Study On Drainage Performance Of New Wicking Geotextile In Fine-Grained Soil Subgrade

Due to the decreasing of high-quality fillers in the country,fine-grained soil is widely used in subgrade filling.A large number of on-site measurements show that under the long-term influence of the atmosphere and groundwater,the soil moisture in the fine-grained soil roadbed far exceeds the optimal moisture content of construction control under long-term operating conditions.The performance degradation caused by subgrade wetting is one of the main reasons for the occurrence of subgrade pavement diseases and the reduction of service life,besides,the wetness and degradation of subgrade is concealed.In actual engineering,it is often found that the roadbed has already been seriously weakened after the road surface is damaged,and the roadbed repair is very difficult,resulting in an increase in the frequency of road maintenance and repair.Therefore,putting forward an effective roadbed humidity control technology has become the key of improving the long-term performance of the road.Based on the above problems,this paper obtains the existing subgrade humidity status through field measurement and literature research,and then adopts a new type of wicking geotextile with drainage fiber according to the survey of subgrade drainage requirements.Through a series of laboratory tests,the working mechanism and drainage effect of the new wicking geotextile in the fine-grained soil subgrade have been studied.The research results are of great significance for improving the stability of the fine-grained soil subgrade and prolonging the service life of the road.The main results and conclusions of the research are as follows:(1)The key to the new wicking geotextile’s water absorption and drainage lies in its hydrophilic micron-level fibers.Evaporation is the main way to determine its longterm water removal ability.(2)Under the same temperature,the water absorption and drainage performance of the new wicking geotextile is affected by the environmental humidity.If the humidity is lower,its water absorption and drainage performance will be better.(3)Under the same working conditions,the drainage effect of the new wicking geotextile in the soil(reduction of water content and rate of water content reduction)is better than that of ordinary wicking geotextiles.When the ratio of the laying length outside the soil to the buried length is 1.5,it can meet the drainage demand of the new wicking geotextile.(4)The water removal efficiency,dynamic and static characteristics of the new wicking geotextile in the roadbed model under cyclic loading are obtained.The moisture content of each layer inside the subgrade does not change much during the loading process.After 43 days of loading,the average moisture content inside the soil decreases from the saturated state to the equilibrium moisture content measured on site;under the same stress level,the saturated sample and the sample of optimal moisture content have little difference of deformation and modulus,indicating that the new wicking geotextile has the function of maintaining the support stability of the saturated sample.