【摘要】 常规的三轴试验通常无法真实模拟实际工程中土体所受的应力状态,因而就不能准确地评价土体的变形特性,尤其是中主应力对土体变形的影响。通过对原有的DTC-199型周期扭转荷载三轴仪进行简单的改造,可进行中主应力对压实黄土动变形影响的试验研究。中主应力的大小σ2通过中主应力系数b(b=(σ2-σ3)/(σ1-σ3))来反映,在其它固结条件不变的前提下,初始中主应力系数b对压实黄土的动剪切模量有一定的影响,随着b的增大,动剪切模量有减小的趋势,最大剪应力也逐渐减小;b对最大动剪切模量基本没有影响。初始中主应力系数b对压实黄土的阻尼比λ基本没有影响,在λ-lgγd的半对数坐标图中,阻尼比随动剪应变的增加有逐渐增大的趋势,并且表现出较好的相关性。更多还原

【Abstract】 Conventional triaxial test cannot authentically simulate the stress conditions of soils in real projects,and it cannot evaluate deformations of soils exactly,especially for the effect of intermediate principal stress on the deformations of soils.After reforming the DTC-199 torsional cyclic load triaxial apparatus,dynamic deformation of compacted loess can be tested under intermediate principal stress.Magnitude of intermediate principal stress is reflected by intermediate principal stress coefficient b(b=(σ2-σ3)/(σ1-σ3)),the initial intermediate principal stress coefficient b has some influence on the dynamic shear modulus of compacted loess when other consolidation conditions are fixed.With b increasing,the dynamic shear modulus shows a decreasing trend,and the maximum dynamic shear stress reduces gradually,but b does not considerably influence the maximum dynamic shear modulus.The initial intermediate principal stress coefficient b has basically no influence on the damping ratio of compacted loess,and the damping ratio has an increasing trend with the increase of dynamic shear strain in the semilog plot of λ-lgγd,and they show good correlation.更多还原