考虑时间效应深挖巨厚泥岩路堑变形特征研究

Study on Deformation Characteristics of Deep Huge Thick Mudstone Cutting Considering Time Effect

以西南地区某高速铁路深挖泥岩路堑为模型,运用FLAC3D大型有限差分程序,基于弹塑性模型和考虑泥岩时效性变形特征的黏弹塑性CVISC流变模型,对深挖路堑卸荷作用引起的基底长期变形规律开展数值模拟,揭示深厚泥岩区深挖路堑基底变形随时间的变化规律。结果表明:开挖卸荷后,由于坡脚应力场分异,一定范围内路基出现以竖向上拱为主的瞬时回弹变形;随着时间的推移,坡体及基底岩体应力逐渐调整,工后约2.5年后基底泥岩由于流变作用产生近似线性的竖向上拱及水平变形,7.5年后逐渐趋于稳定。

Taking the deep mudstone excavation of high-speed railway in southwest Chibna as a model,FLAC3D large finite difference program has been used to carry out numerical simulation research on long-term deformation law of deep cut basement caused by unloading action based on elastic-plastic model and viscoelastic-plastic CVISC rheological model considering mudstone time-dependent deformation characteristics.The deformation law of deep cut basement with time in deep mudstone area has been revealed.The results show that the instantaneous resilience deformation of the roadbed is dominated by the vertical upper arch in a certain range due to the stress field difference at the slope toe after excavation and unloading.As time goes on,the stress of slope and basement rock gradually adjusts.Approximately 2.5 years after construction,the basement mudstone produces approximately linear vertical arching and horizontal deformation due to rheological action,and gradually tends to be stable in 7.5 years.