Research Journal of Mining Volume 1 (2017) Issue 1 Pages 1-11
NUMERICAL MODELLING FOR CIRCLE TUNNEL UNDER STATIC AND DYNAMIC LOADS FOR DIFFERENT DEPTH Jaafar Mohammed1) 1)
Department of Geotechnics and Underground Engineering, Faculty of Civil Engineering, VŠB- Technical University of Ostrava, L. Podéště 1875, 708 33, Ostrava-Poruba, Czech Republic, Email:
[email protected]
Abstract: The aim of this paper is to analyse the effects of internal and seismic loads on the stability of circle tunnels at different depth using response spectrum. A full 3D numerical model using the finite element software program MIDAS GTS NX is established. It is often assumed that the effect of earthquakes on underground structures such as tunnels is negligible but the results of this study show that the stress caused by seismic loads can be harmful to the tunnel stability [22].Most of the researcher explains that shallow tunnels suffer higher damage compared to deep structures. During the Shield TBM excavation, it is assumed that the excavation pressure and the Jack thrust are applied on the shield excavation face the Shield external pressure and segment external pressure are applied around that face. This work study a 3D numerical modelling was prepared to simulate the static and dynamic behavior of circular tunnels, were undertaken to investigate the seismic tunnel response conditions to compare the results in the displacement, stresses, forces and bending moments acting in the tunnel lining .
Key words: Tunnel, FEM, Static , Dynamic, Internal Forces,Deep and Shallow Tunnel 1
INTRODUCTION
A tunnel is an underground structure which has different uses. After tunnel modelling using MIDAS GTS NX, it is run to analyse the tunnel stability in static and dynamic conditions by calculated the value of each mesh node based on 3D finite element method to simulate the effect of loads on tunnel stability. The TBM method used depends on such factors as the ground conditions, length, diameter and depth of the tunnel, etc. Designing tunnel linings are usually performed accounting for the static cases of loading only, without considering the effect of earthquakes. Earthquake loads on tunnels are unpredictable due to the special nature of earthquakes. [29] During service time, a tunnel could be exposed to dynamic loads. While tunnels generally performed better than above ground structures during earthquakes, damage to some of important structures during previous earthquake events highlights the need to account for seismic loads in the design of underground structures. [26] Static and dynamic analysis using finite element method were undertaken to investigate the seismic tunnel response conditions to compare the results with the displacement, stresses, forces and bending moments acting in the final tunnel lining. In static analysis, when analyzing a model with infinite material such as ground, boundaries are set far enough from main analysis area. But in dynamic analysis since effect of waves reflection occurs, if boundaries are set in the same way as static analysis, big error may occur. (MIDAS GTS NX manual). Static and dynamic plane strain finite element (FE) analyses were undertaken to investigate the seismic tunnel response at two sections and to compare the results with the post1
Research Journal of Mining Volume 1 (2017) Issue 1 Pages 1-11
earthquake field observations. The predicted maximum total hoop stress during the earthquake exceeds the strength of shotcrete in the examined section. The occurrence of lining failure and the predicted failure mechanism compare very favourably with field observations. [35] The sizing of the lining of a tunnel requires to consider not only the static loads transmitted from the surrounding rock, but also the effects of earthquakes on the stresses and strains of the lining.[31] Sheared off lining: it occurs for tunnel passing through active faults. Slopes failure induced tunnel collapse: it occurs when the tunnel runs parallel to slopes generating landslides passing through the lining; Longitudinal cracks: it occurs when the tunnel is subjected to higher deformations due to surrounding ground; Traverse cracks: it occurs when the tunnel has weak joints; Inclined cracks: it occurs for a combination of longitudinal and transversal cracks; Extended cracks: it occurs when there is the partial collapse of linings for seismic intense deformation; Wall deformation: it occurs when there is a transverse reduction due to the invert collapse; Spilling of lining: it occurs when the transversal section completely collapses. 2
DEFINITION OF GROUND AND STRUCTURAL MATERIALS
This paper studies the 3D model with gravity in Z direction and using SI unit system (KN, m). The studied parameters of soft rock included modeled of Elasticity model (E=20000 KN/m2) , diameter of tunnel (D=6 m), and 0.3m thickness of concrete lining ,distance between the external diameter of tunnel and ground surface varying ( for deep tunnel, h=78.4 m and shallow h=38.4 m), tunnel had 47 stage sets. Automatic ground boundary condition for static case and ground surface spring to support the bottom for response spectrum; applied loads [selfweight, Drilling or excavation pressure (200kN/m2), and the Jack thrust (- 4500kN/m2, are applied on the shield excavation face. The Shield external pressure (50kN/m2) and Segment external pressure (1000kN/m2) are applied around that face. Design Response Spectrum of UBC (1997) is used as seismic response spectrum. The model has (x=100, z=80, y=80) m. Tab. 1 Ground Materials Name Material Model Type Elastic Modulus (E) [KN/m2] Poisson’s Ratio (ν) Unit Weight (γ) [KN/m3] Ko Drainage Parameters Non-Linear
Soft Rock Isotropic Elastic 20000 0.4 18 0.5 Drainage -
Segment Isotropic Elastic 20000000 0.2 24 1 Drainage -
Tab. 2 Structure Materials Name
Steel Isotropic
Material 2
Grout Isotropic
Research Journal of Mining Volume 1 (2017) Issue 1 Pages 1-11
Model Type Elastic Modulus (E) [KN/m2] Poisson’s Ratio (ν) Unit Weight (γ) [KN/m3]
Elastic 25000000 0.25 78
Elastic 15000000 0.3 23
Tab. 3 Ground Properties Name Type Material
3
Soil 3D Soil
Segment 3D Segment
Steel 2D- Plate Steel
Grout 2D - Plate Grout
RESPONSE OF UNDERGROUND STRUCTURES TO EARTHQUAKES
Studies realized in the past have shown that underground structures are less vulnerable to earthquakes respect to structures built at surface, but the associated risk may be high, since even a low level of damage could affect the serviceability of a wide network. However underground structures cannot be considered completely exempt to the effects of ground shaking. A careful review of the seismic damages suffered by underground facilities shows that most tunnels were located in the vicinity of causative faults. The characteristics of ground motion in the vicinity of the source can be different from that of the farfield. The ground motion is characterized by strong, coherent (narrow band) long period pulses and is severely affected by the rupture mechanism, the direction of rupture propagation relative to the site, and possible permanent ground displacements resulting from fault slip. The seismic analysis of underground structures is a complex process because involves the interaction between several disciplines as soil, rock and structural dynamics, structural geology, seismotectonics and engineering seismology. The difference between underground structures and surface facilities from the seismic effects point of view are due, since the overall mass of the structure is usually small compared with the mass of the surrounding soil and the overall confinement provides high level of radiation damping. The response of an underground structure to a seismic event is basically governed by the behavior of the surrounding ground and not by the inertia characteristics of the structure itself, as the response to such event is substantially depending on the induce ground deformation. 4
SIMULATION AND CALIBRATION OF THE NUMERICAL MODEL
Static and dynamic analyses has been carried out on the 3D model of the tunnel structural complex using the MIDAS GTS NX software to investigate the control of tunnel deformation observed during tunnelling using TBM under earthquake load. Eigenvalue analysis is used to analyze the inherent dynamic properties of the ground/structure, and this can be used to obtain the natural mode (mode shape), natural period (natural frequency), modal participation factor etc. of the ground/structure. These properties are determined by the mass and stiffness of the structure. In other words, if a structure is determined, the natural frequency and vibration mode (natural mode) are also determined and the number of properties is the same as the degree of freedom of the structure. For real cases, the structure does not vibrate at a single mode shape and multiple modes overlap to display a complex vibration shape. (MIDAS GTS NX manual) 3
Research Journal of Mining Volume 1 (2017) Issue 1 Pages 1-11
Fig.1 Schematic of Slurry Shield TBM and pressure components (a portion of image courtesy of Herrenknecht) (after Zili LI, et al, 2015).
Fig.2 Mesh Tunnel profile
Fig.3 The static and dynamic case: Max. Displacement [m]
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Fig.4 The static and dynamic case: Shell Element forces [KN/m]
Fig.5 The static and dynamic case: Bending Moment XX [KNm/m]
Fig.6 The static and dynamic case: Shell Element Stresses - Shear MAX [KN/m ^2] 5
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Fig.7 The Max. Displacement for Shield at #10 in static case for Deep Tunnel
Fig.8 The S-Max. Shear Max. for Shield at #1 in static case for Deep Tunnel
Fig. 9 Total displacement at shallow tunnel
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Fig. 10 Total displacement at deep tunnel In Figure 9 and 10, the displacement in static and dynamic conditions is shown. Due to the application of the static stress the displacement state of tunnel periphery is changed, and the displacement in tunnel to the down is more than to the up side, therefore the balance is disrupted and the potential of instability increases, otherwise the result show that the applied dynamic stress is not negligible for underground structure , but it is less than that on the surface structure.
Fig.11 Modified Response Spectrum using UBC(1997); Damping Ration = 0.05; Seismic Coefficient : Ca = 0.06 Cv = 0.06; Normalized Acceleration
Fig.12 Modified Time History Load Function using The Generate Earthquake Acceleration Record: 1940, EI Centro Site, 270 Deg.; Peak = 0.3569 g and Duration = 53.72 Sec.
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Fig.13 An example of using the value from Eigenvalue to get the Damping Ratio. Tab. 4 The result of static analysis for all depth showing the Maximum value
Tab. 5 The result of Dynamic analysis for all depth showing the Maximum value
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CONCLUSION
It is very important to adequately predict and control ground during the design and construction of tunnels in urban areas especially at / near earthquake zone. They provide very good results when tunnelling conditions are well known especially when using numerical analysis. The paper includes the study of the behavior of tunnel lining due to internal and seismic load by calculating the (Displacement, S- MAX Shear, Shear Force and Bending Moment) in the ground materials (soft rock) during the various stages of construction effected on tunnel lining. For static case the maximum value was taken from the last stage, and for dynamic it was taken from the response spectrum. During the Shield TBM excavation, it is assumed that the excavation pressure and the Jack thrust are applied on the shield excavation face. The Shield external pressure and segment external pressure are applied around that face. The affect of tunnel under different loads like internal , seismic load and etc. depend on several state and parameters ,one of this state is the depth of tunnel under ground surface, also the static and dynamic analysis had different simulation as showing in the tables (4 and 5) and figures (3 - 6) which show the result of this analysis. In Figure 9 and 10, the displacement in static and dynamic conditions is shown. Due to the application of the static stress the displacement state of tunnel periphery is changed, and the displacement in tunnel to the down is more than to the up side, therefore the balance is disrupted and the potential of instability increases, otherwise the result show that the applied dynamic stress is not negligible for underground structure , but it is less than that on the surface structure.
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Research Journal of Mining Volume 1 (2017) Issue 1 Pages 1-11
REFERENCE [1] Ahmad Fahimifar and Arash Vakilzadeh, 2009, Numerical and Analytical Solutions for
Ovaling Deformation in Circular Tunnels Under Seismic Loading. [2] Aissa Jemela Rechlin, 2012, Rock-Mass Classification in Tunneling based on Seismic Velocities and Tunnel Driving-Data using Support Vector Machines. [3] Hamid Alielahi , Mohammad Adampira, 2016, Effect of twin-parallel tunnels on seismic ground response due to vertically in-plane waves. [4] C. Carranza-Torres and J. Zhao, 2008, The Effect of Ground Drainage on the Mechanical Response of Deep lined Tunnels Excavation in Elastic and Elasto-Plastic materials. [5] Carranza-Torres, C., T. Reich, and D. Saftner ,2013, Stability of shallow circular tunnels in soils using analytical and numerical models. [6] Daniele Festa, Wout Broere and Johan W. Bosch, 2013,On the effects of the TBM-shield body articulation on tunnelling in soft soil. [7] Diogo Miguel Mendes Ferreira Torcato, 2010, Seismic behaviour of shallow tunnels in stratified ground. [8] Emilio BILOTTA, Giovanni LANZANO, Gianpiero RUSSO, 2007, PSEUDOSTATIC AND DYNAMIC ANALYSES OF TUNNELS IN TRANSVERSAL AND LONGITUDINAL DIRECTIONS. [9] G. Lanzano, E. Bilotta, G. Russo,Tunnels under seismic loading: a review of damage case histories and protection methods. [10] Guido ANDREOTTI and Carlo G. LAI, 2014 ,SEISMIC VULNERABILITY OF DEEP TUNNELS NUMERICAL MODELING FOR A FULLY NONLINEAR DYNAMIC ANA. [11] Helmut F. Schweiger, 2010, FINITE ELEMENT ANALYSIS OF DEEP FOUNDATIONS AND TUNNELS - PRACTICAL APPLICATIONS. [12] Christos VRETTOS, Dong CHEN, Dimitris RIZOS, 2012, SEISMIC DESIGN OF THE STATIONS AND THE INTER-STATION TUNNELS OF A METRO-LINE IN SOFT GROUND: A CASE STUDY. [13] I. SLITEEN, H. MROUEH,M. SADEK, Three-dimensional modeling of the behavior of shallow tunnel under seismic loading. [14] Inírida Rodríguez Millán, 2008, SEISMIC RESPONSE OF DEEP TUNNELS. CONTINUUM AND DISCONTINUUM NUMERICAL ANALYSIS. [15] J. Waggoner, J. Shamma, S. Klein, Deep Tunnels in Poor Rock Conditions and High Water Head; How Much Can We Ask of TBM Technology? [16] Jaw-Nan (Joe) Wang, 1993, Seismic Design of Tunnels A Simple State-of-the-Art Design Approach. [17] Kais T. Shlash, Nahla M. Salim and Zainab H. Shaker, 2014, Stress Analysis Around Tunnels During Construction Stages Using Finite Elements Method. [18] Lei Hao, Mao Sheng and Lai Jin-xing, 2015, Definition and Analysis of Dividing Line for Deep and Shallow Loess Tunnel. [19] M.A. Zurlo, 2012, Seismic response of circular tunnels - Numerical validation of closed form solutions. [20] MASOUD MONJEZI, BABAK NAFE RAHMANI, SEYED RAHMAN TORABI, TRILOK NATH SINGH, 2012, STABILITY ANALYSIS OF A SHALLOW DEPTH METRO TUNNEL: A NUMERICAL APPROACH. [21] Mirko Corigliano · Laura Scandella · Carlo G. Lai · Roberto Paolucci, 2011,Seismic analysis of deep tunnels in near fault conditions: a case study in Southern Italy. [22] Moreno Pescara, Giuseppe Maria Gaspari, Luca Repetto, 2011, Design of underground structures under seismic conditions: a long deep tunnel and a metro tunnel. 9
Research Journal of Mining Volume 1 (2017) Issue 1 Pages 1-11
Navid Hosseini, Kazem Oraee, Mehran Gholinejad, 2010, Seismic analysis of horseshoe tunnels under dynamic loads due to earthquakes. [24] Ngoc Anh Do, 2014, Numerical analyses of segmental tunnel lining under static and dynamic loads. [25] Nick Barton, 2012, Reducing risk in long deep tunnels by using TBM and drill-andblast methods in the same project–the hybrid soluti. [26] Nina Fotieva, Nikolay Bulychev, Andrey Sammal, Petr Deev, 2005, STRESS STATE AND BEARING CAPACITY OF SHALLOW TUNNEL LININGS UNDERGOING THE INFLUENCE OF NEARBY LOCATED BUILDINGS. [27] Othman A. Shaalan, Tarek N. Salem, Eman A. El shamy, and Randa M. Mansour, 2014, Dynamic analysis of two adjacent tunnels. [28] PIERPAOLO ORESTE, 2011, THE STABILITY OF THE EXCAVATION FACE OF SHALLOW CIVIL AND MINING TUNNELS. [29] Pierpaolo Oreste, 2015, Simplified Analysis of the Lining Behavior During Earthquakes in Deep Rock Tunnels. [30] RAFIK DEMAGH, FABRICE EMERIAULT, FARID HAMMOUD, 2013, 3D MODELLING OF TUNNEL EXCAVATION USING PRESSURIZED TUNNEL BORING MACHINE IN OVERCONSOLIDATED SOILS. [31] Shuangjiang Tao, Bo Gao, Chunlei Xin, 2015, Seismic Damage Analysis of Tunnel Front Slope and Shaking Table Tests on Highway Tunnel Portal. [32] Stavroula Kontoe, Lidija Zdrakovic, David M. Potts and Christopher O. Menkiti, 2008, Case Study on Seismic Tunnel Response [33] T. Ornthammarath, M. Corigliano, and C.G. Lai, 2008,ARTIFICIAL NEURAL NETWORKS APPLIED TO THE SEISMIC DESIGN OF DEEP TUNNELS. [34] T. Svoboda and D. Mašín, 2011,Comparison of displacement field predicted by 2D and 3D finite element modelling of shallow NATM tunne in clays. [35] Tashi Tshering, 2001,The Impact of Earthquakes on Tunnels in different Rock Mass Quality Q - A numerical analysis. [36] Tímea Léber, Alun Thomas, Ana Obradovic, NUMERICAL ANALYSIS OF SHALLOW SPRAYED CONCRETE LINING TUNNEL. [37] Tohid Akhlaghi and Ali Nikkar, 2014, Effect of Vertically Propagating Shear Waves on Seismic Behavior of Circular Tunnels. [38] Tomas Svoboda,David Masin,2009,Comparison of displacement field predicted by 2D and 3D finite element modelling of shallow NATM tunnels in clays. [39] Youssef M.A. Hashasha,, Jeffrey J. Hooka, Birger Schmidtb, John I-Chiang Yaoa, 2001,Seismic design and analysis of underground structures. [40] Z.F. Hu, Z.Q. Yue, J. Zhou, and L.G. Tham, 2003, Design and construction of a deep excavation in soft soils adjacent to the Shanghai Metro tunnels. [41] Zili LI, Jacob GRASMICK,Michael MOONEY, 2015, Influence of slurry TBM parameters on ground deformation. [42] TERAPHAN ORNTHAMMARATH,2007, ARTIFICIAL NEURAL NETWORKS APPLIED TO THE SEISMIC DESIGN OF DEEP TUNNELS. [43] Seyed Mahdi Pourhashemi, Majid Sadeghi, Majid Taromi, Alireza Askarzadeh, 2015, Tunnel Monitoring During the Excavation Phase and Cost Optimization - a Case Study of Hakim Tunnel. [44] H. Alielahi, M. Kamalian, J. Asgari Marnani, M. K. Jafari, M. Panji , 2012, Applying a time-domain boundary element method for study of seismic ground response in the vicinity of embedded cylindrical cavity. [45] C.W.W. Ng, H.W. Huang & G.B. Liu, 2008,Geotechnical Aspects of Underground Construction in Soft Ground Editors. [23]
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Youzhi Shi and Xiufang Li, Analysis on Surface Settlement Caused by Twin Bore Parallel Tunnel Excavation of City Subway. [47] F. Hage Chehade and I. Shahrour, 2008, Numerical analysis of the interaction between twin-tunnels: Influence of the relative position and construction procedure. [48] Еlefterija Zlatanović and Dragan Lukić, 2014, GROUND SURFACE SETTLEMENT INDUCED BY TWIN TUNNELLING. [49] W.Channabasavaraj and B. Visvanath, 2013, INFLUNCE OF RELATIVE POSITION OF THE TUNNELS A NUMERICAL STUDY ON TWIN TUNNELS. [50] Saied Mohammad Farouq Hossaini, Mehri Shaban and Alireza Talebinejad, 2012, RELATIONSHIP BETWEEN TWIN TUNNELS DISTANCE AND SURFACE SUBSIDENCE IN SOFT GROUND OF TABRIZ METRO – IRAN. [51] Hamdy.H.A.Abd-el.rahim, Mahmoud Enieb, Ahmed Abdelmoamen Khalil, Abdou SH.Ahmed, 2015, ANALYSIS OF DIFFERENT LOADS AFFECTING THE URBAN RAILWAY TUNNEL SYSTEMS OF CAIRO METRO UNDERNEATH THE RIVER NILE. [52] Raghavendra, V. and Saravana Raja Mohan, K.,2014, Dynamic Analysis of Tunnels in Urban areas With and Without support systems. [53] RAGHAVENDRA V & STANLEY JOSE, 2015, DYNAMIC ANALYSIS OF BANGALORE UNDERGROUND METRO TUNNELS BY NUMERICAL SIMULATION. [46]
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