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When an underwater tunnel is excavated, the groundwater may flow into the tunnel. The seepage forces consequently induced can have important effects on the effective stresses around the tunnel. Moreover, the influences of the free surface of a shallow underwater tunnel should also be considered. In this research, an analytical solution is presented to calculate the seepage‐induced effective stresses around a shallow underwater tunnel in an elastic half plane. The solution uses the complex variable method and consists of conformally mapping the half plane with a hole onto a transformed circular ring. The coefficients of the various terms in the Laurent series expansions of the stress functions in the transformed region can be obtained from the boundary conditions. The total stress distribution around a shallow underwater tunnel can be calculated by the potentials in the half plane. The effective stress can be obtained by subtracting the pore pressure from the total stress. The analytical solution is validated by numerical simulations and can be used to perform both the short‐term and long‐term analyses. By using the proposed solution, it is found that the circumferential effective stresses around the tunnel increase greatly because of seepage, and they increase with the increase of water depth in both the undrained and drained conditions. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
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富水软弱地层地铁隧道浅埋暗挖施工技术   总被引:6,自引:0,他引:6  
浅埋暗挖法在深圳地铁一期工程 2 3标区间隧道施工中成功运用 ,其中地表降水、旋喷止水帷幕、天桥基础托换和地质超前预报等技术都在含砂、含水、软土地层中成功实施 ,隧道顺利通过富水软弱含砂地层及两座人行天桥 ,施工进度、安全性和施工质量都得到保证 ,并有效地控制了地表沉降 ,取得了很好的经济效益。对各项技术措施、施工工艺及技术难点进行了分析 ,指出该技术在富水软弱地层中广阔的应用价值和前景  相似文献   
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Liu  Dingli  Xu  Zhisheng  Fan  Chuangang 《Natural Hazards》2019,97(3):1175-1189

Frequent fires can affect ecosystems and public safety. The occurrence of fires has varied with hot and cold months in China. To analyze how temperature influences fire frequency, a fire dataset including 20,622 fires and a historical weather dataset for Changsha in China were gathered and processed. Through data mining, it was found that the mean daily fire frequency tended to be the lowest in the temperature range of (20 °C, 25 °C] and should be related to the low utilization rate of electricity. Through polynomial fitting, it was found that the prediction performance using the daily minimum temperature was generally better than that using the daily maximum temperature, and a quadruplicate polynomial model based on the mean daily minimum temperature of 3 days (the day and the prior 2 days) had the best performance. Then, a temperature-based fire frequency prediction model was established using quadruplicate polynomial regression. Moreover, the results are contrary to the content stipulated in China’s national standard of urban fire-danger weather ratings GB/T 20487-2006. The findings of this study can be applied as technical guidance for fire risk prediction and the revision of GB/T 20487-2006.

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