Pull-out Mechanism And Strength Prediction Of Cement-soil Reinforced With Inclined Single Fiber

Muddy soil in the reclamation area of tidal flats is a typical marine sedimentary soil.Due to the extremely low strength of the muddy soil,it is difficult for the engineering development there.In order to adapt to the engineering development in the area,the general cement curing silt technology is hard to deal with the problem that the erosion of seawater caused the poor curing effect of the later expansion of the cement-soil.For coastal areas with large seawater composition in soil,the reinforced cement-soil technology can alleviate the problems caused by the later expansion of the reinforced soil by strengthening the addition of reinforcement,and ensure the bearing capacity of the strengthened soil.The failure mechanism of the fiber reinforce cement-soil depends on the interaction between fibers and cement-soil matrix.The mechanism of fiber reinforcement is revealed by experimental study and the method of introducing pull-out energy.Based on the single fiber pull-out test,the effects of three factors on fiber reinforcement are analyzed by comparing the pull-out curves of cement-soil specimens within four embedded lengths(5-20mm),five embeded angles(0-60 °)and four curing ages(7-90d).The strength of the cement and the reaction between the interfaces affects the tensile strength of the specimen.It is insufficient for only considering the peak value of tensile force or the corresponding fiber displacement in the pull-out curve,so the fiber pull-out energy is introduced which can better reflect the effect of reinforcement.The influence factors of fiber reinforcement are verified by microcosmic method.It is found that the damage of matrix increase with the angle and length,and the fiber fracture occurred with the increase of age.According to the influence of pull-out test and micro-discovery on fiber tensile force,a three-dimensional finite element model was established.The material parameters of brittle crack were used to simulate the matrix failure,the influence of the different embedded length of the tensile peak value in pull-out process was compared,and the tensile peak value in pull-out test was fitted.Based on the prediction theory of bending strength of four-point bending experiment proposed by Armelin et al.,the strength of three-point bending experiment in the experiment was predicted and compared with the measured strength.The theoretical strength can basically fit the experimental strength.