Study On Pull-out Of Single Fiber From Matrix And Failure Mechanism Of Fiber Reinforced Cement Soil

There are a lot of silty soft soil in Zhoushan area.However,there are many unfavorable factors in the construction of buildings on the soft soil which mainly exists on the island.For example,seawater contains a large number of ionic components cause a series of engineering problems,such as low later strength,poor quality molding and cracks.In the actual project,people often add some fiber into the cement to improve its effect,inhibit the appearance of cracks and enhance its strength.On the basic of previous studies,it is reasonable to choose the tension tester,sensors,dial gauge and other instruments for monofilament polypropylene fiber drawing experiment.With the purpose of obtaining the change law of fiber tensile displacement curve in the process of sliding,there are three different embedment length of 5 mm,10 mm,15 mm polypropylene monofilament fibers,setting up time intervals with 3,7,28,90 days,by utilizing fiber tensile displacement curve in the fiber change process.There are three steps involved in for validating the legitimacy of single fiber drawing two-dimensional and three-dimensional finite element model,firstly employing the finite element software ABAQUS to establish two-dimensional and three-dimensional finite element models of single fiber drawing,with the theory of viscous,it is extremely straightforward to calculate the changing interface shear stress of fiber during the process of debonding as well as pulling out,the last step is the comparison between viscosity theoretical calculation results and the results of numerical simulation.With the foundation of reasonable construction in two-dimensional and three-dimensional models,between the transforming fibers and cement soil matrix,the coefficient of friction,the soil matrix,the elastic modulus of fiber,fiber end cohesive force,the fiber mortar,embedment length of fiber,the contact interface attribute,the gradient layer thickness,fiber and cement soil matrix of elastic-plastic,factors such as the cohesive unit parameters,it is necessary to explore the impact of above factors on the fiber pulling force-displacement curve.With the fiber content,fiber length,contact condition under the same conditions,prioritizing the interface unit,from the three-dimensional simulation,pulling force-displacement curve shares similarity with thepulling force-displacement curve,which reveals that the fiber tension partially depends on interface unit.Hence,the root cause of the failure of fiber reinforced is the destruction of the interface layer,then the relative technology research about fiber reinforcement is of great instructing significance for later studies.