冻融作用下隧道围岩稳定性数值模拟研究

对取自新疆某隧道的砂岩岩样开展冻融循环试验,并进一步进行三轴卸围压试验,得到经历不同次数冻融循环后的砂岩的变形模量随变形的变化关系,然后,利用FISH语言编写变形模量随变形动态调整参数程序,为隧道计算模型提供参数值,对隧道围岩稳定性进行了数值模拟。结果表明:经历不同冻融循环次数的砂岩岩样随着围压的逐渐卸除,变形模量随着侧向变形的增大呈非线性下降趋势。经历80冻融循环后隧道围岩应力发生重分布,变形和塑性区逐渐增大,影响了围岩稳定性和支护结构的稳定性,在开挖工程设计和选用支护结构时应给予考虑。

NUMERICAL SIMULATION ON THE STABILITY OF TUNNEL SURROUNDING ROCKS UNDER FREEZE-THAW CYCLE

With the development of the west,more and more rock mass engineering are built in the cold area,so the study on the stability of rock mass engineering under freeze-thaw cycle is of great significance.Firstly,the freezing and thawing cycle tests about the sandstone samples were carried out in this paper,and then the three axis unloading confining pressure test was conducted.The changing relationship between the deformation modulus of sandstone and the deformation was got under different freeze-thaw cycles.Secondly,the program of the dynamic adjustment of the deformation modulus with the deformation was written by using the FISH language,which provided the parameters for the tunnel calculation model,and then the stability of tunnel surrounding was numerically simulated.The results show that the deformation modulus has a nonlinear decreasing trend with gradually removing the confining pressure after undergoing some freeze-thaw cycles.After 80 freeze-thaw cycles,the stress redistribution of tunnel surrounding rock stress distribution occurred and the deformation and plastic zone had a gradual increase,affecting the stabilities of the surrounding rock and the supporting structure.Tbus,these factors should be considered when designing an excavation engineering design or selecting a supporting structure.