基于流变的高速铁路深挖路堑长期上拱变形数值分析

Numerical Analysis on the Long-term Upheaval Deformation ofHigh-speed Railway Deep Cutting Based on Rheology

路基竖向持续上拱变形是威胁高速铁路安全运行的重要因素,为揭示西南地区典型泥岩夹砂岩层深挖路堑长期上拱变形机理,基于软岩流变特性,结合室内试验结果,运用FLAC3D中的CVISC黏弹塑性模型模拟某高速铁路深挖路堑在考虑流变与不考虑流变情况下基底应力及竖向变形。研究结果表明:①工程区泥岩力学性能显著低于砂岩,且泥岩具有显著的流变性,砂岩不具有显著的流变性;②不考虑流变情况下,深路堑开挖后基底出现短期竖向回弹变形,浅层岩体水平压应力较竖向压应力大;③考虑泥岩流变特性后,基底砂岩层出现应力集中,路基出现随时间增长的持续上拱变形,而后逐渐趋于稳定。

The long-term vertical continuous upheaval deformation of subgrade is an important factor to affect the safety of high-speed railway. In order to reveal the mechanism of long-term upheaval deformation of deep cutting located in the typical stratiform mudstone intercalated with sandstone in southwestern, combining with the laboratory tests, numerical analysis was conducted on a certain high-speed railway deep cutting by the FLAC3D. The stress and vertical displacement condition of subgrade, which considered the viscoelastic-plastic CVISC model and elastic-plastic model, were obtained. The results show that:① the mechanical properties of mudstone was significantly lower than that of sandstone, and the mudstone was rheological;②when the rheology was not considered, the basement was vertically rebound and the horizontal stresses were larger than that of vertical in the shallow;③ when considered the rheology, the stress concentration was occurred in the sandstone layer. The basement was continuous upheaval and then trended to be stable. The results can provide reference for the further study on the mechanism of upheaval in high-speed railway deep cutting.