Experimental Study On Cement Solidification Of Eolian Sand In Subgrade Under Freeze-thaw Cycle

As a special type of soil,aeolian sand,due to its poor grading characteristics,loose particle distribution characteristics,and low cohesion mechanical properties,has low strength and is difficult to stabilize as a natural roadbed soil.A large number of such aeolian sand natural roadbeds are distributed in the Shuangliao area of Jilin,causing certain engineering hazards.It is necessary to conduct solidification research on them.At the same time,due to the local location in seasonally frozen soil areas and the impact of freeze-thaw action,the roadbed filling material undergoes at least one freeze-thaw action per year when exposed to the natural environment,resulting in the strength reduction,settlement and other diseases of the roadbed,affecting the safety and normal operation of the road.Therefore,it is of great significance to study the road engineering properties of solidified aeolian sand under freeze-thaw cycles.This paper combines the National Natural Science Foundation of China（42207209）,"Research on Water and Salt Migration Mechanism of Soda Saline Soil under Complex Environment in Cold and Dry Areas",and the Research Science Institute of Jilin Provincial Department of Education,"Research on Disaster Evolution Mechanism and Improvement of Subgrade Expansive Soil in Yanbian Area of Jilin Province under the Effect of Dry wet Freeze thaw Cycle"（JJKH20230345KJ）,and carries out cement solidification research on subgrade aeolian sand in Shuangliao Area of Jilin Province,And analyze the mechanical properties of cement solidified aeolian sand samples under freeze-thaw cycling conditions.Based on the experimental results,a filling roadbed model was established using the finite software FLAC3D for solidified aeolian sand under different improvement conditions and freeze-thaw cycles,and its deformation characteristics were analyzed.The research results can provide a certain reference for the construction of solidified soil roadbed in freeze-thaw areas.The main research content and related achievements of this article are divided into the following aspects:（1）Through on-site investigation and sampling,samples of roadbed aeolian sand in the Shuangliao area of Jilin were obtained.Physical and mechanical indicators such as natural moisture content,particle size composition,and specific gravity of roadbed aeolian sand were tested,and the physical properties of natural soil were determined through compaction experiments.According to the experimental results,the aeolian sand in the Shuangliao area of Jilin can be classified as fine soil sand.The optimal moisture content of the aeolian sand is 7.65%,and the maximum dry density is about1.816g·cm^-3;（2）Cement solidification tests were conducted on windblown sand in the roadbed,with cement ratios of 2%,4%,6%,8%,and 10%added.The influence of cement content on the compaction characteristics of windblown sand was analyzed.The experimental results show that the shear mechanical properties of solidified aeolian sand tend to stabilize after adding 6%cement;（3）Conduct indoor freeze-thaw cycle tests on roadbed windblown sand,conduct0,1,3,5,7,10,and 15 freeze-thaw cycle tests on natural windblown sand and solidified windblown sand with 2%,4%,6%,8%,and 10%cement content,and analyze the mechanical properties of roadbed windblown sand under different conditions to identify the improvement effect of different cement content on roadbed windblown sand in the Shuangliao area of Jilin Province under freeze-thaw cycles.The experimental results show that under the same cement content,as the number of freeze-thaw cycles increases,the peak deviator stress,cohesive force,and internal friction angle of the sample show a downward trend,with the largest decrease occurring 0-5 times and stabilizing after 5 times;（4）Based on the indoor test results,a model of windblown sand roadbed was established using FLAC3D finite element software to analyze its deformation law under different cement content and freeze-thaw cycles.The simulation results show that with the increase of cement content,the displacement of the roadbed significantly decreases,and the displacement tends to stabilize after 6%cement content.As the number of freeze-thaw cycles increases,the settlement displacement first increases and then tends to be gentle.After 7 freeze-thaw cycles,the settlement displacement tends to stabilize.Under the action of freeze-thaw cycles,the lateral deformation of the solidified windblown sand roadbed is relatively small.