Your question was answered by our colleagues above but I want to add some; Since you are design a massive structure, you should be also concerned on mode of failure and structural stability.  You can check the stability by two dimensional gravity method and three dimensional methods such as slab analogy method, trial load twist method and Finite Element Method (FEM). Hope it will be helpful! 

this is a very general question. the considerations may widely vary based on geotechnical properties of base and abutments, hydrological conditions, structure, financial aspects, etc.

please specify your question more.

i want to understand how engineer design the structure of the dam. i understand that the loadings need to consider the hydrostatic pressure and the self weight. but, how about the reinforcement. which code to use design the structure of dam. for malaysia, we use BS8110 to design the reinforce concrete. but, i'm not sure which code to use for designing the structure of dam.

First decide the type of dam, I assume you are only asking about concrete dams, then it comes to concrete gravity or concrete structural(Arch dam). that will depend on the strength of the the geology or the abutments. If you have strong abutments makes sense to chose arch dam if not you have to go to gravity dam, rmeber there are considerable savings in material in arch dam. Once you have finalized the the type of dam, Then you have to decide on the storage of the reservoir and height of the dam, this you should get from the hydrology data i.e. mass curves which will help you in making a decision, When you have finalized the type of dam structure and the height and other criteria then you have to divide it into different components which may need different type of design approaches, e.g. spillways, apron, any structures underground to take care of seepage such as curtain walls, gates, It also depends on the functional characteristics of dam as a hydro power plant may have other components like forebay, tunnels, powerhouse. If you are only involved in designing the main body of the dam, the design for a gravity dam will depend on the overturning and sliding criteria and stressed that are generated in the concrete by virtue of its weight and external forces, Also you need to consider seismic forces(horizontal n vertical) , temperature stress, dynamic load form water etc. If you are designing an arch dam the dam is transferring the load to the abutments through the arch action and thus you have to design the dam basically as a beam (stated in the most crude language) considering the same set of external and internal forces . You can get a lot of literature on basic dam design, and it is a very extensive process, You certainly cant do it using the simple construction code for general concrete structures. I hope I I was able to give you a sense on the enormity of your question and complexity of the problem you are trying to deal with.

thank you very much.. i'm clear now. :)

To design such structure there are many aspects to look into. Firstly is the geotechnical design which considers the soil beneath the dam. Then the hydrological design which looks into the surface water in the catchment area. The hydraulic design considers the impact of water on various hydraulic structures in the project. Then of course the structural design of the dam itself (load and settlement) due to many forces i.e. water, seismic  for example. Other important points are the financial part, viability, risk.

thanks Ideris Zakaria..

how many years we need to consider in design the dam?

Your question was answered by our colleagues above but I want to add some; Since you are design a massive structure, you should be also concerned on mode of failure and structural stability.  You can check the stability by two dimensional gravity method and three dimensional methods such as slab analogy method, trial load twist method and Finite Element Method (FEM). Hope it will be helpful! 

U can use CADAM software for designing the gravity dams

Salam Nik,

The retaining walls are for soil blocking as far as i am aware. However, when you build a concrete dam, like one of the answer suggests, you have to consider the fluid mechanics for the water you will be blocking and also, geotechnical aspect of it for the foundation construction, only after you figure out how much weight you will be putting on (the concrete) on the dam, and also, the structural part, how much concrete to put, how high the dam should be. For the fluid loads, you will need the inflow yearly inflow, also the probability of having an overflow as well. Those are the critical fluid loads for any type of dam along with others.  I am not much of a dam engineer, but once i was an intern for soil-based dam construction. Designing and working on the dams are as fun as designing bridges or predicting earthquakes. 

I hope that it was helpful of considering what is going on within the design process.

Good luck!

Yildiz

I think that our friends have made a lot of explaining.  I just might refer you to the technical manuals of the bureau of Land Reclamation, USA and the American Corps of Engineers.  They have detailed manuals about such design.

It is good to see that all the answers have rightly addressed the issue of soil and structural design. As a material engineer, you also need to consider the mix design for your dam. Since a dam is a mass concrete structure, you need to reduce the heat of hydration generated to reduce the potential for failure due to delayed ettringite formation (DEF). All these components are important

The answers above have covered many important issues. One that has not been highlighted much is the effect of uplift pressures beneath the dam on overturning and sliding stability. Depending on the foundation conditions there may need to be a cutoff such as a sheet pile or cement bentonite wall or grout curtain. With no cutoff it is common to assume a linear variation of pressure across the base of the dam, but this is an assumption that may be invalid. I have reviewed piezometer data from an old masonry dam founded on rock with no cutoff, and the water pressures far exceeded the linear variation to the point at which the dam on 2D analysis was theoretically unstable. A 3D analysis showed that the dam was still standing due to wedging in the valley. The distribution of uplift pressure could become even more unfavourable after seismic loading.

While a grouted cutoff may well improve things (although not 100% effective), positive drainage measures such as pressure relief wells should also be considered for a new dam.

I hope this helps.

David