Experimental and Analytical Research on Frictional Behavior between Cohesive Soil and Construction Materials during Earthquake

本研究对粘土与钢之间的摩擦阻力进行了多组单元试验。影响摩擦阻力的因素有钢的表面粗糙度、加载速率和粘土的固结压力。在剪切箱式试验装置上进行了单调加载和循环加载试验。并将计算结果与相似条件下粘土的剪切试验结果进行了比较。通过对钢材表面孔压的测量，得到如下认识：1.发现存在边界粗糙度R_b，当表面粗糙度大于R_b时，峰值强度、峰值强度、残余强度和粘土层与钢材之间的摩擦角都有上限。反之，当表面粗糙度小于R_b时，上述各值均随表面粗糙度的增大而增大。2.上述上限值与粘土的剪切试验值基本一致。因此，如果表面粗糙度小于Rb，则粘土与钢材之间发生滑移，而如果表面粗糙度大于Rb，则粘土试件发生破坏。3.随着表面粗糙度的增加，加载速率对峰值强度影响较大，但对剩余强度影响不大。这一特性可以在粘土的剪切试验中找到。4.粘土与钢材之间的有效应力摩擦角不受粘土固结压力的影响，且随表面粗糙度的增大而增大。5.在循环荷载作用下，当钢材表面光滑时，剪应力会以多次循环的方式稳定下来，当钢材表面粗糙或粘土剪切试验时，剪应力会逐渐减小。

In this study several sets of element tests on the frictional resistance between clay and steel were carried out. The factors influencing the frictional resistance selected in this study are surface roughness of steel, rate of loading and consolidation pressure of clay. Tests were carried out by the shear box type apparatus under monotonic or cyclic loading. The results are compared to the results of shear tests of clay on similar condition. Pore water pressure was measured on the surface of steel.The knowledge aquired through this study are as follows: 1. It was found that there was the boundary roughness,R_b, by reason of follows; if the surface roughness is larger than R_b, horizontal displacement at peak strength, peak strength, residual strength and friction angle between clay and steel in terms of effective stress have upper limiting values. In contrast, if the surface roughness is smaller than R_b, each above value increses with surface roughness. 2. The above upper limiting values nearly agree with the values of shear tests of clay. Therefore, if the surface roughness is smaller than R_b, the slip occurs between clay and steel, and if the surface roughness is larger than R_b, the failure occurs in clay specimen. 3. The peak strength is much influenced by rate of loading with increse of surface roughness, but the residual strength is not influenced. This behavior is found in shear tests of clay. 4. The friction angle between clay and steel in terms of effective stress is not influenced by consolidation pressure of clay, and increses with surface roughness. 5. Under cyclic loading, the shear stress settles down to the constant value with several cycles when the surface of steel is smooth, and decreses gradually when the surface of steel is rough or in shear tests of clay.