Dissertation > Excellent graduate degree dissertation topics show

Study on Stability for Saline Soil Subgrade and Pile Foundation in Permafrost of Cold and Arid Region

Author: LiuLu
Tutor: WuYaPing
School: Lanzhou Jiaotong University
Course: Road and Railway Engineering
Keywords: Cast-in-place Pile Group Hydration Heat Refreezing Rate Saturated FineSand Creep
CLC: U213.14
Type: Master's thesis
Year: 2013
Downloads: 1
Quote: 0
Read: Download Dissertation

Abstract


With the pace of China’s western development progresses, more and more railways,highways and other transportation projects and facilities are built in the western region andput into use gradually. Such as the Qinghai-Tibet Railway line linking and put into operation,which greatly facilitates the Tibet region and the eastern part of the economic and culturalexchanges. At the same time, in order to accelerate the development of the local economy inQinghai and other western provinces and cities, many local railways are built to facilitate thedevelopment and utilization of regional resources with nearly the pace of large-scaledevelopment of the western region. However, special soil such as permafrost, saline soil isdifferent from the general soil due to the special geographical location and natural climaticconditions of the western, which bring difficulties and inconvenience to the construction ofrailways, roads and other engineering structures and safe use of them.In railway construction process of the permafrost regions, in order to ensure the smoothrailway construction and safe operation, the "Bridge-Instead-of-Embankment" dry bridgestructure to the principle of the protection of permafrost in the design of the Qinghai-TibetRailway construction has been a large number of applications. However, due to drillingfriction heat in the process of bored pile construction, concrete hydration heat, and moldingtemperature, it is inevitable to bring thermal disturbance to permafrost, which may causes soilmelts around the piles, so that the pile bearing capacity drops to affect the progress of theconstruction of the railway and safe operation. In this paper, with railway bridge engineeringexample in the permafrost area, consider the field hydrogeological conditions, atmospherictemperature changes, initial ground temperature field, concrete casting temperature andphase-change effect, deduced three-dimensional heat conduction equation of concretehydration heat within the pile foundation and permafrost, and given the initial conditions andboundary conditions at the same time. On this basis, geothermal field of finite element modelof pile in frozen is established, calculate and analysis impact on foundation permafrostrefreezing process between hydration heat of a common concrete with low temperature earlystrength and hydration heat of a new type of concrete with low hydration heat lowtemperature and early strength. Results obtained both the foundation permafrost temperaturefield is basically the same law. But due to the different hydration heat between the twoconcretes, refreezing time of permafrost which surrounding the ordinary concrete pile lagslightly in the same position at the new low hydration heat low temperature early strengthconcrete pile, while the former refreezing rate also smaller than the latter, and this differencestill can not be completely eliminated in five years after casting. The low hydration heat lowtemperature early strength concrete can significantly shorten the construction time. In order to make more effective development and utilization of the local domain salt lakenatural resources to promote the rapid development of the local economy, the railway isconstructed between Xitieshan and North Hob Johnson in North Hob Johnson Lakes region inQinghai Province. However, in North Hob Johnson Lakes railway subgrade foundationmemory in large tracts of the surface is covered with a salt crust with high salt saturated finesand due to the saline lake of cold and arid region the special engineering geologicalconditions, which causes difficulties in building of the railway in this region. To summarizethe settlement laws of high salt saturated fine sand subgrade, and evaluate the treatment effectof the foundation on this basis, in this paper three-parameter H-K model is selected tosimulation analysis the rheological deformation of the test subgrade, and gives constitutiveequation and creep equation. Using ANSYS finite element software to calculated settlementdeformation of high salt saturated fine sand subgrade model, combined with field settlementtest data, and verify reasonable ground treatment of the region. And at the same time, analysisand forecasting the seasonal frost heave deformation of the subgrade, combined with indoorfrost heaving test and field test. The results obtained that there may be frost heave disease inthis region and it is recommended to take certain anti-frost heave measures.

Related Dissertations

  1. Research of the Influencing Factors on Constrained Concrete Flexural Member Filled with Steel Tube,TU398.9
  2. Studies on Railway Bridge Coupled Vibration of Train Rail-Bridge System Under the Influence of Creep,U441.3
  3. Experimental research of Beijing - Shanghai high-speed railway in deep soft soil section bridge foundation,U443.15
  4. Structural Stress Analysis of Small and Medium Span Expanded Bridge,U441
  5. Analysis and Experimental Study about Extended Structure of Bridge,U441
  6. Lacustrine soft soil physical and mechanical properties and the creep characteristics of,U212.22
  7. The Analysis of Subgrade Settlement after Construction Considering Rheology in Soft Soil Area,U213.1
  8. Experimental Study on Consolidation and Creep of Expansive Soil,TU411
  9. Research on Shrinkage and Creep Effect for High-Pier & Long-Span Continuous Rigid-Frame Bridges,U441.5
  10. Research on Temperature Effects and Shrinkage-Creep Analysis for Long-span Continuous Rigid Frame Bridges,U441.5
  11. Study on Mechanics Properties of Steel-concrete Combinating Beam Curve Bridge,U448.42
  12. Simulation Analysis of Prestressed Concrete Continuous Rigid Frame Bridge,U445.4
  13. Construction Monitoring and Relative Parameter Analysis of Cangxi Extra-Large Bridge,U445.4
  14. Research on the Adhesion Control Mehtods Based on the Optimal Creep Rate,U211.5
  15. Study on Triaxial Creep Characteristics of Loess,TU411
  16. Experimental Study and Ruts Calculation Based on Viscoelastoplastic Model of Asphalt Mixture,U414
  17. Investigation about Reconstruction Technology of Widening for Rigid-frame Arch Bridge of Reinforced Concrete,U445.6
  18. Reaserch on the Long-Term Creep Deflection of Prestressing Concrete Continuous Rigid Frame Bridges,U448.23
  19. Analysis on the Mechanical Responds of Asphalt Pavement under Heavy Traffic and Rutting Prediction,U416.217
  20. The Structure Performance Analysis of Pre-stressed Concrete Hollow Slab Bridge Being Widened and Renovated,U445.6
  21. Study on Temperature Field and Temperature Effect of Long-span Precast Concrete Box Girder,U448.213

CLC: > Transportation > Rail transport > Railway Line Project > Line constructed > Subgrade > Special areas roadbed
© 2012 www.DissertationTopic.Net  Mobile