| In view of the fact that the construction of concrete culverts under the railway line in coal mining subsidence areas takes a long time,does not have the ability to resist deformation,and cannot meet the current situation of safe driving on the upper part,it is proposed to use steel belt reinforced HDPE pipes as water passing pipe culverts.This paper takes the special railway line in Huainan coal mining subsidence area as the research background.Through numerical simulation and comparison with theoretical formula calculation results,the force response law of pipe culvert is studied as the embankment increases and the ground sinks and deforms,and obtains Its scope of application when using traditional backfilling methods.On this basis,the influence of ring stiffness and different backfilling forms on the performance of pipe culverts is studied,and the actual use effect is analyzed and evaluated in combination with engineering applications.The main research results obtained are as follows:(1)When the minimum thickness of the pipe top covering soil is 0.7m,after the completion of construction and backfilling,all pipe diameters and pipe culverts can meet the requirements of rapid construction and resumption of traffic.Within the range of 0～4m of embankment heightening,the deformation and stress growth trends of pipe culverts of different pipe diameters are roughly the same.Within the range of 4～10m heightening of the embankment,the growth trend of deformation and stress began to increase.The load effect of the upper railway gradually weakened after the embankment was raised by 4m.(2)The annular steel belt in the pipe culvert can transmit stress well,and the inner polyethylene generally will not be damaged.The overall safety performance of the pipe culvert is as follows: pipe bottom>pipe top>pipe side.It is recommended that when the pipe culvert is used in the coal mining subsidence area,the allowable vertical diameter deformation rate does not exceed 2%,and the ratio of the yield strength to the maximum von-mises stress,that is,the safety factor,is used as an important criterion.(3)The widening of the pipe side backfill range has a small improvement in the performance of the pipe culvert,which is only 5.04%.After the pipe is backfilled with cement stabilized sand,the lifting effect is obvious,and the impact of surface deformation can be effectively reduced.The central angle of the regional backfill should not be less than 120°,it is recommended to be all-inclusive.When the upper part of the pipe culvert has conditions such as "sandwich type" road embankment ballast water and coal gangue filler penetration and erosion,the backfill must be filled with cement stabilized sand.At this time,the safety performance is increased by 170.18%,which can meet the needs of the pipe culvert in the future embankment.Requirements for safe use when heightened by 10 m.(4)The degree of influence of surface deformation on the performance of pipe culverts is: tilt deformation>positive curvature deformation>negative curvature deformation.The center of the basin in the coal mining subsidence area and the negative curvature area are unfavorable areas for the use of pipe culverts.This paper presents the applicable scope of pipe culverts with different ring stiffness during traditional backfilling.When the future settlement depth exceeds the applicable scope,cement stabilized sand backfill construction needs to be carried out in advance.(5)In the coal mining subsidence area,it is recommended to replace the steel belt reinforced HDPE pipe culvert with the same material with a double small diameter pipe culvert of the same material on the premise of ensuring the water flow rate.Compared with traditional concrete pipe culverts,steel belt reinforced HDPE pipe culverts are easy to construct,have strong anti-deformation ability,can realize fast traffic,and can well adapt to the complex geological environment of continuous subsidence in coal mining subsidence area.There are 61 figures,55 tables,and 92 references in this paper. |
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