Experimental Research on the Unconfined Compressive Strength of Cement Improved Aeolian Sand under High Temperature Curing Condition

Research purposes: The Hetian-Ruoqiang Railway in Xinjiang passes through the southern edge of the Taklimakan Desert, and the surface is dominated by aeolian sand. The cement-improved aeolian sand is the key technology for filling the railway subgrade bed in the desert area. The land surface maximum temperature in the Taklimakan Desert can reach 70℃ in summer, and the mechanical properties and deformation characteristics of cement-improved aeolian sand are easily affected by high temperature. Therefore, in this paper, based on the climatic conditions of the Taklimakan Desert in Xinjiang, series of unconfined compressive strength tests of cement-improved aeolian sand were carried out to study the effects of cement content and compaction coefficient on the stress-strain characteristics, unconfined compressive strength, peak strain and stiffness under the 70℃ high temperature curing condition. Research conclusions:(1) The stress-strain curve of cement-improved aeolian sand is approximately normal distribution, with right-skewed characteristics. (2) Under the 70℃ high temperature curing condition, when the compaction coefficient is 0.95, the unconfined compressive strength of cement-improved aeolian sand corresponding to the cement content of 4%, 5% and 6% is 0.38 MPa, 0.52 MPa and 0.78 MPa, the peak strain is 2.2%, 2.4% and 2.6%, and the stiffness is 10.4 MPa, 16.2 MPa and 22.8 MPa, respectively. (3) Compared with the standard curing condition, the unconfined compressive strength and peak strain of the cement-improved aeolian sand with a cement content of 5% and a compaction coefficient of 0.95 under the 70℃ high temperature curing condition are reduced by 5.5% and 22.7%, respectively, while the stiffness is increased by 5.9%. (4) During the construction of the Hetian-Ruoqiang Railway in summer, considering the 70℃ high temperature curing condition, the cement-improved aeolian sand with 5% cement content can meet the design requirements of subgrade filling. Regardless of the high-temperature climatic condition, the cement-improved aeolian sand with cement content of 4% can meet the design requirements of the filling for the bottom of the railway subgrade bed. (5) The research results are of conference value to construction and design of railway subgrade bed in aeolian sand area in the future. © 2021, Editorial Department of Journal of Railway Engineering Society. All right reserved.