| Strain Monitoring and Stress Analysis of a Post-Prestressed Tunnel Liner |
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| 作者姓名： | 亢景付 王金辉 |
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| 作者单位： | School of Civil Engineering Tianjin University Tianjin 300072 China，School of Civil Engineering Tianjin University Tianjin 300072 China |
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| 基金项目： | Supported by National Natural Science Foundation of China (No. 50578110) . |
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| 摘 要： | The strain monitoring and stress analysis of a new type of post-prestressed tunnel liner were carried out. The instrumentation block of the tunnel liner, with the dimensions of 12.06 m in length, 6 500 mm in diameter, and 650 mm in thickness, was post-prestressed with the unbonded tendons, each of which consists of 8 pieces of double-looped strands and the axial spacing of the tendons is 500 mm. Concrete strain meters, rebar meters, load cell and zero-stress meters were installed for the strain monitoring. The tensioning loads were applied incrementally in three cycles (50%, 77% and 100%) at the concrete age of 28 d and the tensioning work lasted for 187.1 h. Strain readings were taken before and after each cycle during tensioning period and at the specified time interval after tensioning period. It is found that concrete creep developed over tensioning period is 30% of total strain and 41.5% of elastic strain respectively. Prestress force in the unbonded tendon and concrete stress in the liner were evaluated according to the observed strain variations. Both of them are time-dependent, and about 5.3%, 8.3% and 9.0% of the prestress losses are observed at the age of 1 d, 30 d and 60 d respectively after stressing. The distribution of prestress in the liner is relatively uniform and meets the design requirement.
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| 关 键 词： | 损伤监测 压力分析 建筑结构 预应力 隧道衬砌 |
| 收稿时间： | 2006-01-09 |
Strain Monitoring and Stress Analysis of a Post-Prestressed Tunnel Liner |
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| KANG Jingfu,WANG Jinhui.Strain Monitoring and Stress Analysis of a Post-Prestressed Tunnel Liner[J].Transactions of Tianjin University,2006,12(3):215-221. |
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| Authors: | KANG Jingfu WANG Jinhui |
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| Abstract: | The strain monitoring and stress analysis of a new type of post-prestressed tunnel liner were carried out. The instrumentation block of the tunnel liner, with the dimensions of 12.06 m in length, 6 500 mm in diameter, and 650 mm in thickness, was post-prestressed with the unbonded tendons, each of which consists of 8 pieces of double-looped strands and the axial spacing of the tendons is 500 mm. Concrete strain meters, rebar meters, load cell and zero-stress meters were installed for the strain monitoring. The tensioning loads were applied incrementally in three cycles (50%, 77% and 100%) at the concrete age of 28 d and the tensioning work lasted for 187.1 h. Strain readings were taken before and after each cycle during tensioning period and at the specified time interval after tensioning period. It is found that concrete creep developed over tensioning period is 30% of total strain and 41.5% of elastic strain respectively. Prestress force in the unbonded tendon and concrete stress in the liner were evaluated according to the observed strain variations. Both of them are time-dependent, and about 5.3%, 8.3% and 9.0% of the prestress losses are observed at the age of 1 d, 30 d and 60 d respectively after stressing. The distribution of prestress in the liner is relatively uniform and meets the design requirement. |
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| Keywords: | hydraulic structure concrete creep tensioning period instrumentation elastic stress |
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