scholarly journals Problems Encountered during a Railway Tunnel Excavation in Squeezing and Swelling Materials and Possible Engineering Measures: A Case Study from Turkey

2020 ◽  
Vol 12 (3) ◽  
pp. 1166 ◽  
Author(s):  
Ebu Bekir Aygar ◽  
Candan Gokceoglu
Keyword(s):  
High Speed ◽  
Support Systems ◽  
Silty Clay ◽  
Railway Tunnel ◽  
Tunnel Face ◽  
Tunnel Excavation ◽  
Tunnel Support ◽  
Clayey Silt ◽  
Northwestern Turkey ◽  
Under Construction

The T3 railway tunnel—under construction within the scope of the Bursa-Yenişehir high-speed train project—is located in northwestern Turkey and has a length of 1250 m. The tunnel is being constructed entirely in silty clay/clayey silt, sand, and clay units, and it is designed in accordance with the principles of weak ground tunneling described by the new Austrian tunneling method (NATM). When the tunnel excavations began in 2013, during and after portal excavations, a failure occurred at the entrance of the tunnel; thus, a revision of the support systems became mandatory. While the excavation works proceeded after the revision phase, a collapse occurred again at the tunnel face where the overburden thickness was low. This study presents the mechanisms of the collapse that took place at the portal location and in the middle of the tunnel. The proposed tunnel support systems and their numerical analyses are also discussed, because the case is interesting for the tunnel community and will inform future tunnel construction work. For this reason, the relationship between portal excavation and tunnel excavation stability is described. Consequently, tunnels excavated through weak ground conditions are considered, and the importance of considering the face stability of tunnels in tunneling studies is underlined.

scholarly journals Analytical solutions and 3D numerical analyses of a shallow tunnel excavated in weak ground: a case from Turkey

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ebu Bekir Aygar ◽  
Candan Gokceoglu
Keyword(s):  
Support System ◽  
Analytical Solutions ◽  
High Speed ◽  
Support Systems ◽  
Geometric Constraints ◽  
Numerical Analyses ◽  
Silty Clay ◽  
Tunnel Face ◽  
High Speed Railway ◽  
Tunnel Support

AbstractDue to the increasing population and resulting transportation needs, the number of subway and high-speed railway projects has also increased. The geometric constraints of such projects have caused many tunnels to be built in weak ground. Thus, weak ground tunnelling has attracted the attention of tunnel engineers and researchers. The main purposes of this study are to analyse the T4 tunnel excavated in weak ground and to compare the results obtained from the analytical solutions and 3D numerical analyses. This study specifically considers the T4 tunnel support system used in the Ankara İzmir High Speed Railway Project (Afyonkarahisar-Banaz Section). The T4 tunnel route encounters weak ground composed of layers of extremely weak mudstone, clayey sand, weakly cemented sandstone, and silty–clay matrix with pebbles. The tunnel overburden ranges from 10 to 35 m, which is shallow. After the excavation work of the T4 tunnel, severe deformation and critical stability problems in the shallow part (where the overburden is approximately 10 m) were encountered inside the tunnel, leading to a halt in construction. This was followed by revisions to the tunnel support system, leading to successful completion of the tunnel excavation. Numerical simulations of the low overburden section are performed using the commercially available FLAC3D program that uses the finite difference method. The characteristics of insufficient/ineffective support systems and adequate support systems for shallow tunnels excavated through weak ground are discussed in this study. Additionally, problems that pertain to the tunnel itself and its support system are discussed. The results of the 3D numerical analyses and analytical solutions are compared, and the advantages of 3D numerical analyses are discussed. The importance and necessity of tunnel face stability and roof stability for tunnel stability in weak ground is illustrated. Consequently, solutions based on analytical and numerical analyses are presented, and the analysis methodology and solutions proposed in the study can help guide weak ground tunnelling design and evaluation.

scholarly journals Engineering geological investigations for evaluation of excavation method and stand-up time of the DK99-DK100 Jakarta – Bandung high-speed railway tunnel, Indonesia

2021 ◽  
Vol 325 ◽  
pp. 01005
Author(s):  
Linda Ali ◽  
I Gde Budi Indrawan ◽  
Hendarto Hendarto
Keyword(s):  
Rock Mass ◽  
High Speed ◽  
Poor Quality ◽  
Geological Strength Index ◽  
Rock Masses ◽  
Railway Tunnel ◽  
Tunnel Excavation ◽  
High Speed Railway ◽  
Geological Conditions ◽  
Subsurface Engineering

This paper presents the investigation of surface geology and subsurface engineering geology to analyze the excavation method and stand-up time of the DK99-DK100 Jakarta-Bandung high-speed railway Tunnel, Indonesia. Rock mass quality, tunnel excavation method, and stand-up time determined using Geological Strength Index (GSI), Basic Quality (BQ) systems, converted to Rock Mass Rating (RMR) and The Japan Society of Civil Engineering (JSCE) for comparison. The result shows that the study area consists of slightly to completely weathered andesite breccia and slightly weathered andesite lava. The rock masses at the tunnel elevation had very poor to poor quality and were associated with high weathering degrees. The recommended rock excavation method based on the GSI is digging. The recommended tunnel excavation method based on RMR is multiple drifts, top heading, and bench, while based on JSCE is bench cut method. The tunnel stand-up time is 30 minutes - 2 hours based on the RMR, while it is predicted to be unstable without support based on the BQ. The recommended design is expected to be applied effectively according to the geological conditions. It is expected to understand better the tunnel excavation method in poor rock masses, especially in Indonesia.

Site Experiment for Predicting Hazardous Geological Formations ahead of Tunnel Face

2006 ◽  
Vol 326-328 ◽  
pp. 461-464 ◽  
Author(s):  
C.N. Lin ◽  
Yu Yong Jiao ◽  
Q.S. Liu
Keyword(s):  
Spatial Information ◽  
Test Procedure ◽  
Railway Tunnel ◽  
Tunnel Face ◽  
Drilling Method ◽  
The Face ◽  
The Stability ◽  
The Moment ◽  
Under Construction ◽  
Short Time

In the construction of railways in western part of China, more and more long tunnels have been excavated these years, and several ones are under construction at the moment. Because of the complex geologies like faults, fractured zones, karst cavities as well as water bearing formations, the stability and safety of tunnels have been challenging topics in the construction process. In this regard, the advance knowledge of the location, size, and spatial information of the uncertainties ahead of the face is very important to the contractors. In this paper, by using the Tunneling Seismic Prediction (TSP) technique, site experiments are performed to predict hazardous formations ahead of face in a railway tunnel. Through interpretation of the testing data, the wave velocities and the mechanical parameters of the surrounding rock are obtained, and the faults/fractures are recognized. The study shows that compared to time-consuming core drilling method, the wave reflection based TSP method can predict major uncertain formations in long range ahead of the face in short time. The downtime, as we know, is one of the key factors in speeding the tunnel construction. For the prediction accuracy, the TSP technique is able to provide enough information due to its multiple proof-test procedure.

An Application of Comprehensive Geological Prediction Methods in a High-Speed Railway Tunnel

2013 ◽  
Vol 639-640 ◽  
pp. 279-282
Author(s):  
Peng Yin ◽  
Rui Ting Yao ◽  
Xiao Lei Ji
Keyword(s):  
High Speed ◽  
Prediction Methods ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Geological Conditions ◽  
Geological Prediction ◽  
Under Construction ◽  
Prediction Techniques ◽  
Double Track

The tunnel involved in this study is a double-track tunnel with a 4113m length and 390m maximum depth which is currently under construction. By analyzing the specific engineering geological and hydro geological conditions and summarizing the past geological prediction techniques, the comprehensive geological prediction methods are adopted in the project, and the accuracy and feasibility of the theory and techniques are verified in the practical construction process. It is concluded that the comprehensive geological prediction methods are conducive to reduce the risks, accelerate the schedule and guarantee the quality of the construction, and provided a good guidance and reference for the tunnel constructions of this kind

scholarly journals Influence of Hydrogeochemistry on Tunnel Drainage in Evaporitic Formations: El Regajal Tunnel Case Study (Aranjuez, Spain)

2021 ◽  
Vol 13 (3) ◽  
pp. 1505
Author(s):  
Ignacio Menéndez Pidal ◽  
Jose Antonio Mancebo Piqueras ◽  
Eugenio Sanz Pérez ◽  
Clemente Sáenz Sanz
Keyword(s):  
High Speed ◽  
Civil Engineering ◽  
Saturation Index ◽  
The Subject ◽  
Under Construction ◽  
Underground Flow ◽  
Very High ◽  
Over Time

Many of the large number of underground works constructed or under construction in recent years are in unfavorable terrains facing unusual situations and construction conditions. This is the case of the subject under study in this paper: a tunnel excavated in evaporitic rocks that experienced significant karstification problems very quickly over time. As a result of this situation, the causes that may underlie this rapid karstification are investigated and a novel methodology is presented in civil engineering where the use of saturation indices for the different mineral specimens present has been crucial. The drainage of the rock massif of El Regajal (Madrid-Toledo, Spain, in the Madrid-Valencia high-speed train line) was studied and permitted the in-situ study of the hydrogeochemical evolution of water flow in the Miocene evaporitic materials of the Tajo Basin as a full-scale testing laboratory, that are conforms as a whole, a single aquifer. The work provides a novel methodology based on the calculation of activities through the hydrogeochemical study of water samples in different piezometers, estimating the saturation index of different saline materials and the dissolution capacity of the brine, which is surprisingly very high despite the high electrical conductivity. The circulating brine appears unsaturated with respect to thenardite, mirabilite, epsomite, glauberite, and halite. The alteration of the underground flow and the consequent renewal of the water of the aquifer by the infiltration water of rain and irrigation is the cause of the hydrogeochemical imbalance and the modification of the characteristics of the massif. These modifications include very important loss of material by dissolution, altering the resistance of the terrain and the increase of the porosity. Simultaneously, different expansive and recrystallization processes that decrease the porosity of the massif were identified in the present work. The hydrogeochemical study allows the evolution of these phenomena to be followed over time, and this, in turn, may facilitate the implementation of preventive works in civil engineering.

Investigation of a loess-mudstone landslide and the induced structural damage in a high-speed railway tunnel

2020 ◽  
Vol 79 (5) ◽  
pp. 2201-2212
Author(s):  
Shunhua Zhou ◽  
Zhiyao Tian ◽  
Honggui Di ◽  
Peijun Guo ◽  
Longlong Fu
Keyword(s):  
Structural Damage ◽  
High Speed ◽  
Railway Tunnel ◽  
High Speed Railway

The Calculation of Train Slipstreams on Platform of Underground High-Speed Rail Station

2013 ◽  
Vol 842 ◽  
pp. 445-448
Author(s):  
Wei Chao Yang ◽  
Chuan He ◽  
Li Min Peng
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Horizontal Distribution ◽  
Wake Flow ◽  
Railway Tunnel ◽  
Long Distance ◽  
Near Wake ◽  
High Speed Rail ◽  
Numerical Work ◽  
Rail Station

This paper describes the results of numerical work to determine the flow structures of the slipstream and wake of a high speed train on platforms of underground rail station using three-dimensional compressible Euler equation. The simulations were carried out on a model of a simplified three-coach train and typical cross-section of Chinese high-speed railway tunnel. A number of issues were observed: change process of slipstreams, longitudinal and horizontal distribution characteristics of train wind. Localized velocity peaks were obtained near the nose of the train and in the near wake region. Maximum and minimum velocity values were also noticed near to the nose rear tip. These structures extended for a long distance behind the train in the far wake flow. The slipstream in platform shows the typical three-dimensional characteristics and the velocity is about 4 m/s at 6 m away from the edge of platform.

scholarly journals Investigation and Analysis on Crystallization of Tunnel Drainage Pipes in Chongqing

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Xuefu Zhang ◽  
Yuanfu Zhou ◽  
Bin Zhang ◽  
Yuanjiang Zhou ◽  
Shiyang Liu
Keyword(s):  
Groundwater Level ◽  
Laboratory Tests ◽  
Support Structure ◽  
Sem Images ◽  
Tunnel Support ◽  
Site Investigations ◽  
Inner Surface ◽  
Drainage Pipe ◽  
Under Construction

A lot of crystallizations exist on the inner wall of tunnel drainage pipes in Chongqing. Tunnel support structure often bears larger load than usual because the tunnel drainage pipes are blocked easily by the crystals and the groundwater level would rise. In order to investigate what the crystals are, site investigations and laboratory tests of crystals and groundwater were completed. Some valuable results have been obtained. Firstly, the crystallizations are usually discovered in drainage pipe exits of tunnels which are under construction in Chongqing. Furthermore, the results of XRD have confirmed that the crystals are calcite. And calcite morphology could be found in most SEM images. But there are other morphologies in these images other than calcite because calcite is often influenced by some factors, such as important ions in groundwater, pH of groundwater, kinetics effect, and so on. Finally, some steps and solutions to solve blocking of tunnel drainage pipes caused by crystallization are suggested. One of the best solutions is that some special materials which could prevent crystals from being attached to pipes are coated on the inner surface of drainage pipes. The results could contribute to understand the crystallization phenomenon profoundly and help solve the similar situations of tunnel drainage pipe blocking.

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