Failure of gravity dam pdf

Three scenarios are considered normal water condition, c ritical water condition and an earthquake hitting the normal water scenario. This is conducted by determining the limit states and seepage of the dam. Design and construction of concrete gravity dams nptel. In addi tion, the potential for failure planes in the rock below the dam must be considered. Failure of a dam can be categorized into three different failure modes. Earthfill dams are less rigid and more susceptible to failure.

Erosion of soil near to the foundation causing settlement. This means that, for a given initial state of the system, and for the several failure modes considered, it is necessary to estimate the probability of the load events and the conditional probability of response of the system for a given load event, as well as estimating the. Gravity dams are designed so that each section of the. Another type of dams are the gravity dams which are constructed from concrete and masonry. Gravity dams are constructed from masonry or concrete. Different causes of failure of earthfill dams are explained below. There have been a total of 45 dam failures in california. The major causes of failures of gravity dam structures are. The main objective is to obtain the relationships between factors of safety and the probability of failure against sliding for a given damreservoir system.

As consequences of dam failure are devastating, the failure modes and seepage of the dam needs to be analyzed. Tips for selection of materials for high strength concrete pdf. Modes of dam failure and monitoring and measuring techniques. This dam is an earth filled dam capable of holding 36,500 acre feet. Pdf sliding and overturning safety factors of concrete gravity. Like most of engineering structures, earth dams may fail due to. Special emphasis is given to dam breach analysis within the context of the risk assessment process used by the bureau of reclamation reclamation. Sliding along the base of the dam is probably considered the most prevailing mode of failure for gravity dams ghanaat, 2004. Causes of failures of earthfill dams the constructor. Hydraulic failure, seepage failure and structural failure. Abstract concrete gravity dams make up about ten percent of the more than 85,000 dams that. The dam was loaded by fluid pressure on the upstream face and upward forces simulating the uplift pressure. In september 1965 a serious piping failure occurred on the right abutment, with reservoir water percolating along valleyside sheet joints in the sandstone with only 46 feet of head. Past dam failure disasters showed that the loss of life in the event of a dam failure is directly related to the warning time available to evacuate the population at risk downstream of the dam.

A buttress dam is a specific type of gravity dam in which the large mass of concrete is reduced, and the forces are diverted to the dam foundation through vertical or sloping buttresses. Failure of gravity dams causes and its failure modes. In order to study this question, the analysis of probability of failure of a gravity dam for the sliding failure mode has been performed in this thesis according to the theme c in. A gravity dam may fail by the failure of its material, i. Between the years 2000 and 2009 more than 200 notable dam failures happened worldwide. Many dams have failed where the sliding hazard was ignored or given inadequate attention. Gravity dams are massive structure dam which is constructed of concrete or stone masonry. Table of dam failures university of california, davis. All the steps that the methodology comprises have been developed exhaustively, achieving different estimates of the target conditional probability of failure.

Modes of dam failure and monitoring and measuring techniques vii. What is difference between gravity dam,earth dam,arch dam,buttress dam,barrage hindi quikr exam gravity dam. Pdf gravity dam probability of sliding failure with overtopping and. Of these, the most comprehensive is the 1983 volume by jansen 1 published by the u. Dam safety based on risk analysis methodologies demand quantification of the risk of the damreservoir system. Pdf dams have been constructed for millennia, influencing the lives of humans and the ecosystems they inhabit. Gravity dams gravity dams criteria for selection of dam site, construction material, forces acting on gravity dam, modes of failure, stability analysis, safety criteria, methods of design, stress analysis and stress contours, galleries, instrumentation, joints, keys, water seals, temperature control in concrete dams, foundation treatment. There have been several studies of dam failures published in the last 30 years. Tigra dam failure, gwalior, india a case of sedimentary. Slide failure at dam association of state dam safety officials asdso. It is not up to the ferc to prove that failure in a given situation is certain, rather it is up. City of oxnard hazards dam failure city of oxnard 2016 bouquet canyon reservoir bouquet canyon reservoir is located east of interstate 5 and north of castaic junction, highway 126.

Earth dams can also experience seepage and structural failure caused by poor engineering and planning. Any malfunction or abnormality outside the design assumptions and parameters that adversely affect a dams primary function of impounding water is considered a dam failure. Design of gravity dam, calculation in reservoir full. Methodology for estimating the probability of failure by. Gravity dams are constructed of vertical blocks of concrete with flexible seals in the joints between the blocks. Concrete dam analysis arch, gravity and buttress dams chapter 5, concrete dams 3 2014 draft risk analysis does not reverse the burden of proof with respect to the failure of the dam. The self weight of the gravity dam acts through the centre of gravity of the. About 40% of earth dams failure have been attributed to hydraulic failure.

The methodology proposed has been fully applied to a concrete gravity dam and for the sliding along in the damfoundation contact plane failure mode. However, the ultimate cause of failure is generally agreed to be the result of sliding of sections of the gravity dam along the untreated, stratified foundation. Failure of gravity dam occurs due to overturning, sliding, tension and compression. Ferc engineering guidelines riskinformed decision making. Dams are owned and operated by many different types of. A gravity dam depends on its own weight for stability and is usually straight in plan although sometimes slightly curved. A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by primarily using the weight of the material alone to resist the horizontal pressure of water pushing against it. Before a gravity dam can overturn physically, there may be other types of failures, such as cracking of the upstream material due to tension, increase in uplift. Uplift along failure planes within the b ody of the dam shall be assumed to vary from 100% of normal headwater at the upstream face to 100% of tailwater or zero, as the. Chapter 6 concrete dam engineering with examples 1. Stability evaluation of gravity concrete structures dams, retaining walls. For structures consisting of a section of concrete gravity dam within an embankment dam, the concrete section will be designed in accordance with this manual.

Earth and rock fill dams are widely used throughout the world, and most of the dam failures involve such. If you have some, be sure to pay your homeowners insurance. Pdf multiple step method of design of gravity dam and. Like most of engineering structures, earth dams may fail due to various reasons such as faulty design, improper construction and poor maintenance practices, etc.

The purpose of this manual is to provide technical criteria and guidance for the planning and design of concrete gravity dams for civil works projects. Dam awareness may 2018 introduction responsibility and. Kianoush, fembased parametric analysis of a typical gravity dam considering input excitation. A dam failure or dam burst is a catastrophic type of failure characterized by the sudden, rapid, and uncontrolled release of impounded water or the likelihood of such an uncontrolled release. Quantitative failure metric for gravity dams hariri. Examples stacked wood walls its everyones favorite way to go, much less expensive than other support systems. Concrete dam engineering 1 0401544 hydraulic structures university of sharjah dept.

Stability evaluation of gravity concrete structures. Water pressure is the most major external force acting on a gravity dam. That study listed and discussed dam failures that have occurred over the past 900 years. The prevailing mode of failure for gravity dams is probably sliding along the base of the dam or along planes of weakness within the foundation. Chapter iii gravity dams 30 contents title page 31 purpose and scope 31 31. By definition, a gravity dam is one where that depends upon the force of gravity to prevent it from being pushed aside by the water it contains. The relevant yearly probability of failure seems to be in average between 104 and 105 but varies considerably and is difficult to assess for each dam.

A hollow gravity dam is a dam constructed of concrete andor masonry on the outside but having a hollow interior relying on its weight for stability. The development of excessive uplift pressures creating tension at the heel of the dam and downstream scour due to overtopping likely. A smeared crack model for seismic failure analysis of. 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. A crib dam is a gravity dam built up of boxes, crossed timbers, or gabions filled with earth or rock. The various causes leading to the failure of earth dams can be grouped into three categories i. Learning outcome after this lecture, students should be able to 1. An earth fill dam, like other types of dams, benefits. Dams it is important for a gravity or buttress dam to maintain its structural integrity and remain stable against sliding. The federal emergency management agency fema has developed.

It is determined that the proposed damage indices can indeed provide a quantitative metric for the degree of failure in gravity dams in terms of the input dynamic motion. Failures have occurred for a variety of reasons, the most common failure being overtopping. The failure under this category may be due to overtopping, wave erosion, top erosion and gullying. On upstream face pressure exerted by water is stored upto the full reservoir level. In the case of gravity dams on rock founda tions, a failure plane shall be assumed between the dam and the foundation. The effect of reservoir water is considered for calculation of. An advanced threeparameter yield criterion is utilized in finite element formulation. Touileb and others published gravity dam probability of sliding failure with overtopping and conditional drainage. Repeated overtopping can eventually result in a catastrophic collapse of the dam.

Francis failure, but relatively litte attention has been paid to the austin dam. Evaluation of failure modes for concrete dams diva. This manual applies to all hqusace elements, major subordinate commands. Gravity dam design united states army corps of engineers. Fontenelle dam was constructed by the us bureau of reclamation on the green river in wyoming in 196063, with a single line grout curtain. Other dams have failed due to specific shortcomings in the dam itself or an inadequate assessment of the. An experimental study of failure of a gravity dam on a. If it is possible to monitor or measure the hazards that may impact on any particular. The failure can occur either in the interface between dam and foundation or in the foundation itself. Height is the vertical dimension from the downstream toe of the dam at its lowest point to the top of the dam. Stability analysis of nonoverflow section of concrete. A concrete gravity dam is facing with a variety of failure mechanisms include dam sliding on the structure and foundation interaction surface. Conventional concrete and roller compacted concrete are both addressed. Dam failure chapter 5 2019 utah state hazard mitigation plan page 2 a buttress dam is a specific type of gravity dam in which the large mass of concrete is reduced, and the forces are diverted to the dam foundation.

Current methods for predicting embankment dam breach parameters and numerically modeling dam breach events are. Concrete dams case histories of failures and nonfailures with. Civil engineering failures engineering and technology. Causes of failure of earthen dams and suggested remedial. Gravity dam is constructed of concrete andor masonry andor laidup stone that relies upon its weight for stability. Multiple step method of design of gravity dam and comparison with cadam software conference paper pdf available september 2016 with 6,557 reads how we measure reads. Since the failure of the dam was mostly caused by the subterranean rock, the only. Any stability analysis of the dam should seek to apply forces that are compatible with the failure mechanism being assumed. Gravity dam modes of failure and criteria for structural stability of gravity dams a gravity dam may fail in the following ways.