基于收敛约束法的隧道开挖纵剖面变形曲线研究

Study on Longitudinal Deformation Profile in Tunnel Excavation Using the Convergence-confinement Method

收敛约束法是应用于隧道支护设计的一种简化分析方法,纵剖面变形曲线是该分析法的重要曲线。考虑隧道开挖工作面效应和纵剖面变形曲线的关系,进行数值模拟研究,探讨纵剖面变形曲线的影响因素,并与理论公式计算结果进行对比分析。结果表明:隧道纵剖面变形曲线与收敛损失随开挖的变化规律是一致的;弹性条件下隧道的前期位移量为25%~34%,本次模拟结果为32.8%;归一化的纵剖面变形曲线受支护条件影响较大,受埋深、弹模和泊松比影响较小;由二维纵剖面变形曲线的分布,可计算得隧道前期位移量及各个阶段的收敛损失值,了解隧道开挖工作面效应的三维影响,进而能够分析计算隧道围岩结构的应力与位移等变量。

For the design of support system of tunnel,the convergence-confinement method is a simplified analysis theory.The longitudinal deformation profile( LDP) is an important factor in the convergence-confinement method. According to the relationship between the LDP and tunnel advancing effect,a numerical analysis is conducted to investigate the LDP under different conditions,and thus make a comparison with the theoretical result. It shows that,the confinement loss changes in accordance with that the LDP changes; the estimated preconvergence normalized by the maximum convergence value equal from 25% to 34% in elastic condition,this simulation result is 32. 8%; the timbering conditions effect the LDP the most,burying depth,elastic modulus,Poisson's ratios have little influence; the LDP in two-dimensional condition can be used to calculate the convergence loss in every steps,describe the three-dimensional advancing effect,and estimate the variation of stress-displacement of rock mass and support system in tunnel excavation.