TheWest Line of the mega South to NorthWater Diversion project, attracting world attention, will transfer water from the upper reaches of theYangtze River to theYellow River in Qinghai plateau. It is planned to be constructed by 3 stages, costing about 500 billion RMB for transferring 17 billion m3 of water per year. Of which, the 1st stage will deliver 4 billion m3 of water. For the water supply, in the first stage of the project, 4 large dams, 7 tunnels and 2 weirs will be constructed. In this paper, based on the analysis of local natural environment, geological condition and related circumstances in the 1st stage construction of theWest Line of the mega South to NorthWater Diversion Project, double shield TBMs are recommended to be used for rapid excavation of the long, deep tunnels. In addition, several key problems concerning ventilation, high geostress, rock burst, high pressure water inflow etc. are discussed. Finally, some comments and suggestions regarding the construction of theWest Line of the mega South to North Diversion Project in China are put forward.
China has water shortages
China has poor distribution of water resources
China has to transfer water from the south to the north
The whole project consists of three main parts:
Western Line Project,
Middle Line Project,
Eastern Line Project.
These projects will divert water from the upper, middle and lower reaches of the Yangtze River (Changjiang) to northwestern and northern China respectively. Currently, the Eastern Line and Middle Line are under construction, while theWestern Line is under design.
The Project will transfer water from the upper reach of the Yangtze River to the Yellow River in Qinghai Plateau-the source region of the two rivers mentioned above.
The elevation along theWest Line is ranging from 3400 to 4800mA. S. L. with relative height difference of more than 1000 m.
The atmospheric pressure along the diversion area is only 60–70% of that on the sea level.
The oxygen content along the diversion area is 60–70% of that on the sea level.
The minimum temperature is −30°∼−40°C.
For most part of the diversion area, the mean daily air temperature is less than 0° lasting for 5–8 months per year.
The rock formations along the diversion line are consisted of slightly metamorphosed sandstone with compressive strength of 41–128 Mpaand slate with compressive strength of 21–95 Mpa.
Among them, surrounding rock masses of class II and III along the diversion line account for 90% of the total length, while class IV −9.3% and class VI −0.7%.
