Read about START-PROF pipe stress analysis software
Analysis of buried piping with resting supports, guides and other restraints is indefinite task, because support loads depends a lot on accuracy of the mounting. For example, resting supports is added to take a huge weight of a heavy valve. Guides added to fix the pipeline position in flooded soils on piles. Also guides are added at entrance to underground chambers, channels and buildings.
On the picture below three behavior options are shown.
First option - a. Supports are placed at the same level as the trench bottom. In this case the load on the support will be zero because the pipe in supported by soil on the trench bottom.
Second option - b. Supports are placed lower than the trench bottom. For example, piles are hammered a few millimeters below the trench bottom. In this case the load on the support will be zero too because all the pipe weight and weight of backfill soil is taken by the trench bottom.
Third option - c. Supports are placed higher than the trench bottom. For example, piles are hammered a few millimeters higher than the trench bottom. In this case the load on the supports will be huge because all the pipe weight and weight of backfill soil is taken by the supports.
Resting support (pile) on the buried piping modelling
a - piles are hammered at the same level as the trench bottom, b - piles are hammered below the level of the trench bottom, c - piles are hammered above the level of the trench bottom
1 - soil surface, 2 - pipe, 3 - reaction of the trench bottom soil, 4 - support (pile), q - backfilling soil weight, R - reaction in the pile
The real buried support loads depends a lot on mounting accuracy. The small support movement upward or downward cause the great difference in support load. The mounting accuracy is impossible to perform so accurate. That's because of this task is indefinite.
Below is the small example. The buried pipeline with 4 supports. Support 2 has no movement, support 4 has 3 mm downward movement, support 6 has 3 mm upward movement, support 8 has 10 mm upward movement.
The support loads are zero for 2 and 4 supports, 1.6 ton for support 6 and 5.4 ton for support 8.
