There are two forms of buried pipe in pile foundation:
1. Buried pipe between piles.
Burying pipes between piles refers to burying pipes between piles of building foundation. This method is basically the same as outdoor underground pipe construction, and the only thing that needs attention is to cooperate with civil engineering.
a) When the foundation pit of civil engineering is dug well and the pile is completed, the underground pipe will be placed in the site, and the construction period is tight, because too long a construction period will make the foundation pit soil dry, which will have an impact on the construction, and will also affect the construction progress of civil engineering.
b) It should also be noted that the buried pipe needs to be lowered a few meters more, because it is not excluded that the foundation pit needs to be leveled or continue digging after you finish the buried pipe. In this case, part of the buried pipe will be cut off, so the pipe length must be reserved.
2. Buried pipes in piles.
Burying pipes in piles means that buried pipes are placed in the piles of buildings, and there is no need to drill wells separately. The advantage of this method is that it saves the cost of drilling wells. Matters needing attention in construction are as follows:
a) The depth of buried pipes in piles is less than the deepest depth of driven piles, and most of them are about 3 meters, so there will be a lot of piles for buried pipes. This should be done in the design stage.
b) The buried pipe in the pile should be closely combined with civil piling. When laying the pipe, the buried pipe should be fixed on a finished steel bracket first, and then put into the hole of hollow pile or cast-in-place pile. After laying the pipe, it should be poured, and be careful not to damage the pipe.
c) The most difficult thing to do for buried pipes in piles is how to connect the horizontal pipes in the part of foundation pile caps. Be sure to come out from the side of the pile cap, not from above. Of course, it is ok to come out as a computer room, but if it is not a computer room, it cannot come out from above.
In fact, there are still many benefits of burying pipes under the building foundation. For example, pipes are hard to be damaged, because outdoor underground pipes may be damaged due to the change of outdoor ground conditions, so there is no concern under the building.
The above answer is based on my personal experience, and I hope it will be helpful to the landlord.
Answer to supplementary question:
1) According to the project I have done, the pressure question asked by the landlord should not exist in the vertical buried pipe part, so we only need to consider the horizontal connection buried pipe.
The structural bearing point of the building itself should be on the load-bearing piles, and it will not be evenly distributed on the whole foundation plane. Even if there is one on the foundation plane, it is very small. Therefore, in fact, the focus is on the project of burying pipes in piles, and the project of burying pipes between piles does not need to consider the pressure given by the building at all.
if the pipe is buried in the pile, the position where the pipe is most likely to be compressed due to the bearing capacity of the building is the pile cap position of the pile foundation, which also happens to be the joint of the horizontal connecting pipe of the buried pipe in the pile. Here, we can consider adding steel pipe sleeves to solve the problem, as we did in a project.
2) if the building is in settlement, it is hard damage, and it is impossible to guarantee the integrity of the buried pipe. The buried pipe itself has a certain ductility, which can be deformed within a small limit without being damaged. Even if protective measures such as casing are taken, it can only resist vertical pressure to a certain extent, but it cannot guarantee the damage caused by the change of buried pipe environment. At this point, all forms of ground source heat pump projects should consider the future terrain changes and other factors before doing it.