利用离散元法分析初始各向异性砂土在非对称循环荷载下的液化行为。通过生成椭球颗粒制备各向异性砂土试样，采用常体积法开展不排水循环三轴剪切模拟，分析循环加载过程中力学配位数、冗余指数和组构各向异性的演化，揭示砂土在微观层面的液化特征。结果表明，离散元模拟有效反映了非对称循环加载条件下密砂更高的抗液化能力。试样在完全液化时，力学配位数和冗余指数分别降至0.35和2.4，这与是否对称循环加载无关。不同加载条件下，颗粒长轴的组构随着循环加载由各向异性向各向同性转变。在应力反转条件下，液化发生后，颗粒长轴组构各向异性迅速减小，同时，接触法向组构发生显著变化并出现方向切换。初始液化均发生在接触法向组构各向异性变量从负值逐渐接近0的过程中。研究结果有助于深入理解液化的微观力学机制，有助于构建复杂加载条件下各向异性砂土循环液化的宏观本构模型。

The discrete element method (DEM) was used to analyze the liquefaction behavior of initially anisotropic sand under nonsymmetric cyclic loading. Ellipsoidal particles were generated to prepare anisotropic sand samples, and undrained cyclic triaxial shear simulations were conducted by using constant volume method. The evolution of mechanical coordination number, redundancy index and fabric anisotropy during cyclic loading was studied, and the liquefaction characteristics of sand at the microscopic level was revealed. The results show that the DEM simulations effectively reflect that dense sand exhibits higher liquefaction resistance under nonsymmetric cyclic loading conditions. When sand undergoes full liquefaction, the mechanical coordination number and redundancy index decrease to 0.35 and 2.4, respectively, regardless of whether the cyclic loading is symmetrical. Under different loading conditions, the particle orientation fabric transitions from anisotropic to isotropic with cyclic loading. Under stress reversal conditions, once liquefaction occurs, the anisotropy of the particle orientation fabric rapidly decreases, while the contact normal fabric changes significantly and shows a directional switch. Initial liquefaction occurs as the contactnormal fabric anisotropy variable transitions from a negative value to near zero. These findings provide an in-depth understanding of the micromechanical mechanisms of liquefaction, contributing to the development of macroscopic constitutive models for cyclic liquefaction of anisotropic sands under complex loading conditions.