The equation for correlating SPT N to Su is
Su = f1 N (After Stroud and Butler, 1975)
N is uncorrected
f1 = 4.5 to 5 (depends on Plasticity Index - use N=4.5 for PI>40% and N=5 for PI<40%).
Here is the equation for deriving E' for clay from SPT N;
E' = 1 / (450 N) m2/KN
= 1000 / 450N m2/MN.
Note that SPT N is uncorrected.
This is equation is after Stroud and Butler, 1975.
Iandig: You are wrong about the assumption that the test was for CBR.
BigH: iT IS PRESSURE - 934kPa. We carried out 9 window samples and 1 cable percussion borehole. Test schedule has just been prepared for the samples taken from the labs and 1-D oedometer test has been specified on U100...
We are carrying out a ground investigation at a airport in UK. We specified an incremental plate load tests at 3 locations. One of the plate load test result is out. Using a 0.3 m diameter plate and a maximum load of 934kPa, the test was only carried out in 30mins. Settlement was 1.25mm. When...
The first method suggested by Aeoliantexan is the right one. Reason is that friction between soil and pile material in this case is lower than friction within the soil.
So use the first method.
Having read all the contributions above, I submit that a single foundation is an economic option for the structures.
You have to check 3 conditions;
1. Condition of the two silos, filled to the brim. Check that there is adequate FoS against bearing failure and settlement within limit.
2...
Ron - I would expect that the sides of the excavation will be retained,this should remove contribution of overburden pressure from the top of the ground. I agree - better to ignore the overburden pressure.
This is a tricky situation. Considering how the foundation will try to fail, only the overburden pressure from the bottom of the excavation to the base of the strips should be considered. You might also want to use the preconsolidation pressure at the base of the strips in place of the...
I suggest that you use Bousinesq equation for point load. Get the distance of the point load from the retaining wall and calculate horizontal loads at depth due to the point load on the wall until horizontal load is zero. You can use horizontal loads at 1m, 2m, 3m etc depth below top of wall...
First let me say that there was an ommision in my second paragraph. I meant to say 'settlement calculations at the point that the net applied vertival pressure equals the 20% vertical overburden pressure at that point'.
iandid explains it well.
I have done two designs - pile foundation and shallow foundation. The pile foundation founded on Limestone have high capacity but large distance between the piles. For the shallow foundation, I excavated to 3m depth and replaced the soil with gravel. The FoS >> 3 and total settlement (in cLAY)...
I have read many of your threads and I can conclude you are not a geotechnical engineer in any way. Pile design can be basic as well as complicated depending on the structure.
If you can lay your hands on a textbook like' Foundation Design and Construction' by Tomlinson you can get the basic...
Wall deflection of 0.01*retained height is acceptable. Anything higher is not. You might want to estimate roughly the ground movement as a result of the wall deflection. Use CIRIA c580. There are some tables there. This will give u the expected movement of the viaduct foundation. If the movement...
Thanks BigH. 1.25 mbgl means 1.25 metre below groung level. The base of some the tanks will be below ground level. Say 1.25 m to 1.4m. The tank diameter is 20m, height is 16m with liquid vertical level of 14m. Liquid type is waste water.
If I have to replace the fill with compacted sand, we are...
I am designing foundation for a waste steel tanks. The ground condition is 2m soft made ground , over 14m clay (Cu = 40 + 15z) over incompressible limestone. I am thinking of using pile foundation but also considering pad foundation.
Can I design the pile foundation as normal for other civil...
I have done similar calculations before and I will suggest that you use 1m laer thickness in the top meters where you would expect more settlement. You can then increase the layer thickness to 2m and so on. Genrally, using thinner layer thickness may increase the accuracy of the settlement...
