循环剪切下冻黏土与结构接触面剪切异向性研究

Research on Shearing Anisotropy Behavior of Frozen Clay-structure Interface Under Cyclic Loading

为探究冻土与结构接触面的力学行为,使用研制的冻土与结构接触面直剪仪DDJ-1,系统研究循环剪切下人工冻黏土与结构接触面异向性力学特性的基本规律和主要影响因素。实验结果表明:①循环剪切过程中在同一剪切循环内,剪应力-相对剪切位移关系和相对法向位移-相对剪切位移变化规律,在剪切作用的正反2个方向上存在着明显的差异,即接触面异向性,接触面异向性分为接触面剪应力异向性和法向位移异向性;②接触面异向性随粗糙度增大而增加,但当粗糙度增大到一定值后,对其影响程度减弱。剪应力接触面异向性随法向应力的增大先增大后减弱,而相对法向位移异向性则随着法向应力的增大呈衰减性增大。接触面异向性随循环次数增加而减小;③接触面异向性受法向荷载和粗糙度影响,其发挥程度与初次剪切方向和冻土特性有关。研究结果对冻土盾构法施工具有重要参考价值。

In order to explore the mechanical behavior of the surface between frozen soil and structure,the basic laws and main influence factors of anisotropic behavior of artificial frozen clay-structure interface under cyclic shearing were systematically studied by using the developed large frozen soil direct shear instrument DDJ-1.The results showed that:①during the cyclic shearing process,within the same shearing cycle,the relationship between shear stress-relative shear displacement nad the law of relative normal displacement-relative shear displacement changes,there were obvious differences in the positive and negative directions of the shearing actions,namely interface anisotropic,which can be divided into shearing stress anisotropic and normal displacement anisotropic.②The interface anisotropy increased with the rise of roughness,but when the roughness increased to a certain value,the influence was weaken.The anisotropy of shearing interface increased first and then decreases with the rise of normal stress,however,the anisotropy of relative normal displacement decay increased with normal stress.The interface anisotropy decreased with the increasing of cycle times.③The interface anisotropy was affected by normal load and roughness.The development degree of the anisotropy was related to the first shearing direction and properties of frozen soil.The research results have important reference value for shield construction in frozen soil.