Why is Qiantang River Bridge called the miracle of the world?

Because the geological conditions at the bottom of Qiantang River are quite complicated. In some places at the bottom of the river, there is silt more than 40 meters deep, with thick coarse sand pebbles below, and the bottom rock stratum obviously inclines from north to south. After repeated comparisons, the bridge builder finally chose the bridge site at the foot of Yuelun Mountain near Pagoda of Six Harmonies, Hangzhou, where the silt at the bottom of the river is thin and the water potential is relatively slow.

In order to stabilize the foundation of Qiantang River Bridge, the constructors need to drive 1.440 piles on 9 piers, and pass through 4 1 m thick sediment. Because the stake stands on the sand layer, the sand layer is thick and hard, and it can't go down lightly, but it is broken.

Faced with this dilemma, after on-the-spot investigation, the construction personnel decided to adopt the "water injection method" of pumping and piling with deep holes on thick and hard sediment. This is the first successful pneumatic caisson dredging and piling in the history of bridge construction in the world, breaking the prediction that "Qiantang River is too deep to build a bridge". Once this method is adopted, the effect is obvious and the project progress is accelerated.

Erecting steel beam

Because the traditional bridge steel beam construction adopts the "leg method", it is necessary to wait until all the piers are built in order before the steel beam can gradually penetrate into the center of the river from both sides. However, in order to catch up with the construction period, the order of pier completion is disrupted, so this method is not suitable for Qiantang River Bridge.

Therefore, the construction team, represented by Mao Yisheng, humbly asked the local people who are familiar with the hydrological laws of Qiantang River, giving full play to the collective wisdom of the construction workers. Finally, the "floating method" was invented, in which full-hole steel beams were installed on two ships filled with half-tank water, and the steel beams were safely installed in place by skillfully using the gap between the tidal bore of Qiantang River.