Application of back analysis in assessing the stability of an Indian tunnel

2017 ◽  
pp. 525-528
Author(s):  
Anil Swarup ◽  
Shinichi Akutagawa
Keyword(s):  
Back Analysis ◽  
The Stability

scholarly journals Tunnel Back Analysis Based on Differential Evolution Using Stress and Displacement

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Joon-Sang An ◽  
Kyung-Nam Kang ◽  
Ju-Young Choi ◽  
Won-Suh Sung ◽  
Vathna Suy ◽  
...  
Keyword(s):  
Differential Evolution ◽  
Differential Evolution Algorithm ◽  
Back Analysis ◽  
Friction Angle ◽  
Internal Displacement ◽  
Average Error ◽  
Analysis Algorithm ◽  
Evolution Algorithm ◽  
Displacement Based ◽  
The Stability

The stability of tunnels has mainly been evaluated based on displacement. Because displacement due to the excavation process is significant, back analysis of the structure and ground can be performed easily. Recently, the length of a segment-lined tunnel driven by the mechanized tunneling method is increasing. Because the internal displacement of a segment-lined tunnel is trivial, it is difficult to analyze the stability of segment-lined tunnels using the conventional method. This paper proposes a back analysis method using stress and displacement information for a segment-lined tunnel. A differential evolution algorithm was adopted for tunnel back analysis. Back analysis based on the differential evolution algorithm using stress and displacement was established and performed using the finite difference code, FLAC3D, and built-in FISH language. Detailed flowcharts of back analysis based on DEA using both monitored displacement stresses were also suggested. As a preliminary study, the target variables of the back analysis adopted in this study were the elastic modulus, cohesion, and friction angle of the ground. The back analysis based on the monitored displacement is useful when the displacement is significant due to excavation. However, the conventional displacement-based back analysis is unsuitable for a segment-lined tunnel after construction because of its trivial internal displacement since the average error is greater than 32% and the evolutionary calculation is finalized due to the maximum iteration criteria. The average error obtained from the proposed back analysis algorithm using both stress and displacement ranged within approximately 6–8%. This also confirms that the proposed back analysis algorithm is suitable for a segment-lined tunnel.

scholarly journals Stability Evaluation of Overtopped Concrete Hydraulic Structures Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Mario Freitas ◽  
Etienne Favre ◽  
Pierre Léger ◽  
Lineu José Pedroso
Keyword(s):  
Water Pressure ◽  
Back Analysis ◽  
Hydrodynamic Pressure ◽  
Flow Conditions ◽  
Gravity Dams ◽  
Pressure Fields ◽  
Dam Stability ◽  
The Stability ◽  
Resultant Forces ◽  
Safety Guidelines

A particularly challenging aspect in gravity dam stability assessment is the estimation of the induced hydrodynamic water pressure when water with significant velocity is overtopping gravity dams and flowing in or over spillway components. The water flow conditions, including the related pressure fields and resultant forces, are difficult to quantify accurately. Herein, existing dam safety guidelines to estimate the weight of the overflowing water nappe on gravity dams with rectangular crests are first reviewed. Then, a CFD methodology is developed to improve the simplified estimation of hydrodynamic pressure fields acting on the rectangular crests of submerged gravity dams. The CFD pressures are used as input data to classical structural stability analyses based on the gravity method to more adequately quantify the dam stability during overtopping. A back analysis is also performed on the stability of an existing gated spillway that was overtopped during the 1996 Saguenay flood in Québec.

scholarly journals Excavation Method of Reducing Blasting Vibration in Complicated Geological Conditions

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Lixiang Xie ◽  
Wenbo Lu ◽  
Jincai Gu ◽  
Gaohui Wang
Keyword(s):  
Back Analysis ◽  
Blasting Vibration ◽  
Underground Engineering ◽  
Engineering Construction ◽  
Vibration Data ◽  
Geological Conditions ◽  
Blasting Excavation ◽  
The Stability ◽  
Site Test ◽  
Blasting Method

Drilling and blasting method as a common excavation method is widely used in the underground engineering construction. However, in the complicated geological conditions, the path of blasting excavation available has limitation, and then the larger blasting vibration is produced, which influence the stability and safety of the protected structure. To effectively reduce the blasting vibration by optimizing the blasting excavation method, firstly, the site test on blasting vibration is conducted to obtain the blasting vibration data; secondly, the LS-DYNA software is applied to simulate the vibration generated by blasting in site test, based on back analysis on the blasting vibration, the mechanical parameters of the rock mass are obtained, and they are used to simulate six different types of blasting excavation method. According to the analysis on them, the reasonable blasting excavation method is proposed to reduce the blasting vibration which can satisfy the blasting safety regulation.

Stability Assessment of Silin Powerhouse Cavern Based on Displacement Back Analysis Method

2011 ◽  
Vol 243-249 ◽  
pp. 2478-2482
Author(s):  
Yun Hao Yang ◽  
Chong Shi ◽  
Ling Ran Zhang
Keyword(s):  
Orthogonal Design ◽  
Safety Margin ◽  
Back Analysis ◽  
Analysis Procedure ◽  
Support Vector ◽  
Particle Swarm Optimizer ◽  
Hybrid Optimization Algorithm ◽  
Nonlinear Relation ◽  
Measured Displacement ◽  
The Stability

A back analysis procedure synthetically using parameters sensitivity analysis based on orthogonal design variance analysis, support vector regression modeling of nonlinear relation between mechanical parameters and displacement, and a hybrid optimization algorithm of particle swarm optimizer (PSO) and differential evolution (DE), was proposed. Optimum values of elasto-plastic mechanic parameters of rock mass were identified using the back analysis procedure and the measured displacement data. Assigning to the numerical model the optimum values of parameters, numerical simulation of powerhouse construction process was carried out to investigate the reliability of result of back analysis and the stability of powerhouse cavern. The result shows that calculated displacements are in good agreement with the measured, the powerhouse cavern is stable and has a considerable safety margin, and the existing support system can satisfy the need of local stability of powerhouse.

scholarly journals The Influence Evaluation of the Waste Slag Above Tunnel on the Safety of the Structure of the High-Speed Railway Tunnel

2020 ◽  
Author(s):  
Weigong Ma ◽  
Weibo He
Keyword(s):  
High Speed ◽  
Great Influence ◽  
Back Analysis ◽  
Tunnel Lining ◽  
Tunnel Structure ◽  
Destructive Testing ◽  
High Speed Railway ◽  
Lining Structure ◽  
Design Documents ◽  
The Stability

A high-speed railway loess tunnel being built is in the Shallow-Buried Section because the construction party violates the design, and the slag discarded at the top of the tunnel is just down-pressing the main line. In order to ensure that the stability of tunnel structure does not affect the safe operation in the later period, a stratum structure model is established based on non-destructive testing and on-site tunnel monitoring measurement. The parameters of surrounding rock are determined by displacement back analysis method, and the influence of waste slag on the safety of tunnel structure is checked by the parameters obtained from back analysis. Through the comparative analysis of the stress of tunnel lining under two working conditions, combined with relevant codes and design documents, it is considered that the slag has a great influence on the stress of tunnel lining structure, but the sectional strength and maximum crack width of eccentrically compressed components of tunnel lining meet the design requirements, and the structure is within the safety range.

Static and dynamic analyses of the stability of mining wastes (Ravaneti) in the Carrara marble area (Apuan Alps, Italy) / Analiza statyczna i dynamiczna stabilności hałd odpadów górniczych w regionie wydobycia marmurów Carrara (Alpy Apuańskie, Italia)

2012 ◽  
Vol 57 (3) ◽  
pp. 667-686
Author(s):  
Pierpaolo Oreste ◽  
Silvia Soldano
Keyword(s):  
Seismic Wave ◽  
Limit Equilibrium ◽  
Back Analysis ◽  
Friction Angle ◽  
Static Field ◽  
Accurate Analysis ◽  
Civil Infrastructures ◽  
Apparent Cohesion ◽  
The Stability ◽  
Apuan Alps

Abstract The problem of the stability of “ravanetos” (debris piles of mining waste material extracted from the Apuan Alps, Italy) is very relevant, because of the consequences a landslide would have on the people and the existing civil infrastructures throughout the territory. In this work, the stability of two ravanetos that can be considered as representative of those in the Carrara area has been studied: the Polvaccio ravaneto, a recent type of debris pile and the Torrione-Tecchione, an old debris pile at present undergoing re-naturalisation. The study using the LEM (Limit Equilibrium Method) in a static and pseudo-static field, has made it possible to first carry out a back-analysis to define the most probable apparent cohesion and friction angle values of the material that makes up the ravanetos. Subsequently, it was possible to determine the intensity of the seismic wave that would be able to lead the two ravanetos to limit stability conditions and to determine the probability of such a seismic wave occurring in the next 50 years. A more accurate analysis, carried out with a numerical method in the dynamic field, of the most critical condition (the Polvaccio ravaneto) has led to more conservative results (higher safety factors) than those obtained with the LEM. This result allows us to reveal how the LEM can be considered a cautionary instrument to judge the stability of debris piles during a seismic event and that the likelihood of a landslide occurring in the two studied representative ravanetos over the next 50 years is very slim.

Displacement Back Analysis Research on Bolt-Grouting Supporting Parameter of Rock Mass in Jointed Rock Roadway

2004 ◽  
Vol 261-263 ◽  
pp. 1563-1568
Author(s):  
Le Wen Zhang ◽  
Shu Chen Li ◽  
Shu Cai Li
Keyword(s):  
Rock Mass ◽  
Mass Parameter ◽  
Back Analysis ◽  
Jointed Rock ◽  
Singular Value ◽  
Surrounding Rock ◽  
Elastic Model ◽  
Rock Stability ◽  
The Stability ◽  
Rock Roadway

The method of bolt-grouting supporting, grouting into surrounding rock mass by bolts in jointed rock mass roadway, is obtained wide application. However, it is difficult to determine rock mass parameter of bolt-grouting supporting. This paper begins with the displacement, which is measured easily in practice. The method of back analysis is adopted to calculate the equivalent mechanics parameters of bolt-grouting rock mass. In process of back analysis three mechanics models is supposed which are homogeneous elastic model, inhomogeneous elastic model and elastic-plastic model and corresponding algorithm is established. What's more, this paper discusses the stability of inverse algorithm and copes the problem of back analysis parameter probably instable with QR decomposed algorithm and singular value decomposed algorithm, which will be a theoretical base to determine the mechanics parameter of bolt-grouting supporting rock mass and to estimate the surrounding rock stability. In a word, the method is established to estimate mechanics parameters of bolt-grouting jointed surrounding rock mass, and some significant results are obtained, which are of reference for actual project.

Numerical Investigation of the Stability of Toppling Rock Slopes Subjected to Glacier Retreat

2020 ◽  
Author(s):  
Nikola Toshkov ◽  
Jordan Aaron ◽  
Simon Loew ◽  
Franziska Glueer ◽  
Valentin Gishig
Keyword(s):  
Theoretical Analysis ◽  
Water Table ◽  
Rock Slope ◽  
Structural Model ◽  
Numerical Models ◽  
Back Analysis ◽  
Glacier Retreat ◽  
Glacial Retreat ◽  
Slope Instabilities ◽  
The Stability

<p>Glacial retreat is often cited as a cause of rock slope instabilities in mountain regions. Until recently, glacial debuttressing was thought to be the main mechanism by which glaciers influence slope stability, however recent work has questioned the efficacy of this mechanism.  It appears that other mechanisms, including slope kinematics and hydro-mechanical interactions between the glacier and slope are important drivers of paraglacial rock slope instabilities.  In the present work, we use discontinuum numerical models to investigate the interaction between rock slope kinematics, slope/glacial hydrology and glacial retreat. <br>We perform both a theoretical analysis using a simplified slope geometry, as well as a back-analysis of the Moosfluh Landslide.  For the theoretical analysis, we investigate the response of both toppling and sliding slopes to two factors: the weight of the ice, assumed to be applied as a ductile load acting normal to slope topography, and the variation of the slope water table, which is linked to the ice level and lowers as the glacier retreats. We then apply the insights from the theoretical analysis to investigate the Moosfluh Landslide.  This landslide, which is located at the left flank of the Great Aletsch Glacier Valley (Valais, Switzerland), at the present-day glacial terminus, underwent a dramatic acceleration in 2016 in response to glacier retreat.  The landslide was extensively monitored during this acceleration, and analysis of this data has revealed that the kinematics of movement changed from toppling to secondary sliding.  We simulate the behaviour of the Moosfluh Landslide by implementing a structural model determined from field mapping, and systematically lowering the ice level and slope water table, to simulate glacial retreat.<br>We find that the interaction between slope kinematics and glacial retreat leads to a complex slope response.  For sliding slopes, the stability of the slope is relatively insensitive to glacial ice loss.  For toppling slopes, the slope response is highly sensitive to ice loss, and the slope is the most unstable at a critical ice level, before ice has completely retreated.  For the Moosfluh instability, we are able to simulate the initial toppling kinematics of this landslide, as well as the transition to sliding triggered by the ice reaching a critical elevation.  Our analysis has important implications for understanding rock slope response to glacial retreat, and highlights the disparate behaviour of toppling and sliding slopes. </p>

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