重塑黄土一维固结变形的试验与数值模拟

Laboratory tests and numerical simulation for consolidation of remolded saturated loess in 1D

为了研究单轴条件下黄土的固结变形特性,运用ABAQUS软件对重塑饱和黄土一维压缩固结模型进行了数值仿真。采用边界面模型为土体的材料模型,通过与室内试验比对,验证了所建模型的正确性。并依据现有模型,模拟了不同应力率下的固结试验。结果表明:(1)试样在加卸载荷后会产生较大的瞬时变形,变形量随加卸荷量的增大而增大,但在加卸载量相同的情况下,试样的回弹变形要远小于加载过程中产生的变形。(2)常应力率试验中,应力率越大,有效应力增长越快,但最终的有效应力值却最小;有效应力在卸载开始阶段并没有随着总应力的下降而下降,而是表现出一定的滞后性,且应力率越大,这种滞后性越明显。(3)试样的竖向变形速率随着应力率的增大而增大,但最终变形量随应力率的增大而减小,合适的应力率可以兼顾加载时间和密实度。(4)应力率越大,孔压上升越快,所产生的孔压幅值也越大,应力率较小时,孔压在加载过程中出现先升后降的现象,孔压沿试样高度分布较连续。

A numerical simulation based on the software ABAQUS is used to study the consolidation of remolded saturated loess under uniaxial conditions.The numerical model is verified by comparing with the laboratory test results,and the boundary surface model is adopted as the material model.Consolidation simulations at different stress rates are established after the model calibration.The results indicate that large initial deformation occurs after the loading or unloading while the deformation increases with the loading and unloading.However,the rebound deformation in the unloading process is much less than that in the loading process.In the constant stress rate test,the larger the stress rate,the faster the effective stress increases,but the final effective stress is the smallest.The effective stress does not decrease instantly with the decrease of total stress at the beginning of the unloading,but shows a certain lag.The larger the stress rate,the more obvious the lag effect is.The vertical deformation rate increases with the stress rate,but the final deformation decreases with the increase of the stress rate.Both the loading time and the compactness can be simultaneously considered at an appropriate stress rate.The higher the stress rate,the faster the pore water pressure rises,and the larger the amplitude is.When the stress rate is small,the pressure rises and then falls in the loading stage,which shows a relatively continuous distribution along the depth.