湿陷性黄土-混凝土接触面剪切力学特性及破坏型式研究

Study on Shear Mechanical Properties and Failure Mode of Collapsible Loess-concrete Interface

对湿陷性黄土-混凝土结构进行直剪试验,研究接触面剪切力学性质,主要考虑法向应力、混凝土表面粗糙度等影响因素下湿陷性黄土-混凝土结构物接触面的剪切力学特性,进而采用数值分析研究接触面的破坏型式.通过直剪试验发现:在两种介质的接触面上剪切应力-剪切位移出现滑移、弹塑性破坏两种型式.接触面粗糙度不同时,结构接触面的抗剪强度峰值也不同,接触面越粗糙,其黏聚力也越大,内摩擦角越小.数值模拟的结果是:在法向应力较小时,剪切破坏模式以滑移破坏为主;法向应力增大后,会在湿陷性黄土内部产生剪切滑动带.在法向应力相同时,湿陷性黄土内部的剪切滑动带的厚度随着接触面粗糙度的增加而增加.湿陷性黄土-混凝土接触面光滑的情况,随着法向应力的变化,土体剪切滑动带厚度约为13~16 mm;接触面为粗糙面时,随着法向应力的变化,土体剪切滑动带厚度约为15~19 mm.

The direct shear test is used to analyze the shear mechanical properties of the interface between collapsible loess and concrete structure,which mainly considers the shear mechanics of the contact surface of collapsible loess concrete structure under normal stress,concrete surface roughness and other factors,and then uses numerical analysis to study the failure mode of the contact surface.Through the direct shear test,it is found that there are two types of shear stress displacement slip and elastic-plastic failure on the contact surface of the two media.When the roughness of the contact surface is different,the shear strength peak value of the structural contact surface is different.The coarser the contact surface is,the greater the cohesion is,and the smaller the internal friction angle is.The results of numerical simulation are as follows:when the normal stress is small,the shear failure is mainly slip failure;when the normal stress increases,there will be shear slip zone in the collapsible loess.At the same time of normal stress,the thickness of shear slip zone in collapsible loess increases with the increase of contact surface roughness.When the contact surface of collapsible loess concrete is smooth,with the change of normal stress,the thickness of soil shear slip zone is about13~16 mm;when the contact surface is rough,with the change of normal stress,the thickness of soil shear slip zone is about 15~19 mm.