Welcome to class number two on the subject of support of excavation (SOE). Before we get into the new material, I want to recap some of the methods covered in class one. The first one is a trench box that is certainly the quickest and simplest device you can use, but it has some obvious shortcomings. It requires a good deal of space, and also it requires a space which is completely free of utilities. Therefore, it's use is somewhat limited. You will rarely see it out in a typical Suburban Street.
The next method is Timber sheeting. This is perhaps the most widely used method. It's extremely versatile, and it can be installed in almost any shape any configuration, and works very well around existing utilities. This makes it extremely useful and helpful in many, situations. You can also use tight board sheeting to get a very tight installation, which limits the amount of water entering the excavation.it can even be extended somewhat below the water table. This is an excellent solution for a wide variety of excavation problems.
The next method is soldier piles and lagging. That is certainly the go-to method. The first one you should look at when the excavations are getting deeper and wider and can no longer be accommodated by timber sheeting. Some of the important features of soldier piles and lagging is that you can vary the spacing of the soldier piles to accommodate existing utilities. You can also accommodate utilities as you install the lagging between the soldier piles, and that makes it extremely helpful.
Finally, if you're in an area with some obstructions, you can shift the soldier pile, and very often avoid the obstruction or muscle your way through an obstruction. This is an excellent system. You'll find that this is a very useful tool for you to have.
The last method is steel sheet piling. That is the method you go to when you're operating below the water table. Steel sheet piling gives you a continuous uninterrupted surface, which is substantially watertight. Of course, all of the utilities must be cleared before hand to use steel sheet piling.
Again and again, I mention utilities. This is an often neglected subject, but it is well worth investing a good deal of time in exploring what utilities exist and how they need to be accommodated. Early in the project, you should perform preliminary excavations test pit excavations to confirm the actual locations of the utilities. That advanced work will help you achieve successful projects.
I'd like to go back and review some material with respect to driving the steel sheet, piling. As you can see, the sheets are driven in a progressive way. And this is very important. Here's a sheet that's only been partially driven. This joining sheet is substantially driven, and finally, the sheet is fully driven. It's important to advance the sheets as a group as a unit. And only when you can get several sheets perfectly aligned, then you can fall back and drive sheets to their full length.
You should also lay down a horizontal member as a guide to ensure that the sheets are aligned and remain in place, and the finished product winds up exactly where you want it.