A series of undrained tests on loose sand with different pre-shearing histories are conducted in three-dimensional discrete element method (DEM) simulations. The pre-shearing histories are simulated under drained conditions with different pre-shearing strain levels ranging from 0% to 1.57%. Two different pre-shearing history types (pre-shearing cycle and pure pre-shearing) are investigated and compared. The quasi-steady state, or temporary liquefaction, is found in all undrained tests. Both macroscopic and microscopic behaviours show that pre-shearing histories can stabilize the undrained behaviour and even re-establish a solid-like behaviour. The triggering of temporary liquefaction is well captured by the redundancy index and the macroscopic behaviours can be well correlated with the evolution of the redundancy index. There exists a limiting undrained stress path on the stress plane that all the samples with pre-shearing cycles cannot go beyond, indicating that the samples have a ‘memory’. The shear-induced anisotropy in the samples with a pure pre-shearing history leads to higher initial peak values of deviator stress than those for the corresponding samples with pre-shearing cycles under undrained simulations. The ultimate stress ratio of deviator stress against effective mean stress after temporary liquefaction is found to be unique and independent of the types and levels of pre-shearing histories.

在三维离散元方法（DEM）模拟中，对具有不同预剪切历史的松散砂进行了一系列不排水的测试。预剪切历史是在排水条件下模拟的，预剪切应变水平在0％到1.57％之间。研究并比较了两种不同的预剪切历史记录类型（预剪切循环和纯预剪切）。在所有不排水的测试中都发现了准稳态或暂时液化。宏观和微观行为都表明，剪切前的历史可以稳定不排水的行为，甚至可以重新建立类似固体的行为。临时液化的触发被冗余指数很好地捕获，并且宏观行为可以与冗余指数的演变很好地相关。应力平面上存在一条有限的不排水应力路径，所有具有预剪力循环的样本都不能超过该路径，这表明样本具有“记忆”。在不排水的模拟下，具有纯预剪切历史的样品中的剪切诱导各向异性会导致偏应力的初始峰值高于具有预剪切循环的相应样品的偏离峰值。发现临时液化后偏应力与有效平均应力的极限应力比是唯一的，并且与剪切前历史的类型和水平无关。在不排水的模拟下，具有纯预剪切历史的样品中的剪切诱导各向异性会导致偏应力的初始峰值高于具有预剪切循环的相应样品的偏离峰值。发现临时液化后偏应力与有效平均应力的极限应力比是唯一的，并且与剪切前历史的类型和水平无关。在不排水的模拟下，具有纯预剪切历史的样品中的剪切诱导各向异性会导致偏应力的初始峰值高于具有预剪切循环的相应样品的偏离峰值。发现临时液化后偏应力与有效平均应力的极限应力比是唯一的，并且与剪切前历史的类型和水平无关。