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基于目前研究很少关注土拱效应模型的适用条件和演化规律的现状,采用自制平面应变模型对砂填料桩承式路堤在不同桩间距下的宏观土拱形态,以及宏观土拱在桩间土下移过程中可能出现的演化现象进行探讨。模型试验将桩与土相互作用简化为桩间土挡板下移这一位移边界条件,配备可精确控制桩间土下移量的位移控制装置与摄影测量设备。每下移0.02 mm采集一张图片,采用图像分析软件追踪桩间土下移过程中路堤颗粒位移,实现全场位移量测。共进行3种填土高度下3种不同桩间距的模型试验。通过对9组试验填料内部滑移面的分析,揭示桩间土下移过程中均首先出现对称的三角形滑移面,即初始三角拱模型,之后继续增加桩间土下移量,初始三角拱模型存在2种不同的演化模式:在填土高度与桩距比<1.8情况下,随桩间土下移量的增加滑移面逐级张开,称为三角多拱模型;在填土高度与桩距比≥1.8情况下,滑移面则逐级上移,演化为塔形多拱模型。最后,统计各模型的关键参数,为下一步土拱演化条件下的力学分析计算提供依据。
Based on the current researches on the application of the soil arching effect model and the evolution law of the soil arching effect, this paper uses the self-made plane strain model to analyze the macroscopic soil arching patterns of the sand-filled piled embankment under different pile spacing, The evolution phenomenon that may appear during the downward movement is discussed. The model test simplifies the interaction between pile and soil to the displacement boundary conditions that the soil baffles move downwards between the piles. The displacement control device and photogrammetry equipment can be used to precisely control the amount of soil movement between piles. Each 0.02 mm down to collect a picture, the use of image analysis software to track the process of soil under the embankment during the shift of soil particles to achieve the audience displacement measurement. A total of three model tests with three different pile spacings at fill level were conducted. Through the analysis of the internal slip surface of the 9 sets of test packings, it is revealed that the symmetrical triangular slip surface, ie the initial triangular arch pattern, first appears during the process of soil moving downward. The initial triangular arch There are two different evolution modes in the model: when the filling height and the pile-spacing ratio are less than 1.8, the slip surface opens step by step with the increase of soil subsidence, which is called the triangular multi-arch model; With the ratio of the pile spacing ≥1.8, the slip surface moves upward step by step, evolving into a tower-shaped multi-arch model. Finally, the key parameters of each model are calculated, which provide the basis for the next mechanical analysis and calculation under the condition of soil arching evolution.