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Research On The Surrounding Rock Temperature Field And Frost Heave Force Of Qilian Mountains Tunnel Of Lanzhou-xinjiang High-speed Railway

Posted on:2018-11-18Degree:MasterType:Thesis
Country:ChinaCandidate:G YangFull Text:PDF
GTID:2322330533462736Subject:Geotechnical engineering
Abstract/Summary:PDF Full Text Request
The tunnel project in the cold region is a special project in the transportation infrastructure.The cold environment has caused new difficulties and brought more challenges in the design and constru,ction of the tunnel.Also,the higher requirements have been put forward for the operation and management after the completion of the tunnel.So the study of the temperature field and frost force in cold regions has great significance for the tunnel construction.In this paper,the Qilian Mountains Tunnel of Lanzhou-Xinjiang high-speed rail w-as taken as the basis of the project.Analyses of the key data of the on-sit monitoring scheme,the measured temperature monitoring and the laboratory test were performed.And in this paper,theoretic research and the finite element numerical simulated calculation are combined to conduct the systematical research.It was found that the thermal conductivity of sandstone increased first then decreased with the increase of water content in Qilian Mountains area.The thermal conductivity of sandstone increased with the fall of temperature.The volumetric specific heat capacity of the sandstone decreased with the increase of water content.The volumetric specific heat capacity of the sandstone at room temperature was the smallest.With the decrease of the temperature,the volumetric specific heat capacity first increased and then decreased.In the case of negative temperature,the lower the temperature was,the greater the confining pressure was,and the greater the triaxial compressive strength was.With the decrease of temperature,the plasticity of the frozen rock would be weakened and the brittleness would be strengthened.Next,the tunnel temperature monitoring scheme was formulated and an analysis of the field measurement results has been carried out to obtain the distribution characteristics of the surface temperature,the tunnel environmental temperature and the surrounding rock temperature of Qilian Mountain Tunnel.The distribution pattern of the ambient temperature and surrounding rock temperature field of the tunnel were found.The analysis of the monitoring data could provide useful information for the design of the insulation layer.An analysis of the distribution of the temperature field of the surrounding rock without the insulation layer at the temperature of-10?,-20?,-30?,or-40? was also carried out through numerical simulation software FLAC3D.The simulation result indicated that the radial temperature distribution of the surrounding rock agreed well with the actual monitoring results.The distribution of the temperature field in the most unfavorable condition of the surrounding rock with the insulation layer was simulated,and a comparison was conducted between the case with and without thermal insulation layer to provide a basis for selection of the insulation material.Finally,the FLAC3D,was conducted to research the distribution of the frost heave force in the different locations of the tunnel lining and the effects of the surrounding rock grade,depth of freezing and the moisture content of surrounding rock on the frost heave force.And the distribution map of the frost heave force along the tunnel lining was computed.It was found that the distribution characteristics of the frost heave force along the tunnel ling is that the frost heave force in the center of the tunnel invert was the smallest,and the frost heave force at the corner was the largest.Among the three elements of surrounding rock grade,moisture content and frost heave depth,moisture content is the biggest influencing factor to the magnitude and distribution of the frost heave force,the next is the depth of frost heave,the essence of the influence of the surrounding rock grade to the frost heave force is rigid.
Keywords/Search Tags:Cold Region tunnel, Frost heave force, Thermal physical parameters, Temperature field, Monitoring
PDF Full Text Request
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