Stability Analysis of Soil Embankment Slope Reinforced with Polypropylene Fiber under Freeze-Thaw Cycles

Polypropylene fiber is a common soil reinforcement material which is used to reinforce a common clay in northeast China. Numerical analysis method was performed to investigate the effect of polypropylene fibers on stability of embankment slope subjected to freeze-thaw cycles. The orthogonal experiments of three factors (freeze-thaw cycle, fiber content, and fiber length) and three levels were carried out, and the corresponding nine groups of specimens were made, whose shear strength parameters (internal friction angle and bond force) were measured by direct shear test. Then, the experimental results were analyzed by analysis of variance and range analysis so that the optimum fiber content and fiber length can be determined. The finite element model of typical high-fill soil slope of freeway in northeast China was established whose basic material parameters were taken as the parameters of shear strength of different freeze-thaw cycles under the optimum fiber content and fiber length. The concept of shear strength reduction was introduced into the finite element model, and the convergence of the finite element model was taken as the judging criterion of slope stability. Thus, stability analysis of soil embankment slope reinforced with polypropylene fiber under freeze-thaw cycles was realized. The results show that the addition of fibers improves the cohesion under the action of freeze-thaw cycles, and the internal friction angle is improved in the case of freezing and thawing. This phenomenon leads to the improvement of the stability of the embankment slope in a freeze-thaw cycle. The improvement is particularly noticeable in the case, and this improvement effect decreases as the number of freeze-thaw cycles increases