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Turkish Dear colleagues, good day to all. We have a project in which we need to calculate the pile foundation. There will be end piles. I need your information as I have not done a pile foundation project before. I did some research, but I wanted to ask here because there are different opinions. I want to calculate by assuming that the raft foundation will also carry the load, rather than carrying the entire load to the piles. In this sense, in order to provide some economy, I turned to pile raft instead of pile foundation. I have some questions: -How are pile foundation diameters and spacings determined? There are opinions that the intervals should be (2.5-3.5)D or (2-8)D. I have an opinion that the pile foundation may be closely spaced, while the pile-raft may be spaced relatively far apart, is it true? I did some experiments. For example; The load that the pile could carry was 4 times greater than the load on the pile when it was 60cm in diameter and 2m apart. Even if I increase this interval to 4-5m, maybe I will stay within safe limits, but in this case the stakes may not work as a group. How should I make this distinction? Is it right for piles to work as a group? In this case, will the settlement in one pile not affect the others? - Should the upper part of the pile foundation extend to the upper level of the raft foundation or should it terminate under the foundation? -How far should the piles enter the solid layer on which they will sit, is there a certain rate accepted? -In the case of pile foundations, by what percentage would it be reasonable to estimate the raft thickness, should I be looking at the punching factor again? What I am wondering here is whether the raft foundation should be considered as a foundation on its own, or should I think of it as the cap of the piles? -Do we have a chance to do the piles without reinforcement in the program? If we want to make jet grout instead of pile, can we calculate it with the program? The carrying capacity is exceeded by approximately 30%. Thank you in advance to everyone who is interested.
How are pile foundation diameters and spacing determined?
- Thread starter ganymede
- Start date
Hello... First of all, since this subject is in the field of foundation engineering, it would be beneficial to get information or consultancy from an expert geotechnical engineer. Pile foundations are like a completely closed box, researches are continuing, although researches are continuing on all subjects, but there is nothing clear about load sharing. In other words, it seems impossible to reach a definite conclusion since there are many unknowns. You can control the group effect by modeling the piles in 3D. In other words, you may have unnecessary losses because they steal loads from each other according to the intersections of the stress bulbs. Basically, after providing the necessary anchorage conditions, you do not need to extend it up, this is my opinion. It is enough that it is thick enough to meet the punching and moments, of course, it should provide eye safety"ganymede":1hm5kiub" said:
The purpose of making end piles seems to be to reach solid ground. If your tip capacity is not enough, it is useful to enter the solid ground until you provide the necessary friction force. I speak without knowing the upper ground, so I accept that it does not receive friction force. It should be thick enough to prevent the piles from twisting and shearing under the incoming effects, especially right under the foundation. You can look at the net by writing certain diameter ratios according to height in some places. So it shouldn't be delicate. In some systems, it is possible to get rid of the effects of the piles by making a two-layer separate foundation. You can't build end piles without reinforcement, bored piles are reinforced concrete... jet grout is generally used for ground improvement. What exactly is the purpose here? That important bearing capacity, Sitting, Reaching Solid Ground. So, we come back to the beginning. Get support from a specialist in the field of geotechnical, if your project is large, or even from two different people. These controls affect the economy of the business a lot. I told you as much as I know. It would be helpful if other people told us. If we are wrong, we will know. Good work everyone...Not the answer to your questions, but I wanted to remind you anyway. Depending on the class of your building, you may need to agree with the design supervisor if nonlinearity is required. The necessary information is available in the 16th section of the earthquake code. Piles not connected to this intermediate raft foundation are in fashion.
civilization
New Member
As I understand there is an excess of 30% in ground safety. Where did you get this notion? because the calculation of the bearing capacity of the ground is not a single value as it used to be. It varies according to the size of the foundation, its depth, and the horizontal and vertical loads on the ground. Which field and laboratory experiments were carried out in the geological survey studies. As an example, in a work we did, the geological surveyor found an internal friction and cohesion with only uniaxial pressure test. more precisely, he said that the ground was clay and he accepted the direct internal friction angle as zero and gave the cohesion. The resulting value was something like 22t/m2. Scaring the contractor and architect a little, we asked for a few more experiments, even we went again and drilled or something. Our value, which was 22 at first, went up to 50. In short, question your ground a little more at first, then go to the stake. I'm sorry I went a little out of your question, but I wanted to tell you because it was an event that I experienced.
My average stress under the foundation exceeds the soil bearing strength by 30%. I meant this. Your answer is important, of course, even if it is off-topic, information is information. I thank you for that too. I stopped looking at the thread after no response for a long time. Sorry for my late reply to you too.