The boys wanted to study engineering this year. Sadly, I couldn't find a good engineering curriculum for them. Happily, we made our own curriculum. Each week, they watch a video about engineering. Right now, we're watching Extreme Engineering. After watching the video, they write a narration about the video. Throughout the week, they draw something for the subject, read books about the subject, and where applicable, make a model of the subject. This is Dominic's narration for this week.
Tunneling Under the Alps
There were a lot of traffic jams in the streets of Switzerland. The reason for this is because Switzerland is practically in the middle of Europe. It has trucks from Germany, England, everywhere, flowing in and out of Switzerland. They decided to make the streets less crowded by tunneling under the Alps. To do this, they had to use huge TBMs, also called Tunnel Boring Machines. Their main enemy was the rock. The enemy changed. Sometimes it was the rock, changing from hard to soft rock. The TBMs were meant for tunneling through hard rock, so they had to tunnel through the soft rock the old fashioned way, drilling and blowing it up. Another enemy was water because they had to place concrete to make the shelling of the tunnels. They had to do this because the water pressure could get so great it could crack the concrete and start flowing into the tunnel. So, they designed a drain sequence with one shell of plastic, where the water fell around it into the draining sequence, and a second shell of plastic to seal off any other water left from the first layer. Then, they put huge metal molds and poured the concrete behind them. They kept some water running over the concrete as it dried so that the concrete didn't crack. When the concrete was dry, they removed the metal molds, making the walls of the tunnel.