Gravity dams are structures designed so that their own weight resists external forces. Concrete is the preferred material. Forces acting on the dam include water pressure, uplift pressure, earthquake forces, silt pressure, wave pressure, and ice pressure. The dam's weight counters these forces. Dams are checked when full and empty, accounting for load combinations. Gravity dams can fail due to overturning, crushing, tension cracks, or sliding along foundation planes. Design aims to prevent failure from these modes.
Topics:
1. Types of Gravity Dam
2. Forces Acting on a Gravity Dam
3. Causes of failure of Gravity Dam
4. Elementary Profile of Gravity Dam
5. Practical Profile of Gravity Dam
6. Limiting height of Gravity Dam
7. Drainage and Inspection Galleries
The document discusses different types of well foundations used in construction. It describes the key components of well foundations including the cutting edge, steining, bottom plug, top plug, and well cap. It explains the process of sinking well foundations, which involves excavating material inside the well curb to allow the well to sink vertically into the ground. Precautions like maintaining verticality and limiting tilt and shift are important during well sinking.
The document discusses causes of failure for weirs and barrages built on permeable foundations, including piping/undermining, uplift pressure, hydraulic jump, and scouring. It explains that piping occurs when water percolates through the foundation and erodes soil particles, creating a hollow channel. Uplift pressure from percolating water can also cause failure if the structure's weight cannot counterbalance it. Hydraulic jump and high-velocity surface flow can produce suction pressures and scour soil. The document recommends increasing the seepage path using sheet piles, increasing floor thickness to resist uplift, and using energy dissipaters and filters to prevent soil loss and structural failure.
Khosla's theory improved upon Bligh's theory of seepage under hydraulic structures in several ways. Khosla recognized that seepage follows elliptical streamlines rather than the bottom contour as Bligh assumed. Khosla also introduced the important concept of exit gradient and specified that the exit gradient must be less than the critical value to prevent soil particles from being dislodged. While more complex, Khosla's theory provides a more accurate representation of seepage flow compared to Bligh's assumption of linear head loss.
WEIRS VERSUS BERRAGE
TYPES OF WEIRS
COMPONENT PARTS OF A WEIR
CAUSES OF FAILURE OF WEIRS & THEIR REMEDIES
DESIGN CONSIDERATIONS
DESIGN FOR SURFACE FLOW
DESIGN OF BARRAGE OR WEIR
BOUSSINESQ THEORY
VERTICAL STRESS DUE TO POINT LOAD
TABLE FOR VALUES OF BOUSSINESQ’S COEFFICIENT (퐼_퐵)
SOME POINTS FOR USING THE BOUSSINESQ’S EQUATION.
LIMITATIONS OF BOUSSINESQ’S SOLUTION.
This document provides information on spillway and energy dissipator design. It begins with an introduction to spillways, their classification, and factors considered in design. It then focuses on the design of ogee or overflow spillways. It discusses spillway crest profiles, discharge characteristics including effects of approach depth, upstream slope, and submergence. It provides example designs for overflow spillways and calculations for determining spillway length. The key aspects covered are types of spillways, design considerations, standard crest profiles, discharge equations, and worked examples for spillway sizing.
Gravity dams are structures designed so that their own weight resists external forces. Concrete is the preferred material. Forces acting on the dam include water pressure, uplift pressure, earthquake forces, silt pressure, wave pressure, and ice pressure. The dam's weight counters these forces. Dams are checked when full and empty, accounting for load combinations. Gravity dams can fail due to overturning, crushing, tension cracks, or sliding along foundation planes. Design aims to prevent failure from these modes.
Topics:
1. Types of Gravity Dam
2. Forces Acting on a Gravity Dam
3. Causes of failure of Gravity Dam
4. Elementary Profile of Gravity Dam
5. Practical Profile of Gravity Dam
6. Limiting height of Gravity Dam
7. Drainage and Inspection Galleries
The document discusses different types of well foundations used in construction. It describes the key components of well foundations including the cutting edge, steining, bottom plug, top plug, and well cap. It explains the process of sinking well foundations, which involves excavating material inside the well curb to allow the well to sink vertically into the ground. Precautions like maintaining verticality and limiting tilt and shift are important during well sinking.
The document discusses causes of failure for weirs and barrages built on permeable foundations, including piping/undermining, uplift pressure, hydraulic jump, and scouring. It explains that piping occurs when water percolates through the foundation and erodes soil particles, creating a hollow channel. Uplift pressure from percolating water can also cause failure if the structure's weight cannot counterbalance it. Hydraulic jump and high-velocity surface flow can produce suction pressures and scour soil. The document recommends increasing the seepage path using sheet piles, increasing floor thickness to resist uplift, and using energy dissipaters and filters to prevent soil loss and structural failure.
Khosla's theory improved upon Bligh's theory of seepage under hydraulic structures in several ways. Khosla recognized that seepage follows elliptical streamlines rather than the bottom contour as Bligh assumed. Khosla also introduced the important concept of exit gradient and specified that the exit gradient must be less than the critical value to prevent soil particles from being dislodged. While more complex, Khosla's theory provides a more accurate representation of seepage flow compared to Bligh's assumption of linear head loss.
WEIRS VERSUS BERRAGE
TYPES OF WEIRS
COMPONENT PARTS OF A WEIR
CAUSES OF FAILURE OF WEIRS & THEIR REMEDIES
DESIGN CONSIDERATIONS
DESIGN FOR SURFACE FLOW
DESIGN OF BARRAGE OR WEIR
BOUSSINESQ THEORY
VERTICAL STRESS DUE TO POINT LOAD
TABLE FOR VALUES OF BOUSSINESQ’S COEFFICIENT (퐼_퐵)
SOME POINTS FOR USING THE BOUSSINESQ’S EQUATION.
LIMITATIONS OF BOUSSINESQ’S SOLUTION.
This document provides information on spillway and energy dissipator design. It begins with an introduction to spillways, their classification, and factors considered in design. It then focuses on the design of ogee or overflow spillways. It discusses spillway crest profiles, discharge characteristics including effects of approach depth, upstream slope, and submergence. It provides example designs for overflow spillways and calculations for determining spillway length. The key aspects covered are types of spillways, design considerations, standard crest profiles, discharge equations, and worked examples for spillway sizing.
Energy dissipaters are needed when water is released over a spillway to prevent scouring downstream. Various devices can be used, including baffle walls, deflectors, and staggered blocks, which reduce kinetic energy by converting it to turbulence and heat. Hydraulic jumps also dissipate energy by maintaining a high water level downstream. The type of dissipater used depends on the tailwater rating curve in relation to the jump height curve and the flow conditions. Stilling basins, sloping aprons, and roller buckets are suitable for different tailwater classifications.
This document discusses structural analysis methods for statically indeterminate structures. It defines key terms like degree of static indeterminacy, internal and external redundancy, and methods for analyzing indeterminate structures. Specific methods discussed include the flexibility matrix method, consistent deformation method, and unit load method. Examples of statically indeterminate beams and frames are also provided.
The document discusses the design of gravity dams. It begins with basic definitions related to gravity dam geometry and forces that act on gravity dams, such as water pressure, weight of the dam, uplift pressure, and pressure due to earthquakes. It then covers stability analyses to prevent overturning, sliding, crushing, and tension. Finally, it addresses designing the dam section to be economical while satisfying stability requirements, and categorizing dams as low or high based on height.
The document discusses various methods of soil exploration including borings, test pits, and geophysical methods. It describes the objectives of soil exploration as determining the suitable foundation type, bearing capacity, and other factors. The key methods discussed are displacement boring, wash boring, auger boring, rotary drilling, percussion drilling, and continuous sampling boring. Each method is explained along with its suitable soil conditions, advantages, and limitations.
This document discusses theories for designing weirs on permeable foundations to prevent failures from seepage. It describes Bligh's creep theory, Lane's weighted creep theory, and Khosla's theory. Bligh's theory calculates creep length and floor thickness but does not distinguish horizontal from vertical creep. Lane's theory assigns higher weight to vertical creep. Khosla's theory accounts for pressure distributions and recommends cut-offs and aprons. It is commonly used but requires corrections for floor thickness, pile interference, and slope. Inverted filters and launching aprons are also discussed.
This document discusses different types of canal outlets used to release water from distributing channels into watercourses. It describes non-modular, semi-modular, and modular outlets. Non-modular outlets discharge based on water level differences, while modular outlets discharge independently of water levels. Semi-modular outlets discharge depending on the channel water level but not the watercourse level. Specific outlet types are also defined, such as pipe outlets, open sluice, and Gibbs, Khanna, and Foote rigid modules. Discharge equations for different outlet types are provided.
Earthen dams are constructed using natural materials like clay, sand, gravel and rock. They are designed based on principles of soil mechanics. There are two main types - homogeneous and zoned. Zoned dams have an impervious core and outer shells. Components include the core, shells, rock toe, pitching, berms and drains. Stability requires the seepage line be within the downstream slope with minimum 2m cover. Common causes of failure are hydraulic (overtopping, erosion), seepage (piping through core or foundations) and structural issues like cracking. Proper design and construction can prevent these failures.
This document discusses various types of canal regulation works including canal falls, escapes, regulators, and outlets. It describes the necessity and types of canal falls, which are constructed when the natural ground slope is steeper than the designed canal bed slope. The types of falls discussed include ogee falls, stepped falls, vertical falls, rapid falls, straight glacis falls, trapezoidal notch falls, well or cylinder notch falls, Montague type falls, and Inglis or baffle falls. The document also discusses canal escapes, head regulators, cross regulators, silt control devices, and canal outlets/modules. In particular, it explains the functions and construction of head regulators and cross regulators.
This document discusses critical flow in hydraulic engineering. It defines critical flow criteria as when specific energy is minimum, discharge is maximum, and the Froude number equals 1. Critical flow is unstable, and the critical depth is calculated using the section factor formula. The section factor relates water area, hydraulic depth, discharge, and gravitational acceleration. Hydraulic exponent is also discussed as it relates the section factor and critical depth for different channel geometries. Methods for calculating critical depth include algebraic, graphical, and using design charts. The document concludes by defining flow control and characteristics of subcritical, critical, and supercritical flow in a channel.
The document discusses the hydraulic jump, which is the rise in water level caused by the transformation from unstable supercritical flow to stable subcritical flow. It causes energy loss due to turbulence and eddies. Applications include mixing chemicals, maintaining downstream water levels for irrigation, and removing air from pipes. The hydraulic jump typically occurs below structures like weirs, due to obstructions, or changes in channel slope. It dissipates surplus energy and creates disturbances like eddies and reverse flow that can remove pollution. The problem finds the depth of flow after a hydraulic jump in a 4m wide channel with a discharge of 16 m3/s, given an upstream depth of 0.5m.
This document provides an overview of spillways and flood control works for dams. It discusses the key components and design considerations for spillways, including approach channels, control structures, discharge carriers, terminal structures, and energy dissipaters. It describes different types of spillways like overflow, trough, siphon, and side channel spillways. Design aspects for spillway crest gates like radial and drum gates are covered. The document also discusses intake and outlet works for reservoirs, including their components and functions.
The document discusses the design of embankment dams. It defines embankment dams as dams constructed of natural materials like earth or rockfill. It describes the different types of embankment dams including homogeneous dams, zoned dams, and diaphragm dams. It also discusses important design considerations for embankment dams like controlling seepage, providing internal drainage, and ensuring the shear strength of the soil is sufficient to resist failure. Pore water pressure in saturated soils is identified as an important factor that reduces the effective stress and shear strength of soils in embankment dams.
This document discusses the types of loads acting on concrete dams and the methods used for designing gravity dams. It describes primary loads like water pressure and self-weight, secondary loads like sediment and wind, and exceptional loads like seismic activity. It also covers load combinations, factors of safety against overturning and sliding, and considers the shear strength of the concrete and foundation. Design aims to satisfy equilibrium conditions and ensure stresses do not exceed allowable limits.
This document discusses soil mechanics concepts related to lateral earth pressure. It defines active and passive earth pressures and describes Rankine's theory and assumptions for calculating lateral pressures on retaining walls. Equations are provided for determining active and passive earth pressure coefficients and distributions for cohesionless and cohesive soils. The effects of groundwater, surcharges, and sloping backfills are also examined. Sample problems are included to calculate lateral earth pressures and forces on retaining walls for different soil and loading conditions.
This document discusses various concepts related to structural analysis of arches:
1. An arch is a curved girder supported at its ends, allowing only vertical and horizontal displacements for arch action.
2. The general cable theorem relates the horizontal tension and vertical distance from any cable point to the cable chord moment.
3. Arches are classified based on support conditions (3, 2, or 1 hinged) or shape (curved, parabolic, elliptical, polygonal).
4. Horizontal thrust in arches reduces the bending moment and is calculated differently for various arch types (e.g. parabolic) and loading (e.g. UDL).
There are three main modes of failure for earthen dams: hydraulic failure (40%), seepage failure (30%), and structural failure (30%). Hydraulic failures are caused by overtopping, erosion of the downstream toe, or erosion of the upstream or downstream face. Seepage failures occur through concentrated seepage paths that erode soil and cause piping. Structural failures happen due to shear slides in the embankment or foundation, or issues with construction and maintenance such as overly steep slopes. Earthquakes can also induce failures through cracking, overtopping, settlement, shear slides, or liquefaction.
Cross section of the canal, balancing depth and canal fslAditya Mistry
1) The document discusses the cross section of irrigation canals, including configurations for cutting, filling, and partial cutting/filling. It describes the main components of a canal cross section such as side slopes, berms, and banks.
2) Balancing depth is defined as the depth of cutting where the quantity of excavated earth equals the amount required to form the canal banks, resulting in the most economical cross section.
3) Canal FSL (Full Supply Level) refers to the normal maximum operating water level of a canal when not affected by floods, corresponding to 100% capacity.
Khosla modified Bligh's theory for designing irrigation structures on permeable foundations. Khosla accounted for actual flow patterns below impermeable bases, unlike Bligh. Khosla derived equations to calculate uplift pressures and exit gradients at key points for structures with single or multiple piles. He also defined safe exit gradients and developed a method of independent variables to solve complex profiles by breaking them into simple components and applying corrections. Khosla's theory is now used for designing hydraulic structures on permeable foundations.
This document summarizes key aspects of constructing gravity dams, including:
1. It describes the elementary profile of a gravity dam as a right angle triangle with zero width at the water level and base width B at the bottom.
2. It discusses how the base width is governed by ensuring the resultant force passes through the outermost middle third point and that the dam is safe against sliding.
3. It covers design considerations like providing an adequate freeboard between the maximum water level and the dam top to prevent overtopping from waves or floods. The top width is also discussed to balance economics and stability.
This document provides an overview of forces acting on concrete gravity dams and how to compute them. The key forces discussed are:
1. Weight of the dam which provides stability. Other forces include water pressure, uplift pressure, silt pressure, wave pressure, and earthquake forces.
2. Water pressure acts both vertically and horizontally on dam faces based on reservoir level and geometry. Uplift pressure acts upwards through pores and needs to be estimated.
3. Earthquake forces cause random vibrations that impart accelerations and stresses in the dam. The document provides guidelines for computing seismic forces based on dam height and location.
Energy dissipaters are needed when water is released over a spillway to prevent scouring downstream. Various devices can be used, including baffle walls, deflectors, and staggered blocks, which reduce kinetic energy by converting it to turbulence and heat. Hydraulic jumps also dissipate energy by maintaining a high water level downstream. The type of dissipater used depends on the tailwater rating curve in relation to the jump height curve and the flow conditions. Stilling basins, sloping aprons, and roller buckets are suitable for different tailwater classifications.
This document discusses structural analysis methods for statically indeterminate structures. It defines key terms like degree of static indeterminacy, internal and external redundancy, and methods for analyzing indeterminate structures. Specific methods discussed include the flexibility matrix method, consistent deformation method, and unit load method. Examples of statically indeterminate beams and frames are also provided.
The document discusses the design of gravity dams. It begins with basic definitions related to gravity dam geometry and forces that act on gravity dams, such as water pressure, weight of the dam, uplift pressure, and pressure due to earthquakes. It then covers stability analyses to prevent overturning, sliding, crushing, and tension. Finally, it addresses designing the dam section to be economical while satisfying stability requirements, and categorizing dams as low or high based on height.
The document discusses various methods of soil exploration including borings, test pits, and geophysical methods. It describes the objectives of soil exploration as determining the suitable foundation type, bearing capacity, and other factors. The key methods discussed are displacement boring, wash boring, auger boring, rotary drilling, percussion drilling, and continuous sampling boring. Each method is explained along with its suitable soil conditions, advantages, and limitations.
This document discusses theories for designing weirs on permeable foundations to prevent failures from seepage. It describes Bligh's creep theory, Lane's weighted creep theory, and Khosla's theory. Bligh's theory calculates creep length and floor thickness but does not distinguish horizontal from vertical creep. Lane's theory assigns higher weight to vertical creep. Khosla's theory accounts for pressure distributions and recommends cut-offs and aprons. It is commonly used but requires corrections for floor thickness, pile interference, and slope. Inverted filters and launching aprons are also discussed.
This document discusses different types of canal outlets used to release water from distributing channels into watercourses. It describes non-modular, semi-modular, and modular outlets. Non-modular outlets discharge based on water level differences, while modular outlets discharge independently of water levels. Semi-modular outlets discharge depending on the channel water level but not the watercourse level. Specific outlet types are also defined, such as pipe outlets, open sluice, and Gibbs, Khanna, and Foote rigid modules. Discharge equations for different outlet types are provided.
Earthen dams are constructed using natural materials like clay, sand, gravel and rock. They are designed based on principles of soil mechanics. There are two main types - homogeneous and zoned. Zoned dams have an impervious core and outer shells. Components include the core, shells, rock toe, pitching, berms and drains. Stability requires the seepage line be within the downstream slope with minimum 2m cover. Common causes of failure are hydraulic (overtopping, erosion), seepage (piping through core or foundations) and structural issues like cracking. Proper design and construction can prevent these failures.
This document discusses various types of canal regulation works including canal falls, escapes, regulators, and outlets. It describes the necessity and types of canal falls, which are constructed when the natural ground slope is steeper than the designed canal bed slope. The types of falls discussed include ogee falls, stepped falls, vertical falls, rapid falls, straight glacis falls, trapezoidal notch falls, well or cylinder notch falls, Montague type falls, and Inglis or baffle falls. The document also discusses canal escapes, head regulators, cross regulators, silt control devices, and canal outlets/modules. In particular, it explains the functions and construction of head regulators and cross regulators.
This document discusses critical flow in hydraulic engineering. It defines critical flow criteria as when specific energy is minimum, discharge is maximum, and the Froude number equals 1. Critical flow is unstable, and the critical depth is calculated using the section factor formula. The section factor relates water area, hydraulic depth, discharge, and gravitational acceleration. Hydraulic exponent is also discussed as it relates the section factor and critical depth for different channel geometries. Methods for calculating critical depth include algebraic, graphical, and using design charts. The document concludes by defining flow control and characteristics of subcritical, critical, and supercritical flow in a channel.
The document discusses the hydraulic jump, which is the rise in water level caused by the transformation from unstable supercritical flow to stable subcritical flow. It causes energy loss due to turbulence and eddies. Applications include mixing chemicals, maintaining downstream water levels for irrigation, and removing air from pipes. The hydraulic jump typically occurs below structures like weirs, due to obstructions, or changes in channel slope. It dissipates surplus energy and creates disturbances like eddies and reverse flow that can remove pollution. The problem finds the depth of flow after a hydraulic jump in a 4m wide channel with a discharge of 16 m3/s, given an upstream depth of 0.5m.
This document provides an overview of spillways and flood control works for dams. It discusses the key components and design considerations for spillways, including approach channels, control structures, discharge carriers, terminal structures, and energy dissipaters. It describes different types of spillways like overflow, trough, siphon, and side channel spillways. Design aspects for spillway crest gates like radial and drum gates are covered. The document also discusses intake and outlet works for reservoirs, including their components and functions.
The document discusses the design of embankment dams. It defines embankment dams as dams constructed of natural materials like earth or rockfill. It describes the different types of embankment dams including homogeneous dams, zoned dams, and diaphragm dams. It also discusses important design considerations for embankment dams like controlling seepage, providing internal drainage, and ensuring the shear strength of the soil is sufficient to resist failure. Pore water pressure in saturated soils is identified as an important factor that reduces the effective stress and shear strength of soils in embankment dams.
This document discusses the types of loads acting on concrete dams and the methods used for designing gravity dams. It describes primary loads like water pressure and self-weight, secondary loads like sediment and wind, and exceptional loads like seismic activity. It also covers load combinations, factors of safety against overturning and sliding, and considers the shear strength of the concrete and foundation. Design aims to satisfy equilibrium conditions and ensure stresses do not exceed allowable limits.
This document discusses soil mechanics concepts related to lateral earth pressure. It defines active and passive earth pressures and describes Rankine's theory and assumptions for calculating lateral pressures on retaining walls. Equations are provided for determining active and passive earth pressure coefficients and distributions for cohesionless and cohesive soils. The effects of groundwater, surcharges, and sloping backfills are also examined. Sample problems are included to calculate lateral earth pressures and forces on retaining walls for different soil and loading conditions.
This document discusses various concepts related to structural analysis of arches:
1. An arch is a curved girder supported at its ends, allowing only vertical and horizontal displacements for arch action.
2. The general cable theorem relates the horizontal tension and vertical distance from any cable point to the cable chord moment.
3. Arches are classified based on support conditions (3, 2, or 1 hinged) or shape (curved, parabolic, elliptical, polygonal).
4. Horizontal thrust in arches reduces the bending moment and is calculated differently for various arch types (e.g. parabolic) and loading (e.g. UDL).
There are three main modes of failure for earthen dams: hydraulic failure (40%), seepage failure (30%), and structural failure (30%). Hydraulic failures are caused by overtopping, erosion of the downstream toe, or erosion of the upstream or downstream face. Seepage failures occur through concentrated seepage paths that erode soil and cause piping. Structural failures happen due to shear slides in the embankment or foundation, or issues with construction and maintenance such as overly steep slopes. Earthquakes can also induce failures through cracking, overtopping, settlement, shear slides, or liquefaction.
Cross section of the canal, balancing depth and canal fslAditya Mistry
1) The document discusses the cross section of irrigation canals, including configurations for cutting, filling, and partial cutting/filling. It describes the main components of a canal cross section such as side slopes, berms, and banks.
2) Balancing depth is defined as the depth of cutting where the quantity of excavated earth equals the amount required to form the canal banks, resulting in the most economical cross section.
3) Canal FSL (Full Supply Level) refers to the normal maximum operating water level of a canal when not affected by floods, corresponding to 100% capacity.
Khosla modified Bligh's theory for designing irrigation structures on permeable foundations. Khosla accounted for actual flow patterns below impermeable bases, unlike Bligh. Khosla derived equations to calculate uplift pressures and exit gradients at key points for structures with single or multiple piles. He also defined safe exit gradients and developed a method of independent variables to solve complex profiles by breaking them into simple components and applying corrections. Khosla's theory is now used for designing hydraulic structures on permeable foundations.
This document summarizes key aspects of constructing gravity dams, including:
1. It describes the elementary profile of a gravity dam as a right angle triangle with zero width at the water level and base width B at the bottom.
2. It discusses how the base width is governed by ensuring the resultant force passes through the outermost middle third point and that the dam is safe against sliding.
3. It covers design considerations like providing an adequate freeboard between the maximum water level and the dam top to prevent overtopping from waves or floods. The top width is also discussed to balance economics and stability.
This document provides an overview of forces acting on concrete gravity dams and how to compute them. The key forces discussed are:
1. Weight of the dam which provides stability. Other forces include water pressure, uplift pressure, silt pressure, wave pressure, and earthquake forces.
2. Water pressure acts both vertically and horizontally on dam faces based on reservoir level and geometry. Uplift pressure acts upwards through pores and needs to be estimated.
3. Earthquake forces cause random vibrations that impart accelerations and stresses in the dam. The document provides guidelines for computing seismic forces based on dam height and location.
This document discusses the forces acting on gravity dams and their environmental impacts. It outlines various forces like water pressure, weight of the dam, uplift pressure, earthquake pressure, and wave pressure. It also explains how these forces are calculated. Regarding failure, it notes dams can fail through overturning, sliding, compression, or tension. The document concludes by covering environmental impacts of dam construction like pollution, and impacts of reservoirs like habitat destruction and sedimentation.
Gravity dams are solid structures constructed of concrete or masonry across a river to create an upstream reservoir. They resist forces through their own weight distributed in a triangular cross-section. Forces on gravity dams include the weight of the dam, water pressure, uplift pressure, silt pressure, wave pressure, and earthquake forces. Dams are designed to withstand these forces through computation of vertical and horizontal force components and consideration of factors like reservoir level, foundation type, and seismic zone.
This document provides information about diversion and impounding structures. It discusses types of impounding structures like gravity dams and describes their components. Gravity dams are the most commonly used type of dam as they require little maintenance. The document outlines the forces acting on gravity dams and how they are designed. It also discusses earth dams, describing their components and advantages/disadvantages compared to gravity dams. Earth dams are constructed using local natural materials and are simpler and more economical than other dam types.
This document provides information on drainage and inspection galleries in dams. The key points are:
1. Drainage and inspection galleries are tunnels within dams used for inspection, drainage, and access to outlet gates and spillway gates. Large dams have multiple galleries at different levels.
2. Drainage galleries reduce uplift forces in the dam foundation and body. They also facilitate inspection of the dam body.
3. Drainage galleries are typically placed at 7.5% of the dam height and have a minimum distance of 3 meters from the upstream face and foundation. They are usually 1.5 meters wide and 2.5 meters high with reinforcement. Drainage holes release uplift forces in the foundation and body.
The document discusses the elementary profile of a gravity dam, which consists of a basic triangular cross-section without top width or freeboard. It states that the three forces acting on the dam are its own weight, water pressure from the reservoir, and uplift pressure. The base width is determined using no-tension and no-sliding criteria. Practical gravity dams are modified from the elementary profile by adding a top width for stability and freeboard above the maximum water level. Allowable concrete stresses in gravity dams are also outlined.
1. A gravity dam is a solid structure made of concrete or masonry that is constructed across a river to create an upstream reservoir. It resists forces through its own weight and triangular cross-section, with the widest part at the bottom.
2. Forces acting on a gravity dam include water pressure, uplift pressure, earthquake forces, and the weight of the dam itself. Uplift pressure is caused by water seeping through the dam and its foundation.
3. Dams are designed to withstand these forces through their weight and cross-sectional shape. Additional design considerations include drainage systems to relieve uplift pressure, and seismic design using coefficients and response spectrum analysis for earthquake forces.
This document provides information about forces acting on gravity dams. It discusses the main stabilizing and destabilizing forces, including the weight of the dam, water pressure on the upstream and downstream faces, uplift pressure, earth and silt pressures, ice pressure, and other loads. It defines key terms related to gravity dams such as structural height, base width, axis, and explains how to calculate the various forces per unit length of the dam. Uplift pressure is explained as being dependent on the permeability of the dam and foundation materials and effective drainage. Design criteria for calculating uplift forces according to Indian standards is also summarized.
This document summarizes the key loads and design considerations for concrete dams. It discusses the primary, secondary, and exceptional loads that act on gravity dams, including water load, self-weight, uplift, wave load, silt load, wind load, and earthquake load. It also covers the design of gravity dams against overturning, sliding, and material failure. Buttress and arch dam designs are briefly introduced. Thin cylinder theory for arch dam design is explained.
This document summarizes key concepts related to structural analysis including:
- Effects of axial and eccentric loads on columns including direct stress, bending stress, and maximum/minimum stresses.
- Maximum and minimum pressures at the base of dams including calculations of total water pressure, eccentricity, and formulas for stress.
- Concepts related to retaining walls including total earth pressure, stability conditions of no overturning, no tension, and no sliding.
- Forces and stresses on chimneys and walls due to wind pressure including calculations of direct stress, bending moment, and extreme stresses.
This document summarizes key concepts related to structural analysis including:
1) The effects of axial and eccentric loading on columns including direct stress, bending stress, and maximum/minimum stresses.
2) Maximum and minimum pressures at the base of dams and retaining walls including calculations of total water/earth pressure, eccentricity, and stability conditions.
3) Forces and stresses on chimneys and walls due to wind pressure including calculations of direct stress from self-weight, wind force, induced bending moment, and maximum/minimum stresses.
This document discusses the design and construction of gravity dams. It explains that gravity dams resist forces through their massive weight and have vertical or near-vertical faces. The key components, external forces, and methods of stress analysis are described. Failure can occur through sliding, overturning, cracking or crushing, so factors of safety are considered. Joints are used to aid construction and control cracking. High construction costs require stable foundations, but maintenance costs are lower with less water loss.
The document discusses different types of loads acting on columns and how they induce stresses. It defines axial load, eccentric load, and eccentricity. It explains that eccentric loads produce both direct and bending stresses while axial loads only produce direct stresses. It provides equations to calculate the maximum and minimum stresses in a column under eccentric loading. An example problem is worked out calculating the maximum stresses in a T-section column loaded eccentrically. The document also discusses loads, eccentricity, and stresses on dams, retaining walls, and chimneys/walls loaded by wind pressure.
This document discusses optimal and efficient channel cross-sections for open channel flow. It defines an optimal channel section as having minimum construction costs, considering excavation and lining costs. An efficient channel section maximizes discharge for a given cross-sectional area and roughness. The most hydraulically efficient shape allows the greatest flow for a given area. Formulas for uniform flow like Chezy and Manning equations are presented to calculate velocity and discharge as a function of roughness, slope, hydraulic radius and other variables. Examples are given to demonstrate computing the most efficient dimensions for a rectangular channel.
Types of Gravity Dam
Forces Acting on a Gravity Dam
Causes of failure of Gravity Dam
Elementary Profile of Gravity Dam
Practical Profile of Gravity Dam
Limiting height of Gravity Dam
Drainage and Inspection Galleries
- A column subjected to an eccentric axial load experiences both direct compressive stress and bending stress. The maximum stress occurs on the edge of the column closest to the load and the minimum stress is on the opposite edge.
- For a dam, the total water pressure acts below the centroid and combined with the weight of the dam creates an eccentric load. This leads to maximum and minimum pressures at the base that depend on the eccentricity.
- For a retaining wall, it experiences an eccentric load due to the total earth pressure acting below the midpoint. This causes maximum and minimum pressures similar to a dam.
- A chimney or wall subjected to wind pressure on one side experiences direct stress due to its self weight and bending
It contains detailed information about a Gravity Dam........it also conataims the information in brief & pictures giving a clear view of the Gravity Dams...........It also contains formulas with details of their terms.........
This document discusses the key forces acting on a gravity dam, including its weight, water pressure, uplift pressure, silt pressure, wave pressure, and earthquake forces. It defines key terms like structural height, maximum base width, and hydraulic height. It also provides details on how to calculate or estimate the various forces, for example explaining that water pressure acts normal to the face of the dam and can be calculated based on horizontal and vertical components. Uplift pressure is defined as the upward pressure of water seeping through the dam or its foundation. Earthquake forces cause random vibrations that impart accelerations to the dam's foundation.
We have designed & manufacture the Lubi Valves LBF series type of Butterfly Valves for General Utility Water applications as well as for HVAC applications.
Cricket management system ptoject report.pdfKamal Acharya
The aim of this project is to provide the complete information of the National and
International statistics. The information is available country wise and player wise. By
entering the data of eachmatch, we can get all type of reports instantly, which will be
useful to call back history of each player. Also the team performance in each match can
be obtained. We can get a report on number of matches, wins and lost.
Online train ticket booking system project.pdfKamal Acharya
Rail transport is one of the important modes of transport in India. Now a days we
see that there are railways that are present for the long as well as short distance
travelling which makes the life of the people easier. When compared to other
means of transport, a railway is the cheapest means of transport. The maintenance
of the railway database also plays a major role in the smooth running of this
system. The Online Train Ticket Management System will help in reserving the
tickets of the railways to travel from a particular source to the destination.
This study Examines the Effectiveness of Talent Procurement through the Imple...DharmaBanothu
In the world with high technology and fast
forward mindset recruiters are walking/showing interest
towards E-Recruitment. Present most of the HRs of
many companies are choosing E-Recruitment as the best
choice for recruitment. E-Recruitment is being done
through many online platforms like Linkedin, Naukri,
Instagram , Facebook etc. Now with high technology E-
Recruitment has gone through next level by using
Artificial Intelligence too.
Key Words : Talent Management, Talent Acquisition , E-
Recruitment , Artificial Intelligence Introduction
Effectiveness of Talent Acquisition through E-
Recruitment in this topic we will discuss about 4important
and interlinked topics which are
MODULE 5 BIOLOGY FOR ENGINEERS TRENDS IN BIO ENGINEERING.pptx
Gravity dams
1. Gravity Dams
Asst Prof: Mitali Shelke
St. John College of Engineering and Management, Palghar
Department of Civil Engineering
2. Principal and Shear Stresses:
• The vertical stress intensity Pmax or Pmin determined from the equation,
is not the maximum direct stress produced anywhere in the dam.
• When the the reservoir is full the vertical direct stress is maximum at the toe as the the resultant is
nearer to the toe.
• To study the principal stresses that will develop near the toe let us consider a small element ABC
near the toe of the dam.
3. • Let the downstream face of the dam be inclined at an angle ᾳ to to the vertical. This face of
the dam will act as a principal plane because the water pressure p’ acts at right angle to the
face, and also there is no shear stress acting on this plane. Since the principal planes are at
right angles to each other the plane BC drawn right angles to the face AB will be the second
principal plane. Let the stress acting on this plane be σ.
4. • Let ds, dr and db be the lengths of of AB, BC and CA respectively.
• p’ is the intensity of water pressure on the face AB and pv is the intensity of vertical pressure on
face AC and σ is the intensity of normal stress on face BC.
• Considering unit length of dam forces acting on faces AB, BC and CA are p’ds, σdr and pv.db
respectively.
5. • For σ to be maximum, p’ should be zero i.e. when there is no tail water then in such
case:
• If hydrodynamic pressure (pe’) exerted by tail water during an earthquake moving
towards the reservoir is also considered, then net pressure on face AB will be (p’-pe’)
because the effect of this earthquake will be to reduce the tail water pressure.
• The principal stress σ can be given by:
6. Shear stress on horizontal plane near the toe:
• A shear stress ԏ will act on face CA on which vertical stress is acting.
• Resolving all forces in horizontal direction we get:
7. • Neglecting tail water, shear stress is given by,
• If effect of hydrodynamic pressure produced by earthquake moving towards reservoir
is also considered then equation for shear stress near the toe becomes:
8. Gravity Method for stability analysis:
• The preliminary analysis of all gravity dams can be made easily by isolating a typical cross
section of dam of unit width.
• The dam is considered to be made up of a number of cantilevers of unit width each which act
independently of each other.
• Assumptions:
• The dam is considered to be composed of a number of cantilever each of which is 1m thick and
each of which acts independent of each other.
• No loads are transferred to the abutments by beam action.
• The foundation of the dam behave as a single unit
• The materials in the foundation and body of the dam are isotropic and homogeneous.
• The stresses developed in the foundation and body of the dam are within elastic limits.
• No movements of the foundations are caused due to transference of loads.
• Small openings made in the body of the dam do not affect the general distribution of stresses and
they only produce local effects as per St. Venant’s principle.
9. Procedure by analytical method:
• Consider a unit length of the dam.
• Work out the magnitude and directions of all vertical and horizontal forces acting on the dam and
their algebraic sum.
• Determine the lever arm of all these forces about the toe.
• Determine the moments of all these forces about the twoe and find out algebraic sum of all these
moments.
• Find out the location of resultant force by determining its distance from toe x= ∑M/ ∑V
• Find out the eccentricity of the resultant using e= (B/2)-x.
• Determine the vertical stresses at the toe and heel using the equation
10. • Determine the maximum normal stresses that is principal stresses at the toe and heel using the
equation: ԏ= (pv – p’)tan σ and
• Determine the factor of safety against overturning as equal
∑stabilising moment(+)
∑disturbing moment(−)
• Determine the factor of safety against sliding using sliding factor = µ (∑V+Bq)/ ∑H
• Shear friction factor
• Sliding factor must be greater than unity and SFF must be greater than 3 to 5. The analysis should
be carried out for reserve full as well as empty case.
11. Practical profile of a gravity dam:
• The elementary profile of gravity dam is only theoretical. Certain changes will have to be
made in this profile in order to cater to practical needs. These needs are:
a) Providing a straight top width for road construction over the top of the dam.
b) Providing a free board above the top water surface so that water may not spill over the top of
dam due to wave action.
12. This addition will cause resultant force to shift towards the heel. Hence tension will be developed at
the toe.
In order to avoid this tension some masonry or concrete will have to be added to the upstream side as
shown in the figure.
13. Elementary profile of gravity dam:
The elementary profile of a dam subjected only to external water pressure on upstream side will be
right angle triangle having zero width at the water level and base width B at bottom.
14. When the reservoir is empty the only single force acting on it is self weight W of the dam and it acts
at a distance B/3 from the heel.
The vertical stress distribution at the base when the reservoir is empty is given as
The maximum vertical stress equal to 2W/B will act at heel and the vertical stress at toe will be 0.
15. When the reservoir is full the base width his governed by:
1. The resultant of all forces that is P, W and U passes through the outermost middle third point.
2. The dam is safe in sliding.
For the first condition to be satisfied the equation should be given by
Where Sc= specific gravity of concrete i.e. material of the dam.
C = constant called as seepage coefficient
According to USBR recommendation value of C is equal to 1 in calculation and 0 when no uplift is
considered.
16. If B is taken equal to or greater than H/√(Sc-C) no tension will be developed at the heel with full
reservoir,
when C = 1
If uplift pressure is not considered,
17. For second condition to be satisfied (the dam is safe in sliding) the frictional resistance should be
equal to or more than the horizontal forces
Equation can be given as:
From the above two equations of B the greater value should be chosen for design purpose.
18. In vertical stress distribution maximum stress will occur at the toe because the resultant is near the
toe. Hence the equation is given as:
And Pmin at the heel = 0.
The principal stress σ near the toe which is maximum normal stress is given by equation:
The shear stress ԏ at horizontal plane near the toe is given by equation:
19. Design considerations and fixing the section of dam:
1. Freeboard:
The margin between the maximum reservoir level and top of the dam is known as freeboard.
This must be provided in order to to avoid the possibility of water spilling over the dam top due to
wave action. This can also help as a safety for unforeseen floods higher than the designed flood.
The freeboard is generally provided equal to 3hw / 2.
Where,
These days freeboard equal to 4% to 5% of the the dam height is provided.
20. 2. Top width:
The effects produced by the addition of of top width at the apex of elementary dam profile and their
remedies are explaind below:
Let AEF with the triangular profile of dam of height H1.
Let element ABQA be added at the apex for providing top width ‘a’ for road construction.
Let M1 and M2 be the inner third and outer third points on base. Thus AM1 and AM2 are the inner
third and outer third lines.
The weight of element W1 will act through the CG of
this triangle i.e. along CM.
Let CM and AM1 cross at H, and CM and AM2 cross at
K.
21. 1. Reservoir empty case: We know that in the elementary profile the resultant of the force passes
through the inner third point when reservoir is empty.
The height H1’ below which the upstream batter is required can be worked out as:
Thus for the height greater than H1’ upstream batter is necessary.
22. 2. Reservoir full case: When the reservoir is full the resultant of all the forces acting on elementary
profile passes through the outer third point.
When W1 is added to this initial resultant at any plane below the plane PKQ the resultant will shift
towards upstream side of dam.
For economic point of view the resultant should lie near the the downstream face of dam and hence
the slope of the downstream face may be flattened from QE to QE’.
23. Thus an increase in top width will increase the masonry or concrete in the added element and increase
it on upstream face, but shall reduce it on downstream face.
The most economical top width without considering earthquake forces has been found by Creager to
be equal to 14% of the dam height.
It's useful value varies between 6m to 10m and is generally taken approximately equal to √H, where
H is the height of maximum water level above the bed.
雅虎竞拍
煤炉代买
paypay商城
乐天二手
日本亚马逊
乐天新品
ZOZOTOWN
