| 地铁盾构隧道上方基坑开挖卸荷-加载影响研究 |
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| 引用本文： | 姚爱军,张剑涛,郭海峰,郭彦非.地铁盾构隧道上方基坑开挖卸荷-加载影响研究[J].岩土力学,2018,39(7):2318-2326. |
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| 作者姓名： | 姚爱军 张剑涛 郭海峰 郭彦非 |
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| 作者单位： | 北京工业大学 城市与工程安全减灾教育部重点实验室，北京 100124 |
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| 基金项目： | 国家自然科学基金项目(No. 51578023)。 |
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| 摘 要： | 为提升地铁盾构隧道的防灾减灾能力，以北京某典型地铁盾构隧道及邻域的基坑工程为基础，应用相似材料模型试验与数值模拟相结合的方法，研究了上方基坑开挖卸荷-加载作用下地铁盾构隧道的变形特征及围土压力分布规律，并对基坑底部与盾构隧道顶部净距和基坑加载强度的影响进行了分析。研究结果表明：盾构隧道上方基坑开挖卸荷-加载过程中，随着基坑开挖卸荷的进行，盾构隧道逐步上浮，基坑开挖至底部时，竖向位移达到最大值；随着基坑加载的进行，竖向位移可得到适量恢复，最大竖向位移差及最大水平位移差均出现在基坑开挖卸荷完成阶段，此时应尽早完成基础底板封闭施工。基坑开挖卸荷-加载过程中，盾构隧道围土压力始终呈葫芦型对称分布，盾构隧道顶部及底部土压力较大，腰部土压力较小，基坑开挖卸荷完成后，长轴方向土压力明显减小，基坑加载完成后，土压力有所恢复，但并未达到最初状态。随着基坑底部与盾构隧道顶部净距的增加，盾构隧道结构位移、拱顶与拱底竖向位移差及水平收敛均逐步减小，当净距大于3 h（h为基坑深度）时，上方基坑卸荷-加载对盾构隧道影响逐步趋于轻微。在基坑加载强度为卸载强度的2倍时，盾构隧道竖向位移可恢复至最初状态。
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| 关 键 词： | 盾构隧道 土体卸荷 基坑加载 相似材料模型试验 土压力 |
| 收稿时间： | 2016-09-20 |
Influence of unloading-loading of foundation on shield tunnel underneath |
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| YAO Ai-jun,ZHANG Jian-tao,GUO Hai-feng,GUO Yan-fei.Influence of unloading-loading of foundation on shield tunnel underneath[J].Rock and Soil Mechanics,2018,39(7):2318-2326. |
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| Authors: | YAO Ai-jun ZHANG Jian-tao GUO Hai-feng GUO Yan-fei |
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| Institution: | The Key Laboratory of Urban Security and Disaster Engineering, Ministry of Education, Beijing University of Technology, Beijing 100124, China |
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| Abstract: | To improve the disaster prevention and mitigation of metro shield tunnel, model test of similar material and numerical calculation is studied in this paper to simulate the construction of building adjacent to foundation pit in Beijing. Under unloading-loading conditions of the foundation pit above, the mechanical characteristics of shield tunnel are studied, and the influence of spacing between the bottom of the foundation pit and the shield tunnel top and the loading strength of foundation pit are also analyzed. As shown by calculation, in unloading stage, the vertical displacement of shield tunnel gradually increases. When the foundation pit is excavated to the bottom, the vertical displacement reaches the maximum value. Under loading condition, the vertical displacement of shield tunnel can be restored. The greatest impact on shield tunnel always occurs at the end of the foundation excavation. At this point, the work of foundation slab construction should be completed as soon as possible. In the unloading-loading process of foundation pit , earth pressure of shield tunnel presents calabash type symmetrical distribution. At the top and bottom of the shield tunnel the earth pressure is larger than the soil pressure in the middle of the shield tunnel. In unloading stage, the earth pressure of shield tunnel vertical axis was significantly reduced. In loading stage, the earth pressure of shield tunnel can be restored. With the spacing between the bottom of foundation pit and shield tunnel top increases, the displacement of shield tunnel, the displacement difference between arch bottom and arch and the horizontal convergence are incrementally reduced. When the spacing greater than 3 times of the depth of deep excavation, the additional deformation of shield tunnel caused by foundation pit unloading-loading effect is slightly. When the loading strength of foundation pit 2 times than the unloading strength, the vertical displacement of shield tunnel can be restored to its original state. |
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| Keywords: | shield tunnel soil unloading the foundation loading model test of similar material earth pressure |
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