The world’s first ultra-high voltage integrated pipe gallery across the Yangtze River connected
In the north guiding station in Nantong economic and technological development zone at 9:12 on 21 August morning, as tunnel boring machine ‘Zhuo Yue’ came out of the soil, the world’s first ultra-high voltage tunnel project in deepest depth with highest water pressure – Sutong GIL(gas insulated transmission line) integrated pipe gallery was joined all through.
Huainan- Nanjing – Shanghai 1000 kilovolt ultra-high voltage alternating current transmission and transformation project is one of the 12 major electricity transmission channels of national action plan of air pollution control and prevention, is an important part of East China ultra-high voltage main grid. The project was approved by National Development and Reform Commission on 21 April 2014 and was started in July of that year.
Sutong GIL integrated pipe gallery is a part of Huainan-Nanjing-Shanghai project. It is located at 1 km upstream of Sutong Yangtze River Bridge. It starts from the south bank (Suzhou) lead station and stops at the north bank (Nantong) lead station. The length of the tunnel is 5468.5m. The diameter of the tunnel boring machine is 12.07m. It is hailed as the greatest tunnel of the Yangtze River. It is also the first time in the world that ultra-high voltage GIL is used in important transmission channels. The pipe gallery reserved two 500 kilovolt cable areas and spaces for municipal general pipelines including telecommunication and TV cables. ‘One time construction, multiple benefits’ can be realized.
Since the tunnel boring machine started on 28 June 2017 until the tunnel was completed, 14 months have passed. The average daily boring length is 14.12m, which is a new record of global large diameter tunnel boring machine construction.
There are lots of technical difficulties for construction of such long distance tunnel under the Yangtze River. Why not cross the river from the top, but build a tunnel? As Mao Xintong from owner project department of state grid Jiangsu electric power co., Ltd. explained, the width across the Yangtze River is over 5000m, if overhead construction was used, the height of steel rack tower would be over 400. There would be great technical difficulty and the cost would be high, ever more than GIL construction. The river surface area between Nantong and Suzhou is the golden waterway of the Yangtze River. Across the river using integrated pipe gallery can prevent the influence to the Yangtze River shipping lane of overhead construction, save precious land resources and promote protection of the Yangtze River.
The investment of Sutong GIL integrated pipe gallery project is 4.764 billion Yuan. The planned completion and start of operation is in next September. After completion, it can reduce about100 million tons of coal used for electricity generating, 480 thousand tons of sulfur dioxide, 470 thousand tons of nitrogen oxide and 60 thousand tons of smoke. In the future, east China ultra-high voltage alternating current net which goes through Anhui, Jiangsu, Zhejiang and Shanghai will be formed through this channel.
▲Sutong GIL integrated pipe gallery boring site