A THEORETICAL AND PRACTICAL INVESTIGATION ON BEARING CHARACTERISTIC CURVES IN TUNNELLING -AN APPROACH TO QUANTITATIVE EVALUATION OF THE LOAD BEARING CAPACITY OF THE ROCK MASS-

主动调动围岩承载力是NATM支护理念的特点。然而，这种承载能力的任何定量表达式尚未得到普遍认可。在本研究中，二维弹性圆形隧道的“围岩的支撑荷载”、“衬砌的支撑荷载”和“隧道的总支撑荷载”通过使用一个共同的指标来明确地评估，即支撑刚度，该指标由每个支撑的相对刚度与开口内移除的岩石的原始刚度来定义。利用这三种支护刚度，合理地实现了弹性岩体掘进承载特征曲线的理论构建。为说明隧道掘进的特征曲线，进行了颗粒装配仿真。分析的目的是得到随岩体应力-应变特性和初始压力水平而变化的特征曲线。最重要的结果是出现了三种典型的特征曲线：弹性型到弹塑性型、Fenner-Pacher型或灾变型。根据理论程序原理对这些曲线进行讨论，有利于对岩体承载力进行定量评价。隧道衬砌行为是一个地基-衬砌相互作用问题，它取决于衬砌与地基的相对刚度以及初始应力条件。常用的指标“支撑-刚度”对于评价这类问题一定是有用的。最后，导出了衬砌界面全滑移和无滑移情况下的相对刚度的严格解，并对解进行了修正，使相互作用不受掘进前初始应力的直接影响。用常用指标评价的分析结果可为实际应用和进一步发展隧道支护设计提供参考。少

Active mobilization of bearing capacity of surrounding rock mass characterizes the NATM concept of supporting. However, any quantitative expressions of this bearing capacity have not been recognized commonly. In the present investigation, "a support load of surrounding rock mass", "a support load of lining" and "the total support load of a tunnel" for a two-dimensional elastic circular tunnel are distinctly evaluated by using a common index, support-stiffness, which is defined by a relative stiffness of each support to the original stiffness of the rock removed from within the opening. The theoretical construction of bearing characteristic curves of elastic rock masses in tunnelling is rationally achieved with these three support-stiffnesses.Granular assembly simulations were executed to illustrate characteristic curvea for tunnelling. The aim of this analysis is to get characteristic curves which may be varied depending on the stress-strain property of the rock mass and the initial ea … More rth pressure level. The most important result is that there appear to be three typical characteristic curves : elastic type to elasto-plastic type, Fenner-Pacher type, or catastrophic type. The discussion of these curves based on the principles of theoretical procedure gives us advantages to quantitative evaluation of the bearing capacity of rock mass.The behavior of a tunnel lining is a ground-lining interaction problem which depends on the relative stiffnesses of lining and the ground as well as the initial stress conditions. The common index "support-stiffness" must be useful to evaluate such problems. Finally, a strict solution of the relative stiffness is derived for both full slip and no-slip conditions at the ground-lining interface, moreover, the solution is modified for the interaction to be not affected directly by the ground movements due to the initial stresses before tunnelling. The analytical results evaluated with the common index can be used for practical purpose and the further development of tunnel support design. Less