Abstract
This study proposes a new waterproof sealing layer to reduce the impact of water on subgrade beds. The proposed waterproof sealing layer is composed of a polyurethane adhesive (PA) mixture, which aims to control interlaminar deformation and prevent seepage. A variety of laboratory tests were first performed to analyze the attenuation characteristics and mechanical properties of various polyurethane polymer (PP)-improved gravel mixtures under thermohydraulic coupling effects. In addition, a waterproof performance model test of the PP-improved gravel layer was conducted to investigate its waterproof and drainage performance and hydraulic damage mechanism. Finally, the feasibility and effectiveness of the surface structure of the waterproof drainage subgrade bed containing the PA mixture was tested in combination with the treatment project of the Ciyaowan station of the Baoshen heavy-haul railway. According to the experimental and model results, (1) the waterproof layer containing the polyurethane mixture exhibited satisfactory stiffness, elasticity and flexibility. The waterproof layer containing the polyurethane mixture also controlled the deformation between layers, and its mechanical properties remained stable. (2) The waterproof layer with the dense polyurethane mixture performed well in terms of the waterproof aspect, and no infiltration occurred under cyclic load (3). Long-term field monitoring revealed that the effect of the implementation of a PP-improved gravel layer to treat mud pumping was remarkable. The settlement of the PP-improved gravel layer only reached 13.21 mm, and the settlement remained stable in the later stage.
Highlights
In recent years, the waterproof layer has been found that to suffer many defects, e.g., cracks, breakage, pulverization and other diseases, when applied in the ballastless track of high-speed railway subgrade surfaces [1,2,3]
The dynamic detection method was applied to evaluate the effect of the polyurethane polymer (PP)-improved gravel layer in the mud pumping treatment
The effectiveness and feasibility of the PP-improved gravel layer in the mud pumping treatment of the Baoshen heavy-haul railway were confirmed through data analysis of the dynamic detection results
Summary
The waterproof layer has been found that to suffer many defects, e.g., cracks, breakage, pulverization and other diseases, when applied in the ballastless track of high-speed railway subgrade surfaces [1,2,3]. Different degrees of hydraulic damage to the subgrade surface layer have been reported [4,5,6], especially in high-rainfall areas. These distresses mainly result from insufficient consideration of the specific operating environment and performance of the ballastless track subgrade [7,8,9]. Many scholars have performed studies on the hydraulic damage to the subgrade bed surface In these studies, the method to improve water stability and prevent erosion has attracted considerable attention [10,11,12,13]. Wpaotseitreprsotroufcmtuorederleqteusitrsemwenretscofntdhuecsteudbgtoravdeerbifeyd thsuereffafceectiinveanheisgsho-rfatihnefaPllPa-irmeap, raosveerdiegsroafvlealbloaryaetro.ry tests considering the thermohydraulic coupFilninagllyef,fceocmtsbwinaesdpweriftohrtmheedp.raNcteixcta,lwenagteinrpeerorionfgmcaosdeeol ftethstesBwaeorseheconnhdeuacvtye-dhatoulvreariilf-y wthaye,etfhfeectciovnenstersuscotifotnhefePaPs-ibimiliptyroovfedthgeraPvPe-limlayperor.ved gravel mixture as the waterproof sealingFilnaaylelyr,ocfotmhebsiunbedgrwadiethbethdesuprfaaccteicaanl denthgeineefefercintigvecnaessesooff the PBPa-oimshpernovhedavgyr-ahvaeul l mraixiltwuraey,inthseucbognrastdreucbteiodndfieseaasisbeiltirteyaotmf tehnet PwPe-riemvperroivfied.gravel mixture as the waterproof sealing layer of the subgrade bed surface and the effectiveness of the PP-improved gravel
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