Research On The Reasonable Distance Between Kunlunshan Rail Tunnel And The Proposed Highway Tunnel

This paper considers the temperature field,aiming at looking for the reasonableminimum distance between two cold regions tunnels.It focus on changes in thedistribution of temperature field within the rock between two tunnels over time.In order to minimize the scope of environmental damage,also convenient refer tolines have been completed for survey, design, construction, and avoid wasting extramanpower, material and financial resources. More things will appear that the newtunnel close to the existing tunnel.In this paper, based on the Kunlunshan tunnel of theQinghai-Tibet railway,there is a a new highway tunnel,it is25m~35m to the right sidewall of the existing tunnel from the horizontal position.With numerical simulation, datacomparison method,it can analyze the distribution of temperature field within the rockbetween two adjacent tunnel in cold regions. This paper also studied the rocktemperature in three specific locations at different times, different spacing andtemperature changes in different conditions. Finally, there is also using ANSYSsoftware optimization module (/OPT), the optimal design considering the temperaturefield to determine the the feasible region of two cold regions tunnels, and ultimatelydetermine the minimum reasonable distance between two cold regions tunnels isBHmin.First, for the influence of two adjacent temperature fields in cold region tunnels,combined with engineering examples,using means of numerical simulation of transienttemperature analysis,and chose25m35m spacing of the two extreme models and as atypical working conditions,it considered two cases:to build and not built,then calculatethe different states of temperatures within the rock at different times near theKunlunshan rail tunnel.the study shows influence of the temperature field within therock near the existing tunnel.The main rule is that the impact on the temperature fieldwithin the rock between two tunnels during construction period is much larger than theperiod after the new tunnel opended to traffic. The entire temperature field wassignificantly began to stabilize After the new tunnel opened to traffic(16years).Then use the ANSYS optimization module.The goal is that when the new tunnelopened to traffic,the interference due to the new tunnel construction with the existingtunnel original temperature field can be eliminated. Calculated in the same kind ofconstruction program,the impact of the new highway tunnel on the Kunlunshan railtunnel,then giving the optimal design constraints and critical condition,and ultimatelyto find a reasonable distance BH,and find the smallest reasonable distance BHmin.The main constraint condition for the optimal solution must meet isB∈[25m,35m],the critical condition must meet ΔT16max≤0.2℃,when B=BHmin,atthe D15position which is15m away from the existing tunnel,ΔT16max=0.19426℃＜0.2℃.the results are correct.Under the optimal solution,after the opening of the new tunnel,the highesttemperature within rocks between the two tunnels ranges from-2.681℃to-2.752℃.itdrops ranges only from1.9%to4.6%than the10year highest temperature. This suggests that,after the new tunnel opened to traffic, the interference to the originaltemperature field within rocks between two tunnels has been basically eliminated.