隧道剖面量測技術及相應應力增量回溯分析

Tunnel Profile Measuring Technology and Traceback Analysis of the Incremental Stress

邱雅筑(Ya-Ju Chiu)

指導教授 ： 鄭富書

國立臺灣大學/工學院/土木工程學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.02008

摘要

台灣島地形以山地、丘陵、臺地、平原為主，其中山地與丘陵約占總面積三分之二，且中央山脈從中將台灣一分為二，不論由交通亦或整體發展來看，聯絡各地又能穿越山麓、丘陵帶之隧道工程確為規劃交通路線時不可或缺之要件。然而目前所使用之隧道量測儀器動輒花費百萬至千萬，無法因應經常性的隧道檢測；針對此落差，曹峻瑋(2006)將W. J. Ni and H. Capart (2005)用於地下水湧出之地形的雷射掃描量測技術與攝影測量成像方法改良後應用於隧道工程。本研究延續其成果，由掃描技術的速度著手，設計一操作簡易、節省操作時間之雷射載具；於降低誤差方面，改採扭曲較小的鏡頭；實驗施做時有別於前人以全測站量得單一剖面做為所有雷射掃描剖面量測值的比較基準，將雷射剖面掃描儀所掃出的剖面描繪於模擬隧道上，再以全測站進行量測，如此可避免比較基準面與雷射掃描面並非同一剖面可能引致的誤差。
　　隧道剖面量測技術之開發主旨在提供連續的隧道剖面資料，從而監測隧道位移情形，以決定維修補強時機。與此技術配合，本研究提出一個由剖面量測結果反推隧道應力增量的方法。研究過程中先以數值分析軟體ABAQUS進行數個隧道受不同型式外力的案例，再從這些案例中歸納出應力增量回溯的流程。首先定義隧道受力之後的任何行為為位移(d, displacement)，位移分為剛體運動(t, rigid body motion)與變形(ut, deformation)兩種，變形又可細分成遠域應力變化造成的變形(uf, deformation induced by far field stress changes)和近域應力變化造成的變形(un, deformation induced by near field stress changes)。其中剛體運動即為位移後剖面各點坐標之平均值，故將剛體運動扣除後便可得到各點之變形大小。遠域應力變化造成的變形反應於隧道剖面整體，但近域應力變化造成的變形則僅出現於剖面局部位置，且遠域外力依不同的主應力比(σ3/σ1, principal stress ratio)而有不同之位移曲線。研究結果發現扣除剛體運動後，最大與最小變形量必定與最大或最小主應力方向相同，且近域應力變化造成的變形可經由濾除遠域應力變化造成之變形得到。另外建立一僅有襯砌之數值模型，將前述案例之節點位移輸出，以位移控制加於襯砌模型，便可得到襯砌所受之節點外力。然此外力並非直接等同於襯砌所受外力，而是襯砌所受之應力增量表現於選定數量節點上的等值外力。
　　藉由本研究所開發的隧道剖面量測技術與應力增量回溯分析，不僅可提供量測時間內隧道剖面的變化，且能進一步得到此區間內襯砌周圍應力增量的等值外力，直接便能判斷何處最有可能發生破壞，除可作為維修補強設計的參考外，尚能解釋隧道剖面變形與應力增量的關係。未來應用時可於雷射載具再稍做改良，並進行其他形狀的隧道剖面之數值分析，以使功能更加完善。

關鍵字：隧道、隧道檢測、雷射掃描、攝影測量、數值分析、回溯分析

關鍵字

隧道 ； 隧道檢測 ； 雷射掃描 ； 攝影測量 ； 數值分析 ； 回溯分析

並列摘要

In Taiwan, mountains and hills constitute about over 2/3 of the island’s land area. The Central Mountain Range forms a native barrier which divides Taiwan into two parts, and this makes tunnel the most essential components when programming traffic route. In addition, regular survey is important to make sure the safety of tunnel. However, it is difficult to conduct regular survey and inspection due to the high cost of measurement system (about 1~10 million N.T. dollars). Therefore, Chun-Wei Chao (2006) applied the laser scanning technology and imaging principle using to measure gullies (W. J. Ni and H. Capart, 2005) to fulfill the needs.
　　Based the Chao’s results, this research designed a laser vehicle which is easy to handle and shortens operation time substantially. In order to lower the error, lens with smaller distortion is used. When doing laser scanning tests, describe each laser profile projected by laser vehicle on a simulative tunnel and measure it by total station one by one rather then taking one profile as all profiles.
　　The aim of the profile measuring technology is to provide continuous profile data and monitor displacement of tunnel, and it is helpful to decide when the tunnel needs to be repaired or reinforced. To cooperate with the technology, this research proposes a method that can analysis backward tunnel incremental stress from profile measuring results. First, several cases in which tunnel sustain different appied forces by numerical software ABAQUS were considered. From those cases, we conclude the procedure of tracing backward the incremental stress. Any behavior of tunnel profile with applied force was defined as displacement, d. Displacement can be divided into rigid body motion t and deformation ut, furthermore, deformation can also be separate into deformation induced by the changes of far field stress uf changes and of near field stress un. If there is no near field stress changes, rigid body motion equals to the average of every points’ coordinate on the profile.
　　Therefore, by subtracting rigid body motion, we can get the amount of deformation. Deformation induced by far field stress changes infected the whole area of the profile, but that induced by near field stress changes would show only on part of the profile. Our research shows that after subtracting rigid body motion from displacement, the position of maximum and minimum deformation always represent the direction of maximum or minimum principal stress, and deformation induced by near field stress can be obtained by deducting deformation induced by far field deformation. In addition, a numerical model with tunnel lining was established. The displacement obtained from the above-mentioned cases was applied on nodes and nodes reaction forces can be found. However, it should be kept in mind that the nodes reaction forces doesn’t equal to the stress which act on lining, but it represents the equivalent force of incremental stress.
　　By using the tunnel measuring technology and tracing backward the incremental stress can not only provide the changes of tunnel profile during measurement time but also get equivalent force of the incremental stress. From these data, engineers can judge where the most possible place that failure would occur. This would both be helpful references when proceeding rehabilitation and can explain the relationship between profile deformation and incremental stress.

Keywords: tunnel, tunnel surveillance, laser scanning, photogrammetry, numerical analysis, traceback analysis

並列關鍵字

tunnel ； tunnel surveillance ； laser scanning ； photogrammetry ； numerical analysis ； traceback analysis

參考文獻

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