| To control the deformation of surface layer of subgrade,the overall settlement of subgrade and to resist the destruction of various adverse factors,for high-speed railway,are the key technical issues in the designation of ballastless track.At present,the common fillers of surface layer of subgrade,which is used at home and abroad,are mainly graded broken stone and asphalt concrete.In order to improve the mechanical behavior of high-railway structure,this thesis introduces the fiber reinforced foamed lightweight concrete(FRFLC)into surface layer of subgrade of high-speed railway,according to the main functional requirements of filler of surface layer of subgrade and the successful application of FRFLC in civil engineering in recent years.While there is still little research about the application of FRFLC in The structure of surface layer of subgrade,Therefore,this thesis uses the method that combine indoor test and numerical analysis to carry out the study on the effect of this new materials.The main research work and conclusions are as follows:(1)In order to study the effects of glass fiber on properties of foamed lightweight concrete,uniaxial compressive strength tests,tensile splitting tests and flexural strength test were used on the specimens with four of lengths and different contents.The results show that the mechanical strengths of FRFLC are higher than that of ordinary lightweight concrete,for the four sets of foamed lightweight concrete,the unconfined compressive strength,the splitting tensile strength and the flexural strength first decreased and then increased with the increase of fiber content.There are optimal values of fiberglass content:When the fiber length was 6mm and the content was 0.4%,the unconfined compressive strength and the splitting tensile strength of the foamed lightweight concrete were the hightest,increased more than 50%compared with the content was 0.For the results of the flexural strength test,the maximum flexural strength was 1.01MPa increased by 108.5%when the length was 3 mm and the content was 1.0%.(2)To introduce FRFLC into surface layer of subgrade structure,after adding fiber,the maximum elastic modulus of the foamed lightweight concrete is 364.94?401.81MPa,which is larger than the elastic modulus of bottom layer of subgrade,meets the theory of stiffness matching.The static analysis and dynamic analysis of track-subgrade system were taken out by large finite element analysis software ANSYS in this paper.In the static analysis,non-deformability and anti-crack resistance are analyzed.The results show that all of the four sets of foamed lightweight concrete meet the the requirement,and D6(when the length was 6mm,the content was 0.4%)performed best.To compare the vertical variation of the dynamic stress and dynamic displacement of four sets of fiber reinforced subgrade bed structures in subgrade center,below the rail and the edge of base plate,the results show that,the resistance to deformation and the ability to reduce dynamic stress and dynamic displacement in the subgrade of D6 when train passes is strongest.(3)Comparing with graded broken stone and asphalt concrete,the results showed that the material properties of the three fillers have their own advantages and disadvantage,and there are some characteristics of FRFLC that the others don't have,such as light quality and good construction characteristics.In terms of static response and dynamic response,the resistance to deformation and the ability to reduce dynamic stress and dynamic displacement in the subgrade of D6 when train passes is strongest.While its crack resistance is slightly inferior to the asphalt concrete reinforced structure.Economic analysis shows that D6 was slightly more expensive than asphalt concrete reinforced structure,did not have a direct economic advantage. |
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