Assessment and Numerical Analysis of Hydropower Tunnel in Lesser Himalayan Region of Nepal- A Case Study

Khadka, Shyam Sundar; Karki, Sujan; Chhushyabaga, Bimal; Maskey, Ramesh Kumar

doi:10.1088/1742-6596/1266/1/012015

Cited by 4 publications

(6 citation statements)

References 6 publications

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“…The design follows the guidelines laid out in the AASHTO LRFD 2012 Bridge Design Code and takes into account a hypothetical building timeline. 15,[32][33][34][37][38][39] F I G U R E 3 Construction sequence top-down method. 32,33 TUNNEL SECTION GEOMETRY Reinforced concrete was used in the tunnel's construction to make it a strong, long-lasting structure.…”

Section: Methods Of Constructionmentioning

confidence: 99%

A possible underground roadway for transportation facilities in Kathmandu Valley: A racking deformation of underground rectangular structures

Sahani,

Khadka,

Sahani

et al. 2023

Engineering Reports

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The increasing number of private cars, public transportation vehicles, and pedestrians, as well as the absence of adequate space for these ground amenities, are one of the primary causes of traffic congestion and accidents in the Kathmandu Valley. Investigations have indicated that the Kathmandu Valley has the greatest traffic accidents despite the heavy presence of the government and its agencies there. Most teens and young adults suffer injuries while using motor vehicles. The study's primary objective is to foresee and prevent such complications by planning for sufficient subsurface infrastructure (a cut‐and‐cover rectangular tunnel) for the Kathmandu Valley's transportation network. The overlying pressure, lateral earth pressure, live load, uplift pressure, and live surcharge are some of the forces acting on the tunnel, creating unique stress and moment zones. The tunnel meets the following geometric requirements: (a) Each of the tunnel's two cells has a clear span of 10 m and a clear height of 5.5 m. The side walls, inner walls, top slab, and bottom slab are all 700 mm thick. Soil has built up to a height of 4 m over the tunnel's roof. The analytical method is used in the tunnel segment's analysis. Furthermore, the designed tunnel has been evaluated for stability, considering the deflection and shear resistance. The analysis indicates that the tunnel meets the stability requirements. This implies that the structure is capable of withstanding the applied forces without excessive deflection. Non‐linear dynamic time history analyses of the El Centro earthquake and the Gorkha earthquake were computed. From the El Centro earthquake, the maximum displacement was 23.63 mm at 10.59 s, and from the Gorkha earthquake, the maximum displacement was 16 mm at 0.19 s for the modeled structures.

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Section: Methods Of Constructionmentioning

confidence: 99%

A possible underground roadway for transportation facilities in Kathmandu Valley: A racking deformation of underground rectangular structures

Sahani,

Khadka,

Sahani

et al. 2023

Engineering Reports

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“…Khadka et.al. (2019) have suggested that the rock mass classification approach is not adequate for design and estimation of tunnel support in the Lesser Himalayan Region of Nepal [9].…”

Section: Static Design Of Tunnel Practice In Nepalmentioning

confidence: 99%

“…The support was seen as inadequate for the moment of Rock class III and Rock class IV. Khadka [13] analyzed the rock mass in terms of good and poor rock separately. He has recommended that when the elastic-plastic model is used, residual parameters are not required for the extremely weak rocks (GSI value less than 30).…”

Section: Rock Mass Propertiesmentioning

confidence: 99%

Seismic Assessment of Underground Structures in the Weak Himalayan Rock Mass for Hydropower Development

Thapa,

Karki,

Khadka

2023

J. Phys.: Conf. Ser.

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This study focuses on the seismic assessment of underground structures in the transition of Higher Himalayan and Lesser Himalayan region of Nepal. Due to fragile geology of the Himalaya, most of the underground structures are constructed in the highly jointed rock mass. Rock mass classification approaches are extensively used for the estimation of supports without seismic consideration. Design of the underground structures like tunnels and cavern seismic effect is rarely considered in the Nepal Himalaya. For the sustainable development of hydropower project tunnel and caverns plays vital role in terms of its stability. Presence of faults, and crushed zone, along the alignment of tunnel, the existing in-situ stress increases beyond its critical level and strength. The long-term seismic behaviour of an underground structure is very essential in weak rock mass. A detailed dynamic analysis of underground response is evaluated using 2D numerical analysis with the geological data, rock mass and fault encountered in hydropower tunnel, through case study. A comparison is then made between the analysis result of the tunnel response with and without seismic consideration.

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“…Due to the fact that Nepal stretches along the Greater Himalayas and is situated close to the collisional boundary between the Indian and Eurasian plates, there is a notable risk of a major earthquake occurring in this region [1]. Nepal is characterized by three major fault systems: the Main Central Thrust (MCT), Main Boundary Thrust (MBT), and Himalayan Frontal Thrust (HFT), alongside numerous smaller faults, totaling 92, running throughout the country's limited width [2][3][4]. The Kathmandu Valley's peak ground acceleration (PGA) variation was calculated to be between 0.4 and 0.55 g [5] and the PGA of the Banepa&Dhulikhel area was calculated between 0.29 and 0.35 g for bedrock and 0.46 to 0.55 g for free field [6].…”

Section: Introductionmentioning

confidence: 99%

The Estimation of Shear Wave Velocity for Shallow Underground Structures in the Central Himalaya Region of Nepal

Thapa,

Paudel,

Bhusal

et al. 2024

Geosciences

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A subsurface investigation was conducted to assess the suitability of a site for potential tunnel construction, focusing on the determination of shear wave velocities (Vs) in subsurface materials. This study employed three distinct methods to analyze Vs in weathered soft rock: drilling mechanism, multichannel analysis of surface waves (MASW), and microtremor array measurement (MAM). Through the utilization of MASW and MAM, empirical relationships were established, enabling the determination of Vs based solely on soil type and depth, offering a practical alternative to the limitations of SPT N-Value, particularly when exceeding 50 blows. The comparison of Vs values obtained from these methods revealed a close alignment between empirical techniques and MASW/MAM, which proved to be cost-effective and an efficient alternative to drilling for comprehensive underground structure assessments. The reliability of MASW was further underscored through its comparison with existing empirical methods. Moreover, the empirical approach demonstrated its efficacy in predicting velocities in weathered soft rock within the Central Himalayan region of Nepal, thus enhancing the feasibility study of underground structures. Lastly, this study proposed a Vs-Depth correlation specifically tailored for highly weathered meta-sandstone bedrock resulting in clay and sandy soils.

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Assessment and Numerical Analysis of Hydropower Tunnel in Lesser Himalayan Region of Nepal- A Case Study

Cited by 4 publications

References 6 publications

A possible underground roadway for transportation facilities in Kathmandu Valley: A racking deformation of underground rectangular structures

A possible underground roadway for transportation facilities in Kathmandu Valley: A racking deformation of underground rectangular structures

Seismic Assessment of Underground Structures in the Weak Himalayan Rock Mass for Hydropower Development

The Estimation of Shear Wave Velocity for Shallow Underground Structures in the Central Himalaya Region of Nepal

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