Conference Paper

Behavior of Underground Tunnel under Strong Ground Motion

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Abstract

The design of the tunnel demands an adequate analysis to access the possible damage to the tunnel under different conditions of loading. A huge amount of research studies has already been reported by many investigators, over the performance of the tunnel under static loading conditions. However, their performance under dynamic loading is still very rare. The present paper discusses the response of the tunnel under varying levels of seismic loading. The finite element analysis has been used to understand the behavior of underground tunnel under three different earthquakes input motions, i.e., 0.3g, 0.5g, and 0.7g, in addition to varying load from the superstructure constructed over it. The study has been performed using the finite element software OPTUM G2. The thickness of the tunnel lining has been kept constant as 250 mm, which is widely accepted in many tunneling projects. The cross-section and diameter of the tunnel adopted in the study are 50m x 54m and 6.35m respectively with 18m of depth of overburden. An Elasto-plastic constitutive material model has been used to model the tunnel lining and the surrounding soil. As the seismic intensity increases, it prompts the catastrophic change in the behavior of tunnel. The magnitude of the earthquake for which the tunnel is being designed must be considered based on past earthquake history of the region. This paper highlights the behavior of tunnel lying in the northern region of India.

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... Tunnels are studied using a variety of experimental, analytical, and computational techniques, with numerical analysis methods becoming more common as computer efficiency improves. These approaches make it easier to analyze tunneling issues based on various features and loading kinds (Shah et al., 2020;Zaid et al., 2019;Shahin et al., 2011;Pakbaz et al., 2005;and Mroueh et al., 2003). Among numerical techniques like the finite element method (FEM), the finite difference method (DFM), the discrete element method (DEM), and others, the 2D FEM is commonly the most used technique for analyzing tunnel stability (Negro et al., 2000;Muniz et al., 2004). ...
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The tunnels are one of the most significant infrastructures for facilitating mobility in mountainous terrain. It has several benefits, including shortening distances, time, and ease of transportation. To make it easier, developed countries create several tunnels close to each other. Engineers face the necessity of building these new tunnels near existing ones; this infrastructure must be safe. In this paper, for this numerical study, we used the OptumG2 software to analyze the position of a new tunnel created in six locations: bottom, top, left (two places at 12 m and 32 m), and right (two places at 12 m and 32 m) by the finite element method. This study was analyzed using two criteria: the equivalent of Drucker Prager and Mohr Coulomb. We are interested in the total field of the displacement, the vertical displacement of the model, the displacement, bending moment, shear, and normal force of the concrete lining. The findings of this numerical analysis using the Drucker Prager and Mohr Coulomb behaviors to determine the ideal locations for building a new tunnel next to an existing one show that the new bottom tunnel might have a significant influence on the stability of the existing tunnel. It was also observed that the maximum displacement present when we add a new tunnel at the bottom meets the Drucker-Prager criteria.
... At this time, there are several ways to forecast surface settling brought on by tunnel construction, including as, the airy stress function approach [8][9][10][11][12], the stochastic medium theory [13][14][15], the empirical formula method [16][17][18][19], the elastic strain method [20][21][22][23], and the numerical modelling method [24][25]. Numerous parameters and many loading types are typically analyzed for tunneling difficulties using the numerical method [26][27][28][29][30]. For tunnelling, the procedures and technologies depend on groundwater levels, the application for which the tunnel is being used, the location, geotechnics, geology, length, form, and diameter of the tunnel, among other criteria. ...
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The tunnels offer a workable method for creating transportation and utility infrastructure in metropolitan regions. Sometimes we need more than one tunnel in the same place. However, building of the new tunnels inevitably causes settlements and ground displacements, threatening nearby constructions or the old tunnels. In this paper aims to investigate to control the settlement of the soil after the excavation, and the effects of new tunnel on the old tunnel. The study illustrates the importance of the positions of the new tunnels and their effects on the old one. Results show that, the building of a new tunnel below an existing one is the worst location. We note that in order to preserve and protect an existing tunnel, we build new tunnels to the left or right of the existing tunnel, while maintaining a safe distance between the two tunnels.
... The tunnels may be studied using different experimental, analytical, and numerical methods. Because of better com puter efficiency, the numerical technique is commonly used to analyze tunneling problems for various properties and differ ent loading types [4][5][6][7][8]. ...
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... The tunnels may be studied using different experimental, analytical, and numerical methods. Because of better com puter efficiency, the numerical technique is commonly used to analyze tunneling problems for various properties and differ ent loading types [4][5][6][7][8]. ...
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Purpose. To understand the effect of fissured material on tunnels. These infrastructure tunnels must be safe in all respects, including construction, materials, and more. One of the challenges which engineers face is the need to consider material types as well as fissured material. As a result, in order to ensure the safety of the tunnel, it is important for us to anticipate possible precipi tation, displacements, stresses and strains caused by the construction of tunnels in fractured environments. Methodology. The OPTUMG2 software was used for this numerical study, the tunnel was modeled applying the hypothesis of twodimensional plane deformation with the use of the finite element method, which is used to model continuous media. The MohrCoulomb criterium was considered to simulate the elastoplastic nonlinear behaviour of this model. Findings. The findings demonstrate that the orientation of weakness planes can have a major impact on tunnel stability. Thus, it was observed that 45, and 60° for angle α 1 , and 110, and 135° for the second angle α 2 present the most critical situations. The influence of fissured material (soil) on civil engineering projects such as tunneling should be taken into consideration. Originality. The tunnel's stability is determined by the measuring of the displacement (settlement), stresses, and deformation, under the effect of the fissured material in the environment. In this paper we simulated a model with various crack angles. As for the orientation of plane, for the angl3e α 1 the values are changed to 0, 20, 45, 65, and 90°, the second angle α 2 was changed from 110, 135, 155, 175, to 180°. Practical value. The number of tunnels and infrastructure projects is constantly increasing. This is because they are important for the development of countries and for accelerating economic growth, shortening distances and travel time by linking urban areas that have natural obstacles such as mountains. We found that the orientation planes can have a major impact on tunnel stability. Thus, it was observed that 45, and 60° for first angle, and 110, and 135° for the second angle present the most critical situations.
... It is possible to predict ground settlements caused due to construction of second tunnel by using equations given by Peck, O'Reilly & Fresh, and Mair et al, along with various modifications. The distribution of the surface, subsurface settlements along the current tunnels was found to be broader than for single tunnels [27][28][29][30][31][32]. Due to the presence of the first tunnel, the degree of volume loss caused by the newly formed tunnel system is increased. ...
... Considering the complexities in a problem, numerical method of analysis have become a favourable tools to study the behavior of underground structure under static as well as dynamic loading conditions [8][9][10][11][12][13]. The stabilization of tunnels by different types of reinforcement has been checked over the time and analysed following numerical methods [14][15][16]. ...
Chapter
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... It is possible to predict ground settlements caused due to construction of second tunnel by using equations given by Peck, O'Reilly & Fresh, and Mair et al, along with various modifications. The distribution of the surface, subsurface settlements along the current tunnels was found to be broader than for single tunnels [27][28][29][30][31][32]. Due to the presence of the first tunnel, the degree of volume loss caused by the newly formed tunnel system is increased. ...
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Tunnels are a major underground structure used for transporting passengers, water, wastewater, etc. Design of a tunnel/twin tunnel requires fixing the spacing between tunnels, assessment of hazards to surface structure due to tunnelling and protection measures, etc. Experimental, numerical, analytical methods or a combination of the above techniques are used to design and investigate the stability under static and dynamic conditions. Ground settlement due to tunnel construction, the spacing between the tunnels, the tunnel response during earthquake loading, influence of alignment, etc., have been reviewed and summarized from the past published literature. A summary of the different design criteria for twin tunnels is reviewed and presented here. The present paper will be helpful for engineers and researchers working in this area.
... Thus these double arch tunnels save times by making distances shorter which in result declining the fuel usage of vehicles contributing to of pollutions. Since the start of underground tunnels, safety problems in tunnel construction have received much interest [10]. A significant number of operating tunnels, indeed, have different security issues resulting from the design constraints of geological conditions and other factors [11]. ...
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The seismic performance of large underground structures in soils, e.g., subway and highway tunnels, has been an important topic followed the damages of such structures in recent large earthquakes. The dynamic behavior of a subway station in saturated sandy deposit was investigated using the fully coupled dynamic Finite Element code DYNA Swandyne-II. A generalized plasticity model that can simulate both cyclic liquefaction and pressure dependency of soils was incorporated in the program to model the sandy deposit. A Mindlin beam element was also included and used to model the underground structure. The effects of vertical earthquake motions and the buried depth of the underground structure were analyzed. It is found that the effects of vertical motions depended on the characteristics of the excitations. It is also found that the increase in buried depth improved the safety of the underground structure against earthquake damage. A mitigation method against the floatation of underground structures using injection grouting was also studied and it was proved to be effective.
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The use of underground structures such as tunnel for subways, highways, material storage, and sewage and water transport is increasing in developed countries. The safety of these facilities during operation in areas with seismic activities such as in Japan, Taiwan and Turkey in recent earthquakes has been questioned. Dynamic effects on these structures are in the form of deformations that they experience during earthquakes. In this paper, first latest methods on the subject are reviewed and then the interaction between the ground and tunnel lining during earthquake excitation is investigated by a finite difference computer program (CA2). Analysis show that a good agreement between analytical closed form and numerical solutions exist. According to the results obtained in this study some practical suggestion for using closed form solution are also given.
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Underground facilities are an integral part of the infrastructure of modern society and are used for a wide range of applications, including subways and railways, highways, material storage, and sewage and water transport. Underground facilities built in areas subject to earthquake activity must withstand both seismic and static loading. Historically, underground facilities have experienced a lower rate of damage than surface structures. Nevertheless, some underground structures have experienced significant damage in recent large earthquakes, including the 1995 Kobe, Japan earthquake, the 1999 Chi-Chi, Taiwan earthquake and the 1999 Kocaeli, Turkey earthquake. This report presents a summary of the current state of seismic analysis and design for underground structures. This report describes approaches used by engineers in quantifying the seismic effect on an underground structure. Deterministic and probabilistic seismic hazard analysis approaches are reviewed. The development of appropriate ground motion parameters, including peak accelerations and velocities, target response spectra, and ground motion time histories, is briefly described. In general, seismic design loads for underground structures are characterized in terms of the deformations and strains imposed on the structure by the surrounding ground, often due to the interaction between the two. In contrast, surface structures are designed for the inertial forces caused by ground accelerations. The simplest approach is to ignore the interaction of the underground structure with the surrounding ground. The free-field ground deformations due to a seismic event are estimated, and the underground structure is designed to accommodate these deformations. This approach is satisfactory when low levels of shaking are anticipated or the underground facility is in a stiff medium such as rock. Other approaches that account for the interaction between the structural supports and the surrounding ground are then described. In the pseudo-static analysis approach, the ground deformations are imposed as a static load and the soil-structure interaction does not include dynamic or wave propagation effects. In the dynamic analysis approach, a dynamic soil structure interaction is conducted using numerical analysis tools such as finite element or finite difference methods. The report discusses special design issues, including the design of tunnel segment joints and joints between tunnels and portal structures. Examples of seismic design used for underground structures are included in an appendix at the end of the report.
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Zaid, M., Mishra, S. & Rao, K. S. Finite Element Analysis of Static Loading on Urban Tunnels. in IGC-2018 (2018).
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