scholarly journals Wedge stability analysis and rock squeezing prediction of headrace tunnel, Lower Balephi Hydroelectric Project, Sindhupalchok District, central Nepal

2011 ◽  
Vol 42 ◽  
pp. 125-136
Author(s):  
Biraj Gautam
Keyword(s):  
Stability Analysis ◽  
Stress Condition ◽  
Tunnel Support ◽  
High Tunnel ◽  
Hydroelectric Project ◽  
Central Nepal ◽  
Rock Bolting ◽  
Headrace Tunnel ◽  
Squeezing Prediction ◽  
Tunnel Depth

The wedge stability and stress analyses are important in tunnel stability assessment. The identification of the wedge stability and stress condition for the headrace tunnel suggests the required tunnel support in Lower Balephi Hydroelectric Project in Sindhupalchock District, central Nepal. The planned tunnel of the project is 4.5 min diameter and 4.2 km in length. The main litholog ies of the area along the tunnel axis are phyllite and phyllitic quartzite of the Kunchha Formation, Nawakot Complex. Wedge stability analysis in the headrace tunnel showed that the structural wedge would form due to excavation and can be stabilized with the help of rock bolting and shotcreting. Rock squeezing is predicted to occur in high tunnel depth in phyllite and it may be stabilized with the installation of roc k support consisting steel rib.

scholarly journals Stability and stress analyses of headrace tunnel, Upper Seti Storage Hydroelectric Project, Western Nepal

1970 ◽  
Vol 10 ◽  
pp. 45-54
Author(s):  
Niraj Kumar Regmi ◽  
Prakash Chandra Adhikary ◽  
Jayandra Man Tamrakar ◽  
Rabindra Prasad Dhakal
Keyword(s):  
Concrete Gravity Dam ◽  
Tunnel Support ◽  
Underground Powerhouse ◽  
Hydroelectric Project ◽  
Rock Bolting ◽  
Headrace Tunnel ◽  
Mass Classification ◽  
Intake Portal ◽  
Storage Type

The Upper Seti (Damauli) Storage Hydroelectric Project has a capacity of 128 MW, the storage type scheme, and includes 1000 m long horse shoe headrace tunnel, 140 m high concrete gravity dam, two diversion tunnels of lengths 712 m and 881 m and an underground powerhouse. The study was carried out to identify stability and stress conditions for the headrace tunnel to suggest the required tunnel support. The project area extensively covers dolomite and minorly covers slate. The rock mass classification showed fair to good quality of dolomite and poor to fair quality of slate. The surface wedges would form in intake portal and powerhouse site. In the headrace tunnel, structural wedges would be formed due to underground excavation and would be stabilized with the help of shotcrete and rock bolting.   doi: 10.3126/bdg.v10i0.1419 Bulletin of the Department of Geology, Tribhuvan University, Kathmandu, Nepal, Vol. 10, 2007, pp. 45-54

scholarly journals The Use of Self Supporting Capacity of Rock Mass for Sustainable Hydropower: An Analysis of the Middle Marsyangdi Headrace Tunnel, Nepal

1970 ◽  
Vol 6 ◽  
pp. 18-26
Author(s):  
Kiran K. Shrestha ◽  
Krishna K Panthi
Keyword(s):  
Rock Mass ◽  
Stability Analysis ◽  
Concrete Lining ◽  
Rock Support ◽  
Hydroelectric Project ◽  
Tunnel Section ◽  
Geological Conditions ◽  
Headrace Tunnel ◽  
Support Principle

The history of hydropower development in the Himalaya indicates that many tunnels have suffered from cost over- runs and delays. These issues are directly dependent on the quality of rock mass and the permanent rock support applied in underground excavation. Right judgment and proper evaluation of the self supporting capability of the rock mass and the use of optimum rock support systems help considerably in reducing construction cost and delays. This paper examines such issues as geological conditions in the Himalayas and varying approaches and costs in tunnel construction. An assessment is made regarding the exclusion of permanent concrete lining in the headrace tunnel of the 72MW Middle Marsyangdi Hydroelectric Project in Nepal. The project has 5.2 km fully concrete lined headrace tunnel that passes through fair to poor rock mass. The evaluation is based on the use of actually recorded rock mass quality of the headrace tunnel during construction and rock support principle used at the comparable Khimti Hydro Project headrace tunnel. The evaluation includes calculation of equivalent tunnel section for similar headloss, stability analysis, assessment of possible water leakage, and required injection grouting measures. We conclude that the headrace tunnel without permanent concrete lining was possible and would have been equally stable, at considerable fnancial savings.Key words: Equivalent tunnel section; Squeezing; Tunnel lining; Stability analysis; Leakage control; Hydropower; NepalDOI: 10.3126/hn.v6i0.4188Hydro Nepal Vol 6, January 2010Page : 18-26Uploaded Date: 23 January, 2011

scholarly journals Construction of a tunnel under thin rock overburden in Middle Marsyangdi Hydroelectric Project, Central Nepal

2004 ◽  
Vol 29 ◽  
Author(s):  
Kaustubh Mani Nepal
Keyword(s):  
Rock Mass ◽  
Support System ◽  
Deformation Monitoring ◽  
Actual Condition ◽  
Support Design ◽  
Tunnel Support ◽  
Hydroelectric Project ◽  
Central Nepal ◽  
Rock Overburden ◽  
Smooth Blasting

This paper deals with an application of New Australian Tunnelling Method (NATM) in low cover tunnelling in Lesser Himalaya of Nepal. The length of the tunnel is 365.8 m with a 8.2 m finished diameter. The average thickness of the rock overburden is 16- 18 m with a maximum of 30 m, whereas average side cover is 40 m. Top heading and multiple benching methods were applied for tunnelling work. The rational support design techniques were conceived together with Bieniawski's Support Guideline for each standard support classes. Standard initial support system was designed according to NATM, to provide complete stabilization of excavation. It consisted of a combination of systematic rock bolts and shotcrete.  The smooth blasting technique was adopted for the tunnel excavation. The specific charge was 1.39-1.47 kg/m3 A special emphasis was given in the collection of discontinuity data so that the rock mass could be evaluated effectively. Geomechanics classification for rock mass was used for the rock mass evaluation. The rock mass was also back evaluated by using Q and GSI classification on the basis of installed support. After the careful assessment of the data, the rock mass in the tunnel was classified into fair to poor according to RMR and Q and blocky / disturbed to very blocky / fair according to GSI. The rock mass parameters collected during the construction stage agree with the data collected at surface during feasibility and tendering stages. The rock mass classification based on the surface outcrop survey and drillings was a considerable success and found to be very close to the actual condition. The effectiveness of revised support system with steel rib was found to be negligible or minimum for tunnel support. Rock support deformation monitoring in the tunnel was regularly carried out to determine the efficiency and adequacy of the installed support.

scholarly journals STABILITY ANALYSIS OF TUNNEL SUPPORT SYSTEMS USING NUMERICAL AND INTELLIGENT SIMULATIONS (CASE STUDY: KOUHIN TUNNEL OF QAZVIN-RASHT RAILWAY)

2019 ◽  
Vol 34 (2) ◽  
pp. 1-11 ◽  
Author(s):  
Reza Mikaeil ◽  
◽  
Hadi Bakhshinezhad ◽  
Sina Shaffiee Haghshenas ◽  
Mohammad Ataei ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Support Systems ◽  
Tunnel Support

scholarly journals Dynamic Monitoring and Stability Analysis of Rock-bolted Crane Girder In large Cavern With Layered Surrounding Rock

2020 ◽  
Vol 165 ◽  
pp. 03025
Author(s):  
Jing Liu ◽  
Xiaomin Liu ◽  
Shengjie Di ◽  
Xi Lu
Keyword(s):  
Stability Analysis ◽  
Stability Condition ◽  
Stress Condition ◽  
Surrounding Rock ◽  
Monitoring Data ◽  
Dynamic Monitoring ◽  
Power Station ◽  
Load Bearing ◽  
Underground Cavern ◽  
Normal Law

The large and medium-sized hydropower projects underground cavern group are basically in relatively integrate surrounding rock, so there are few engineering examples in layered surrounding rock with type III surrounding rocks as the main rock, and lack of successful experience. According to rock-bolted crane girder under the layered surrounding rock of a large underground power station, analyzing prototype dynamic monitoring data of the excavation, unloading and load-bearing test .The distribution of the monitoring data conforms to the normal law, and there are no large outliers, under the action of a large number of bolts, rock-bolted crane girder basically forms a good integrity with the layered surrounding rock, and the load-bearing test has no effect on the stress condition and stability condition of surrounding rock.

Stability Analysis of Tunnel Surrounding Rock Based on Coupled Fluid-Solid Theory

2011 ◽  
Vol 90-93 ◽  
pp. 1900-1903
Author(s):  
Fu Ming Wang ◽  
Xiao Long Li ◽  
Yan Hui Zhong ◽  
Xiao Guang Chen
Keyword(s):  
Stability Analysis ◽  
Plastic Zone ◽  
Coupling Effect ◽  
Plastic Zone Size ◽  
Wall Rock ◽  
Surrounding Rock ◽  
Maximum Deformation ◽  
Calculation Results ◽  
The Stability ◽  
Tunnel Depth

Taking Chaijiazhuang Tunnel of Lingnan Expressway as project background, the stability analysis of surrounding rock was performed based on the coupled fluid-solid theory. The distributions of stress field, displacement field and plastic zone of rock mass after excavation of tunnel were discussed considering coupled effect between flow and stress under the condition of different rock level and tunnel depth. Compared with the calculation results of not considering coupling effect, the maximum deformation, maximum principle stress and plastic zone size of wall rock were obviously increased when considering coupling effect, which showed a remarkable influence of coupled fluid-solid effect on the stability of tunnel surrounding rock. Some conclusions were drawn and may provide some guidance to the design and construction of tunnels in water-rich strata.

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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