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991.
992.
Complex variable analysis for stress distribution of an underwater tunnel in an elastic half plane
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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
993.
Measurements on a 14.5‐m diameter bored tunnel have shown that the mechanised assembly of a segmented tunnel lining results in a permanent longitudinal bending moment in the tunnel lining. An analytical model for the beam action of the tunnel lining during the construction phase of bored tunnels is presented. The model incorporates many of the essentials in staged beam construction. It takes into account the influence of forces from the TBM, the loading of the tunnel lining by the grout in the liquid phase, and linear elastic properties of the tunnel lining and soil. Calculations are compared with measurements at the Groene Hart Tunnel (GHT), 20 km south of Amsterdam: the bending moment curve and vertical inclination of tunnel lining segments were compared. The measured bending moment curve is well reproduced. The measured vertical inclination of the lining segments is found to be governed by the beam action of the tunnel lining plus the influence of shear force in the lining. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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995.
A multiscale method for the dynamic analysis of underground structures is proposed, which involves the concurrent discretization of the entire domain with both coarse‐scale and fine‐scale finite element meshes. The coarse‐scale mesh is employed to capture seismic response characteristics of the integral system, whereas the fine‐scale mesh describes in detail the dynamic response in positions of potential damage or interest. For both the coarse‐scale and fine‐scale meshes to overlap, a bridging scale term is introduced so that compatibility of dynamic behavior between the coarse‐ and fine‐scale models is enforced. Both material and contact nonlinearities are considered in the multiscale model. As an application, the model is used for large‐scale seismic response of a newly built long‐distance shield tunnel. Results show that this multiscale method does not have spurious wave reflections at the fine/coarse interface and does not need filtering procedures, which is an advantage compared with the displacement coupling method. Stress and deformation response in lining segments and their connecting bolts are investigated and analyzed within the fine‐scale model, and the capacity of critical structural components, such as bolts and joints is evaluated. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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997.
近年来,由于我国高速铁路和高速公路的大力发展,隧道工程的地质问题研究也越来越多.作者从地质填图和实测剖面入手,分析隧道及其周围的构造特征和变形特性.研究隧道所涉岩体的节理特征及其对隧道稳定性的影响;断层特征及其对隧道稳定性的影响;围岩产状特征及其对隧道稳定性的影响.此文章对于隧道的设计和施工都有较大的借鉴意义. 相似文献
998.
总结论述了急倾斜地层中矿井水平巷道、倾斜巷道,在不同的岩层、煤层及煤层与岩层的组合条件下呈现出的非均衡性围岩压力、顶板的对角线侧压、后期冲击顶侧压、巷道差异性变形、倾斜顺穿层巷道的倒楔形塌洞等不利于安全的工程地质现象,对同类矿井的井巷施工和探索更好的井巷施工技术有一定的指导作用 相似文献
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