Experimental Characterization And Application On Bond Behavior Of Tensioned GFRP Tendons Embedded In Cemented Soil

Reinforced cement-soil pile and anchor structure(RCSPAS)is a widely used geotechnical solution to stabilize slope and fexcavation in engineering practice.Metal materials such as steel bar are conventionally adopted as reinforcement in such structures which are defected by the corrosion occurred in water-rich and corrosive environment.Glass fiber reinforced plastic(GFRP)tendon tends to be a very competitive alternative of steel bar and other metal material due to its high tensile strength and strong corrosion resistance.Aiming to extend the application of GFRP reinforcement in RCSPAS,experimental characterization and theoretical interpretation of interface bond behavior of GFRP reinforcement embedded in cemented soil were carried out in this work as a pioneer investigation.This work comprised of three separate parts with respective achievements as described in the following context as.Firstly,element pullout tests and uniaxial compression tests were carried out on 150 groups of pullout specimens and cubic specimens with varying cement content,soil moisture content and curing time.The impact of the above three testing variables on interfacebond behaviorof reinforced cemented soil and compressive strength of cemented soil.Furthermore,interface bond strength and unconfined compressive strength were correlated with cement content,soil moisture contentandcuring time respectively using fitting technique.Based on the measured bond-slip curve and failure characteristics,bond-slip mechanism of GFRP tendons embedded in cemented soil was qualitatively interpreted and interface bond-sliop model was established accordingly.Recommended values of bond stress and slip displacement corresponding to each characteristic point of bond-slip model were given through statistical analyses.Secondly,interface shear creep test setup was specially designed based on the element pullout test,and was used to obtain time history of shear creep displacement of GFRP tendon-cemented soil interface subjected to multi-grade loading.Chen's Method was used to transform the time history of interface shear creep displacement into a group of shear creep curve under different loading levels.The fashion of interface shear creep rate over time subjected to varying shear stress levels was analyzed.The linear viscous element in the original Burgers model was replaced by a non-linear viscous element expressed byanexponential function.The model was validated to be capable of fitting and predicting the interface shear creep behavior of GFRP tendon embedded incemented soil under constant load.Eventually,the findings and fruits obtained in this work were applied to the load transfer analyses of an case example in practice.Incorporating with tri-linear model characterizing interface between cemented soil and GFRP tendon,the presented interface bond-slip model in this work was used to derive the stress and deformation of the GFRP reinforcement.The ultimate bearing capacity and retaining stiffness of the reinforced cement-soil anchor were determined based on the load-displacement curve at top of the reinforcement.The applicability of GFRP reinforcement in RCSPAS was verified in the above design calculation of specific case example.