Research on Indoor Experiment and Construction Technique of Cement Reinforcing Collapsible Loess Railway Foundation
|Course||Traffic and Transportation Engineering|
|Keywords||Passenger transport subgrade collapsible loess Construction Technology|
The formation of collapsible loess is that: Under certain pressure, when wetted by water,the soil structure of the loess destroyed rapidly and the significant collapsible deformationoccurred as the loess intensity decreases.There are two types of collapsible loess whoseproperties were defined respectively as deadweight collapsibility and non-deadweightcollapsibility.The roadbed of the high speed railway was composed of three parts which are foundation,bed (surface and ground floor) and the filled soil under the bed.The bed and the filled soilunder the bed were composed of granular media which has poor performance on vibrationresistance and deformation.So they become the most unstable part of the whole structure inhigh-speed railway system.Such subgrade will bring a significant impact on the operatingconditions of the high-speed railway.Under the action of repeated load, the roadbed willproduce large deformation and cause subgrade settlement which will lead to the verticalsettlement of the track. The final result is that the lines have poor stability and smoothnesswhich will cause inconvenience in the subsequent maintenance of the High speed railway.Zhengxi Passenger Railway was the first passenger line built in the loess area in China. Itwas from Zhengzhou to Xi’an and the intermediate stations included Luoyang, Sanmenxiaand Weinan. This line was the important part of the Long-Hai railroad in the rapid railwaypassenger network which was called the "four vertical and four horizontal" system in the"eleventh five-year" plan of China ministry of communications.The whole line, along whichthe loess section was80%coverage, was built on the quaternary loess layer characterized asnon-deadweight.collapsibility. According to relevant provisions, the collapsible classificationlevel of the loess layer wasⅠ. The thickness was9.000m to13.000m. The loess layerbelonged to the ordinary soil of level Ⅱ.Based on the research at home and abroad, in combination of the engineering practice ofpassenger transport from Zhengzhou to xi’an,The physical and mechanical characteristics andparticle grading of the raw material were studied. The padding impact on the collapsibility ofloess on the line was also explored.By making comparative analysis on the chemical andphysical properties of the collapsible loess before and after the soil improvement, the Construction Technologies and key parameters of soil improvement was studied and theconstruction program was determined through experiment.The research results will haveguiding significance on the subsequent loess improvement construction and have referencevalue for future engineering practice.