中低速磁浮低置结构路基基床关键技术研究

Research on Key Technologies for Subgrade Bed of Ground Structure of Medium and Low Speed Maglev

为了确定基床合理的技术参数,完善其技术标准,对时速200 km及以下的中低速磁浮低置结构路基基床关键技术进行理论分析研究,采用布什理论明确动荷载影响深度,采用动变形、临界动应变控制指标明确不同基床填料所需的最小变形模量,据此进一步明确了基床结构、厚度、填料及其压实标准,并与现有技术标准进行对比。研究结论如下:(1)低置结构路基基床厚度可取为1.5 m,按两层结构设计,基床表层厚为0.3 m,基床底层厚为1.2 m;(2)基床表层采用级配碎石或A组填料填筑,压实系数不宜小于0.95,地基系数K30不小于150 MPa/m;基床底层采用A、B组填料或改良土填筑,压实系数不小于0.93, A、B组填料地基系数K30不小于130 MPa/m,改良土填料地基系数K30不小于100 MPa/m;(3)本文研究成果与现行应用成果相比,基床结构尺寸、压实标准等进行了合理减小或降低,其设计结果更为合理,也较为经济。

In this paper, the key technologies of subgrade bed of ground structure at the speed of 200 km/h and below are theoretically analyzed and studied. The influence depth of dynamic load is defined by Bush theory, and the minimum deformation modulus required by different bedding fillers is determined based on dynamic deformation and critical dynamic strain control indices. On this basis, the structure, thickness, packing and compaction standards of the foundation bed are further clarified. And these technical standards are compared with the existing technical standards so as to confirm reasonable technical parameters and improve technical standards of the subgrade bed. The conclusions of this paper are as follows:(1)The thickness of subgrade bed can be 1.5 m. According to the two-layer structure design, the thickness of the surface layer of the subgrade bed is 0.3 m and that of the bottom layer is 1.2 m.(2)Graded macadam or group A filler can be used to fill the surface layer of subgrade bed, and compaction coefficient should not be less than 0.95 and foundation coefficient K30 should not be less than 150 MPa/m;Groups A and B or improved soil are used to fill the bottom layer of subgrade bed, and the compaction coefficient is not less than 0.93;ground coefficient K30 of group A and B is not less than 130 MPa/m, and that of improved soil is not less than 100 MPa/m.(3)Compared with current application results, the size and compaction standard of the subgrade bed are reduced reasonably, and the design results are more reasonable and economical.