Tunnel Profile Measuring Technology and Traceback Analysis of the Incremental Stress
Date Issued
2007
Date
2007
Author(s)
Chiu, Ya-Ju
DOI
zh-TW
Abstract
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
Subjects
隧道
隧道檢測
雷射掃描
攝影測量
數值分析
回溯分析
tunnel
tunnel surveillance
laser scanning
photogrammetry
numerical analysis
traceback analysis
SDGs
Type
thesis
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