Load Mechanisms and Design Method for Karst Subgrade Reinforced by Horizontal Geosynthetic Reinforcement

In order to solve the problem that the existing design methods do not consider the frictional effect of the horizontal reinforcement, and the deformation of the railway surface was underestimated, the load mechanism for railway karst subgrade reinforced by horizontal geosynthetic reinforcement was studied and a new design was proposed. Firstly, the mechanism of load transfer and mechanical model were indicated. And then, from the perspective of strictly controlling the deformation of railway subgrade surface, on the basis of the existing design methods, taking into account the frictional effect, assuming that the strain in anchorage zone changes linearly, the correction formula of reinforcement deflection was established by introducing the relaxation length. Furthermore, the design method considering the frictional effect for railway karst subgrade reinforced by horizontal reinforcement was put forward; in addition, the verification content and design process were also proposed. Finally, the method proposed was applied to a model test, and the result was compared with the results of model test and numerical analysis. The research results show that: considering the frictional effect can effectively modifier the calculated deformation of subgrade surface, which can increase from 0.18 m to 0.25 m, and was close to the model test value of 0.23 m and the numerical analysis value of 0.21 m; the method proposed is reasonable and can provide reference for actual design.