【摘要】 为西昌昔格达组地层场地地震安全性评价提供基础性数据,对西昌经久乡昔格达组粉砂岩进行了一系列动三轴试验。研究结果表明:西昌昔格达组粉砂岩在一定条件下(σ3c=100、200、400kPa,kc=1.0、1.5、2.0)的骨干曲线符合幂函数模型;动剪应力随着固结围压σ3c或固结主压力比kc增大而增大;在偏压状态下产生相同动剪应变所需要的动剪应力比均压状态所需要的动剪应力大。不同固结应力条件下,动剪切模量随固结压力或固结主压力比增大而增大,随动剪应变增加而减小并趋于稳定;最大动剪切模量Gd0与σ3c/Pa、kc均有良好的幂函数关系。阻尼比随动剪应变增大而增大,但增大幅值随动剪应变增大而迅速减小;阻尼比随围压或固结主压力比增大而减小;不同固结应力条件下(λ/λmax)与(1-Gd/Gd0)有良好的幂函数关系并可归一化处理。西昌昔格达组饱和粉砂岩的动剪应力τd随固结围压σ3c或固结主压力比kc增大而增大,随振动次数增加而减小;τd/σm随固结围压σ3c增大而减小,随固结主压力比kc增大而增大;动剪应力τd与平均压力σm、固结主压力比kc有较好的线性关系。更多还原

【Abstract】 In order to provide basic data for seismic safety evaluation of Xigeda formation site in Xichang city,a series of dynamic triaxial tests were conducted for Xigeda formation siltstone at Jingjiu site.Experimental results indicate that under certain conditions(σ3c=100,200,400 kPa,kc=1.0,1.5,2.0),the relation between dynamic shear stress and dynamic shear strain accords with power function model.Dynamic shear stress increases with the increase of confining pressure σ3c or consolidation principal pressure ratio kc;under condition of anisotropic consolidation stress,Xigeda formation siltstone in Xichang city produces larger dynamic shear strain than that obtained under condition of isotropic consolidation stress.Under condition of different consolidation stresses,dynamic shear modulus increases with the increase of confining pressure or consolidation principal pressure ratio,and decreases with the increase of dynamic shear strain and stabilizes.Power function correlations among maximum dynamic shear modulus Gd0 and σ3c/Pa、kc are obtained,respectively.Damping ratio increases with the increase of dynamic shear strain,but the amplitude of increase becomes smaller rapidly;it decreases with the increase of confining pressure or consolidation principal pressure ratio;Power function correlations between(λ/λmax)and(1-Gd/Gd0) are obtained and normalized under condition of different consolidation stresses.Dynamic shear stress τd increases with the increase of confining pressure σ3c or consolidation principal pressure ratio kc,but decreases with the increase of vibration number.The ratio τd/σm decreases with the increase of confining pressure σ3c,but increases with the increase of consolidation principal pressure kc;dynamic shear stress τd has linear relations with the mean pressure σm and the consolidation principal pressure ratio kc,respectively.更多还原