以隧道变形量测资料分析掘进效应与约束损失

 收敛–约束法理论为应用于隧道工程支撑设计的简化分析方法，所采用之约束损失更是此分析模式的关键因子。针对约束损失的计算与影响性分析，以隧道工程广泛使用的变形量测收敛资料为依据，以掘进效应函数探讨隧道因前进开挖引致工作面围岩变形与应力变化，并以反计算方法评估约束损失分布情况，进而应用于台湾八卦山公路隧道工程案例分析，以了解实际掘进效应的影响。研究分析结果包含：(1) 提出掘进效应函数描述隧道收敛资料与约束损失的关系；(2) 说明掘进效应函数的参数适用范围及其物理意义；(3) 提出约束损失方程用以预估隧道开挖引致前期与掘进距离的收敛值；(4) 反计算方法可以预估约束损失可能的重新分布趋势与前期收敛；(5) 掘进效应函数分析结果与三维有限元计算结果相近。

ANALYSIS OF ADVANCING EFFECT AND CONFINEMENT LOSS BY USING DEFORMATION MEASUREMENTS IN TUNNEL

For the design of support system of tunnel，the convergence-confinement method is a simplified analysis theory. Obviously，the confinement loss used by the theory is an important influence factor. For analyzing the influence of the confinement loss，the deformation measurements widely used in tunneling engineering are investigated；and the advancing effect function is particularly proposed to examine the alterations of deformation and stresses of rock mass around tunnel. The back calculation procedure is a technique proposed to assess the redistribution of the confinement loss. The case study of Baguashan tunnel in Taiwan is taken account of the advancing effect during construction. According to the obtained results and the comparison between numerical calculation and theoretical analysis，it is shown that：(1) the relationship between deformation measurements and confinement loss can be described by the proposed advancing effect function；(2) the parametric study of advancing effect function is examined；(3) the equations proposed for the confinement loss can be used to estimate the pre-convergence due to excavation；(4) the back calculation procedure is also proposed to understand the redistribution trend of confinement loss；and (5) the results obtained by the three-dimensional finite element analysis and the advancing effect function respectively are approximately coincident.