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Dam outlet works
Published in P. Novak, A.I.B. Moffat, C. Nalluri, R. Narayanan, Hydraulic Structures, 2017
P. Novak, A.I.B. Moffat, C. Nalluri, R. Narayanan
Fuse plugs are used as auxiliary spillways. They are basically broad-crested weirs with a crest higher than the main spillway crest but below the maximum water level, and an earth embankment on top of the spillway, designed to fail at a predetermined reservoir level. The sudden flow after the fuse plug failure must be taken into account when choosing the site of the auxiliary spillway, which usually discharges into a (side) valley other than the main spillway. The downstream face of the weir must be suitably protected, e.g. by concrete plain or wedge-shape blocks (Section 4.7.6) or reinforced grass (CIRIA, 1987).
Semiclassical Transport Theory
Published in Dragica Vasileska, Stephen M. Goodnick, Gerhard Klimeck, Computational Electronics, 2017
Dragica Vasileska, Stephen M. Goodnick, Gerhard Klimeck
Two other satellite valleys L and X are in the directions [111] and [100], respectively. At low electric fields, the conduction band electrons occupy the bottom of the central valley. By applying an electric field, the electrons accelerate until they collide with the imperfections of the crystal lattice. Via collisions, the electrons lose a component of their momentum, which is directed along the electric field, and some kinetic energy that raises the lattice temperature (Joule heating). As the electric field is incremented further, the mean electron energy becomes higher and higher energy states can be occupied in the conduction band. When the electron kinetic energy reaches the intervalley transfer energy ΔE = EL – EΓ (for GaAs equals 0.32 eV), electrons have the additional choice of occupying one of the satellite valleys (for GaAs the L-valley), as long as a suitable momentum transfer is also involved. The electron effective mass m* is depending on the curvature of the band structure E(k). In the satellite valleys, the curvature is higher and the effective mass of the electrons is up to six times the Γ-valley effective mass. Electrons with sufficient energy have the choice of occupying either valley. For these electrons, there is a higher probability of occupying the satellite valleys, which provide a relatively high DOS. In the satellite valleys, the electrons not only posses a higher effective mass, but also undergo strong scattering processes [22]. The combination of these two effects explains why the mobility in the side valley μL is up to 70 times lower compared with that in the central valley μΓ. If nΓ and nL are the electron density in the central and satellite valleys, respectively, the mean drift velocity vd(E) is
Evaluation of in-situ stress state along the shotcrete lined high-pressure headrace tunnel at a complex Himalayan geological condition
Published in Geosystem Engineering, 2021
Chhatra Bahadur Basnet, Krishna Kanta Panthi
As shown in Figure 2, the headrace tunnel is located along the right bank of the Tamakoshi River. The highest elevation of the nearest hill from the tunnel is about 4500 MASL and the lowest elevation is at the Tamakoshi River, which is about 1250 MASL. The level difference is about 3300 m within the horizontal distance of about 5500 m and the slope of the terrain is about 30° to 40°. The slopes and the level differences show that the Tamakoshi River is a deep valley and the topography represents a high relief. In addition to the Tamakoshi River, there is a side valley represented by Gongar Khola near the outer reach of the headrace tunnel. This deep valley is connected to the Tamakoshi valley making a confluence at an elevation of about 1250 MASL. It is logical to assume that there will be stress attenuation towards both Tamakoshi and Gongar valleys and will have complex stress regime nearby the confluence. Hence, both valleys have to be considered in the stress state analysis for the correct estimation of the stress state of the project area.
Numerical analysis on mining-induced fracture development around river valleys
Published in International Journal of Mining, Reclamation and Environment, 2018
C. Zhang, R. Mitra, J. Oh, I. Canbulat, B. Hebblewhite
The simulated fracture pattern highlights a distinct variation of dipping bedding plane influence on the failure response of the rock mass in the valley base. As can be seen from the figure, when the bedding planes dip in 30°, the failure of the rock mass is more induced by the extension of bedding planes. A dominated shear band is developed along the bedding plane which is initiated from the corner of the valley floor, with the maximum shear displacement being 0.16 m. There are no obvious tensile displacements observed in the valley base only with a minimal tension split occurring on the valley wall. The presence of the dipping beddings is in alignment with the major principal stress especially beneath the right side valley wall. Therefore, this compression effect caused the formation of the major shearing band as well as the shearing fractures.