粗砂与结构物接触面的剪切特性试验研究

利用同济大学研制的大型多功能界面剪切仪,对粗砂与结构物的剪切变形特性进行研究.采用在剪切盒内灌注彩色砂条的方法研究剪切带的空间分布特性.结果表明,彩色砂条的变形可以反映剪切带厚度和空间分布.剪切带厚度为6～11 mm,厚度随着法向应力的增加呈增加的趋势;剪切带厚度在空间上的分布呈现出不均匀性,在剪切方向(X轴方向)上呈现中间大两端小的趋势,在垂直剪切方向(Y轴方向)上离散性较小、分布近似均匀.剪切板凹槽的约束作用,使得凹槽内的砂土颗粒带动附近砂土颗粒运动,从而形成剪切带.土体的剪胀特性是由于剪切带内砂土的变形导致的,剪切初始时剪胀速率较快,达到抗剪强度后剪胀速率减慢.

Experimental Study on Shear Behavior of Interface Between Coarse Sand and Structure

The shear stress characteristics of the interface between coarse sand and structure were quantitatively analyzed and discussed by using the multi functional interface shear instrument. The colored sand strips were fixed into a shear box to characterize the movement of sand particles during the tests. The results show that the spatial distribution of shear zone after shear experiment could be reflected by the color sand strips. The thickness of the shear zone formed in the shear experiments are about 6~11 mm, and the thickness of the shear zone increases with normal stress. The spatial distribution of the shear zone is irregular. In the shear direction (X direction), the shear zone exhibits a tendency that shear zone is thick at the central position and thin at both ends of the shear box. The thickness of the shear zone is approximately uniform in the vertical shear direction (Y direction). Under the friction action between particles, the sand particles in the groove drive the sand particles nearby to move together and thus the shear zone is formed during the tests. The dilatancy of sand is caused by the deformation of the sand particles in the shear zone. The dilatancy rate is fast at the initial of the experiment, and then the dilatancy rate slows down after the shear strength reaches the peak.