加卸载作用下加筋垫层变形特征试验研究

加筋垫层由于具有诸多优点而被广泛应用于反复加卸载作用下公路、铁路路基等工程构筑物中。为研究加卸载作用下加筋垫层结构的变形特征,针对加筋与未加筋垫层2组模型,开展了单次加卸载静力试验。测试并获得了不同荷载作用下垫层竖向变形、筋材应变变化规律,对比分析了加筋与未加筋垫层的变形特征,并从能量角度对加筋垫层工作机制进行了探讨。结果表明:与未加筋情况相比,荷载作用下加筋垫层(加载板处)的沉降变形和残余变形更小。加筋后垫层表面(加载板范围外)的竖向变形及其受影响范围均增大,且在卸载过程中垫层表面竖向变形的水平分布曲线特征由"凹"型变为"凸"型,其加卸载曲线呈"∞"型。格宾网筋材应变沿横向呈现非均匀分布特点,其最大应变小于0.06%,筋材始终处于弹性变形状态。加筋垫层中筋材具有储存、释放及横向传递应变能效应,这使得加筋后垫层具有更好的承载能力与弹性性能,进而可降低循环加卸载作用下垫层的塑性变形或累计变形。

Experimental study on deformation characteristics of reinforced soil cushion subjected to loading and unloading

Reinforced cushion has been widely used in engineering structures such as highways and railway subgrades subjected to repeated loading and unloading due to its many advantages. To study the deformation characteristics of reinforced cushion under loading and unloading, a single loading and unloading static test was carried out for the two models of gabion mesh reinforced and unreinforced cushions. Variations of vertical deformation of the cushion and reinforcement strain under different loads were monitored and obtained. The deformation characteristics of the reinforced and unreinforced cushions were compared and analyzed, and the working mechanism of the reinforced cushion was discussed in terms of energy. The results show that the settlement and residual deformations of the reinforced cushion (at the location of the loading plate) under loading are smaller than those without reinforcement. The vertical deformation of the surface of the cushion after reinforcement (outside the range of the loading plate) and its affected range have increased. The shape of the horizontal distribution curve of the vertical deformation during the unloading process changes from concave to convex, and its loading and unloading curve shows a shape of “∞”. The reinforcement strain shows a non-uniform distribution along the transverse direction, and the maximum strain is less than 0.06%. The reinforcements are always in an elastic deformation state. The reinforcement in the reinforced cushion has the effect of storing, releasing and laterally transmitting strain energy, which results in better bearing capacity and elastic property of the reinforced cushion, thereby reducing plastic deformation or cumulative deformation of the cushion under cyclic loading and unloading.