(Enorth.com.cn)Comparing with underwater express passing through the underwater of the lake, the viaduct and the overpass bridge on the expressway will lose their attractions. This is the first time for Tianjin to construct such a project. It is known that the city has begin to construct a underwater tunnel that pass through the Xidahu Lake of Beining Park, thus, the Eastern Longitudinal Expressway will realize the ground and underground connection. At present, the foundation pit of tunnel is in digging. In the future, an unbelievable picture with ships sail in the water and cars run under the lake will be showed.
On the locale of the construction, the water in the lake has been taken out, a great foundation pit appears at the bottom of the lake. Steel girders have been used to support the top, and the underground tunnel of the expressway will be built in this pit. The technologists said that, the lake is of a depth of 2m, and the silt in it is of a depth of 1.3m. The water in this lake will be taken out and transferred to other lakes and the silt will be cleaned up for digging the tunnel. Then, the silt will be filled back, and the water will be infused back. Since the Xidahu Lake is an important sight of the park, it should be reverted to the original look after the construction.
According to the related staff, the tunnel starts from the Zhichengdao Overpass in the north to the junction of front Zhongfang Street and Wanliucun Street in the south. It passes through the bottom of Beizhan Overpass and crossed uprightly with Zhongshan Road, and finally extends into the bottom of the Xidahu Lake. On average, the distance between the bottom of the lake and the tunnel is about 1m, and the tunnel is 1.25 km long. There are 6 double-way driveways, one upper tunnel and one lower tunnel. The width of each tunnel is 13.25m, and has 3 single-way driveways. The height of the tunnel is 5.2m and the max height of the car should be 4.5m.
The standards for designing the road surface of the underwater tunnel are different from that for the expressway. The tunnel will allow buses and large trucks to pass through it. Since the tunnel and the viaduct have an equal performance in the traffic capacity, the traffic will not be affected.
A technologist said, “Underground space of a city is a kind of fortune, and reasonable development and use of it will not only save the land resources but also reduce the conflicts caused by the intension of the land use. It is real a fantastic project to construct a underwater expressway at the bottom of Xidahu Lake.”
Unveil the secret of the underwater tunnel
1.How to solve the problem of ventilation?
The tunnel is under the ground, so the ventilation of the inner part is of great importance. It is know that jet fan will be installed in the tunnel to solve the problem. The jet fan units will be installed every 200m and will be operated for 24 hours each day. Thus, the best ventilation effect will be achieved.
2.How to guarantee the safety?
According to the designer, the designs on the fireproofing and waterproofing are strict. The wall of the tunnel adopts special fireproofing materials. The waterproofing work focuses on the disposal of the top. When the top of the tunnel is constructed, special waterproofing materials will be adopted to guarantee that water will not flow in the tunnel. In addition, lightings will be installed in the tunnel to guarantee the visibility inside.