By means of the three-dimensional discrete element method, we study the long-time evolution toward liquefaction state in granular materials composed of spherical particles under multidirectional cyclic shearing at constant volume. Extensive simulations were carried out along 1-D linear, 2-D linear, circular/oval, and 8-like shear paths, and the evolution of the system was analyzed in terms of pore pressure, shear strain, and granular texture. The macroscopic stress path and stress–strain response agree well with laboratory experiments. We find that the liquefaction resistance, i.e., the number of cycles necessary to reach the liquefaction state, is generally lower under multidirectional loading as compared to unidirectional loading. As the transient vanishing of mean stress does not occur for all stress paths, we introduce a shear strain-based liquefaction criterion that can be consistently applied to all strain paths. The granular texture is monitored through the coordination number, particle connectivity, force and fabric anisotropies, and friction mobilization. In particular, a particle-void descriptor, named centroid distance, is found to be closely related to the shear strain accumulation. We show that the force anisotropy tensors become almost proportional to the deviatoric stress tensor more quickly than the fabric anisotropy tensor, which takes most of the pre-liquefaction period to follow the external loading. The relationship between deviatoric stress ratio and the force and fabric anisotropies, known to hold in monotonic triaxial loading, also holds with high accuracy in the studied multidirectional cyclic shearing paths; the contributing weights of the anisotropies level off in the post-liquefaction period and do not depend on the shear path.

通过三维离散元方法，我们研究了由球形颗粒组成的颗粒材料在恒体积多方向循环剪切下向液化状态的长期演变。沿一维线性、二维线性、圆形/椭圆形和 8 形剪切路径进行了广泛的模拟，并在孔隙压力、剪切应变和颗粒结构方面分析了系统的演变。宏观应力路径和应力应变响应与实验室实验一致。我们发现液化阻力，即达到液化状态所需的循环次数，与单向加载相比，在多向加载下通常较低。由于并非所有应力路径都发生平均应力的瞬时消失，我们引入了一种基于剪切应变的液化准则，该准则可以一致地应用于所有应变路径。通过配位数、粒子连通性、力和织物各向异性以及摩擦动员来监测颗粒纹理。特别是，发现称为质心距离的粒子空隙描述符与剪切应变积累密切相关。我们表明，与织物各向异性张量相比，力各向异性张量几乎与偏应力张量成正比，织物各向异性张量需要大部分的预液化时间来跟随外部载荷。偏应力比与力和织物各向异性之间的关系，已知在单调三轴加载中成立，在研究的多向循环剪切路径中也具有高精度；