三孔平行隧道開挖應力互制行為數值分析

Stress Interaction Behaviors during the Excavation of Parallel-three-hole Tunnel by Numerical Analysis

李國維(Kuo-Wei Li)

指導教授 ： 陳水龍

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2006年)

https://doi.org/10.6841/NTUT.2006.00224

摘要

本研究利用有限元素法軟體PLAXIS 3D TUNNEL version 2，模擬三孔平行隧道導坑與主坑先後開挖過程中，對於岩柱造成的應力影響行為。
本論文分別就岩覆深度、岩體類別、岩柱寬度等變數進行數值分析並考量分階開挖、輪進長度及延時支撐等因素，計算在不同現地應力、不同材料強度與不同岩柱寬度下，隧道岩柱的安全性。
藉由計算岩柱內部的應力狀態，求出平均有效應力、軸差應力不變量、羅德角，再配合材料本身的彈性模數、柏松比、凝聚力、摩擦角，求出岩柱在每一個開挖階段的應力狀態。透過應力狀態與材料所能提供強度的比值，可以瞭解在每一個開挖過程的應力狀態是否趨向穩定或危險。
本研究提供一正規化之「三孔平行隧道開挖岩柱應力強度比」圖表，代入由岩覆深度求出之「現地應力」、現地鑽探得知岩體類別求出之「材料強度」、具有幾何特性代表性之「岩柱寬度」，就可以求出該模型之SSR(應力強度比)。

關鍵字

三孔平行隧道 ； 岩覆深度 ； 岩體類別 ； 岩柱寬度 ； 應力狀態

並列摘要

During the process of excavation of parallel-three-hole tunnel, tunnel may fail under the stress interaction behavior particularly when the rock pillar widths are inadequate among the tunnels. Thanks to the modern computing technology, it is fairly easy to do the numerical analysis nowadays. This thesis is all about the simulation and discussion on the stress interaction behavior issue.
With variables like the rock overburden depth, rock mass classification, and rock pillar width, to run the numerical analysis and think about the factors individually. What is expected from the numerical analysis result is the safety under different In-Situ stress, material strength, and rock pillar width.
In order to study the influence of the stress applied on the rock pillar, the whole process of the excavation of parallel-three-hole tunnel can be simulated via the finite element method based software “PLAXIS 3D TUNNEL Version 2”. And then from a series of calculation to get to know the stress state of every step that will lead to a stable status or a dangerous one.
SSR(stress strength ratio) of the model can be calculated by a normalized diagram which is provided in this thesis and then plugged it into the In-Situ stress, material strength, and rock pillar width to do the calculation work.
Three important conclusions in this thesis are:
(1)How does the anchor affect the rock pillar? (with the calculated SSR)
(2)The category of failure under the stress status of the rock pillar during excavation.
(3)Interaction among rock overburden depth, rock mass classification, and rock pillar width. (In order to meet the construction safety requirements, it is expected to predict the stress status of the rock pillar right after the excavation is done in the preliminary design stage.)

並列關鍵字

Parallel-three-hole Tunnel ； Rock overburden depth ； Rock mass classification ； Rock pillar width ； Stress state

參考文獻

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