I work with someone that worked in a large coal strip mine. I didn't see this happen but heard the story from him. They were moving the large drag line. and decided to take a short cut. These machines move really slow, slower than you can walk, so the shortcut probably seemed like a good idea at the time. They got the thing stuck. My coworker worked as a supervisor at the mine at the time on a different shift. When he got to work that day they told him to get it out and all the equipment at the mine was available to him. Attached is a picture of a similar machine. I believe it took them over two days to get the thing out. It took several D8's and backhoes. They didn't pull it out but kept digging under the edges and putting rock under it. It doesn't move on tracks but has huge outriggers that pick the belly pan up, than drag the entire dragline forward, then it rests on the belly pan and the outriggers pick up and move forward and start the process again. The problem is the belly pan was stuck, almost by suction in the mud. When something this big gets stuck it really get stuck.
The size of these things has to be seen in person. It is the size of a large building. The bucket is big enough to park several pickup trucks in. They are all electric.