Is any In-situ Settlement Test / Evaluation method includes flooding or submerging !!!

[MohdTalaat]

A big duct supported using isolated footings of (4 x 9 m) size, normal sand under the footing ; A gap noticed in that duct at a support and they discovered a foundation settlement , the consultant made a test using water trucks submerging the footing area, and 70 mm settlement recorded after that submergence .

My questions are:
1- What is the testing procedure allows to submerge the footing soil to test / evaluate the settlement ?
2- Is that allowed to be used ? / in such cases ?
3- What is the possible reasons for this settlement after flooding by water ?

I made a quick search between the codes but I couldn't reach to something solid can be used ; Please help .

 

[Ron]

The consultant likely suspected that the sand had not been properly compacted. Flooding the sand below the foundation allowed in-situ compaction of the sands from the load of the footing and caused settlement.

No...though I don't know where you are located or to what code you must adhere, tests like this are usually not covered by codes. This is an evaluative test done from the judgment of the consultant. It apparently showed what he wanted to show, so it was likely successful in that respect.

 

[oldestguy]

Sounds to me more like a procedure to see what would have happened if the footing had been placed on a fully submerged sand (high water table). Might be called a proof test or an overload procedure. Given two conditions of the same dry density of the sand, same footing size and load, a footing placed on the saturated sand would have an effective imposed stress depth (at 10 percent of existing) going much deeper, thus applying higher imposed stresses as a percentage of existing stresses, resulting in greater settlement.
In summary, I don't see it as anything other than getting the most settlement now rather than at some future date where water table may be higher then. Whether or not Ron's statement on a compactive effect applies is not known. It would be one more factor to remove future possible problem.

The consultant may have presumed the history of the site had no high water table, but it was coming up now and he wanted to get rid of that question still there in case of higher future water table. In any case, future settlements now are unlikely as a result of water table rising.

 

[MohdTalaat]

Many thanks for your response , it is my first thread , and it is great to get that response in that way

I am located in Saudi Arabia , and they are using here American and British standards in addition to their local standards .

Ron , I got the same for the purpose of that flooding although the ducts were already installed !!, but I thought it is according to some procedure of a code or standard , you are right it seems to be evaluative .

Oldestguy , The site location in the dry desert where there is no water table interfaces to the foundations , It seems that your statement is right unless that the duct is already erected , so I think it is evaluative action , and it seems to be successful !

I will back to you if for any updates , Thanks again