Experimental Analysis Of Mechanics Characteristics Of Improved Soil By Aught-Set Solidified Agent Under Freeze-Thawing Impacts

High-speed railway develops rapidly in China. However, as China has a vast territory area, the construction of the high-speed railway is limited by a variety of environmental factors. In the seasonal frozen soil area, the railway subgrade needs to overcome the freeze-thawing impacts. Therefore, an improved method which is able to effectively resist to freeze-thawing cycles is needed. Also, as the cyclic loading effects of the train to the subgrade, the improved subgrade needs to possess quality dynamic characteristics. In recent years, the improved soil by solidified agent is a new technique in improving soil properties, and has been broadly used at home and abroad. In this paper, we mainly analyze the static and dynamic characteristics of the improved soil by "Aught-Set" solidified agent under the impacts of freeze-thawing cycles by experiments. We take the Harbin-Dalian railway as the object background, and our major work includes the following contents:First, we carried out the unconfined compression strength comparative experiment between the plain soils which don't have the freeze-thawing cycles and the improved soils by solidified agents. Then, we simulated the impacts of the freeze-thawing cycles on the railway subgrade, and concluded the effects of the negative temperature and the frequency of the freeze-thawing cycles to the unconfined compression strength of the improved soil. Furthermore, we modeled the surrounding pressure of the real subgrade, conducting a conventional triaxial experiment with the 20kPa surrounding pressure to the freeze-thawing cyclic improved soil, and obtained the stress and strain variation of the improved soil under the freeze-thawing cyclic impacts.Second, in order to understand the kinetic effects of the solidified agent to the plain soils without freeze-thawing cycles, we conducted the dynamic triaxial experiment to both the plain soils and the improved soils. Then, the dynamic triaxial experiment was carried on the improved soil by Aught-Set solidified agent to get the variation of dynamic indexes, which were affected by freeze-thawing cycles. The index variations include the variation of the critical dynamic stress, the dynamic modulus, and the dynamic strength, with the decrease of the negative temperature of the freeze-thawing, and the increase of the freeze-thawing times.