Modelling with Phase2 finite element software by Rocscience

[Doc09]

We recently purchased a copy of Phase2 by rocscience and we've been getting some weird results when modelling a shored excavation. The program is coming back with higher delflections and reactions for the example WITHOUT hydrostatic pressure. Somehow I could not get my point across to rocsience (although they were very courteous) and still ended up without an answer to my question. It seems to me that, by inspection, a shoring system exposed to water pressure behind it whould experience higher reactions.

Anyone out there with experience with Phase2 or with an opinion on the subject is welcome to contribute.

Thanks

 

[DRC1]

Do not have experience with Phase2 but am planning to try it out soon. Assuming you are using limit state, if the soil is submerged, the soil will have the bouyent weight multiplied by the cofficent of active pressure, and the full 62 psf pressure for the water. I know this sounds like soils 101, but sometimes getting new programs to do what you want them to do isn't as easy as they make it out to be. I would check to make sure that the water pressure is being added and it is not being factored by Ka. If it is, the load would be less than dry soil.

 

[Doc09]

I think the problem is beyond using the soil's boyant weight factor by Ka, because even then the unfactored hydrostatic pressure of the water is still applicable and it should result in higher reactions, which is not hapening.

I have also compared it to Plaxis and to our inhouse software, the trend is consistent. After several correspondences with Rocscience they ended up suggesting modelling the pile as a liner and aply the ater presure as a distributed load, which is not practical at all especially for phased construction simulation. I mean we buy the software in order to optimize on our time and reduce the possibility of error.

The correspondence with Rocscience was courteous but the technical response was not convincing and it seems that we were going in circles to resolve what should be straight forward issue. Bottom line I do not see myself able to release the software for utilization by our engineers before I am reasonably satisfied of its adequacy, whcih does not seem to be the case for shored excavation where a water table is involved.