有限土体刚性挡墙平动模式被动土压力试验研究

Experimental analysis of passive earth pressure against rigid retaining wall under translation mode for finite soils

经典的库仑或朗肯土压力理论无法适用有限土体情况下的土压力问题。利用研制的土压力试验模型装置,进行了一组不同填土宽度的刚性挡墙平动模式室内模型试验,采用微型土压力盒量测从静止状态到被动极限状态的水平土压力分布的变化,利用颗粒图像测速技术研究土体内滑裂面发展规律。试验结果表明:半无限土体情况下的被动土压力大小、分布和合力作用点与库仑被动土压力较为接近。而有限宽度情况下移动挡墙上各深度的被动土压力值均大于库仑被动土压力,且土体宽度越窄,挡墙的被动极限位移有增大趋势,挡墙下部的被动土压力增大更明显,土压力分布的非线性程度愈高,被动土压力系数越大,被动土压力合力作用点明显往墙底移动。随着填土宽度的减小,填土表面的隆起愈明显,滑裂面的倾角略有增大。当移动挡墙达到或接近极限状态时,固定边界上的水平土压力随填土宽度的减小而逐渐增大,甚至接近库仑被动土压力。

It is inappropriate to calculate the earth pressure for finite soils using the classical Coulomb or Rankine earth pressure theory. A series of laboratory model tests with different widths of backfill are conducted for the passive case of a rigid retaining wall subjected to horizontal translation. The change in lateral earth pressure distribution from the at-rest condition to the passive condition is monitored by using a set of pressure cells. The particle image velocimetry technique is employed to observe the development of a failure zone in the soils. The experiment results show that there is a good agreement between the measured earth pressures and the Coulomb＇s solution in the case of infinite soils. However, the passive earth pressures on the moving retaining wall for finite soils are much more than the Coulomb＇s solution. With the decrease of the soil width, the limited displacement of the wall under passive state seems to increase, and the passive earth pressures also increase significantly when the heights of the application points of the resultant earth pressure move down gradually. Moreover, with the decrease of the soil width, the heave of the backfill surface increases gradually, the inclination angles of the slip surface increase slightly, and the lateral earth pressures on the fixed boundary also increase gradually.