Himalayan rock mass and possibility of limiting concrete lined pressure tunnel length in hydropower projects in the Himalaya

2015 ◽  
Vol 18 (1) ◽  
pp. 45-50 ◽  
Author(s):  
Krishna Kanta Panthi
Keyword(s):  
Rock Mass ◽  
Tunnel Length ◽  
Pressure Tunnel ◽  
The Himalaya

scholarly journals Predicting Tunnel Squeezing: A Discussion based on Two Tunnel Projects

2013 ◽  
Vol 12 ◽  
pp. 20-25 ◽  
Author(s):  
Krishna Kanta Panthi
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Uncertainty Analysis ◽  
Fault Zones ◽  
Tectonic Fault ◽  
Rock Support ◽  
Reliable Prediction ◽  
Rock Mass Strength ◽  
Tunnel Convergence ◽  
The Himalaya

Tunnel squeezing is a phenomenon, which is frequently confronted while tunneling through Himalayan rock mass. Weak and schistose rocks like mudstone, shale, slate, phyllite, schist, highly schistose mica gneiss and the rock mass of the tectonic fault zones are incapable of sustaining high stresses. A reliable and trustworthy prediction on the extent of squeezing is therefore essential. The reliable prediction results help to make strategy regarding stabilizing measures and optimization of tunnel rock support well in advance. This paper is mainly focused in analyzing the tunnel squeezing that took place in connection with the two tunnel cases; i.e. Kali Gandaki 'A' and Middle Marsyangdi headrace tunnels. The main focus is given to look on the applicability of squeezing analysis using Hoek and Marinos approach in combination with the equation proposed by Panthi for the estimation of rock mass strength for highly schistose rocks of the Himalaya. The measured tunnel convergence (squeezing) and lab tested mechanical properties of the rocks from these two headrace tunnels have been used to verify the applicability of the proposed methods and also the uncertainty analysis approach on squeezing introduced by Panthi.Hydro Nepal; Journal of Water, Energy and EnvironmentVol. 12, 2013, JanuaryPage: 20-25DOI: http://dx.doi.org/10.3126/hn.v12i0.9027Uploaded Date : 10/28/2013

Modelling the hydro-mechanical behaviour of high-pressure tunnel with emphasis on the interaction between lining and rock mass

2021 ◽  
Vol 139 ◽  
pp. 104382
Author(s):  
Wei Zhang ◽  
Ming Liu ◽  
Kang Bian ◽  
Pei-Tong Cong ◽  
Wei-Hai Yuan
Keyword(s):  
High Pressure ◽  
Rock Mass ◽  
Mechanical Behaviour ◽  
Pressure Tunnel

scholarly journals Arc-parallel shears in collisional orogens: Global review and paleostress analyses from the NW Lesser Himalayan Sequence (Garhwal region, Uttarakhand, India)

2022 ◽  
Author(s):  
Tuhin Biswas ◽  
Narayan Bose ◽  
Dripta Dutta ◽  
Soumyajit Mukherjee
Keyword(s):  
Rock Mass ◽  
Driving Forces ◽  
Regional Scale ◽  
Microstructural Analysis ◽  
Hydrocarbon Exploration ◽  
Plate Interface ◽  
Natural Rock ◽  
Ductile Shear ◽  
The Himalaya ◽  
Shear Planes

Interest in hydrocarbon exploration from the the Lesser Himalayan Sequence (LHS) has recently been revived amongst petroleum geoscientists. Understanding the paleostress regime and the deformation processes are the two important steps to understand the structural geology of any (petroliferous) terrane. Arc-parallel shear is an integral deformation process in orogeny. The scale of the consequent deformation features can range from micro-mm up to regional scale. Unlike orogen-perpendicular shear, different driving forces can produce orogen-parallel shears. We review these mechanisms/theories from several orogens including the Himalaya and compile 44 locations worldwide with reported orogen-parallel shear. Due to continuous crustal shortening by the India-Eurasia collision, the squeezed rock mass at the plate interface has produced the Himalayan Mountain chain. In addition, the rock mass also escapes laterally along the orogenic trend. Tectonic stress-field governs this mass flow. Field study and microstructural analysis in the northwest LHS (India) reveals orogen-parallel brittle and ductile shear movement. Y- and P- brittle shear planes, and the S- and C- ductile shear planes reveal the following shears documented on the ~ NW-SE trending natural rock selections: (i) top-to-NW up, (ii) top-to-SE up, (iii) top-to-NW down, and (iv) top-to-SE down. Our paleostress analysis indicates top-to-SE down and top-to-NW down shears occurred due to stretching along ~ 131°-311° (Dext), whereas top-to-SE up and top-to-NW up shear fabric originated due to shortening along ~133.5°-313.5° (Dcompr). Previous authors considered that the orogen-parallel extension generated ~ 15-5 Ma due to vertical thinning of the Himalaya. The NE-trending Delhi-Haridwar Ridge below the LHS plausibly acted as a barrier to the flowing mass and piled up the rock mass in the form of NW-SE/orogen-parallel compression. The NW-SE compression can be correlated with the D3 of Hintersberger et al. (2011) during ~ 4-7 Ma.

Design of Pressure Tunnel with Reinforcement Concrete Lining under Consolidation Grouting

2012 ◽  
Vol 446-449 ◽  
pp. 2731-2735
Author(s):  
Kai Su ◽  
Yin Li
Keyword(s):  
Rock Mass ◽  
Permeability Coefficient ◽  
Concrete Lining ◽  
Water Leakage ◽  
Pressure Tunnel ◽  
Rock Mass Deformation ◽  
Control Water ◽  
Walled Cylinder ◽  
Mass Deformation

Following the thick-walled cylinder theory, a design progress of pressure tunnel with reinforcement concrete lining is carried out in the condition of water flow continuity. When rock consolidation grouting is adopted to increase rock mass deformation module and to decrease tunnel water leakage, the equivalent permeability coefficient is introduced to tell the influence of consolidation grouting. And the results of a certain tunnel show that the method of consolidation grouting can sharply lower the tunnel water leakage, and the quality of consolidation grouting is more important than the depth of grouting to control water leakage.

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