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QUANTITATIVE EVALUATION OF THE BEARING CAPACITY OF SURROUNDING ROCK MASS AND THEORETICAL CONSTRUCTION OF THE CHARAVTERISTIC CURVE OF TUNNEL SUPPORT FOR NATM

新奥法围岩承载力定量评价及隧道支护特征曲线理论构建

基本信息

批准号：
13650542
负责人：
KIYAMA Hideo
金额：
$ 2.3万
依托单位：
TOTTORI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Active mobilization of bearing capacity of rock mass surrounding an underground opening characterizes the NATM (New Austrian Tunneling Method) concept of supporting. There have been many attempts to give quantitative expressions for this capacity but no one has ever completely solved the question. In the first part of this paper theoretical relations between support pressure and tunnel wall displacements are briefly discussed. We derive a simplified solution of a circular lined-tunnel in an elastic ground under the plain strain for full-slip and no-slip conditions. These two conditions at the ground-lining interface make it possible to explain the effects of shear stress transmission and relative shear displacement. The lateral free-field ground stresses for this solution are restricted to a fixed value of the vertical stresses (σ_v* = -p, σ_H* = -kp). An actual tunnel opening is excavated and supported after the load corresponding to the free-field stresses. We introduce an assumption … More of the actual "excavation unloading" conditions that occur during tunneling. By advancing this derivation, the strict solution is utilized successfully to construct a theoretical characteristic curve of tunneling. The characteristic curve shows clearly the bearing capacities of a tunnel lining, the surrounding ground and the total by using an index "relative-support-stiffness".The elastic theory of the stress distribution around tunnels demonstrates that the deviatoric stresses are maximum at the periphery of the excavation. Discussion here should include the dependence of the characteristic curve on the zone of yielded ground and the discontinuity in the ground. We have carried out numerical simulations for a discontinuous ground with Distinct Element Modeling. The realistic ground reaction curves by the analyses are examined with the theoretical solution derived above. We will learn that while the ground may work, more or less, as a load bearing structural component to the load corresponding to the free-field stresses, overestimation must be avoided. Less

新奥法是一种主动调动地下洞室围岩承载力的支护方法。人们曾多次尝试用定量的方法来表示这种能力，但还没有人完全解决这个问题。本文第一部分简要地讨论了支护压力与洞壁位移之间的理论关系。本文推导了弹性地基中圆形衬砌隧道在平面应变下全滑移和无滑移条件下的简化解。这两个条件在地面衬砌界面上可以解释剪应力传递和相对剪切位移的影响。该解的侧向自由场地应力被限制为一个固定的垂直应力值（σ_v* = -p，σ_H* = -kp）。实际隧道洞口开挖后，相应的自由场应力的负载和支持。我们引入一个假设 ...更多信息隧道开挖过程中实际发生的“开挖卸载”情况。通过推导，成功地利用严格解构造了隧道掘进的理论特性曲线。特征曲线以“相对支承刚度”为指标，清晰地反映了隧道衬砌、围岩及整体的承载能力，隧道周边应力分布的弹性理论表明，隧道周边偏应力最大。这里的讨论应包括特性曲线对地面屈服区和地面不连续性的依赖性。本文采用离散单元法对不连续地基进行了数值模拟。用上述理论解检验了分析得到的实际地面反应曲线。我们将了解到，虽然地面可能或多或少地作为一个承重结构部件，承受与自由场应力相对应的荷载，但必须避免高估。少