基于不同速率的格栅与标准砂拉拔试验及界面位移图像分析

Pull-out test and interface displacement image analysis of geogrid and standard sand based on different velocity

为了研究不同拉拔速率下筋土界面的摩擦特性,进行了5种不同拉拔速率、4种不同法向应力的拉拔试验并结合数字图像分析技术揭示了砂土的位移变化规律。结果表明:随着拉拔速率的增加,存在一个临界拉拔速率v=1.5 mm/min,该速率下的拉拔力最大;不同拉拔速率下的峰值拉拔位移均随着法向应力的增加而增加,且两者呈指数函数关系;界面似摩擦角以及界面似黏聚力随着拉拔速率的增加均会发生变化,而界面似黏擦角表现出先增后减再增的趋势,其最大值与最小值两者相差8.86°,但界面似黏聚力则表现出先增后减的趋势,其最大值为最小值的1.23倍;拉拔界面的颗粒随着拉拔前进的方向一起平行移动,离拉拔界面越近颗粒位移越大,离拉拔界面越远颗粒位移越小,且拉拔界面上部颗粒的位移较下部有显著的差异。

In order to study the friction characteristics of reinforced soil interface under different pull-out velocities, five different pull-out velocities and four different normal stresses were tested, and the displacement variation of sandy soil was revealed by digital image analysis technology. The experimental results show that with the increase of drawing rate, there is a critical drawing rate v=1.5 mm/min, and the drawing force is the largest at this rate. The peak drawing displacement at different drawing rates increases with the increase of normal stress, and the relationship between them is exponential function. The interface-like friction angle and interface-like cohesion will change with the increase of drawing rate, while the interface-like friction angle shows a trend of first increasing, then decreasing and then increasing, and the difference between the maximum and minimum values is 8.86°. But the interfacial cohesion first increases and then decreases, the maximum value is 1.23 times the minimum value.The particles in the drawing interface move parallel with the direction of drawing forward. The closer to the drawing interface, the larger the particle displacement is. The farther away from the drawing interface, the smaller the particle displacement is. The displacement of the upper part of the drawing interface is significantly different from that of the lower part.