摘要
地震荷载作用下堆石等土料会发生颗粒破碎,从而导致其动力特性与不发生颗粒破碎的土料有很大的区别.为了探讨破碎粒状材料在循环荷载作用下的力学特性,对人工制备的粒状破碎土料进行了频率为 1.0 Hz的循环加载固结不排水(consolidation undrained,CU)三轴试验,试验围压为100、200、300、400 kPa.研究结果表明:试样均为压缩破坏,呈应变硬化型;且不同激振力下的轴向应变曲线分为三段,即初始骤升段、中间平衡段和最终破坏段,并且每一阶段的长短和试样的变化均有所不同;动孔压随循环振次增大而增大,且在相同围压下激振力越大动孔压上升得越快.对动强度曲线分析发现,应力比越小动强度曲线越低;阻尼比整体上随着动剪应变的增大而逐渐增大,并且相同围压下激振力越小则阻尼比越小.颗粒破碎的影响因素有激振力、围压和振次等共同作用,不同围压(激振力)下各因素的影响大小不一、此消彼长,且随着围压增大颗粒破碎程度均逐渐增大.
Abstract
Under seismic loads,coarse-grained soil materials like rockfill materials usually crush,which leads to their dynamic features are distinct greatly from those without particle breakage.In order to investigate the cyclically dynamic properties of crushable grain materials,dynamic triaxial tests are performed on these kinds of materials under consolidation undrained(CU)conditions with the frequency of 1.0 Hz,and the applied confining pressure is respectively 100,200,300 and 400 kPa.It is experimentally demonstrated that all the samples were axially contracted at failure,and behave strain hardening.The axial strain curves can be divided into three stages of the initially rapid increase stage,the middle stability stage,and the last failure stage,and the duration for the three stages is distinct,so is the variation of the samples.With the increase of the cyclic times,the dynamic pore pressure will increase,and the higher the excitation force under the same confining pressure,the faster the dynamic pore pressure rises.For the dynamic strength,the smaller the stress ratio,the lower the dynamic strength curve.The damping ratio increases in a whole with the increase of dynamic shear strain,and under the same confining pressure,the smaller the axially excited force,the smaller the damping ratio.Many factors including the excited force,confining pressure,the cyclic number can affect the particle crushing,and their contributions to particle breakage vary greatly under the same confining pressure(or the axially excited force),and with the increasing confining pressure,the grain crushing occurs more easily.
NETL
NSTL
维普
万方数据