Conversion Timing of Tunnel Excavation Methods in Upper-Soft and Lower-Hard Stratum Based on Displacement Direction Angle Theory: Case Study

2019 ◽  
Vol 19 (4) ◽  
pp. 05019003 ◽  
Author(s):  
Wei Wang ◽  
Mingjun Hu ◽  
Hengwen Zhang ◽  
Xuemin Zhang
Keyword(s):  
Tunnel Excavation ◽  
Direction Angle ◽  
Displacement Direction ◽  
Excavation Methods

scholarly journals Numerical Modelling of The Behavior of Tunnel in Soft Surrounding Rock. A Case Study of Djebel El-Ouahch Tunnel, Algeria.

2021 ◽  
Author(s):  
Barkane Aicha ◽  
Sami Mezhoud
Keyword(s):  
Reference Model ◽  
Soil Behavior ◽  
Tunnel Excavation ◽  
Circular Section ◽  
Geological Conditions ◽  
The Stability ◽  
Tunnel Cross Section ◽  
Calculation Code ◽  
Surrounding Soil

Abstract The response of a massif to stresses generated by tunnel excavation depends essentially on the geological conditions, the geometry of the tunnel and its underground position. The major problem related to the construction of these structures is to ensure the stability of the whole tunnel-ground, by controlling the various deformation generated during the constructionIn this context, the present paper examines the effect of these conditions on the behavior of tunnels and the surrounding soil. The study is applied to a real tunnel, in this case the tunnel of Djebel El Ouahch, Algeria was taken as a reference model. The research includes a parametric study to evaluate the effect of several parameters on the behavior of the tunnel and surrounding soil such as the tunnel anchoring depth, the tunnel-soil interface rate, and the shape of the tunnel cross section. The analysis is performed using the PLAXIS 3D TUNNEL calculation code with an elastoplastic Mohr-coulomb model for the soil behavior. The results show that the strongest and most stable position is the mid-deep tunnel with a circular section, with a non-slip interface between the tunnel and the ground. These outcomes can help to understand the effects of various influences parameters which control the stability of the tunnel in a soil with bad characteristics.

A multi-dimensional approach to the assessment of tunnel excavation methods

2011 ◽  
Vol 48 (7) ◽  
pp. 1077-1085 ◽  
Author(s):  
Mojtaba Golestanifar ◽  
Kamran Goshtasbi ◽  
Mostafa Jafarian ◽  
Siamak Adnani
Keyword(s):  
Dimensional Approach ◽  
Tunnel Excavation ◽  
Excavation Methods

scholarly journals Evaluation of the Influence Caused by Tunnel Construction on Groundwater Environment: A Case Study of Tongluoshan Tunnel, China

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Jian Liu ◽  
Dan Liu ◽  
Kai Song
Keyword(s):  
Indicator System ◽  
Field Investigation ◽  
Assessment Method ◽  
Tunnel Construction ◽  
Moderate Degree ◽  
Tunnel Excavation ◽  
Construction Period ◽  
Environmental Investigation ◽  
Groundwater Environment

Problems related to water inflow during tunnel construction are challenging to designers, workers, and management departments, as they can threaten tunneling project from safety, time, and economic aspects. Identifying the impacts on groundwater environment resulting from tunnel drainage and making a correct assessment before tunnel construction is essential to better understand troubles that would be encountered during tunnel excavation and helpful to adopt appropriate countermeasures to minimize the influences. This study presents an indicator system and quantifies each indicator of Tongluoshan tunnel, which is located in southwest China with a length of 5.2 km and mainly passes through carbonate rocks and sandstones, based on field investigation and related technological reports. Then, an evaluation is made using fuzzy comprehensive assessment method, with a result showing that it had influenced the local groundwater environment at a moderate degree. Information fed back from environmental investigation and hydrologic monitoring carried out during the main construction period proves the evaluation, as the flow of some springs and streams located beside the tunnel route was found experiencing an apparent decline.

scholarly journals TUNNEL PORTAL INSTABILITY IN LANDSLIDE AREA AND REMEDIAL SOLUTION: A CASE STUDY

2019 ◽  
Vol 59 (5) ◽  
pp. 435-447 ◽  
Author(s):  
Farhad Farhadi Ayoublou ◽  
Majid Taromi ◽  
Abbas Eftekhari
Keyword(s):  
Geological Structure ◽  
Construction Process ◽  
Site Location ◽  
Landslide Area ◽  
Tunnel Excavation ◽  
Excavation Process ◽  
Geological Formations ◽  
Zagros Region ◽  
Tunnel Portal

The construction of tunnel portals in mountainous or slope areas often involves problems, which are closely related to factors, such as slope topography, geology, geotechnics, construction geometry and the tunnel excavation method. The activation of landslides or the acceleration of these events is one of the main challenges faced in the construction of tunnel portals. In this paper, we address the instability problem in Sabzkuh tunnel portal that has been excavated with a complex geological profile and high seismicity in Iran’s High Zagros region. The complexity and intense heterogeneity in geological formations, land acquisition problems and the lack of appropriate monitoring programs led to the instability of the tunnel portal. The excavation process started without applying appropriate techniques for a ground stabilization. The use of inappropriate tunnel excavation methods for this unstable geological structure resulted in an activation of an old Solaghan fault and several collapses in the tunnel. Crossing the collapsed areas and reinforcing the tunnel portal took about 7 months and imposed heavy costs on the project. This case study deals with the importance of the choice of the site location, ground and underground monitoring, analysing and summarizing the collected data in order to prepare a geological model before and during the construction process.

Dealing with asbestos presence in tunnel excavation: the Castagnola case study and the importance of the geological model

2020 ◽  
Author(s):  
Oliviero Baietto ◽  
Francesco Amodeo ◽  
Martina Vitaliti ◽  
Giovanni Parisi ◽  
Alberto Scuderi ◽  
...  
Keyword(s):  
Surface Investigation ◽  
High Velocity ◽  
Ventilation System ◽  
Geological Model ◽  
Tunnel Excavation ◽  
Naturally Occurring ◽  
Naturally Occurring Asbestos ◽  
Storage Methods ◽  
And Storage

<p>The presence of Naturally Occurring Asbestos (NOA) is one of the greatest danger during excavations and tunneling.  The most important instrument for the NOA content prediction is the geological model.</p><p>As part of the consultancy provided in the works of the "Terzo valico dei Giovi" which includes the excavation of numerous tunnels in areas potentially affected by rocks containing asbestos, the case study of the tunnel called "Castagnola" is illustrated. The opera is the new high velocity railway connection between Genova and Milano and the case study is located in the Piedmont southern area near Fraconalto (AL).</p><p>The “Castagnola” tunnel area is characterized by greenish - reddish rocks metabasalt covered by recent grey shales in the upper part of the area; it refers to the ophiolitic Figogna Unit, elongated in a north-south direction, which belongs to Sestri-Voltaggio Zone.</p><p>Starting from geological sections and thanks to surface investigation and core drilling, an effective geological model was built.</p><p>This study highlights how, during the progress of the works, situations other than the forecast geological model are encountered. It also highlights the importance of the environmental monitoring of the airborne fibers dispersion inside the tunnel, which has proved extremely effective even in the presence of low asbestos content in the excavated rock.</p><p>Moreover, this study describes the trends in asbestos content in the material excavated during the route of the tunnel in comparison with the concentration of airborne fibers. Furthermore, the management of the asbestos problem, from the abatement of dust to the excavation and storage methods and the installation of efficient technologies such as an aspirating ventilation system already successfully tested in a previous excavation phase, are presented.</p>

scholarly journals Impact of Construction Method and Ground Composition on Headrace Tunnel Stability in the Neelum–Jhelum Hydroelectric Project: A Case Study Review from Pakistan

2021 ◽  
Vol 11 (4) ◽  
pp. 1655
Author(s):  
Hafeezur Rehman ◽  
Abdul Muntaqim Naji ◽  
Kyoungmin Nam ◽  
Saeed Ahmad ◽  
Khan Muhammad ◽  
...  
Keyword(s):  
Successful Operation ◽  
Tunnel Excavation ◽  
Cost Overruns ◽  
Tunnel Stability ◽  
Hydroelectric Project ◽  
Related Data ◽  
Headrace Tunnel ◽  
Excavation Area

During underground construction, the behavior of the ground is influenced by characteristics of the rock mass with situ stresses and ground water, cross section of the excavation area, excavation method, and the rate of excavation. These fundamental features are considered to ensure the support and stability of underground excavations and achieve long-term successful operation. However, the ground composition of the Himalayas hinders tunnel excavation, especially in case of mechanized tunneling; this causes time and cost overruns. This study has reviewed the recently completed Neelum–Jhelum Hydroelectric Project; the project complexities, geological environments involving significant overburden and tectonic stresses, and effects of the excavation method on tunnel stability were analyzed. The major challenges that were encountered during construction are discussed herein along with their countermeasures. An analysis of project-related data reveals that latest techniques and approaches considering rock mechanics were used to complete the project; the existing approaches and methods were accordingly verified and extended. Apart from ground composition, the excavation methods used play an important role in the occurrence of severe rock bursts. Thus, the findings of this study are expected to be helpful for future tunneling projects in the Himalayas.

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