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 Back calculation of in-situ rock stresses for a tunnel project in Himachal, India

2011 ◽  
Vol 42 ◽  
pp. 117-124
Author(s):  
Krishna Kanta Panthi
Keyword(s):  
Rock Mass ◽  
Element Model ◽  
The State ◽  
Stability Assessment ◽  
Rock Support ◽  
Hydroelectric Project ◽  
State Of Stress ◽  
Headrace Tunnel ◽  
Tunnel Instability

Determination of in-situ stresses in the rock mass is necessary for stability assessment and proper design of underground openings. It is important to know the state of stress surrounding the opening so that right and optimum rock support is assigned as preliminary and permanent rock support. However, the majority of long tunnels with high rock cove r face severe tunnel instability problems related to rock stresses. The headrace tunnel of Parbati II hydroelectric project is one of such tunnels, especially the tunnel segment passing through Manikaran quartzite. It is known fact that the extent and type of stress induced instability vary greatly upon rock type, deformability properties, jointing and inter-bedding characteristics in the rock mass. This paper back calculates the state of stress using Phase 2  finite element model  in a TBM  bored segment of  the tunnel and  also briefly reviews mechanical properties of the  intact rock that may have direct link on the  nature of stress induced  instability. It is believed that back calculated stress magnitude may be useful for the stability assessment in other segment of headrace tunnel.

scholarly journals Analysis of engineering geology conditions based on the quality of rock mass in the Tiga Dihaji Dam’s diversion tunnel, South Sumatera, Indonesia

2021 ◽  
Vol 325 ◽  
pp. 05001
Author(s):  
Zekrinaldi ◽  
Ferian Anggara ◽  
Hendy Setiawan
Keyword(s):  
Rock Mass ◽  
Geological Strength Index ◽  
Strength Index ◽  
Diversion Tunnel ◽  
Rock Mass Quality ◽  
Geological Conditions ◽  
Q System

This research has examined the rock mass quality case study in the Tiga Dihaji Dam’s diversion tunnel. Observations of geological conditions were carried out on the surface and subsurface of the study site and show that the study area consists of tuffaceous sandstone and carbonate interbeds. The method of this study is based on the classification of the Geological Strength Index (GSI), Rock Mass Rating (RMR), and the Q-system. The results indicate that tuffaceous sandstone has a GSI value of 15 - 87.5 (very poor - very good), RMR 48 - 82 (fair - very good), and Q-system 0.01 – 60.0 (exceptionally poor - very good). Meanwhile, carbonate interbeds have a low value, with a GSI value of 10.5 - 77.5 (very poor to very good), RMR 17.0 – 56.0 (very - poor fair), and Q-system 0 - 35.2 (exceptionally poor - good). Moreover, a correlation was made between rock mass quality for conditions in the study area. The correlation between GSI and RMR was obtained by the equation GSI = 2.2885RMR 82.567 (R2 = 0.6653), RMR and Q-system RMR = 2.0175ln(Q) + 63.061 (R2 = 0.4987), and GSI and Q-system GSI = 7.2119ln(Q) 54.578 (R2 = 0.8095).

scholarly journals Engineering geological study of the Mai Khola Hyroelectric Project, Ilam, eastern Nepal

2018 ◽  
Vol 56 (1) ◽  
pp. 55-63
Author(s):  
Pusker Raj Joshi ◽  
Kamal Kant Acharya ◽  
Rabindra Dhakal
Keyword(s):  
Rock Mass ◽  
Surge Tank ◽  
Surface Mapping ◽  
Concrete Dam ◽  
Hydroelectric Project ◽  
Hill Slope ◽  
Headrace Tunnel ◽  
Middle Siwalik ◽  
The Hill ◽  
Poor Relation

The Mai Khola Hydroelectric Project, a run-of-river scheme, has a capacity 15.6 MW. It has design discharge of 16 m3/s, design net head of 112.71 m and includes 2192 m long inverted-D shaped headrace tunnel with 4.3 m diameter, concrete dam of 10.6 m height and semi-surface powerhouse. The project area consists of rocks of the Middle Siwalik Subgroup, comprising of sandstone, siltstone and mudstone, inter bedded frequently. Sandstone is predominant in head works area, headrace tunnel and is completely absent in a surge tank, and penstock alignment. Siltstone alternating with thin layer of mudstone is predominant in powerhouse area. The headrace tunnel outlet portal and surge shaft lie on the hill slope characterized by colluvial deposits. The penstock alignment passes through highly weathered siltstone and mudstone. The semi-surface powerhouse and the tailrace canal lie on the lower alluvial terrace. The Main Boundary Thrust (MBT) is the major structure observed at about 90 m upstream from the weir axis. The average Q-value of rock mass along the headrace tunnel surface mapping was 0.062–1.33 and after excavation the value was 0.004–0.23. An extremely poor to poor relation was observed between the rock mass class on surface mapping and exceptionally poor to very poor on excavation. Analysing the results of the surface and underground study of the rock mass, the excess support is required during construction.  

scholarly journals Evaluation on the TBM Performance at a Hydropower Project in Ecuador

2019 ◽  
Vol 24 ◽  
pp. 10-16
Author(s):  
Krishna Kanta Panthi ◽  
Jhonny Encalada
Keyword(s):  
Rock Mass ◽  
San Francisco ◽  
Penetration Rate ◽  
Tunnel Boring Machine ◽  
Quality Parameters ◽  
Hydropower Project ◽  
Tbm Performance ◽  
Rock Mass Quality ◽  
Geological Conditions ◽  
Headrace Tunnel

The aim of this manuscript is to discuss the Tunnel Boring Machine (TBM) performance along the recently constructed headrace tunnel of Minas-San Francisco Hydropower Project in Ecuador. Firstly, the manuscript briefly describes the importance of TBM tunneling and about the Minas-San HPP. Further, discussions are made on the engineering geological conditions along the headrace tunnel. Detailed evaluations are made on the performance of TBM tunneling considering influence of rock mass quality on the TBM penetration rate. The manuscript emphasizes that the knowledge of the rock mass quality parameters and cutter technology available at present are among the key factors that influence the estimation of the net penetration rate of the TBM. It has been demonstrated that the hard to very hard rock masses of high abrasivity that were encountered along the headrace tunnel alignment caused very low penetration giving slow progress, which was not predicted during planning phase design. The authors investigated a fairly good link between TBM penetration and the mechanical strength of the rock mass.

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 Assessing the quality of drilling-and-blasting operations at the open pit limiting contour

2021 ◽  
pp. 42-48
Author(s):  
B Hussan ◽  
M.I Lozynska ◽  
D.K Takhanov ◽  
A.O Oralbay ◽  
S.L Kuzmin
Keyword(s):  
Rock Mass ◽  
Blast Waves ◽  
Open Pit ◽  
Elastic Response ◽  
Final Position ◽  
Geological Conditions ◽  
Drilling Quality ◽  
Seismic Vibrations ◽  
Seismic Impact

Purpose. To develop a methodology for assessing the quality of drilling-and-blasting operations when setting the side to the final position. In this regard, it is necessary to study the nature of deformations in the near-side masses of the design open-pit contours and to assess the seismic impact of blast waves in accordance with damage in the near and far zones from the open-pit boundary, as well as the level of generated seismic vibrations. Methodology.A methodology for assessing the quality of drilling-and-blasting operations at the limiting contour of open pits is developed using the analysis of the mining-and-geological conditions of the rocks constituting the field, in-situ surveying of the state of the open-pit sides, analysis of the physical-mechanical properties of the host rocks, analytical studies and instrumental measurements of the blasting effect. Findings.Based on the analytical methods, the calculation and analysis of the seismicity coefficient of the rocks at the field have been performed. By means of instrumental measurement of the blasting effect in open pit, data have been obtained on the seismic impact of blasting operations on the near-side mass. Based on the results of these works, a methodology for assessing drilling-and-blasting operations at the limiting contour of the open pit has been developed. Originality.In this work, to assess the blasting effect, the seismicity coefficient of the rock mass is used, which characterizes the degree of elastic response to external dynamic influence and is a parameter that determines the elastic seismic wave intensity with distance from the site of blasting operations. Based on the calculation, a map of the seismicity coefficient distribution in the open-pit area has been compiled. Using the method of instrumental measurements, which serves to determine the seismic impact of blasting on a rock mass, the degree of blasting effect on a near-side mass has been revealed. This made it possible to develop a method for assessing the blasting quality, based on determining the percentage of permissible deviations in the face drilling quality. Practical value.The results of the work will be used to calculate the safe parameters of conducting the blasting operations when setting the side to the final position. This method for assessing the quality of drilling-and-blasting operations can be applied at any mining enterprise conducting open-cut mining of minerals.

Early Stage Tunnel Lining Experimental Study of Jinhuashan Railway Tunnel Construction within Soft and Weak Rock Mass

2012 ◽  
Vol 204-208 ◽  
pp. 1532-1537
Author(s):  
Li Qiao Jin ◽  
Tai Quan Zhou ◽  
Bao Hua Lv
Keyword(s):  
Rock Mass ◽  
Reinforced Concrete ◽  
Early Stage ◽  
Tunnel Lining ◽  
Fiber Reinforced Concrete ◽  
Concrete Lining ◽  
Fiber Reinforced ◽  
Railway Tunnel ◽  
Tunnel Section ◽  
Lining Structure

Polypropylene fiber reinforced concrete can improve the common concrete flexibility and it is beneficial for interaction between concrete lining structure and rock mass. The use of fiber reinforced concrete with wet sprayed concrete technique can improve the concrete lining structure construction quality and improve the rock mass self-bearing capacity. The wet-sprayed fiber reinforced concrete is first introduced in Jinhuashan railway tunnel early stage lining structure within soft and weak rock mass. The design of Jinhuashan railway tunnel lining structure using fiber reinforced concrete is introduced and the requirement of material used is explained. To evaluate the lining effect using wet-sprayed fiber reinforced concrete, the online monitoring method is used to measure the rock mass pressure and the concrete lining layer stress for both the experimental tunnel sections and comparison tunnel section. The monitoring data result shows that the rock mass pressure in experimental section is even distribution with lower rock mass pressure and lower concrete lining layer stress. The value of rock mass pressure and tunnel lining layer stress in comparison tunnel section is a little higher than that in experimental tunnel section. The experimental tunnel section using fiber reinforced concrete has good lining effect.

scholarly journals Engineering geology of Kankai Hydroelectric tunnel alignment

2006 ◽  
Vol 31 ◽  
pp. 67-74
Author(s):  
Sunil Kumar Dwivedi ◽  
Prakash Chandra Adhikary
Keyword(s):  
Rock Mass ◽  
Poor Quality ◽  
Project Area ◽  
Hydroelectric Project ◽  
Headrace Tunnel ◽  
Quality Category ◽  
Tunnel Alignment ◽  
The Stability ◽  
Quality Categories ◽  
Intake Portal

This paper describes the engineering geological characteristics of rock mass in the headrace tunnel, powerhouse, and intake portal of the Kankai Hydroelectric Project. The project area lies in the Lower Siwaliks of east Nepal and consists of alternating sandstone and mudstone beds with frequent siltstone intercalations. The rock mass of the project area was classified according to rock mass rating (RMR) and rock mass quality index (Q) systems. It is of very poor, poor, to fair quality (categories V, IV, and III) in the headrace tunnel; of very poor quality (category V) in the powerhouse; and of fair quality (category III) in the intake portal. The stability analysis of irregularly jointed and fractured rocks of the area was carried out using SWEDGE and UNWEDGE. The analysis gave the safety factor of 0.45, 0.64, and 0.45, respectively for the powerhouse, intake portal, and headrace tunnel. The final safety factors obtained after the installation of support for powerhouse, intake portal, and headrace tunnel were 1.14, 3.33, and 4.53, respectively.

scholarly journals Analysis of Squeezing Phenomenon in the Headrace Tunnel of Chameliya Project, Nepal

2014 ◽  
Vol 13 ◽  
pp. 44-51 ◽  
Author(s):  
Pawan Kumar Shrestha ◽  
Krishna Kanta Panthi ◽  
Chhatra Bahadur Basnet
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Cross Section ◽  
Support Pressure ◽  
Rock Mass Properties ◽  
Tunnel Wall ◽  
Hydroelectric Project ◽  
Mass Properties ◽  
Headrace Tunnel ◽  
Tunnel Cross Section

The headrace tunnel of Chameliya Hydroelectric Project, Nepal has faced severe squeezing problems from chainage 3+100m to 3+900m. Due to the severe squeezing and deformation, the tunnel cross section has narrowed considerably along this 800m long tunnel stretch. The tunnel wall closure (deformation) is mostly well over 1 m and the maximum recorded closure exceeds 2m. This paper assesses the squeezing phenomenon along this tunnel stretch through evaluation of rock mass properties and support pressure. Three different methods (two analytical and one 2D finite element numerical modeling program) are used in this analysis. The finding is that it is possible to predict extent of squeezing in tunnel if more than one method is used to verify rock mass mechanical properties. DOI: http://dx.doi.org/10.3126/hn.v13i0.10039HYDRO NEPAL Journal of Water, Energy and EnvironmentIssue No. 13, July 2013Page: 44-51Uploaded date: 3/13/2014

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.

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