Research On Application Of Aeolian Sand And Improved Aeolian Sand In Subgrade Engineering Of Menghua Heavy Railway

With the rapid development of high-speed railway and heavy-duty railway in China,the requirements of strength,stiffness and stability of subgrade in railway subgrade are getting more and more higher,and requirements of packing of the physical and mechanical characteristics and construction technology of roadbed are getting more stringent.However,for constructed railway in the western desert,the excellent filler is the lack of around,there are only rich aeolian sand resources.Aeolian sand is a group of C filler,can only be used for the following parts of the roadbed filling,can not meet the requriements of roadbed bottom.This article relies on Menghua heavy rail railway aeolian sand roadbed engineering,based on the indoor experiment,the physical characteristics,mechanical properties and compaction characteristics of aeolian sand and modified aeolian sand are studied.Through the field test,the parameters such as compaction mechanical selection,compaction number,load combination,filling thickness and moisture content of heavy load railway subgrade roadbed are analyzed,and studies construction technology of the heavy railway subgrade of seolian sand.The calculation model of heavy load railway subgrade is established by FLAC3 D,and the deformation law and stability of aeolian sand and improved aeolian sand roadbed are studied.The main research work and conclusions are as follows:(1)The physical properties of aeolian sand show that the particles of the aeolian sand are very fine and very uniform,the nonuniformity coefficient is between 1.94 and 2.08,the curvature coefficient is between 0.99 and 1.05,and particle size 0.075 mm above the sample quality exceeds the total sample quality of 85%,belonging to the particles gradation bad fine sand,in accordance with the norms of classification belongs to the C group filler.(2)The compaction test of aeolian sand and cement improved aeolian sand is carried out.The results show that the compaction curves of aeolian sand and cement improved aeolian sand are inverted S-type,and the maximum dry density of cement modified aeolian sand is higher than the aeolian sand,and the maximum dry density increases with the increase of the cement content.(3)The moisture content of natural aeolian sand is very low,the frictional resistance between the particles is larger,and the instantaneous shear strength of the compaction work on the surface layer of the aeolian sand is less than the instantaneous shear strength,the surface sand is difficult to compact.Compaction method of aeolian sand subgrade recommended wet compaction.The wetting method is impacted greatly by the penetration and evaporation.The moisture content of the aerosol fillers is decline very greatly in 0 ~ 2h,and gradually close to the natural water content after 2h.In order to ensure the quality of compaction and control costs,should be sprinkled in the water drying about 1 hour or so rolling effect is better.(4)The results of on-site rolling test show that the loosening coefficient of aeolian sand is 1.2 ~ 1.3,and the geogrid is laid on every 60 cm thick layer.In order to facilitate the construction of the proposed selection of fill the thickness of loose piles of about 40 cm,after the compaction of the thickness of about 30 cm filling program is more reasonable;With the bulldozer paving,and combined loader compaction 5 times,double control index foundation coefficient K30 and compaction coefficient K can meet the following subgrade compaction standards.(5)Through the establishment model of the aeolian sand embankment is analysised,Whether reinforcement,whether the embankment with slope protection and optimization of the reinforcement analysis.It is concluded that the reinforcement of the aeolian sand roadbed is more suitable.