Friction and energy dissipation along the interface between sand and construction materials

本研究涉及地基与结构基础之间的界面特性。对砂土与建筑材料的摩擦进行了室内试验。在此基础上，分析了影响摩擦阻力的因素。本研究还尝试将界面滑动解释为能量耗散过程。以下是本研究的结论。钢-砂屈服摩擦系数随钢的表面粗糙度、中值直径和砂的类型而变化。提出的归一化粗糙度是Rmax中钢的粗糙度与砂的中值直径之比。摩擦系数与归一化粗糙度之间存在高度相关性。由于砂结构的扰动，沿粗糙界面形成剪切带。单调加载作用下，沿光滑界面未形成剪切带。当界面反复滑动时，即使沿光滑界面也会形成剪切带。当界面粗糙时，摩擦阻力随循环加载次数的增加而减小。这是由于沿界面形成了剪切带。当界面光滑时，沿界面颗粒破碎明显，摩擦阻力随加载次数增加而增大。在重复加载下，摩擦阻力收敛于砂土的最大剪应力比值。砂-混凝土摩擦系数随混凝土粗糙度和中位粒径的变化而变化。用Rp而不是Rmax计算的粗糙度与摩擦系数有较高的相关性。在界面屈服时，沿界面的塑性功大于砂体的塑性功。沿界面的能量耗散主要归因于界面滑移、剪切带的形成和剪切带的变形。

This study concerns the behavior of interfaces between ground and structural foundation. Laboratory tests were carried out on the friction between sand and construction materials. Based on the results, analyzed were the factors influential to the frictional resistance. This study also includes an attempt to interpret the interface sliding as an energy dissipation process. Followings are conclusions of this study.Sand-steel coefficient of friction at yield varies with surface roughness of steel, median diameter and type of sand. Normalized roughness proposed is the ratio of the steel roughness in Rmax to the median diameter of sand. There are high correlations between coefficient of friction and normalized roughness.A shear zone formed along a rough interface due to the disturbance in sand fabric. There was no formation of a shear zone along a smooth interface under monotonic loading. When the interface slid repeatedly, a shear zone formed even along a smooth interface.When the interface was rough, the frictional resistance decreased with the increase in number of in cyclic loading. This is due to the formation of a shear zone along the interface. In case of smooth interface, the frictional resistance increased with loading number if particle crushing was significant along the interface. The frictional resistance converged to the value of maximum shear stress ratio of sand under repeated loading.Sand-concrete coefficient of friction varies with roughness of concrete and median particle diameter. The roughness evaluated by Rp rather than Rmax showed a high correlation with the coefficient of friction.At the yield of interface, plastic work along the interface become larger than that of sand mass. The energy dissipation along the interface is attributed to the slipping of interface, shear zone formation and the deformation of shear zone.