Study On The Effect Of Moisture On Frozen Subgrade Deformation And Drainage Measures

Moisture is one of the key factors that affect the permafrost roadbed stability. This paperstudied on the moisture affect deformation of permafrost subgrade supported by Beian toHeihe highway, Yichun to SuiHua highway and Linkou to Daluomi highway in Heilongjiangprovince. The main results are as follows:1）To analysis the types and reasons of highway diseases, based on the investigation ofthe natural environment and the highway site to the typical section in the Heilongjianprovince, with the method of site investigation and data collection.This paper analysis hydrothermal changing characteristics in subgrade at different stage,such as initial frozen stage, the developing frozen stage of development, the initial melt stageand the developing melt stage, based on temperature and moisture data.2）Based on the phase transition temperature field control equation and moisturemigration control equation considering moisture migration caused by the temperature gradient,the deformation field control model was established. It put forward the method to solvedeformation field model with the thermal-fluid coupling model of finite difference softwarethe FLAC3D.3）This paper established subgrade temperature field numerical model with roadsidewater and analyzed the impact of moisture on the subgrade temperature fields. Studiesshowed roadside water was the key factor to cause the uneven deformation in permafrost.4）It established subgrade deformation field numerical model with seasonal roadsidewater and analyzed water effects on the subgrade deformation. On this basis, this paper alsocalculated the development process of the roadbed deformation field under the condition ofdifferent water area and time. The results showed that the water area in3meters apart fromfoot of the slope significantly affected subgrade deformation. In order to reduce moistureaffect on subgrade deformation, roadside water should be discharged in the range of10daysas soon as possible.5）This paper put forward drainage principle and drainage measures from reducing theroadside water and improving the structure of the subgrade, based on the simulation of the water changing characteristics and water infiltration effects on frozen embankment.