循环荷载作用下红黏土与混凝土接触面剪切特性试验研究

摘要

The mechanical behavior of interface between red clay and concrete was investigated by direct shear tests of different normal stress and roughness under cyclic loading.The strength and deformation with the varia-tion of the number of cyclic loading were analyzed under different normal stress and roughness of the concrete surface.The experimental results show that the minimum or maximum value of shear stress in each cycle corre-sponded respectively to the maximum shear displacement and minimum shear displacement in the process of cy-clic shear.The maximum shear stress occurs at the first cycle,and with the increase of the cycle number,the maximum shear stress in each cycle gradually reduces and finally remains a constant.The maximum of the aver-age peak shear stress tend to increase with the increment of normal stress.The roughness has little effect on the average peak shear stress when normal stress is low,while with the increase of the normal stress,the roughness gradually comes into play.The cohesion and friction angle of the contact surface are large at the beginning of the cyclic shear test,and then decrease rapidly and finally tend to constant with the increment of cycle number. When the normal stress is low,the displacement of the sample has shear shrinkage at the first cycle,then shows shear dilation from the second cycle,and the dilatancy amount eventually remain stabile.However,with the in-creasing number of the normal stress,shear shrinkage appears,and the shrinkage magnitude eventually reaches a stable number.With the increase of normal stress and roughness,the shrinkage amount and rate of shear shrink-age also increase.%采用大型直剪仪对红黏土与混凝土结构接触面进行循环荷载作用下直剪试验，分析不同法向应力与不同混凝土表面粗糙度条件下结构接触面的强度及变形随循环加载次数的变化规律。研究结果表明：在循环剪切过程中，每个循环内剪切应力极小值和极大值分别对应于剪切位移的最大值、最小值处，剪应力的最大值均出现在第1个循环内，随着循环次数的增加，剪切应力最大值逐渐减小，最后趋于稳定。平均峰值剪应力最大值随法向应力的增大而增加；当法向应力较低时，粗糙度对平均峰值剪应力变化影响较小，随着法向应力的增强，粗糙度对其影响逐渐发挥。在循环剪切试验过程中，接触面的黏聚力和摩擦角刚开始时较大，随着循环次数的增加迅速减小，最后趋于稳定。当法向应力较低时，试样在第1循环内发生剪缩，从第2循环开始出现剪胀，剪胀量最终趋于稳定；随着法向应力的增大，试样出现剪缩，剪缩量最终趋于稳定，最终剪缩量随着法向应力和粗糙度的增加而增大，减缩速率也随着之增加而增大。