Study On Calculation Method Of Subgrade Settlement Of High-speed Railway In Goaf Site

With the rapid development of China’s high-speed railway network,some high-speed railways inevitably pass through mined-out areas in some areas where mineral resources are widely distributed.The premise of high-speed train running is to ensure the smoothness and stability of high-speed railway track.The most critical problem in building high-speed railway in mined-out area is to strictly control the subgrade settlement.Therefore,it is very important to study the calculation method of subgrade settlement of high-speed railway in mined-out area.Based on the engineering background that the section DK259+135.95-DK259+710.00 of Taiyuan-Jiaozuo high-speed railway crosses the goaf site,this paper studies the settlement calculation method of the high-speed railway subgrade in the goaf site by combining theoretical analysis,settlement calculation,settlement prediction and numerical simulation.The main conclusions are as follows:(1)This paper analyzes the main factors affecting the settlement of high-speed railway subgrade in goaf,analyzes and sums up the settlement mechanism of high-speed railway subgrade in goaf from macroscopic and microscopic aspects,expounds the main components of subgrade settlement,and reveals the interaction mechanism between goaf foundation and high-speed railway subgrade.(2)The calculation method of subgrade settlement of high-speed railway in goaf site is established,including subgrade settlement during filling,subgrade settlement under train load,and surface settlement in goaf under subgrade load.Based on the field measured data of high-speed railway subgrade settlement,six methods are used to predict and analyze the high-speed railway subgrade settlement.Based on the variable weight combination theory,15 combination prediction models of high-speed railway subgrade settlement are established,and the applicability of each prediction model is evaluated.The results show that the combined prediction models of hyperbolic method-Poisson curve method and Poisson curve method-Hoshino method have the highest accuracy and are more applicable to the prediction of high-speed railway subgrade settlement.(3)Using FLAC3 D software,the main influencing factors of high-speed railway subgrade settlement in goaf site are numerically analyzed.The results show that the settlement of high-speed railway subgrade increases linearly with the increase of subgrade height,and the disturbance range of subgrade load on goaf overburden increases with the increase of subgrade height.With the increase of train speed,the subgrade settlement increases nonlinearly,and the attenuation of vertical displacement mainly occurs in the subgrade structure.When the high-speed railway subgrade is located directly above the center of the goaf,the disturbance degree to the overburden rock in the goaf is the greatest,and the subgrade settlement is the largest.As the subgrade is far from the center of the goaf,the subgrade settlement gradually decreases,and the position of the maximum settlement shifts to the direction of the goaf,and the slope degree of the subgrade surface gradually increases.When the high-speed railway subgrade is located directly above the boundary of the goaf,the slope degree of the subgrade surface is the largest,and the uneven settlement degree of the subgrade is the highest.(31 pictures,15 tables,84references)...