Hundred Families Help Plan to rebuild a Tarim River and rock tunnel excavation method.
The excavation of rock tunnels is inevitable in water diversion projects, and its cost is high and the construction period is long. Even rocky tunnels with a diameter of 10 meters or more will cost hundreds of millions. The utilization rate of the water transfer head is low (the pressure of the reservoir in front of the hole is unstable, which will cause hydraulic loss).
The best way to achieve low-cost water transfer is to avoid rocky geological routes. Water diversion in shallow burial depths and soft soil conditions. However, under no circumstances can it be guaranteed that the rock geology will not be avoided, and the rock tunnel excavation method is still required, and the muck can be transferred, which can be converted into soil tunnel building materials or protective substrates on the water diversion line.
The selection of buried depth on the water diversion line is based on the water source and the water volume of the receiving area.
For example: from the Heihe River (weak water) in Gansu Province to the route of Lop Nur Dunhuang. It is expected that the water diversion line can adjust the water volume of 10 billion tons, use tunnels with a diameter of more than 14 meters, the total length of which does not exceed 30 kilometers, and the buried depth is less than 100 meters. Tens of billions of tons of water are also not enough for the use of the Dangxiang River basin.
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The adjustable water volume from the Tongtian River to the Qaidam Basin is also at the level of 10 billion tons. The tunnel is about 200 kilometers long, but the buried depth will be less than 150 meters. In the later stage, 20 billion tons of water can be transferred from the upper reaches of the Lancang River and the Nu River, and the water will be diverted through the canal formed by the collapse of the tunnel.
The two lines will charge less than 1 yuan per ton of water, and a total of 40 billion tons of water can be transferred to the Taklamakan Desert in Xinjiang after completion. Rebuild the Tarim River. After 20 years, there will be no more water transfer fees.
As shown in Fig. For rock tunnels, such as mountain tunnels of highways and railways, as well as water diversion and water conveyance tunnels of water conservancy and hydropower projects, there are two main excavation methods commonly used, namely drilling and blasting method and TBM (roadheader) method.
Modern tunnels are commonly used in construction and excavation methods.
Comparison of two types of tunnel excavation methods.
The circular hydraulic non-pressure tunnel with a diameter of 4m, a buried depth of 100 500m, a slope of 1 800, 40% of the surrounding rock above the class, 30% of the surrounding rock, 20% of the surrounding rock and 10% of the surrounding rock has been studied, and the economic comparison of the drilling and blasting method, open TBM and double shield TBM in the three cases of length 3km, 5km and 10km respectively.
The results show that when the length of the hole is 10km, the cost per linear meter of drilling and blasting method is 2880,000 yuan, and the cost of open TBM per linear meter is 2310,000 yuan, double shield TBM cost per linear meter is 2830,000 yuan, the drilling and blasting method increased by about 65% compared with the hole length of 3km, while the cost per linear meter of open TBM began to decrease, and decreased by 6% when the hole length was 5km, and the cost per linear meter of double shield TBM also decreased, which decreased by 12% when the hole length was 3km. The construction cost of open TBM is the lowest, the construction period is 3 months longer than that of the double shield TBM, and 16 months shorter than the construction period of the drill and blast method, and the total cost of the construction of the double shield TBM is the same as that of the drill and blast method, and the construction period is 19 months shorter than that of the drill and blast method. Regardless of the benefit of the construction period, the tunnel with a tunnel length of less than 5km adopts the drilling and blasting method, which is more economicalThe length of the tunnel is 5 9km, the cost of drilling and blasting method increases significantly, and the TBM begins to gradually reflect the advantages, and the open TBM is more economicalThe length of the hole is more than 9km, the cost of drilling and blasting method increases more obviously, and the construction advantages of TBM are obvious, the economy of TBM is better than that of drilling and blasting, the economy of open TBM is better than that of double shield TBM, and the economy of double shield TBM is better than that of drilling and blasting method.
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