Load Mechanisms and Design Method for Karst Subgrade Reinforced by Horizontal Geosynthetic Reinforcement
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摘要: 为了解决现有设计方法未考虑水平加筋体的滑移效应，低估铁路路基面变形的问题，对水平加筋体加固铁路岩溶路基的受力机理进行了研究，提出了一种新的设计方法. 首先，明确了荷载传递机制和水平加筋体受力模型；然后，从严格控制铁路路基面变形的角度出发，在现有设计方法的基础上，考虑滑移效应并假定锚固区加筋体应变呈线性变化，通过引入加筋体松弛量建立了加筋体挠度修正公式；再次，提出了考虑滑移效应的水平加筋体加固铁路岩溶路基的设计方法，明确了验算内容和设计流程；最后，将所提方法应用于某模型试验，并与实测值及数值分析值进行了对比. 研究结果表明：考虑滑移效应能够有效修正路基面变形计算值，路基面变形值由0.18 m修正为0.25 m，接近于实测值0.23 m和数值分析值0.21 m，方法准确，可为实际设计提供依据.Abstract: 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.
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图 5 某水平加筋体的张拉力-应变-时间特征曲线
Figure 5. Tension-strain-time curve of horizontal reinforcement
表 1 模型试验和数值计算的参数
Table 1. Parameters of model test and numerical analysis
参数 取值 填方高度/m 1 填料重度/（kN•m–3） 15.65 填料内摩擦角/（°） 36 溶洞直径/m 2.2 水平加筋体拉伸模量/（kN•m–1） 2 988 附加荷载/kN 0 锚固长度/m 3 
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表 2 路基面变形对比
Table 2. Comparison of deformation of subgrade surface
模型试验 数值分析 RAFAEL方法 本文方法 0.23 0.21 0.18 0.25
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