含水量对粘土与结构物接触界面单剪特性影响规律试验研究

Experimental study of the influence of water content on clay and structure contact interface single shear characteristics

采用升级改造后的DSJ-2型直剪仪,在不同法向应力水平下,开展了不同含水量的粘性土与不同介质性质的地下结构物接触界面的单剪试验,探索揭示粘土含水量变化对接触界面的剪切力学行为影响规律。研究结果表明:随着粘土含水量的增大,基底刚度较大时,剪应力-剪切位移曲线应变硬化现象愈来愈明显,反之,愈来愈不明显。剪切法向应力处于较低水平时,粘土的含水量对刚度较大的混凝土基底界面剪应力峰值强度影响更明显,反之,刚度相对较小的木材基底更明显。不同性质基底同粘土单剪时,随其含水量的不断提高,接触界面的内摩擦角均是不断降低,但其降低幅度不尽相同,结构物的刚度对接触界面内摩擦角起控制作用。随着粘土含水量的增大,接触界面的粘聚力总体变化规律为先增大,增大到某一峰值点后降低,界面的粘聚力由土体与结构物共同控制,且同结构物的刚度大小和界面自身特性均密切相关。

In order to explore the influence of water content of clay on the shear mechanical behavior of contact Interface with the help of modified DSJ 2 electric quadruple strain direct shear experimental system, single shear experiment for clay soil with different water content and for contact interface between underground structure and different medium properties were carried out under condition of different normal stress levels. Results show that with the increase of water content of clay, the strain hardening phenomenon of shear stress-shear displacement curve is more and more obvious when base stiffness is larger, and vice versa. Under lower normal stress level, the shear stress peak strength of contact interface with larger stiffness is more sensitive to water content of clay, however, under higher normal stress level, the contact interface of timbering with smaller stiffness is more sensitive. The friction angles of contact interface all reduce with the increase of water content of clay, but the reduction amplitude varies and the sensitivity is different. Cohesion force of contact interface increases first and then decreases with the increase of water content of clay, which has a peak point. Cohesion force of contact interface is closely related with both clay and structure, it is not only related to the structural stiffness, but also to the structure interface characteristics.