Assignment 9A

After the overturn, Dr. Fuji was so stupefied and so tightly squeezed by the beams gripping his chest that he was unable to move at first, and he hung there about twenty minutes in the darkened morning. Then a thought which came to him_that soon the tide would be running in through the estuaries and his head would be submerged_inspired him to fearful activity; he wriggled and turned and exerted what strength he could (though his left arm, because of the pain in his shoulder, was useless), and before long he had freed himself from the vise. (p22-23)

I think that this passage doesn't tell me much about Dr.Fuji freed himself. I understand that he get caught in something and he tried to let himself freed. I want to know what happen in this passage and how did Dr.Fuji freed himself.