Assumptions about the "West Route Project of South-to-North Water Diversion"
The problems of drought and water shortage, deterioration of the ecological environment, and desertification in northwest my country have become severe challenges restricting the survival and development of the Chinese nation. The West Route of the South-to-North Water Diversion Project is widely concerned and welcomed because it will greatly improve the ecological and living environment in northwestern my country.
I. The existing major western line engineering schemes and their advantages and disadvantages
Currently, there are two major influences in the western line project plans:
One is the Western Route Water Diversion Plan Two (hereinafter referred to as the "Western Planning Plan") that passed the project planning review in 2001. The Dadu River, the Yalong River tributaries Daqu-Jiaqu joint artesian line diverts 4 billion cubic meters of water, the Yalong River Ada-Jiaqu artesian line and builds the Ada water diversion hub on the main stream of the Yalong River to divert water 5 billion cubic meters, the Tongtian River side imitates the Yalong River-Jiaqu artesian line and builds a water diversion hub on the side of the Tongtian River to transfer 8 billion cubic meters of water, forming three lines plus a second hub for a total of 17 billion water transfers The "Western Plan" of cubic meters.
The second is the "Red Flag River" project proposed by the S4679 research team in January 2018. The plan uses the Yarlung Zangbo River, Nu River, Lancang River, Jinsha River, Yalong River, and Dadu River as the water source, and bypasses the Qinghai-Tibet Plateau. The whole process of self-flow method of water transfer. The annual water transfer volume is 60 billion cubic meters.
Advantages and disadvantages of the "Western Planning Scheme": The advantages are short water transfer lines, project locations within first-level terraces (excellent geological conditions), strong seismic resistance of the project, small investment and quick results. The disadvantage is that the water diversion is located in the high-altitude area of the Qinghai-Tibet Plateau where the ecological environment is fragile. Not only is the construction conditions poor, but the water transfer may have a significant environmental impact on the high-altitude area of the Qinghai-Tibet Plateau. That is to say, the possible consequence is that the ecology of the Yellow River basin has been improved, but the ecology of the Qinghai-Tibet Plateau has been sacrificed.
The advantages and disadvantages of the "Hongqi River" scheme: The advantages are ①The water diversion points are located on the lower edge of the Qinghai-Tibet Plateau and on the main stream of large rivers with abundant water. Impact; ②The large amount of water diversion has a greater effect on improving the ecological environment of the water-receiving areas in northwest my country. Disadvantages are ① diverting the water from the Yarlung Zangbo River, endangering the Nyingchi-Yani National Ecological Wetland Park, which should cause international disputes; ② the water diversion line bypasses the Qinghai-Tibet Plateau along the first and second terrace transition zone, which has complex geological conditions and frequent high-intensity earthquakes. (I.e. the occurrence zone of the Wenchuan earthquake) will bring great harm to the stable operation of the water diversion project; ③It needs to be thousands of kilometers long, with an average mountain slope of 30°～40° and many sections even reaching 60°～70° An artificial river with an average diversion flow of about 2800 cubic meters per second was excavated on the slopes of the lofty mountains of China. From an engineering point of view, it should be a fantasy (Note: The annual water diversion of the "Hongqi River" is 60 billion cubic meters, and the frost-free period of Dadu River is 180 days. The average frost-free period of ~320 days is 250 days to calculate the water diversion, it is necessary to excavate a large river with an average flow rate greater than 2778 cubic meters per second).
Two. Principles to be followed in the West Route Project
Under scientific, reasonable, environmentally friendly, feasible and economical conditions, the principles to be followed in the west route plan of the South-to-North Water Diversion Project are as follows:
1. It is necessary to ensure that the ecological environment of the Qinghai-Tibet Plateau in the water source area is not affected. The water diversion site must be on the lower edge of the Qinghai-Tibet Plateau and on the main stream of major rivers with abundant water. From this point of view, the selection of water diversion points for the "Hongqi River" program is more reasonable.
2. In order to protect the Nyingchi-Yani national ecological wetland and avoid international disputes, water diversion from the Yarlung Zangbo River is not considered.
3. In order to avoid the great harm to the stable operation of the water diversion project caused by the first and second terrace transition zone with complex geological conditions and frequent earthquakes of high intensity, the water diversion line should avoid the first and second terrace transition zone.
From this point of view, the water diversion line of the "Western Planning Program" is more reasonable, and the water diversion line of the "Hongqi River" program in the transition zone is the Achilles heel of the program.
4. In order to improve the seismic capacity of the water diversion project, it is advisable to use a pressure diversion tunnel buried deep in the mountain to divert water.
5. The number of days available for diversion of the water diversion project should take into account the effects of the freezing period of the lead-in and lead-in areas. Based on the fact that the frost-free period of the Dadu River is 180 to 320 days (an average of 250 days), 250 days are appropriate for calculating the annual diversion volume.
6. To divert water from major rivers, dams must be used to divert water. In addition to the function of equalizing the diversion flow, the diversion reservoir can also store upstream floods to reduce the pressure of downstream flood control, and increase the ability to supply water downstream during the dry season.
7. According to international practice, in order not to affect the ecological environment of the water source extraction area, the total water withdrawal should not exceed 40% of the total runoff of each water diversion section.
3. Assumption plan for the west route of the South-to-North Water Transfer Project
Following the above seven principles, this article proposes a project plan for the west route of the South-to-North Water Diversion Project consisting of 5 diversion reservoirs + 5 diversion tunnel groups (hereinafter referred to as the "plan"). A total of 5 reservoirs were built on the Yalong River and the Dadu River. The rivers are connected by a group of caves, and then the group of caves is used to introduce water to the Liujiaxia Reservoir on the Yellow River. For the plan layout and project characteristics, see the project layout drawing and project characteristics table of the project plan for the West Route of the South-to-North Water Diversion Project.
It can be seen from the engineering layout drawing and characteristic table of the "Scenario Plan" that the "Scenario Plan" has the following characteristics:
1. Diversion of water along major rivers along the lower edge of the Qinghai-Tibet Plateau will not adversely affect the Qinghai-Tibet Plateau ecology;
2. The Nyingchi-Yani national ecological wetland is protected by not diverting water on the Yarlung Zangbo River, avoiding international disputes;
3. The water diversion line successfully avoided the first and second terrace transition zone, laying a good foundation for the stable operation of the water diversion project in the future;
4. The diversion volume of each diversion point is less than 40% of the runoff of the diversion section;
5. The water diversion method of building a reservoir and a group of pressurized water diversion tunnels is adopted, which has strong earthquake resistance. It can not only ensure the stable flow of water to the Yellow River basin, but also improve the flood control and water supply ecology in the downstream of the water diversion point;p>
6. The total annual water diversion is 38 billion cubic meters, which can greatly improve the ecological environment of the water-receiving areas of the Yellow River Basin.
But there are still three uncertainties in the "Scenario":
1. Conventional drilling and blasting methods should not be used for long tunnel excavation. If TBM (full-face hard rock tunnel boring machine) is used, can TBM be applicable to long tunnels?
2. For high geothermal, high geostress, high seismic intensity, active geothermal water environment, and tunnel excavation with a buried depth of thousands of meters, can TBM adapt to it?
3. At present, the diameter of the domestic large-diameter TBM hole is about 10 meters (the diameter of the domestic TBM Yunling cutterhead used in the Yunnan Central Yunnan Water Diversion Project is 9.83 meters), and the annual excavation speed is 10 to 14 kilometers (in Jilin Province). In the first section of the "Song-in-Chang" tunnel, the domestic TBM has a maximum monthly excavation speed of 1209.8 meters). For the Dadu River to Yellow River tunnel group with a single tunnel length of about 540 kilometers, the time required for one-way excavation is unbearable, that is, can TBM move in both directions? Can the tunnel be excavated in sections?
The currently completed Gaoligongshan Tunnel on the Dali-Rui-Li-Railway has a total length of 34.5 kilometers and a total contract cost of 3.628 billion yuan. It has high geothermal, high ground stress, high seismic intensity, active neotectonic movement, and active The high geothermal water environment, 19 fracture zones, maximum buried depth of 1155 meters and other harsh construction geological conditions, the tunnel is excavated with a TBM hard rock tunneling machine, with a cutterhead diameter of 6.39 meters. The whole tunnel adopts the auxiliary tunnel setting plan of "through flat guide + 1 inclined shaft + 2 vertical shafts". The inclined shaft is 3850 meters long and the No. 1 shaft is 762.9 meters deep. This example shows that in the face of complex geological conditions, the domestic TBM can adapt to and excavate a long tunnel in sections.
The Xianglushan tunnel with a total length of 62.596 kilometers (annual water diversion volume of 3.4 billion cubic meters) of the Yunnan-Dianzhong water diversion project was excavated by Yunling, the largest-diameter open hard rock roadheader currently made in China. The Yunling has a diameter of 9.83 meters, a weight of 2050 tons, a total length of 235 meters, a maximum thrust of 31,526 kN, a total power of 5,600 kilowatts, and a turning radius of 500 meters. It is suitable for tunneling with a slope of -8% to +8%, and has a maximum diameter of 30. Centimeters of expansion capacity.
The two TBMs in the water delivery project of Dahuofang Reservoir in Liaoning Province adopt the construction method of assembling in the tunnel, indicating that it is feasible to disassemble and assemble the TBM in the tunnel. This also solves the problem that the TBM can be repaired and replaced in the long-distance tunneling (except for the cutter head, because the overall cutter head is generally not broken and difficult to replace), indicating that TBM is suitable for long tunnels Of excavation.
Four. The required construction period of the "plan"
The construction method of the tunnel group of about 540 kilometers from the Dadu River Diversion Reservoir to the Liujiaxia Reservoir is the key point to control the construction period of the "plan". Adopting the construction method of the Gaoligongshan Tunnel on the Dali-Rui (Li) Railway with sloping tunnels, shafts and other branch tunnels, dividing the long tunnel into several sections for construction can effectively shorten the construction period. Consider dividing the 540-kilometer long cave into three sections (the section from Badi Town of Dadu River to Jimu Township of Dadu River, the section from Jimu Township to Ala Township of Taohe River in Gansu, and the section from Ala Township to Liujiaxia Reservoir), with an intermediate section of about 320 kilometers in length Two TBMs are used for construction. According to the current domestic construction technology and schedule (conservatively adopts an annual excavation speed of 10 kilometers), it will take 16 years for the tunnel to penetrate. Considering the preliminary preparations and unforeseen factors, then " The construction period required for the "Concept Plan" can be controlled within 20 years. (Note: The TBM counter-moving construction method means that at the point where the two TBMs are about to meet, the two machines are turned and staggered, and then the joints are repaired by manual drilling and blasting. The two counter-opening functions can be removed Just demolish, and those that cannot be demolished are buried in the mountains.)
V. "Scenario" investment estimate
The Gaoligongshan Tunnel is 34.5 kilometers long, with a total cost of 3.628 billion yuan and a comprehensive cost of 105 million yuan per kilometer. Taking into account the long and difficult construction of the tunnels of the "plan", taking the comprehensive cost of 200 million yuan per kilometer, the cost of 5 tunnel groups with a total length of 6550 kilometers per tunnel is about 1,310 billion yuan. At present, the unit price of each domestic TBM is about 150 million yuan to 200 million yuan (the price of the first domestic hard rock TBM "Changchun" is 180 million yuan). Taking into account that the "design plan" is the factor of ultra-long holes, take each TBM The comprehensive unit price is 400 million yuan. Taking into account factors such as TBM replacement and backup, the "concept plan" is priced at 60 TBMs, including the purchase of other required equipment, and the comprehensive equipment cost is 35 billion yuan. The five water diversion reservoirs are 170 meters high, and if each investment is 30 billion yuan, the total cost of the five reservoirs is 150 billion yuan. If the contingency fee is accrued at 30%, the estimated investment of the "plan" is: (13100+350+1500)×1.3=1.9435 billion yuan, that is, the conservative estimate of the investment in the "plan" will not exceed 20,000 100 billion yuan, the average annual investment will not exceed 100 billion yuan.
To sum up, the "concept plan" is a scientific, reasonable, environmentally friendly, economical, and existing domestically-made equipment and construction technology. It has strong seismic capacity and can safely and stably It is a feasible plan to introduce 38 billion cubic meters of high-quality water from the Yellow River by gravity, which can produce huge ecological, social, political and economic benefits.
Note: The Dadu River Diversion Reservoir and the Yalong River Diversion Reservoir in the "planning plan" can be constructed using the Dadu River Shuangjiangkou Reservoir and the Yalong River Lianghekou Reservoir currently under construction, but the "planning plan" The investment estimate should still include the investment in the Shuangjiangkou Reservoir and Lianghekou Reservoir, because the water diversion project needs to buy out the property rights of the two reservoirs and also need to compensate for the power generation losses of the two reservoirs and the downstream cascade power stations.
The Jinsha River Diversion Reservoir is built in the upper reaches of the proposed Jinsha River Yebatan Reservoir. It is recommended that the Yebatan Reservoir be moved up and merged with the Jinsha River Diversion Reservoir. The Lancang River Diversion Reservoir utilizes the planned Lancang River Kagong Reservoir. It is proposed to move the planned Kaxi Reservoir on the Nujiang River and merge it with the Nujiang River Diversion Reservoir.