有限宽度土体被动土压力及滑裂面试验研究

采用无黏性砂开展平动模式(T模式)、绕墙底转动模式(RB模式)、绕墙顶转动模式(RT模式)下有限宽度土体模型试验,利用微型土压力计测试了移动挡墙上的土压力,利用数字图像相关法分析土体变形图像得到了剪切应变(滑裂面)、水平和竖向位移等变形特征。结果表明:(1)T模式下,有限宽度土体滑裂面经过移动挡墙墙踵、固定挡墙墙顶,被动土压力值大于库仑被动土压力,位于挡墙下部H/3范围的土压力受B/H影响较大;(2)RB模式下,滑裂面呈现为以挡土墙顶为中心的多道弧线,弧线半径为H/3~H,被动土压力为“鼓”形分布,当B/H≤1.0时,受固定挡墙影响,滑裂面半径缩小;(3)RT模式下,滑裂面线型特征与T模式相似,被动土压力较大值位于挡墙下部,当B/H减少时,挡墙下部土压力值增大,土体滑裂面范围缩小;(4)不同被动变位模式下,土体位移均可形成大小不同的水平土拱、竖向土拱,土拱形状和大小与变位模式、B/H均密切相关,两土拱的外边缘与滑裂面曲线基本一致。

Experimental Study on Passive Earth Pressure and Slip Surface of Limited Width Soil

Use non-cohesive sand to carry out model tests of limited width soils in translation (T mode), rotation about wall base (RB mode) and rotation about wall top (RT mode), and test the earth pressure on the removable retaining wall with a micro earth pressure gauge, using digital image correlation method to analyze soil deformation images to obtain deformation characteristics such as shear strain (slip surface), horizontal and vertical displacement. The results show that: (1) In the T mode, the limited width soil slip surface passes through the moving retaining wall heel and the fixed retaining wall top, and the passive earth pressure value is greater than the Coulomb passive earth pressure, the earth pressure in the H/3 range at the lower part of the retaining wall is greatly affected by B/H. (2) In the RB mode, the slip surface presents a multiple arcs centered on the top of the retaining wall, and the arc radius is H/3~H, the passive earth pressure is distributed in a “drum” shape, when B/H≤1.0, the radius of the slip surface will be reduced due to the influence of the fixed retaining wall. (3) In the RT mode, the linear characteristics of the slip surface are similar to the T mode, and the larger value of the passive earth pressure is located at the lower part of the retaining wall. When the B/H decreases, the earth pressure value under the retaining wall increases, and the range of the soil slip surface decreases. (4) Under different passive displacement modes, the displacement of the soil can form horizontal soil arches and vertical soil arches of different sizes. The shape and size of the soil arches are closely related to the displacement mode and B/H. The outer edges of the two soil arches are basically the same as the curve of the slip surface.