We are planning on studying a building with 9 storeys plus 4 underground parking lot . The soil layer which we will be constructing our raft foundation upon ( 10 m x 10 m raft dimensions ) is made of marl with limit pressure PL of about 25 MPa . This marl starts from a depth of -8 m and our raft anchor depth is at (-12 m )deep . All the soils above the anchoring depth will eventually be removed
My questions are :
1- How do we deal with such deep rafts in term of bearing capacity ? does the same analytical equations for shallow footings apply in this case ?
2-Does the bearing capacity calculated from say analytical methods or pressumeter test pertains to the vertical load divided by the raft area or should we divide it by the area afterwards ?
3-What about computing the bearing capacity using pressumeter results for this semi-deep foundation? i proposed to my colleagues to use load-unload cycles in the pressumeter test ?
4-The oedometer test should also have an unloading cycle by removing the same amount of effective stress at the depth of -12 m and then continuing the test ? and is it possible that after an unloading cycle in this test to have void ratio get about the initial value at the start of the test ?