不同位移模式下衡重式路肩墙离心模型试验研究

以某山区公路旧路拓宽改造工程中新建的衡重式路肩挡土墙为原型,设计了墙体在平移(T)、绕墙趾转动(RB)、绕墙顶转动(RT)以及平移与绕墙趾转动复合形式(T+RB)4种位移模式的土工离心模型试验,讨论了挡墙位移模式对墙背土压力和路基填土变形的影响,分析了墙后不同深度土体进入主动状态的进程,试验表明:1位移模式对上墙土压力大小及分布形态基本无影响,但上墙浅层土体在挡墙位移与墙高比值小于0.3%~0.5%时,存在墙–土摩擦引起的土拱效应,使水平土压力系数增大;2由于衡重台的存在,对下墙距衡重台约1/3下墙高度范围的土压力有遮蔽作用,其结果是降低了土压力合力作用点位置;3位移模式对填土沉降有明显影响,在墙体位移最大值相同时,T位移模式的填土沉降明显大于RB和RT位移模式,而RT位移模式,衡重台向下偏转,促进了填土下沉,最终使其填土沉降大于相同位移面积的RB位移模式,也更容易使上墙出现第二破裂面。

Centrifugal model tests on shoulder balance weight retaining wall with various motion modes

Using the new shoulder balance weight retaining wall of an old embankment widening project of a mountainous highway as the prototype, four groups of geotechnical centrifugal model tests are designed based on the wall motions under translation (T), rotating around base (RB), rotation around top (RT) and T+RB modes, the impact of wall motion modes on earth pressure and deformation of the filling is discussed, and the process of soils at various depths entering in to the active earth pressure is analyzed. The results show that: (1) The wall motion modes almost have no influence on the values and distribution of earth pressure on the upper wall, but when the ratio of displacement to height of retaining wall is less than 0.3%~0.5%, the shallow layer fills behind the upper wall have soil arching effect which is caused by wall-soil friction, and the coefficient of horizontal earth pressure increases; (2) The equilibrator has a shadowing effect on the down wall earth pressure, and the influence area is about 1/3 height of the down wall below the equilibrator. The results reduce the position of the acting point of earth pressure resultant force; (3) The motion modes have obvious impact on the fill settlement. When the maximum wall displacements are the same, the fill settlement of the T mode is significantly larger than that of the RB and RT modes. Under the RT mode, although it has the same displacement area as the RT mode, the equilibrator deflects downward. The fill settlement is promoted, leading to that the fill settlement of the RT mode is larger than that of RB mode, and the second fracture surface occurs easier on the upper wall.