Experimental Research On Creep Properties Of The Geosynthetics In The GRPS Embankment

As a new type of road improvement technology,the Geosynthetic-reinforced and pile-supported embankment(GRPS embankments)has very broad development prospects in the treatment of bad soil subgrade.The Creep of geosynthetic materials in GRPS embankment may affect the deformation of embankment to some extent and threaten the safety and stability of the superstructure.At present,the creep properties of geosynthetic materials of GRPS embankment are rarely studied at home and abroad,and the standard value of creep of reinforcement is often calculated by conventional tensile test method in embankment design specifications.There is also a certain difference between the stress mode of the conventional creep test device and the GRPS embankment.In particular,the geosynthetic material in the GRPS embankment will be affected by the vertical top pressure of the pile foundation.Conventional creep test equipment has been unable to meet the requirements of creep properties test research.In order to provide an effective new testing device for creep properties of geosynthetics,a creep test device under top pressure was developed in this paper.The research on creep properties of geosynthetics of GRPS embankments under the action of top pressure is still to be carried out.The main conclusions of this paper are as follows:(1)Based on the analysis of the stress mechanism of the GRPS embankment,it is found that there is a difference between the stress properties of the top-pressure creep and the traditional creep.From the perspective of the top-pressure creep,five groups of bursting tests and three groups of 2500 h top-pressure creep tests are carried out in this paper.The test results showed that the top pressure creep properties of geosynthetic materials can be fitted by logarithm function and power function,and the fitting curve correlation index was generally higher than 0.98;When the design life is 1010 h,the lower limit of long-term allowable bursting strength of Mirafi PET geosynthetic materials ranges from 1086.3N to 1094.36 N.(2)The top pressure creep displacement curve was mainly composed of three types of line segments,showing a change rule of rapid growth to gentle growth to slight change to stable.The creep of Mirafi PET geosynthetics changed slightly at the time of >240 h,and the creep degree remained basically unchanged.(3)From the perspective of top pressure creep,the conventional creep reductionfactor,gauge creep reduction factor and top pressure creep reduction factor were compared and analyzed in this paper.The results showed that the creep reduction coefficient used in engineering was far lower than the real value,which caused certain danger to the safety of engineering.In order to ensure the safety of the GRPS embankment,it is necessary to consider the creep properties of the geosynthetic materials of the GRPS embankment.The reduction factor of top pressure creep strength of Mirafi PET geosynthetic material is between 3.35 and 3.37,which has important guiding significance for the long-term development of GRPS embankment.