摘要
依托某供水工程输水隧洞建立三维数值模型,采用有限差分法和Mohr-Coulomb屈服准则进行施工开挖过程的数值模拟,研究不同围岩条件下隧洞支护时机的估算。首先,基于收敛-约束法进行隧洞开挖推进过程中的变形规律研究,分析监测断面的围岩变形特征,研究发现围岩位移的收敛规律与围岩质量相关,提出隧洞纵向变形曲线的修正公式。然后,采用一步挖穿分期释放的模拟方法,研究监测断面位移随开挖荷载释放的变化规律,以相同的位移释放系数为出发点,构建,开挖面推进距离与荷载释放率之间的关系,并将对应的围岩位移陡增点作为施加支护的推荐时机,得出不同围岩条件下施加支护与开挖面之间的控制距离。研究结果表明,提出的纵向变形公式相关参数确定过程简单,拟合效果良好,推荐的支护与开挖面之间的控制距离符合工程实际规律。
Combining with a three-dimensional numerical model for a TBM tunnel of Lanzhou water supply project, the tunnel excavation process is simulated with finite difference method and the Mohr-Coulomb failure criterion to estimate the support installation time. Based on the convergence-confinement method, the deformation tendency of the monitoring section can be analyzed during the tunnel advancing. It is shown that the regularity of longitudinal displacement is related to the surrounding rock quality. The modified formula of longitudinal deformation curve can be fitted by the change regularity. With the method of virtual supporting force, the tunnel excavation can be assumed as an instantaneous progress in unique step to analyze the regularity between the deformation of surrounding rock and the excavation load releasing ratio. And the advance distance could be correlated to the excavation load releasing ratio with the same displacement completion ratio. So the supporting installation location away from the tunnel advance face can be determined by the excavation load releasing ratio when the deformation increases abruptly. The results show that the related parameters in the modified formula are convenient to be determined and satisfied with the fitting features. And the recommended supporting installation locations meet well with the common sense.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2017年第S1期471-478,共8页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.51579194)
国家重点研发计划(No.2016YFC0401803)~~
关键词
隧洞
开挖
纵向变形曲线
位移释放系数
支护时机
tunnel
excavation
longitudinal deformation curve
displacement completion ratio
support installation time
