ground investigation 中的trial pits 是什麼來的?

Please note that there are tons of underground utitilities (UU) below the ground surface.

Trial pits, which have to be done by hand tool, is used to identify any UU at the proposed GI location.

When you want to use the boring machine to drill hole, you have to dig a trial pit to check any utilities below the ground. So the pit is not for taking soil sample. Soil sample may be collected by mazier, etc.

GROUND INVESTIGATION 是指建築的探土, 探土時要開一些試井trial pits 來收集那處土地的樣本是什麼土質.