Analysis of an Underground Structure Settlement Risk Due to Tunneling- A Case Study from Tabriz, Iran (original) (raw)
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IEEE Transactions on Consumer Electronics - IEEE TRANS CONSUM ELECTRON, 2012
The assessment of settlement induced damage on buildings during the preliminary phase of tunnel excavation projects, is nowadays receiving greater attention. Analyses at different levels of detail are performed on the surface building in proximity to the tunnel, to evaluate the risk of structural damage and the need of mitigation measures. In this paper, the possibility to define a correlation between the main parameters that influence the structural response to settlement and the potential damage is investigated through numerical analysis. The adopted 3D finite element model allows to take into account important features that are neglected in more simplified approaches, like the soil-structure interaction, the nonlinear behaviour of the building, the three dimensional effect of the tunnelling induced settlement trough and the influence of openings in the structure. Aim of this approach is the development of an improved classification system taking into account the intrinsic vulnerability of the structure, which could have a relevant effect on the final damage assessment. Parametrical analyses are performed, focusing on the effect of the orientation and the position of the structure with respect to the tunnel. The obtained results in terms of damage are compared with the Building Risk Assessment (BRA) procedure. This method was developed by Geodata Engineering (GDE) on the basis of empirical observations and building monitoring and applied during the construction of different metro lines in urban environment. The comparison shows a substantial agreement between the two procedures on the influence of the analyzed parameters. The finite element analyses suggest a refinement of the BRA procedure for pure sagging conditions.
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Tunnel construction in highly populated and busy cities has to be executed with utmost care. When a tunnel is excavated, there will be subsidence, which may cause damage to surface at structures. Mellat tunnel with a length of 3 km is considered for Tehran city (12,000,000 populations). Thus, in this paper, a Finite Element Method analysis was conducted to investigate the effects of a tunnel on the subsidence. The tunnel of the Tehran, Iran, will pass near the under buildings. It was constructed in accordance with the Sequential Excavation Model (SEM).Distance between the tunnel crown and the building foundation will probably cause collapse or unallowable subsidence during the tunnel construction. In this paper, a method of risk level assessment for structures is defined on based the building conditions, such as frame and foundation type, number of floors. Moreover, the value of the structure subsidence is estimated using numerical methods for a Bank building. The subsidence risk level of the Bank building structure is determined based on presented definitions about risk classification. Consequently, finite element analyses results had shown the maximum subsidence of bank building is equal to 9 cm on the right corner of bottom and tunneling processes in this section need a special monitoring system and consolidation measures before the passage of the tunnel under building.
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In the present paper a critical synthesis of the state of art on geological risk assessment in tunnelling is proposed. According to this, a methodological approach is taken, then applied to the Underground Line 7 of Teheran. The studied tunnel involves different geological hazards. Among these, considering the highly urbanized context, the hazard arising from surface settlements is studied in the risk analysis procedure. Therefore, the statistical characterization of the soil deformability parameters enables to carry out the stochastic modelling of its behaviour in response to the underground opening. Taking into account critical thresholds, hazards are assessed using different excavation methods.
A Review on Methods of Predicting Tunneling Induced Ground Settlements
The purpose of this review paper is to present the techniques, approaches and methods for assessing the ground settlements induced by tunneling. Tunneling operation poses threat to adjacent structures by creating subsidence, heave, and vibrations which make the structure more vulnerable. With the advent of urbanization and innovative technologies, utilizing underground space is becoming a sustainable practice day by day. The assessment of ground settlement induced by tunneling is significant to policy makers, practitioners and designers associated with tunneling. The versatility of geological strata and condition has led the practice even more challenging. The multidimensional aspects and problems of tunnel applications has made the practice a complex one requiring incorporation of interdisciplinary nature of this study such as geology, civil engineering, mining engineering specially rock engineering and rock mechanics. This paper also addresses the issues regarding various methods, constitutive models, different ground conditions for instance, mixed faced soil and rock interface ground), roles effect of dimensions on analysis and prospects of multi and interdisciplinary roles.
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Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, 2020
Purpose. Development of a combined method for qualitative and quantitative assessment of risk factors accompanying the construction and operation of underground constructions based on expert analysis and mathematical modeling by numerical methods. Methodology. When creating a comprehensive method for ranking the underground construction route by the degree of prob lems, we used methods of expert assessment, statistical analysis and mathematical modeling, which allow us to assess the state of each section by summing the points of risk factors assessment. findings. Based on the results of practical application of the developed method for ranking the Almaty metro route sections by the degree of problems, the method has shown its effectiveness in solving the problems of ensuring the safety of construction and operation of the metro and has been adopted for implementation. originality. Assessment of the condition of the underground construction route section according to the degree of problematic ity in accordance with the principle of adding risk factors through conditional points established by the results of expert analysis and mathematical modeling. Practical value. The method improves the effectiveness of monitoring the state of the underground construction route, im proves the quality of situational control as well as the forecast of the manifestation of risk situations and their development. The method can be used for solving similar problems in underground construction of different objects, including the development of mineral deposits.
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It has been discovered that the underground structures are vulnerable to seismic phenomena mainly due to permanent ground deformations caused by earthquakes rather than the dynamic seismic movement itself. Several models (empirical formulae) have been developed to estimate such deformations. In this paper, measured settlements from the tunnelling excavation for the extension of Line 3 of the Athens Metro (from Egaleo station to Chaidari) are used for the verification and calibration of such formulae. Firstly, some general information is presented concerning the progress of Line 3 so far. Typical buildings, infrastructure and utility grids that can affect the design and construction of the tunnel are examined. Typical geological, hydrogeological and geotechnical conditions along the axis of the excavation, as specified by laboratory tests, are presented as well. According to these conditions, ground settlements are predicted along the tunnel. Secondly, a comparison is made of the act...
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Potential risks and earthquake effects to the underground structures For centuries, mankind has excavated caverns and tunnels for various purposes. Use of underground spaces and tunnels has been increasing year by year. Road and railway tunnels, water conveyance tunnels, hydropower station caverns, oil and gas storage caverns, caverns for defence, tunnels and caverns for mining, waste deposition caverns and underground sport halls are some of the examples of this kind of applications. Through the development of science and technology, tunnel design and construction methods have been very much improved. It is safe to site underground constructions in hard and competent rock from a rock mechanical point of view. However, the tunnels required to meet the present day infrastructural demands cannot always be optimally sited in competent rock, so future tunnelling will to a greater extent than today be carried out in weak rock. When an underground excavation is made in a rock mass, the mechanical resistance, ability to transmit a force and the ability to hold a water pressure are removed in the space created. Thus it causes three primary effects posing risks to the underground stability. In addition, tectonic activities have added stability problems with the fragile regional geology and mountainous topography. Some of the main risks to the underground structures are: • Occurrence of sheared zone due to faults • Ground water problem: ingressing and leakage • Stress induced problem: squeezing and rock burst • Weak rock mass • Thin rock cover • High temperature condition • Hazardous Gas: inflammable, toxic. • Tunnel portal blockade OR flood/debris into tunnel by landslide, GLOF, LDOF. Sometimes earthquake event may cause stability problem to the underground structures but at certain situation only.Empirical correlation of seismic ground shaking-induced damage to over 100 excavated tunnels is given in the Figure 1. Underground structures with seismic risks needs to be designed with the consideration of dynamic loads generated by earthquake.
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Nowadays, tunnel excavation plays a major role in development of countries. Due to the complex and challenging ground conditions, a comprehensive study and analysis must be done before, during and also after the excavation of tunnels. Hence, the importance of study and evaluation of ground settlement are dramatically increased, since many tunnel projects are performed in the urban areas where there are plenty of constructions, buildings and facilities. For this reason, the control and prediction of ground settlement is one of the complicated topic in the fields of risk engineering. Therefore, in this paper, proportional hazard model (PHM) is used to analyze and study the ground settlement induced by Tabriz Metro Line 2 (TML2) tunneling. The PHM method is a semi-parametric regression method that can enter environmental conditions or factors affecting settlement probability. These influential factors are used as risk factors in the analysis. After establishing a database for a case st...
Case Study of Damage on Masonry Buildings Produced by Tunneling Induced Settlements
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This paper analyzes the structural response of a group of masonry buildings subjected to real ground movements experienced during the construction of the L9 Metro tunnel in Barcelona, bored by a Tunnel Boring Machine (TBM)-Earth Pressure Balance Machine (EPB). The studied one-storey small dwellings represent a common building typology frequently used in those days in Barcelona's outskirts (more than 1000 were erected). Real settlement profiles are compared with the ones provided by empirical methods, which estimate the shape and the area of the trough according to the ground properties and the volume loss (inherent to the tunneling construction method). The first aim of the paper is to evaluate the effectiveness of two techniques used to predict damages in buildings resulting from tunneling subsidence: 1) the 'equivalent beam' and its subsequent refinements, and 2) the appliance of a non-linear Finite Element macro-model. The real structural damage presented in the buildings is compared with the predictions given by this two methods. Main model parameters have been determined by means of characterization experiments developed on the site and in the laboratory, thus giving a much higher significance to the analysis. The obtained predictions present a high correspondence with the actual damage registered, particularly in crack pattern and in crack widths.