ANALYSIS OF NEGATIVE PRESSURE DISTRIBUTION OF VERTICAL DRAINAGE CHANNELS FOR STABILIZATION OF ROADBED BY VACUUM PRELOADING

Three negative pressure distribution modesline mode,parabola mode and exponent mode were respectively applied in the vertical drainage channels of the vacuum preloading test section of Beijing-Shanghai High-Speed Railway under identical conditions.Finite element simulation was made in calculation of the consolidation process of roadbed.The calculation results were compared with measured data.Differences of calculation results were found with the above mentioned three distribution modes.Reasons causing the differences between calculation results and measured data of the three distribution modes were analyzed.Analysis results show that,it is not very rational that negative pressure linearity-decrease from one value to zero or the other value along up-to-down vertical drainage channels.This will cause too much difference between calculation results and measured values.The negative pressure distribution mode of exponent type is commended to apply in silts.But the negative pressure distribution mode of line type is available to the vertical drainage channels in crust up silt.