on microbiological bacterial stimulation. In this method, nutritious material is added to the soil for the growth of bacteria and the cultivation processes take place inside the soil in all stages. But, the second method is based on adding the bacteria to the soil and all growth stages of bacteria and the cultivation processes are performed in the laboratory by using a special fermenter. In this method, necessary nutrients must be provided to survive the bacteria and other materials are required to create the chemical reaction of urea and calcium chloride. In this way, deposition of calcium carbonate and adherence of grains together are created and soil engineering properties increase. For this purpose, the best ways is the injection of Calcium chloride into the Bacillus Pasteurii background. Cementation of particles together with calcite precipitation increases soil strength. Although the strength of this kind of samples increases remarkably, environmental conditions can reduce this kind of strength. However, the remarkable point that has not been considered so far is the effect of disturbance on the structure of this kind of cementation, which can be tremendously effective in method performance. The disturbance can be carried out directly by disturbing the structure of a stabilized soil or by environmental temperature changes. This paper aims to assess these types of disturbances in the soil stabilized biologically. For this purpose, several stabilized samples were made via a biological method. These samples were then subjected to structural disturbance
and also the disturbances, caused by freeze and thaw cycle, in order to investigate the effect of such factors on decreasing the resistance of the biologically stabilized soil.