Hello Everyone,
I was wondering what the best way to model a basic seepage problem is, within Plaxis 2D. The problem involves an enclosed casing with the top open and exposed at the surface, the rest of the casing is below the ground surface. The casing would then be filled with water, and overtime the water would drain out of a small hole in the bottom of the casing into the soil, solely due to gravity. The goal is to only look at the direction and magnitude of the groundwater flow leaving the bottom of the casing, once all the water has drained out of the casing, over however long it takes.
I would like to model this with a dry soil profile, to really understand how the flow is coming out of the bottom of the casing. So, I have been trying to place the global groundwater table level beneath the Ymin boundary of the model. However, I'm not sure if this will work, or what the best way is to only place the water inside the finite area of the inside of the casing. I have tried using both plates for the casing walls in conjunction with interfaces to induce flow. And have also tired using a well. However, a few problems with the well. I'm not sure this is the best model since the well represents a line where discharge is present over that space, and also I would need to specify a discharge value which I want to avoid. So, my issue comes down to really figuring out the best way to "place" water inside the casing, and let gravity drain the water out with no other influence. Then what the best way would be to analyze the flow within the calculations.
Any help would be greatly appreciated.
-Alex Lefebvre
Dear Alex,
The available options include using volume elements ("soil" cluster) or plate elements for the casing. The starting condition can be specified using WaterConditions of the cluster inside casing by choosing a Head or Custom water level.The hole can be either a gap in the casing or a small-sized interface that allows for cross-permeability.
The flow will be governed by the permeability values used in the soil, however, note that the simulation of the unsaturated soil is simulated using retention curves which by default might not fit your purpose. This means that you may need to manually define the behaviour in the soil material data set. More information can be found in our Reference manual.
Since you already have made some models it will be useful to check them directly and assist you further. Please submit a service request.
Then, one of our support engineers can help you in detail: https://apps.bentley.com/srmanager/ProductSupport