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1.
Grigorios Tsinidis Kyriazis Pitilakis Christos Anagnostopoulos 《Bulletin of Earthquake Engineering》2016,14(10):2903-2929
The paper discusses the seismic response of circular tunnels in dry sand and investigates the efficiency of current seismic analysis methods at extreme lining flexibilities. Initially, a dynamic centrifuge test on a flexible circular model tunnel, embedded in dry sand, is analyzed by means of rigorous full dynamic analysis of the coupled soil–tunnel system, applying various non-linear soil and soil–tunnel interface models. The numerical results are compared to the experimental ones, aiming to better understand the recorded response and calibrate the numerical models. Then a series of numerical analyses are conducted using the validated numerical model, in order to investigate the effect of the tunnel lining rigidity on the dynamic response of the soil–tunnel system. In parallel, the accuracy of currently used simplified analysis methods is evaluated, by comparing their predictions with the results of the a priori more accurate and well validated numerical models. The comparative analyses allow us to highlight and discuss several crucial aspects of the soil-tunnel system seismic response, including (1) the post-earthquake residual values of the lining forces, which are amplified with the increase of the flexibility of the tunnel and (2) the importance of the soil-tunnel interface conditions. It is finally concluded that simplified analysis methods may provide a reasonable framework for the analysis at a preliminary stage, under certain conditions. 相似文献
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双洞隧道主隧道与横通道交接部位是隧道抗震中的薄弱位置,以穿越高烈度区隧道为背景,采用MIDAS GTS-NX有限元分析软件,对在汶川地震动作用下的公路隧道横通道进行地震响应分析。在X方向和Y方向地震动荷载的共同作用下,通过对围岩和衬砌的计算结果研究,得出以下结论:隧道整体的最大相对位移主要发生在主隧道与横通道拱顶和连接处;衬砌相对位移随埋深增加而减小;隧道产生的横向变形更大;横通道边墙位置更容易受到剪切破坏,主隧道与横通道连接处拱脚的弯矩、剪力、最大主应力和最大剪应力最大,应重点采取设防措施。 相似文献
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基于ABAQUS软件平台,应用自行开发的流固耦合动力模型孔压单元模拟场地土体,并通过黏弹性人工边界方法实现地震动的输入,对饱和土体场地中的双孔隧道结构在地震荷载作用下的动力反应进行研究。计算结果表明:在地震反应结束时刻,场地土体位移幅值在两隧道之间以及两隧道的附近区域较大,而远离隧道的区域则较小;场地底部区域土体的孔压幅值较大,而场地顶部区域土体则较小;隧道左右两侧拱腰部位的衬砌的应力较大,而拱顶部位则较小。计算结果同时表明了流固耦合动力模型孔压单元在饱和土体-隧道体系地震反应研究中的适用性。 相似文献
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The effect of ground stratification on the seismic response of circular tunnels is investigated, as most practice-oriented studies consider homogeneous ground. A finite element plain-strain model of a circular tunnel cross-section embedded in a two-layered ground is used to highlight the influence of stratification on the tunnel׳s seismic response. The layers interface was placed at the crown, centre and invert level.It is proved that ground stratification has an important role in the lining seismic forces. When the tunnel is fully embedded in one of the layers, the seismic lining forces may vary significantly in comparison with the single-layer case. If the tunnel intercepts both layers, maximum lining forces aggravation occurs when the lower layer is very stiff. 相似文献
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地下结构的地震响应主要取决于由地震波传播产生的土体变形与土结相互作用。剪切波传播过程中将会引起隧道衬砌的椭圆化变形,进而降低衬砌有效承载力。剪切波作用下的深埋圆形隧道可认为处于均质的纯剪状态,基于相对刚度法的拟静力解析解可充分考虑土结相互作用对隧道结构内力的影响。基于此,本文将通过有限元数值分析获得的自由场地地基变形引入不滑移状态下深埋圆形隧道内力求解公式,并结合二维和三维数值模拟途径,将动力分析结果与解析解结果进行对比分析,以评价各种解析方法的适用性和数值途径的可靠性。 相似文献
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Tunnel behaviour under earthquake loading is affected by many factors such as shape, depth and stiffness of the tunnel lining and the nature of the input motion. However, current knowledge on the effects of these parameters on the seismic behaviour of tunnels is limited to lack of experimental or field data. Existing analytical methods are based on assumptions, the validity of which needs to be established using carefully conducted experimental studies and numerical analyses. This paper focuses on the effects of input motion characteristics on seismic behaviour of circular and square tunnels. Dynamic centrifuge tests were carried out on model tunnels using input motions of different amplitude and frequency. Accelerations and earth pressures around the tunnels were measured. Complementary Finite Element analyses were conducted with different types of input motions. Results show that magnitude of the maximum input acceleration plays a crucial role on the maximum and residual lining forces, which the tunnel experiences. 相似文献
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This paper uses numerical and analytical methods to examine the static and seismic response of tunnels with intact and degraded segmental concrete tunnel liners. Concrete degradation is simulated using a non-linear finite element (FE) model that accounts for soil-structure interaction and the non-linear stress–strain response of the soil and concrete. The non-linear FE model is used to calculate radial stresses in tunnel linings with local concrete delaminations and that are subject to both static and seismic loads. Then, the FE results are compared with an analytical solution for jointed tunnel linings in order to assess the accuracy of the solution for predicting stresses in degraded liners. The analyses and results presented in this paper illustrate a simple method for estimating and evaluating the effect of concrete degradation on the distribution of thrust and moment in segmental tunnel linings subject to either static or seismic loads. 相似文献
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An analytical procedure is presented for evaluating the stresses in linings of bored tunnels caused by kinematic soil–lining interaction. Three cases of plane–strain interaction are treated as produced by (1) relaxation of in situ soil stresses near a lining following its installation, (2) overburden pressure at the soil surface, and (3) two-dimensional free-field soil response normal to the lining axis as produced by an earthquake. The procedure is applied separately to a steel lining and a concrete lining for a site located at the lower end of Market Street in San Francisco through which a BART (Bay Area Rapid Transit) tunnel passes. © 1998 John Wiley & Sons, Ltd. 相似文献
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以棋盘石穿越断层破碎带段隧道为背景,采用理论计算与数值模拟相结合的方法,对棋盘石隧道在汶川波作用下的地震响应分析进行了系统研究。探讨了断层破碎带衬砌在地震荷载作用下的破坏方式,并且把数值模拟结果与汶川特大地震震害的公路隧道进行对比分析。结果表明:用松动圈折减系数法估算出衬砌最大弯矩和剪力的数值与数值模拟的结果基本一致,验证了MIDAS/GTS-NX模拟隧道地震时程分析的可行性;同时根据对有限元模型进行时程分析的结果,探讨了断层破碎带处衬砌的破坏方式,并提出合理可行的防治及加固措施。 相似文献
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利用黏弹性人工边界和等效地震荷载时域波动输入方法,结合土层和半空间的精确动力刚度矩阵,实现了地震波斜入射下层状场地地下综合管廊地震反应分析,建立了不同场地条件下地下综合管廊分析模型。计算结果表明:地震波倾斜入射情况下,综合管廊结构地震响应与垂直入射时具有显著差异,一般SV波以30°临界角附近入射时结构地震反应最为剧烈;地下综合管廊动应力集中主要分布在管廊角部、中柱上下端;成层土波速结构变化对地下综合管廊地震反应亦具有显著影响。总体上看:当穿越软夹层时管廊结构地震反应更为剧烈,且覆盖层越厚,管廊结构内力幅值越大。因此地下综合管廊结构抗震设计宜考虑地震波倾斜入射及场地土层性质的影响。 相似文献
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Dynamic interaction of twin vertically overlapping lined tunnels in an elastic half space subjected to incident plane waves 
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下载免费PDF全文 The scattering of plane harmonic P and SV waves by a pair of vertically overlapping lined tunnels buried in an elastic half space is solved using a semi-analytic indirect boundary integration equation method. Then the effect of the distance between the two tunnels, the stiffness and density of the lining material, and the incident frequency on the seismic response of the tunnels is investigated. Numerical results demonstrate that the dynamic interaction between the twin tunnels cannot be ignored and the lower tunnel has a significant shielding effect on the upper tunnel for high-frequency incident waves, resulting in great decrease of the dynamic hoop stress in the upper tunnel; for the low-frequency incident waves, in contrast, the lower tunnel can lead to amplification effect on the upper tunnel. It also reveals that the frequency-spectrum characteristics of dynamic stress of the lower tunnel are significantly different from those of the upper tunnel. In addition, for incident P waves in low-frequency region, the soft lining tunnels have significant amplification effect on the surface displacement amplitude, which is slightly larger than that of the corresponding single tunnel. 相似文献
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The first part of this paper presents an extensive validation of four analytical solutions for the seismic design of circular tunnels. The validation is performed with a quasi-static finite element (FE) model which conforms to the assumptions of the analytical solutions. Analyses are performed for a wide range of flexibility ratios, slippage conditions at soil–lining interface, assuming both drained and undrained behaviour. Based on the numerical predictions the relative merits of the considered analytical solutions are discussed and recommendations are given for their use in design. The second part of this paper explores the use of equivalent linear soil properties in analytical solutions as an approximate way of simulating nonlinearity. The results of equivalent linear site response analyses are used as an input for the analytical solutions. The comparison of the analytical predictions with nonlinear numerical analysis results is very satisfactory. The results of this study suggest that analytical solutions can be used for preliminary design using equivalent linear properties and the corresponding compatible strain as an approximate way of accounting for nonlinear soil response. 相似文献
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在隧道的施工和运营中,隧道衬砌不可避免会产生裂纹。裂纹和地震荷载的相互作用将加剧隧道的破坏,因此研究带裂纹隧道衬砌地震荷载作用下的破坏具有重要的意义。为了证明本文二维有限元数值模拟计算结果的正确性,首先用相互作用积分的方法计算动载作用下的静态裂纹,并与解析解进行比对,发现二者的吻合性很好。计算结果表明相互作用积分法可以用来精确地计算动载作用下带裂纹结构的动应力强度因子。用这种经过验证的方法来计算带裂纹重载铁路隧道衬砌的动应力强度因子和动承载力安全系数,可以看出在地震荷载作用下,I型裂纹的动应力强度因子在隧道结构的安全中起控制作用。当裂纹的长度大于某特定值时,隧道处于很危险的状态。 相似文献
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In this paper, different approaches aimed at investigating the dynamic behaviour of circular tunnels in the transverse direction are presented. The analysed cases refer to a shallow tunnel built in two different clayey deposits. The adopted approaches include 1D numerical analyses performed modelling the soil as a single-phase visco-elastic non-linear medium, the results of which are then used to evaluate the input data for selected analytical solutions proposed in the literature (uncoupled approach), and 2D fully coupled FE simulations adopting visco-elastic and visco-elasto-plastic effective stress models for the soil (coupled approach). The results are proposed in terms of seismic-induced loads in the transverse direction of the tunnel lining. The different constitutive hypotheses adopted in the coupled numerical approach prove to play a significant role on the results. In particular, the plasticity-based analyses indicate that a seismic event can produce a substantial modification of loads acting in the lining, leading to permanent increments of both hoop force and bending moment. 相似文献
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Mohammad Hassan Baziar Masoud Rabeti Moghadam Yun Wook Choo Dong-Soo Kim 《地震工程与工程振动(英文版)》2016,15(3):457-476
Flexibility of underground structures relative to the surrounding medium, referred to as the flexibility ratio, is an important factor that influences their dynamic interaction. This study investigates the flexibility effect of a box-shaped subway tunnel, resting directly on bedrock, on the ground surface acceleration response using a numerical model verified against dynamic centrifuge test results. A comparison of the ground surface acceleration response for tunnel models with different flexibility ratios revealed that the tunnels with different flexibility ratios influence the acceleration response at the ground surface in different ways. Tunnels with lower flexibility ratios have higher acceleration responses at short periods, whereas tunnels with higher flexibility ratios have higher acceleration responses at longer periods. The effect of the flexibility ratio on ground surface acceleration is more prominent in the high range of frequencies. Furthermore, as the flexibility ratio of the tunnel system increases, the acceleration response moves away from the free field response and shifts towards the longer periods. Therefore, the flexibility ratio of the underground tunnels influences the peak ground acceleration (PGA) at the ground surface, and may need to be considered in the seismic zonation of urban areas. 相似文献
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A method to cover a tunnel lining with a soft and thin coating is discussed herein as a possible measure for mitigating seismic damage to tunnels. Long‐term earthquake observations at different tunnel sites within a variety of alluvial soil deposits have demonstrated that a circular tunnel is liable to deform in such a way that its two diagonal diameters crossing each other expand and contract alternately. Narrowing down vibration modes, in order to discuss this particular and the most important mode, any of the essential items of the soil–tunnel system, namely the soil, the coating and the tunnel lining, has only one degree of freedom, allowing the coating effect to be simply evaluated in terms of a limited number of key parameters. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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历次震害表明隧道等地下结构受地震影响较大,当地震动的卓越频率与结构的固有频率一致时,引发的共振会对结构产生更严重的破坏。针对共振这一地震中的特殊现象,通过ANSYS分析研究浅埋偏压黄土隧道在双向地震耦合作用下隧道衬砌各处的共振响应和围岩至衬砌段共振响应峰值的变化规律,同时考虑偏压角度和断面最大跨径对共振响应峰值的影响。研究结果表明：浅埋偏压黄土隧道具有多阶固有频率,衬砌的位移和应力均出现了共振现象且共振不表现出结构的自振频率特征;从围岩至衬砌段的共振响应具有放大效应;水平位移峰值随偏压角度的增大而减小;适当增大断面最大跨径对于抵抗共振是有利的;拱腰和拱脚处的主应力受共振影响较大,在隧道的抗震设计中应予以加强。 相似文献