Design of riprap slope protection for embankment dams pdf

Typical projects requiring riprap protection are highway embankments, bridges, flood channels. The top 2 feet of the blanket were excavated and screened to obtain minus 1inch material for the membrane subgrade and earth cover. Embankment dams were low on the scale of public confidence for many centuries. Embankment dams chapter 2 embankment design ds29 6192 1 2. The bureau published two reports esmiol 1968 and davis 1973.

To meet the dam safety requirements, the design, construction, operation, and modification of an embankment dam must comply with the following. A demonstration project in itasca and aitkin counties in northern minnesota installed protection on lakeshore sites beginning in 1988. The newly placed fill tends to slide down the slope of the hillside or the existing embankment. It replaces the soil conservation services minnesota technical release no. No single approach will be successful, especially if the slope is steep or has highly erodible soils see table.

Consideration for earth and rockfill dams, engineer manualno. General design and construction considerations for earth and. Design wind velocity versus probability of nonexceedence chart for dam a. A minimum of 300 mm thick riprap over 150 mm thick filter layer may be provided upto the top of the dam. Ministry of environment and climate change strategy. Experimental facilities, riprap characteristics, and data acquisition. This technical release has been developed to specifically address lakeshore protection in minnesota. A summary of the phase i study and the specific findings follows.

The empirical design equation for angular rock riprap is expressed as follows. Upstream slope protection association of state dam safety. Embankment dams are defined as those constructed primarily of the natural materials of the earth, namely soil and rock. These design techniques encompass timber cribs, sheetpiles, riprap and gabions, reinforced earth and concrete overtop. Dams are a critical and essential part of the nations infrastructure for the storage and management of water in watersheds. Design of riprap for slope protection against wave action. The preliminary design of an earthen dam is done on the basis of past experiences on similar types of dam regarding their performance and life. Riprap remains one of the most common and costeffective means of providing erosion protection, structure stability, and slope stabilization from overtopping flow conditions. Therefore, the dam embankment design must consider the potential. A series of 52 flume experiments was conducted in which riprap was placed on an embankment s and subjected to cvertopping flows. In recent years, riprap has been specified for the protection of small, low hazard dams with flatter slopes during small overtopping events of short.

Properly sized and graded rock overlying a suitable bedding, filter, or both has provided adequate slope protection 1. Design guidelines for rock riprap are presented in chapter 4. Rock riprap consists of a heterogeneous mixture of irregular shaped rocks placed. This can cause erosion of the embankment material and if severe enough, waves can overtop the embankment, both of which are dam safety issues.

Riprap protection section 1 introduction to riprap section 2 channel characteristics section 3 design guidance for stone size section 4 revetment toe scour estimation and protection section 5 ice, debris and vegetation section 6 quality control. Stone weight and equivalent stone dimension figure 23. This engineer manual em provides guidance for analyzing the static stability of slopes of earth and rockfill dams, slopes of other types of embankments, excavated slopes, and natural slopes in soil and soft rock. The two primary types of slope protection used on embankment dams are riprap. The dam had an upstream soil cement member to act as a riprap to protect. Embankment dams can be built on a wider variety of foundations and topography than can concrete dams. Chapter 2 embankment design is an existing chapter last revised june 1992. Publish white paper on design and performance of riprap slope protection for embankment dams. A central core rockfill dam of good design and careful construction. Civil engineering embankment slope protection with drain. The upstream slopes of embankment dams and dikes typically require protection against the damaging effects of wave action, surface runoff, weathering, ice, and floating debris.

Rcc roller compacted concrete has also been used as slope protection and is designed and. Design manual for rcc spillways and overtopping protection prepared by urs greiner woodward clyde por tland cement association. Further, empirical relationships for sizing of dumped riprap stones at an embankment dam toe based on key conclusions from research area the of s design of dumped ripraps and embankment dam toes are proposed and the validity of these criteria is tested with available experimental data. United states army corps of engineers engineering manual em. Many studies have been published that provide guidance for determining the wave runup height on slopes. The principal vulnerability of an embankment dam is that it may be damaged or even destroyed. May 27, 2014 riprap has long been used for embankment dams to prevent rill erosion of slopes due to surface runoff and to prevent wave erosion at the interface between embankment slopes and standing water. Riprap design and construction guide ministry of environment. Piping by internal erosion of finegrained soils from the embankment dam. General design and construction considerations for earth. Embankment dams generally have certain advantages over concrete dams with regard to site conditions and economy. Riprap has been widely used in arid areas and on steeper embankment slopes up to about 1.

These design procedures are limited to rock used as riprap protection against wave action. Embankment dams computation of h10 h10 was calculated using equation 5 from the 20 update of reclamations design standards, embankment dams, chapter 7. Experimental facilities, riprap characteristics, and. Slope protection basics protecting slopes from erosion requires several actions that must be taken together. United states army corps of engineers engineering manual. Riprap design involve s the following general procedures. Alternative techniques to riprap bank stabilization. The runup from a significant wave on an embankment slope with riprap protection can be predicted using. Slfllllllllll llelllllleeei eeeiiiieeiiii eeelllllllelhe. Protection of embankment dam toe and abutments under overtopping conditions. Upstream slope protection association of state dam safety asdso.

For ponds with a permanent pool area of 2 acres or more, protection shall be provided across the earth fill at normal pool elevation elevation of the inlet of the mechanical spillway on the upstream side of the. Optimum riprap side slope for a given size riprap figure 24. For riprap installations, normally the maximum recommended face slope is 1v. To protect slopes or similar areas subject to erosion by water. Protection of embankment dam toe and abutments under. Riprap is a common material used to protect embankment slopes against erosion associated with waves on a reservoir or surface runoff during rainfall events. The longitudinal transition embankment foundation condition is encountered where the alignment places the embankment alongside a hillside or where an existing embankment is to be widened. Thousands of embankment dams exceeding 20 meters in height have been constructed throughout the world. Embankment dams can be built on a wider variety of foundations and. Erosion protection may include vegetation, the placement of riprap or some ot. Riprap and other slope protection material were first removed from the earth blanket.

Modifications to embankment dams to accommodate new or revised inflow. Riprap design, interstitial flow, critical shear stress. Save this page as a printable dam owners fact sheet pdf. Cut a keyway in stable material at the slope base to reinforce the toe. Today, embankment dams exist in excess of 300 meters high with volumes of many millions of cubic meters of fill. Important conclusions are drawn related to the use of riprap for overtopping flow protection on typical embankment dam slopes. Determining wave characteristics and design wave heights based on the design wind velocity see section 7. Dam faces and spillways abutment protection typical applications geoweb slope protection systems may be designed with a variety of infill materials to meet project requirements for aesthetics, stability, environmental impact, material availability, and erosioncontrol. Guidelines for the design of other types of riprap are presented in chapter 6. Stability, safety and evaluation of embankment dams. Pdf protection of embankment dam toe and abutments under.

Publish white paper on laboratory testing of fill strength parameters for embankment dams. Manual 5 and 6, and the engineering geology field manual 7 and 8. This manual presents fundamental principles underlying the design and construction of. Slope protection for dams and lakeshores natural resources. Embankment dam safety under extreme loading conditions. Dam embankments, and tr21069, riprap for slope protection against wave action, as applicable.

The downstream slope protection is ensured by turfing or riprap. Embankment slopes of 1, 2, 8, 10, and 20% were protected with median. Consideration for earth and rockfill dams, engineer manual no. Slope protection is usually needed to protect the upstream slope against erosion. Riprap slope protection riprap slope protection is an erosion control measure consisting of geotextile fabric and stone riprap that is placed on an unvegetated slope to protect the soil from erosive forces. Extent of riprap protection on a channel bend figure 17. Introduction riprap is a common material used to protect embankment slopes against erosion associated with waves on a reservoir.

Downstream slope erosion protection is commonly constructed of coarse. Riprap tends to increase the speed of water flow along an armored. Problems arise because the effects of riprap do not stop at the point of installation. The system also provides protection to impervious liners. Rock riprap design methods and their applicability to long. Embankment overtopping protection by riprap considering.

No single approach will be successful, especially if the slope. The upstream slope protection is ensured by providing riprap. Riprap may be placed on slope either by hand or it may be simply dumped. Riprap protection against wave action is generally satisfactory for protecting the slope from other attacks. Because slope protection can represent a significant cost, the design requires a proper balance between the initial cost for constructio n and future maintena nce costs, while ensuring safety of the structure. The best slope protection type for a given situation depends on the conditions where the installation is to be made, availability of protection material, cost of the various types, and protection desired. An evaluation study of the design and construction of an. Riprap design for overtopped embankments us bureau. Embankment dams are typically built from materials excavated at or near the dam site, and usually only require minimal processing. If needed to protect the slopes of the dam from erosion, special measures, such as berms, rock riprap, sandgravel, soil cement, or special vegetation, shall be provided technical releases 56, a guide for design and layout of vegetative wave protection for earth dam embankments. Small dams made of cohesive embankment soils have often performed well without such protection. This chapter presents guidelines for sitespecific design of riprap slope protection figure 7.