Find water flow through weep hole in retaining wall

RE: Find water flow through weep hole in retaining wall

Nitharshan — Tue, 25 Apr 2023 10:38:28 GMT

Noted, thanks.

RE: Find water flow through weep hole in retaining wall

Dennis Waterman — Tue, 11 Apr 2023 05:32:13 GMT

Dear Nitharshan,

Because the water is flowing in the direction of the negative x-axis ....

With kind regards,

Dennis Waterman

RE: Find water flow through weep hole in retaining wall

Nitharshan — Thu, 06 Apr 2023 16:36:16 GMT

Dear Mr. Dennis,

I modelled the wall with thin layer with the permeability is equal to the adjacent soil and the results are shown below. Why negative discharge was came inside that thin layer?

RE: Find water flow through weep hole in retaining wall

Nitharshan — Thu, 06 Apr 2023 08:08:21 GMT

Dear Mr. Dennis,

Noted thanks. Will check based on your guidelines.

RE: Find water flow through weep hole in retaining wall

Dennis Waterman — Thu, 06 Apr 2023 07:47:35 GMT

Dear Nitharshan,

Something considerably higher than the soil permeability. The discharge will be largely determined by the permeability of the soil, not by that of the pipe.
Note that if in reality it's a single pipe, a 2D analysis will not be very good as it will calculate it as an infinitely long gap instead of a single hole. This means the flow pattern will be different, so simply using the 2D discharge per meter length and multiply it by the pipe diameter will not be very accurate. For a single pipe it would require a 3D flow analysis.

With kind regards,

Dennis Waterman

RE: Find water flow through weep hole in retaining wall

Nitharshan — Thu, 06 Apr 2023 07:43:57 GMT

Dear Mr. Dennis,

Thanks for the reply.

Since the weep hole is an open pipe, what permeability value can we provide to match the actual condition (permeability of soil is 1E-6 m/s)?

Thanks,

RE: Find water flow through weep hole in retaining wall

Dennis Waterman — Thu, 06 Apr 2023 07:19:16 GMT

Dear Nitharshan,

A drain element is only a boundary condition, it does not have flow. If you want to model the flow, you would have to define a thin area with a higher permeability in your wall. Alternatively you could do it with an interface (instead of the drain you use now) and specify a longitudinal permeability in the interface. However, if you're also planning to do a deformation analysis, an interface may be hard to control in terms of deformation and the thin zone with the same stiffness/strength as the wall, but with high permeability would work better.

With kind regards,

Dennis Waterman