The development and application of a boundary friction meter is presented. The friction meter was designed to allow for the measurement of a resultant shear stress on a planar interface between a structural boundary and a soil mass. Calibrations illustrate the repeatability of the device and its moderate level of parasitic interaction due to the presence of normal pressure. The friction meter was used to consider the development of shear stresses along a vertical, non-yielding model retaining wall, subjected to uniform vertical pressure at K₀ conditions. Testing was performed with a uniform, fine-grained dune sand, placed at loose and medium dense conditions. The surface of the model wall was configured to have three distinct levels of roughness; from very smooth to the geometrical roughness of the sand itself. Measurement of normal soil pressures was performed in tandem to the shear stress measurements. The results illustrate that interface stress paths are unique to surface roughness. Angles of interface friction are defined and independent of soil density. The development of a shear stress along the vertical wall during unloading is significantly different than that measured during loading and the direction of the vertical shear stress reverses as vertical pressures approach zero.

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土壤边界摩擦仪的开发：在比例模型测试中的应用

介绍了边界摩擦仪的研制与应用。摩擦计设计用于测量结构边界和土体之间平面界面上的合成剪切应力。校准说明了设备的可重复性以及由于存在正常压力而导致的中等水平的寄生相互作用。摩擦计用于考虑沿垂直、非屈服模型挡土墙的剪切应力的发展，在K _{0处承受均匀的垂直压力}条件。测试是使用均匀的细粒沙子进行的，放置在松散和中等密度的条件下。模型墙的表面被配置为具有三个不同级别的粗糙度；从非常光​​滑到沙子本身的几何粗糙度。正常土壤压力的测量与剪切应力测量同时进行。结果表明，界面应力路径对表面粗糙度是唯一的。定义了界面摩擦角并且与土壤密度无关。卸载期间沿垂直壁的剪应力的发展与加载期间测量的明显不同，并且随着垂直压力接近零，垂直剪应力的方向反转。