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1.
Mehmet Ozcelik 《Geotechnical and Geological Engineering》2018,36(6):3437-3449
Mechanized tunnelling is a well-established tunnel construction method which allows constructing tunnels in various conditions including mixed ground conditions as well as tunnels in vulnerable urban areas. The selection of the excavator suitable for the geological structure is important in terms of realizing an efficient tunnel excavation. Tunnel excavation studies of Istanbul Kabatas–Mecidiyeköy Metro tunnels are implemented as a double tube. Geology in this section is composed of sandstone, siltstone, mudstone interbedded or as separate units along with dyke intrusions. Calcareous clay, clayey limestone, clayey sand are also rarely observed. Between the Kabatas–Mecidiyekoy tunnels includes two types of mechanical excavation methods namely tunnel boring machine (TBM) and new Austrian tunnelling method (NATM). Main purpose of this study is mixed ground and their impacts on mechanized tunnelling. At the end, some issues have been presented which seems to be important for the success of TBM and NATM in the mixed grounds. As the tunnel excavation studies continued, the problem of collapse on the ground surface of Barbaros Boulevard in Besiktas station increased the importance of tunnel excavation under mixed ground conditions. 相似文献
2.
The roadway tunnel is considered a good solution for the success of modern roadway networks. It can help to overcome possible traffic congestion and considerably reduce journey time. The continuous growth of traffic volumes leads to increase congestion and decrease safety. This leads to the need for extra tunnel space. The extra tunnel space can be achieved either by the widening of the existing tunnel or by adding a new one. The choice of the suitable method is dependent on many factors like tunnels alignment, site conditions, construction method, tunnel operation, risk assessment…etc. The current research investigates the second alternative through a specific case study as an example. The method comprises adding two new tunnels to an existing twin roadway tunnels. The investigated problem considers the new tunnels to be added vertically or horizontally. The influence of the new tunnel construction on the existing tunnels is investigated considering both the variation of relative position and spacing distance in a parametric study context. Several numerical models are employed to check the construction sequence and the tunnelling safety. These models are used to evaluate the induced stresses in surrounding ground for two different soil types, straining actions in tunnels’ liner and deformations of both ground and liner. The result demonstration shows how to find out the minimum practical and safe spacing distance between the driven new tunnels and the existing ones without the need for the relatively expensive soil strengthening techniques. 相似文献
3.
The interaction between twin‐parallel tunnels affects the tunnelling‐induced ground deformation, which may endanger the nearby structures. In this paper, an analytical solution is presented for problems in determining displacements and stresses around deforming twin‐parallel tunnels in an elastic half plane, on the basis of complex variable theory. As an example, a uniform radial displacement was assumed as the boundary condition for each of the two tunnels. Special attention was paid to the effects of tunnel depth and spacing between the two tunnels on the surface movement to gain deep insight into the effect of the interaction between twin‐parallel tunnels using the proposed analytical approach. It is revealed that the influence of twin tunnel interaction on surface movements diminishes with both the increase of the tunnel depth and the spacing between the two tunnels. The presented analytical solution manifests that, similar to most of the existing numerical results, the principle of superposition can be applied to determine ground deformation of twin‐parallel tunnels with a certain large depth and spacing; otherwise, the interaction effect between the two tunnels should be taken into account for predicting reliable ground movement. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
4.
深埋长隧道TBM施工关键问题探讨 总被引：2，自引：0，他引：2
针对深埋长隧道开挖所面临的高水压、高地压、高地温、大变形、难支护等问题,分析总结传统钻爆法开挖与支护技术、全断面隧道掘进机（TBM）施工技术、TBM导洞扩挖技术应用中的优劣,TBM导洞扩挖法为深埋长隧道开挖提供了新的设计思路。由于深埋长隧道的建设环境与浅埋隧道建设环境存在显著差异,TBM施工将面临3个关键问题--岩爆问题、卡盾（大变形）问题和未准确探测前方地质而发生的施工事故（涌水、突泥等）。为揭示TBM施工过程中卡盾的存在性,分别针对某一特定地质条件下深埋软、硬岩TBM施工进行理论分析和数值模拟研究。结果表明,软岩地层TBM施工发生卡盾,而硬岩完整地层TBM施工未发生卡盾。 相似文献
5.
Claudio di Prisco Luca Flessati Gabriele Frigerio Pietro Lunardi 《Acta Geotechnica》2018,13(3):635-649
In spite of the increasing diffusion of tunnel boring machines, conventional tunnelling is still largely employed in the excavation of both deep and shallow tunnels characterized by a particularly irregular tracing. Under difficult ground conditions, in conventional tunnelling, the front is frequently reinforced by using fibreglass tubes partially removed during the excavation. This technique is expensive, time-consuming and its design is based on either empirical or very simplified theoretical formulas. Thus, the ultimate objective of the research developed by the authors is to introduce a more sophisticated design approach for this front reinforcement technique. A first step in this direction is this numerical study, in which the mechanical response of deep tunnel faces under undrained conditions is analysed by employing the front characteristic curve: a useful tool largely employed in the literature in analogy with what done for the cavity. The main result of this paper is the “Front Mother Characteristic” curve, obtained by introducing appropriate non-dimensional variables, allowing the designer, once both the system geometry and the soil mechanical properties are assigned, to assess the displacements of tunnel fronts without performing any numerical analysis. 相似文献
6.
In densely built areas, the development of underground transportation systems often involves twin tunnels, which are sometimes unavoidably constructed adjacent to existing piled foundations. Because soil stiffness degrades with induced stress release and shear strain during tunnelling, it is vital to investigate the pile responses to subsequent tunnels after the first tunnel in a twin-tunnel transportation system. To gain new insights into single pile responses to side-by-side twin tunnelling in saturated stiff clay, a three-dimensional coupled-consolidation numerical parametric study is carried out. An advanced hypoplasticity (clay) constitutive model with small-strain stiffness is adopted. The effects of each tunnel depth relative to pile are investigated by simulating the twin tunnels either near the mid-depth of the pile shaft or adjacent to or below the pile toe. The model parameters are calibrated against centrifuge test results in stiff clay reported in literature. It is found the second tunnelling in each case resulted in larger settlement than that due to the first tunnelling with a maximum percentage difference of 175% in the case of twin tunnelling near the mid-depth of the shaft. This is because of the degradation of clay stiffness around the pile during the first tunnelling. Conversely, the first tunnelling-induced bending moment was reduced substantially during the second tunnelling. The most critical location of twin tunnels relative to the pile was found to be the tunnels below the pile toe. This is because the entire pile was located within the major influence zone of the twin tunnelling. Two distinct load transfer mechanisms can be identified in the pile, namely downward load transfer in case of tunnels near mid-depth of the pile shaft and next to the pile toe and upward load transfer in case of twin-tunnelling below the pile toe. These two transfer mechanisms can be useful for practitioner to assess the pile performance due to twin tunnelling. 相似文献
7.
In this paper, a numerical simulation method for evaluating tunnelling-induced ground movement is presented. The method involves discrete element simulation of TBM slurry shield advancement and considers explicitly soil excavation from the face, effects of varying face support pressure, and the influence of tunnel cover depth. For the cases studied, it is found that for tunnel cover depths (C/D) between 0.7 and 2.1, ground deformations inducing by the tunnelling can be controlled within a certain extent and tunnel face stability can ensured, provided the support pressure ratio (N) lies between 0.8 and 1.5. The proposed method is reasonably benefited to modeling the face stability in shield-driven tunnels in soft soils. 相似文献
8.
A.R. Selby 《Geotechnical and Geological Engineering》1999,17(3-4):351-371
Tunnelling through soils results in ground loss, causing surface settlements and transverse movements. Where the tunnel drive passes below an existing structure, it is important to estimate the effects upon the structure. However, the free ground deformations should not simply be imposed upon a structure, because the structure contributes to stiffening of the ground. A computational soil-structure interaction analysis is required, to otain detailed stress–deformation response. First, linear finite element and Lagrangian finite difference methods are used to estimate ground movements due to a tunnel in free ground, and the results are compared with values based on empirical equations. The two linear methods and an additional hybrid FE method are then used to assess with soil-structure interaction; two cases of a typical short wall and a long wall lying across the route of tunnels of different depths. The results support the validity of the hybrid method which is used to estimate interactive ground settlements for comparison with a reported case of tunnelling below a building in central London. A more detailed case study is then undertaken to assess building damage caused by gross settlements during tunnelling in mixed soils, at a site in Workington, west Cumbria. A survey allowed estimation of free ground movements. Analysis by the hybrid method on the soils plus uncracked structures indicated intolerable horizontal stresses. Re-analysis with major cracks introduced into the structures resulted in close agreement between measured and computed settlements. 相似文献
9.
A numerical Round Robin on tunnels under seismic actions 总被引：3，自引：0，他引：3
Emilio Bilotta Giovanni Lanzano S. P. Gopal Madabhushi Francesco Silvestri 《Acta Geotechnica》2014,9(4):563-579
Although the seismic behaviour of shallow circular tunnels in soft ground is generally safer than aboveground structures, some tunnels were recently damaged during earthquakes. In some cases, damage was associated with strong ground shaking and site amplification, which increased the stress level in the tunnel lining. Pseudo-static and simplified dynamic analyses enable to assess transient changes in internal forces during shaking. Nevertheless, experimental evidences of permanent changes in internal loads in the tunnel lining would suggest that a full dynamic analysis including plastic soil behaviour should be performed when modelling the dynamic interaction between the tunnel and the ground. While sophisticated numerical methods can be used to predict seismic internal forces on tunnel structures during earthquakes, the accuracy of their predictions should be validated against field measurements, but the latter are seldom available. A series of centrifuge tests were therefore carried out at the University of Cambridge (UK) on tunnel models in sand, in the framework of a research project funded by the Italian Civil Protection Department. A numerical Round Robin on Tunnel Tests was later promoted among some research groups to predict the observed behaviour by means of numerical modelling. In this paper, the main results of five selected numerical predictions are summarized and compared with the experimental results. 相似文献
10.
As demonstrated by recently excavated reconnaissance tunnels, uncontrolled water ingresses frequently pose a risk to tunnels
and the tunnelling crew despite ever-improving tunnelling methods. This is regardless of the type of rock encountered and
can result in significantly increased construction costs. 相似文献
11.
《Computers and Geotechnics》2006,33(4-5):234-247
For shield-driven tunnels, the influence of the soil and grout material properties and of the cover depth on the surface settlements, the loading and deformation of the tunnel lining and the steering of the TBM is investigated numerically. To this end, comparative numerical simulations of a mechanised tunnel advance in homogeneous, overconsolidated, soft, cohesive soil below the ground water table are performed and sensitivities are evaluated. The advancement of the step-by-step tunnel construction process is modelled using a three-dimensional finite element model, which takes into account all relevant components of shield tunnelling. The material behaviour of the saturated soil and the tail void grout is modelled by a two-field finite element formulation in conjunction with an elasto-plastic Cam-Clay model for the soil and a hydration-dependent constitutive model for the grout. The analyses provide valuable information with regard to the significance of the investigated parameters and demonstrate the complexity of the various interactions in shield tunnelling. 相似文献
12.
修建海底隧道技术难度高、施工风险大,其中不良地质段是施工高风险地段。厦门翔安海底隧道是中国大陆地区第一条海底隧道,长6.05 km,最深处位于海平面下约70 m,采用设置服务隧道的3孔隧道方式,设双向6车道,钻爆法施工。隧道场区以花岗岩地层为主,主要不良地质段包括两端陆域及浅滩全强风化地段和海域多处风化深槽,其施工期风险管理尤为重要。应用风险评估与分析理论,探讨了海底隧道施工风险发生机制及风险水平评估方法。针对厦门翔安隧道施工图设计阶段的地质勘测、土建结构设计和拟采用的施工方法,对不良地质段施工期的典型地质风险和施工风险进行识别与风险水平评估,研究了降低风险的相应对策,以便在施工中对风险进行管理,采取必要措施保障施工安全与质量。 相似文献
13.
随着城市内地铁盾构区间隧道临近城市道路桥桩工程的增多,急需研究盾构隧道临近桥桩施工对桥桩的变形影响问题。采用有限元数值计算方法,结合盾构隧道穿越桥桩实际工程,建立了盾构隧道施工对临近桥桩影响的数值分析模型,模拟盾构隧道施工,对盾构隧道穿越临近桥桩的桩体沉降、桩体侧移、地表沉降进行了数值分析研究,盾构隧道穿越时及穿越后桩体沉降、桩体侧移、地表沉降控制结果较为理想,桩体处于稳定状态。结合现场监测成果,对数值计算结果和监测结果进行对比分析,表明采用的数值分析计算模型、参数取值对盾构隧道施工对临近桥桩影响的模拟是可靠的,可以运用文中的数值计算方法预测后续盾构隧道施工引起临近桥桩沉降、桩体侧移和地表沉降结果。 相似文献
14.
In large-span tunneling projects, the mechanical behavior of the rock changes in response to different sequential excavation methods (SEMs) of advancing the tunnel face. The double side drift method (DSDM), which is a development of SEM, was widely used in loess tunnels with large cross sections in China for its ability to limit ground displacement. This paper presents the deformation characteristics of large-span loess tunnels of the high-speed railway line in China. Field monitoring and numerical simulations were conducted to determine the optimal construction approach and reveal the deformation properties of large-span loess tunnels in China. The construction approaches, support measures, ground surface, and subsurface deformation characteristics associated with DSDM are demonstrated. The ground surrounding the loess tunnel underwent vertical settlement at the arch part and at the ground surface because of the metastable structure of the loess. This study provides an in-depth illustration of the influence of face-advancing sequences on ground displacement induced by tunneling, which helps us implement the most effective SEMs. 相似文献
15.
A simplified method of numerical analysis has been developed to estimate the deformation and load distribution of piled raft foundations subjected to ground movements induced by tunnelling and incorporated into a computer program ‘PRAB’. In this method, a hybrid model is employed in which the flexible raft is modelled as thin plates, the piles as elastic beams, and the soil is treated as interactive springs. The interactions between structural members, pile–soil–pile, pile–soil–raft and raft–soil–raft interactions, are modelled based on Mindlin's solutions for both vertical and lateral forces. The validity of the proposed method is verified through comparisons with some published solutions for single piles and pile groups subjected to ground movements induced by tunnelling. Thereafter, the solutions from this approach for the analysis of a pile group and a piled raft subjected to ground movements induced by tunnelling are compared with those from three‐dimensional finite difference program. Good agreements between these solutions are demonstrated. The method is then used for a parametric study of single piles, pile groups and piled rafts subjected to ground movements induced by tunnelling. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
16.
G. Preisig A. Dematteis R. Torri N. Monin E. Milnes P. Perrochet 《Rock Mechanics and Rock Engineering》2014,47(3):869-884
Interception of aquifers by tunnel excavation results in water inflow and leads to drawdown of the water table which may induce ground settlement. In this work, analytical and numerical models are presented which specifically address these groundwater related processes in tunnel excavation. These developed models are compared and their performance as predictive tools is evaluated. Firstly, the water inflow in deep tunnels is treated. It is shown that introducing a reduction factor accounting for the effect of effective stress on hydrodynamic parameters avoids overestimation. This effect can be considered in numerical models using effective stress-dependent parameters. Then, quantification of ground settlement is addressed by a transient analytical solution. These solutions are then successfully applied to the data obtained during the excavation of the La Praz exploratory tunnel in the Western Alps (France), validating their usefulness as predictive tools. 相似文献
17.
For long deep tunnels as currently under construction through the Alps, mechanized excavation using tunnel boring machines (TBMs) contributes significantly to savings in construction time and costs. Questions are, however, posed due to the severe ground conditions which are in cases anticipated or encountered along the main tunnel alignment. A major geological hazard is the squeezing of weak rocks, but also brittle failure can represent a significant problem. For the design of mechanized tunnelling in such conditions, the complex interaction between the rock mass, the tunnel machine, its system components, and the tunnel support need to be analysed in detail and this can be carried out by three-dimensional (3D) models including all these components. However, the state-of-the-art shows that very few fully 3D models for mechanical deep tunnel excavation in rock have been developed so far. A completely three-dimensional simulator of mechanised tunnel excavation is presented in this paper. The TBM of reference is a technologically advanced double shield TBM designed to cope with both conditions. Design analyses with reference to spalling hazard along the Brenner and squeezing along the Lyon–Turin Base Tunnel are discussed. 相似文献
18.
Ngoc-Anh Do Daniel Dias Pierpaolo Oreste Irini Djeran-Maigre 《Geotechnical and Geological Engineering》2014,32(1):43-58
Tunnel excavation is a three-dimensional (3D) problem. However, despite recent advances in computing resources, 3D models are still computationally inefficient and two-dimensional (2D) simulations are therefore often used. Modelling the tunnelling process in a 2D plane strain analysis requires a specific approach that allows a 3D tunnelling effect to be taken into consideration. As far as the urban tunnels are concerned, most cases reported in the literature have focused on estimating the applicability of these equivalent approaches that are based on the evaluation of the settlement that develops on the ground surface, without considering the influence of segment joints. The main objective of this study was to provide a 2D numerical investigation to highlight the influence of two equivalent approaches, that is, the convergence-confinement method (CCM) and the volume loss method (VLM), on the behaviour of a tunnel built in an urban area, in terms of not only the surface settlement but also the structural lining forces, taking into account the effect of segment joints. A technique that can be used to simulate the tunnel wall displacement process, based on the principles of the VLM, has been developed using the FLAC3D finite difference program (Itasca in FLAC fast Lagrangian analysis of continua, version 4.0; User’s manual, http.itascacg.com, 2009). A comparison with 3D numerical results has been introduced to estimate the precision of these 2D equivalent approaches. The results have shown a significant influence of the tunnel boundary deconfinement technique and segment joints on the tunnel lining behaviour and surface settlements. The structural forces obtained by means of the CCM are often smaller than those determined with the VLM for the same surface settlement. Generally, the structural lining forces determined by the CCM are in better agreement with the 3D numerical results than the ones obtained with the VLM. However, in order to obtain an accurate estimation of the structural forces, the impact of the construction loads during tunnelling should be taken into account. 相似文献
19.
Analysis of shield tunnel 总被引：1，自引：0，他引：1
This paper proposes a two‐dimensional finite element model for the analysis of shield tunnels by taking into account the construction process which is divided into four stages. The soil is assumed to behave as an elasto‐plastic medium whereas the shield is simulated by beam–joint discontinuous model in which curved beam elements and joint elements are used to model the segments and joints, respectively. As grout is usually injected to fill the gap between the lining and the soil, the property parameters of the grout are chosen in such a way that they can reflect the state of the grout at each stage. Furthermore, the contact condition between the soil and lining will change with the construction stage, and therefore, different stress‐releasing coefficients are used to account for the changes. To assess the accuracy that can be attained by the method in solving practical problems, the shield tunnelling in the No. 7 Subway Line Project in Osaka, Japan, is used as a case history for our study. The numerical results are compared with those measured in the field. The results presented in the paper show that the proposed numerical procedure can be used to effectively estimate the deformation, stresses and moments experienced by the surrounding soils and the concrete lining segments. The analysis and method presented in this paper can be considered to be useful for other subway construction projects involving shield tunnelling in soft soils. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
20.
在目前众多的预测隧道开挖引起的地层变形的方法中,经验公式法最为简便,也是目前应用最为广泛的方法,为此介绍了多种预测隧道开挖引起的地层沉降和水平位移的经验公式。并以青岛胶州湾海底隧道不对称双连拱断面为工程背景,由位于主隧道与匝道交叉口段的典型断面ZK2+800.78的几何参数和地质资料构建三维数值计算模型,采用岩土体工程通用有限差分软件FLAC3D进行动态施工三维数值模拟。通过对FLAC3D模拟和各经验公式计算的地层沉降和水平位移的对比分析,评价了FLAC3D软件和各经验公式在不对称双连拱隧道断面地层变形预测中的适用性。结果表明,当地层埋深较浅时,不同埋深地层的地层沉降和水平位移可近似用各经验公式来预测;但随着地层埋深的增大,各经验公式预测的偏差不断增大;经验公式只能对单一地层、单一隧道的地层变形进行估算,存在明显的局限性,而在预测复杂地质条件下不对称双连拱隧道断面开挖引起的地层变形时,FLAC3D较各经验公式有明显的优势 相似文献