Structural stability and 2d finite element analysis of. Bureau of indian standard, new delhi, 1984 using distinct element. Dams are classified on several aspects, some of the important aspects are as follow. Nonlinear time history analysis of concrete gravity dam. First draw the profile of the gravity dam at the deepest section. Uplift reduction due to drainage assumes that the drainage system vents the high pressure area under the dam to tailwater pressure. To prevent sliding the contact with the foundation and the foundation itself must have appreciable shear strength. Seismic structural stability of concrete gravity dams considering transient uplift pressures in cracks. Static and coupled hydromechanical analyses of concrete. Application of the model to a typical concrete gravity dam with a penetrated crack at the base reveals that the seismic behavior of the dam is markedly affected by the seismic uplift pressure. Effect of seismic uplift pressure on the behavior of concrete. Uplift pressure is the upward pressure exerted by water as it seeps through the body of the dam or its foundation. To adequately estimate the seismic behavior of cracked concrete gravity dams, a seismic uplift pressure model is proposed for a penetrated crack.
I am calculating uplift pressure for a gravity dam with stilling basin. For a gravity dam of 100 m, the foundation uplift pressure is approximately. Water resources engineering ii notes pdf wre ii notes pdf. Gravity dams are constructed from masonry or concrete. Pdf gravity dam design engineer manual ivan ramirez. In two dimensional analysis of a gravity dam, a unit length of the dam is considered.
It is now accepted for design purposes that uplift pressures act on the full area of the section. Gravity dams arch dams buttress dams 3 based on usage of dam. Calculating forces on components of hydraulic structures. Gravity dam loads on concrete dams loads can be classified in terms of applicabilityrelative importance as primary loads, secondary loads, and exceptional loads. Elementary profile of a dam subjected only to external water pressure on upstream side, will be right angled triangle, having zero width at water level and a base width b at bottom, i. Sep 06, 2019 first draw the profile of the gravity dam at the deepest section.
Comparison of design and analysis of concrete gravity dam. The intensity of the pressure varies triangularly, with a zero intensity at the water surface, to a value wh at depth h below the water surface. Gravity dams forces acting on gravity dam the various external forces acting on gravity dam may be. Basic theory e statistical model of foundation upli pressure of concrete gravity dam. Gravity dam y910026 free download as powerpoint presentation. This paper presents a worked 3d example of a generic archgravity dam subjected to a static structural analysis, from the initial calculation of the prescribed pore pressure and uplift to the resulting effective stresses in the dam body.
C uplift pressure, 4 earthquake forces, e earth and silt pressures, f ice pressure, d wind pressure, 4 wave. Comparison of assumed and uplift pressures on a gravity dam shasta. Uplift pressure on dam foundation strategies for prevention of uplift pressure dewatering procedure may help to control the water away from construction site, but it cannot keep the dewatering the whole life span of the construction as it is not an economical move. Total weight of the dam acts at the center of gravity of this section. Previous ferc gravity dam guidance dealt with nappe forces by ignoring the. There are various forces acting on the gravity dam mainly hydrostatic pressure, silt pressure, wave pressure, ice pressure, wind forces, selfweight of the dam, uplift pressure and seismic forces etc. Request pdf influences of hydraulic uplift pressures on stability of gravity dam a study of the influences of the hydraulic uplift pressures underneath the base. Uplift calculation for gravity dam constructed items. Determination of various forces which acts on the structure is the first step in the design of dams. Such stress c oncentration leads to localized failure zones in the structure. These forces are considered to act per unit length of the dam.
The different components of concrete gravity dams and their layouts. Jan 17, 2019 for the love of physics walter lewin may 16, 2011 duration. Concrete gravity dams should be evaluated to accommodate. The importance of geology in controlling uplift and dam. Furthermore, uplift pressure effects on the lefm scale law for the maximum water level carried by cracked gravity dams are examined. The article investigates the effect of rock joint orientation and spacing on the stressdeformation behavior and uplift pressure distribution of a damfoundation system under two specific static load combinations lca, and lcb as specified in is. The foundation uplift pressure of concrete gravity dam is mainly influenced by the reservoir water level, rainfall, bedrock temperature, and timevarying characteristic of dam material. Uplift pressure calculation for dams with drainage system near upstream face. All the predominant forces that act on the dam have been shown in the figure itself. Written by civil engineers, dam safety officials, dam owners, geologists, hydraulic engineers, and risk analysts, this handbook is the first cooperative attempt to provide practical solutions to dam problems within the financial constraints faced by dam owners.
However, constant uplift pressure, which is suitable for the static case only, was adopted in almost all the seismic analyses of cracked concrete gravity dams. Seeping water exerts pressure on the base of the dam and it depends upon water head. A parametric study on the influence of uplift pressure on stress intensity factors and crackpropagation angle is performed. Gravity dams 30 contents title page 31 purpose and scope 31 31. Measured and computed uplift pressures for shasta dam. Types of dams, factors affecting selection of type of dam, factors governing selection of site for a dam. Concrete gravity dam section using the reclamation engineering procedure and the corps uplift pressure distribution dl appendix e. Research article the analysis of the concrete gravity dam s foundation uplift pressure under the function of typhoon kaizhu, 1,2,3 chongshigu, 1,2,3 jianchunqiu, 1,2,3 andhaoli 1,2,3 state key laboratory of hydrologywater resources and hydraulic engineering, hohai university, nanjing. A concrete gravity dam is a massive concrete structure, roughly triangular in shape, and designed so that its weight ensures structural stability against the hydrostatic pressure of the impounded water and other forces that may act on the dam. In order to reflect the uprush feature of the pressure during typhoon.
Uplift, pore pressure, concrete dams, finite elements, effective stress. Monitoring of uplift pressures at foundation drains within the gallery of a concrete gravity dam. For preliminary design purposes, uplift pressure distribution in a gravity dam is assumed to have an intensity at the line of drains that exceeds the tailwater pressure by onethird the differential between headwater and tailwater levels. Analyzing stability of a dam using matlab 1manikanta kotti, 2j k chaitanya, 3bh vamsi varma. However, if unusual circumstances exist at a facility, such as the geometry of the worstcase location for hydraulic uplift is unique to one phase, it is a small portion of the phase, pumping of water out of the. Research article the analysis of the concrete gravity dam s. The complex nature of a gravity dam including its galleries, drain holes, roads and ancillary buildings, the variable nature of concrete, the heterogeneous foundation, the. Effect of seismic uplift pressure on the behavior of. Different forces acting on gravity dam civil engineering notes.
We can assume that drain wells do not have a large unloading effect or that the uplift pressure of water seeping from the lower pool is not determining in the presence of the formed overall picture of seepage in the foundation from the. Finite element analysis of gravity dam with drainage gallery. This engineer manual supersedes em 111022200 dated 25 september 1958. Independent 2d slices across the dam body resting each one on a hypothetical horizontal foundation w weight. The uplift pressure near the pressure relief drain has the big curvature vertically and horizontally. A drainage gallery is generally provided in order to relieve the uplift pressure exerted by the seeping water. Drilling foundation drains within gallery of concrete gravity dam to relieve uplift pressures under the dam. The effect of uplift pressure can be reduced by using a drainage gallery. On plugging the drain wells the uplift pressure of water on slabs increases insignificantly by 1020%. For this reas on, it is less important to determine what the uplift pressures on a dam ar e at present than it is to determine what they would be during failure. Further details on temperature control methods are provided in chapter 6. Let b base width of the elementary dam abc the various forces acting on the dam are shown in figure. A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using the weight of the material alone to resist the horizontal pressure of water pushing against it. Different types of forces acts on a dam structure such as water pressure, self weight, wave pressure etc.
The uplift distributions reco mmended herein are consistent. Adi forces acting on gravity dam ce in hindi youtube. Gravity dams may be classified by plan as straight gravity dams and curved gravity. Forces acting on a gravity dam, causes of failure of a gravity dam, elementary profile and practical profile of a gravity dam, limiting height of a low gravity dam, factors of safety stability analysis. Pdf shake table sliding response of a gravity dam model. Gravity dams depend mainly on its own mass to resist the effecting uplift pressure. Concrete gravity dam of constant height resting on a ground of variable quality. Let the dam extend 300 m from the us edge to the ds edge, in th. The complex nature of a gravity dam including its galleries, drain holes, roads and ancillary buildings, the variable nature of concrete, the heterogeneous foundation, the indeterminacy of the forces acting on the dam including the restraint of the foundation and abutments, all lead to a three dimensional problem as complex and insolvable in exact terms as could possibly be met in. The pressure force is the integrated pressure over the surface area of a body. Maximum or 100% uplift on any section through a dam would be a triangular pressure diagram as shown in figure 5. In general, the residual downstream sliding is considerably enlarged. Water pressure uplift pressure pressure due to earthquake forces silt pressure wave pressure ice pressure the stabilizing force is the weight of the dam itself 9. Concrete gravity dams should be evaluated to accommodate full.
Practical methodology for inclusion of uplift and pore. Mark the height of the maximum water level on the upstream side and the maximum water level on the downstream side. The analysis of the concrete gravity dams foundation. The foundation uplift pressure of concrete gravity dam is mainly influenced by the reservoir water level, rainfall, bedrock temperature, and timevarying characteristic of dammaterial. The loads assumed on the concrete dam for stability analysis are water pressure, uplift force, wind. In carrying out stability calculations for any proposed section of a dam, the uplift must be taken into account. In the present paper, uplift pressure effects in cracked concrete gravity dams are studied.
The analysis of the concrete gravity dams foundation uplift. Uplift pressure calculation for dams with drainage systems. It is the second major external force and must be accounted for in all calculations. The pressure gradient is then extended to headwater and tailwater levels, respectively, in straight lines.
Ppt gravity dam powerpoint presentation free to view id. Comparison of design and analysis of concrete gravity dam 19. Design and construction of concrete gravity dams nptel. The optimum position of the drainage gallery under gravity dam results maximum drain reduction factor. A detailed sketch of a gravity dam is shown in fig. The gravity dam has to maintain its stability against the l oads from its structural mass and strength of concrete.
Shear resistance on an existing joint in rock foundation of a gravity dam 4. A gravity dam can be combined with an arch dam into an archgravity dam for areas with massive amounts of. Concrete and masonry dams the national academies press. Forces acting on a gravity dams with diagram geography. It might be external water pressure or uplift pressure. The upward force caded uplift pressure has the effect ofreducingthe effective weight ofthe downstream portion ofa dam and can materially reduce dam stability. In design guidlines, uplift pressure at toe of the dam is considered as equal to tailwater depth x gama. Shake table sliding response of a gravity dam model including water uplift pressure. A gravity dam is designed in such a way that it resists all external forces acting on the dam like water pressure, wind pressure, wave pressure, ice pressure, uplift pressure by its own selfweight. How to calculate the uplift pressure on a gravity dam quora. Failure of gravity dams causes and its failure modes.
Concrete gravity dam section using the corps engineering procedure and the corps uplift pressure distribution cl appendix d. Gravity dams are designed so that each section of the dam is stable and independent of any other dam section. This paper presents a worked 3d example of a generic arch gravity dam subjected to a static structural analysis, from the initial calculation of the prescribed pore pressure and uplift to the resulting effective stresses in the dam body. But if tailwater is present at the toe or above stilling basin it should reduces the uplift pressure as it also apply weight of water over the stilling basin. Research article the analysis of the concrete gravity dam. When a dam rests on a porous material, such as sand or gravel, through which. Pdf in recent past, researches have done to properly investigate the uplift pressure effect at the base level of concrete dams, in particular for a. The selected dams were built between 1912 and 1974 and ranged from 30 to 170 m in height. In order to reflect the uprush feature of the pressure during typhoon, the mutation factor is introduced in this paper. Below the base of a dam with no cutoff, the pressure diagram is trapezoidal if, at the.
Stability analysis of concrete gravity dam a n overview. The developed model in this study can be used for the evaluation of the effects of seepage flow under gravity dam. Gravity dam with stilling basin uplift pressures civil. Two factors directly affect the design of a dam, the intensity of hydrostatic pressure at various points within or under the dam and the area upon which pressure acts. Influences of hydraulic uplift pressures on stability of gravity dam. A comprehensive study of uplift pressures at existing gravity dams was undertaken to meet these objectives. Failure of gravity dam occurs due to overturning, sliding, tension and compression. Diagrams of base pressures acting on a gravity dam. Jan 28, 2014 gravity dams uplift pressure water seeping through the pores, cracks and fissures of the foundation material, and water seeping through dam body and then to the bottom through the joint between the body of the dam.
Ppt gravity dam powerpoint presentation free to view. The design of rcc gravity dams is similar to conven. Forces acting on a dam structure and calculations the constructor. The intensity of pressure may be represented by the diagram showing the ideal. Pdf seismic structural stability of concrete gravity. Any stability analysis of the dam should s eek to apply forces that are compatible with the failure mechanism be ing assumed. The cross section of the gravity dam is approximately triangular in shape and having an apex at top and maximum width at bottom. Reservoir water pressure uplift pressure forces due to waves in the reservoir ice pressure temperature stresses silt pressure seismic forces wind pressure 3. However, the drainage galleries control the pressure distribution and in present problem, the uplift pressure at drainage gallery is given as 50% of total uplift pressure h80m 84m 8026. The weight of a gravity dam and the width of its base prevents it from being overturned when subjected to the thrust of impounded water kennard, 1995. The forces that come in this category are weight of the dam, weight of water acting on inclined faces of the dam, uplift pressure etc. Study set 912 static of fluids center of pressuresubmerged surfaces. On the influence of uplift pressure in concrete gravity dams. The upstream face may be kept throughout vertical or partly slanting for some of its length.