基于FLAC^(3D)的粉砂岩压缩蠕变试验数值模拟研究

Numerical simulation study on compression creep experiment of siltstone based on FLAC^(3D)

基于FLAC3D,建立粉砂岩单轴压缩蠕变数值试验模型,调用自定义本构模型进行单轴蠕变数值模拟试验研究,探讨单轴压缩条件下不同应力水平粉砂岩蠕变特性。数值模拟试验表明,无论是应变量值还是蠕变整体变化趋势,数值模拟的结果均与室内蠕变试验结果十分相近,反映了所建立的数值分析模型和自定义本构模型开发的正确性和适应性。分析还表明,试件顶部的瞬时应变和蠕变均较试件底部明显,反映应力由上至下的传递过程。试件形状改变对轴向蠕变影响很小,而对径向蠕变的影响极为明显;同等条件下,长方体试件的径向蠕变明显大于圆柱体试件。试件的直径和高度的变化对轴向蠕变、径向蠕变影响均很小。所获结论对室内岩土蠕变试验有较好的指导意义。

By using the FLAC3 D,a numerical simulation model was generated for the uniaxial creep behavior of siltstone.Based on the user-defined constitutive model,the numerical tests for the uniaxial creep behavior of siltstone were carried out,and furthermore,the uniaxial creep properties of siltstone under different stress level were investigated. The results show that the numerical simulations may confirm the test results in either the strain magnitude or the general tendency of creep,indicating that the self-developed model is effective and feasible. The analysis also discloses that the instantaneous strain and creep at the top of specimen are more evident than those at the bottom,reflecting the stress transferring process from the top to the bottom. The change of specimen shape has little influence on the axial creep,but has a remarkable impact on the radial creep. Under the same conditions,the radial creep of cuboidal specimen is obviously larger than that of cylindrical specimen. However,the changes in diameter and height of specimens have little effect on the axial or radial creep. Hence,the conclusions attained can provide a good guidance to the laboratory creep experiment.