This is a very long river on the edge of the desert, with a total length of two thousand kilometers. Outflowing from the eastern foothills of Oasis Mountain, there are more than twenty broad tributaries that crisscross each other, forming a river network. Like a general leading his soldiers, they flow eastward into the Yellow River.
I saw that the scope of the water area was getting wider and wider. From a distance, I saw a large plain with high and low mountains and hills. The trickle turned into a rushing river. The plains and mountains were divided into grids.
The car parked in the driveway and crossed some small rivers, but stopped when it encountered a wide river.
Zheng Xiling said: "Can these parking vehicles be driven directly across the river? Can the river be submerged to build the vehicles?"
Qi Yanliang said: "It shouldn't work. The wires will short-circuit when exposed to water."
Zheng Xiling said: "It would be nice if there was a waterproof device."
Dai Zhao said: "But it should be difficult to add a waterproof layer, and these rivers are very deep. In some places, it is 10 meters to 20 meters. Then the construction vehicles will be completely submerged and there will be no way to cross."
Zheng Xiling said: "What should we do? Otherwise, just go around."
Qi Yanliang said: "Can we use the same method as in the gully just now, which is to use two pillars below and then build a simple bridge."
Dai Zhao said: "But we have already spent two construction trucks. The two construction trucks slipped and fell into the deep valley. There is no way to climb up again. We have no extra construction trucks."
Dai Zhao walked up and down along the river, and then looked around again.
Zheng Xiling said: "What are you looking at?"
Dai Zhao said: "I remember that there should be an underground tunnel near here, but only part of it was dug out, and the entrance and exit were later sealed."
Qi Yanliang said: "You are talking about tunnels. Don't the underground tunnels go through those mountains?"
Dai Zhao said: "There is also a tunnel under the river, which can pass through the river."
Dai Zhao walked around, always looking for the entrance to the original tunnel. Dai Zhao participated in a construction task many years ago and accumulated more experience in tunnel construction during this construction.
At that time, they wanted to open a road that would extend from Oasis City to Yu City. But there are deserts, Gobis, mountains, and rivers in the middle. They built roads in the desert and Gobi, and later encountered rivers.
They are trying to use a TBM to create a tunnel under the river from below.
Car thieves are always complaining, why didn't others build the bridge?
On the one hand, he is complaining about everything, but on the other hand, he is doing nothing. Shift all responsibilities to other engineers and city lords.
Dai Zhao said: "We ourselves are engineers. Tools are used to transform the world. We ourselves research and manufacture tools. We can transform the world ourselves. Why should we wait for others? Why should we pass the responsibility to others?"
"Such a big project cannot be completed by a small group of us. We still need to wait for the city lord to speak and mobilize others to do it."
But back then, when Dai Zhao was full of energy and most motivated, he thought that the tunnel project under the river would be completed soon. It was already halfway built, so why did it stop again.
Dai Zhao said: "You are only concerned about your own petty profits. If you have immediate benefits, you will do it. If you don't have immediate benefits, you will not do it. You may even benefit yourself at the expense of others."
Shu said: "The benefits you talk about are too far away and unrealistic. So what if I only care about the immediate benefits."
The tunnel under the river, which could have been completed soon, was delayed again and again, and finally stopped.
He pulled out the original water map. I think this entrance should be nearby. Qi Yanliang took down the detector from the car. Probe nearby for the hollow part below.
This unfinished tunnel is 1,200 meters long and 12 meters wide in diameter, which means that it can accommodate cars and large construction vehicles in both directions.
The river water here carries a large amount of sediment downstream from the plateau. When it reaches here, the flow speed slows down, causing the sand to settle on the river bed. The sediment may collapse at any time, causing all previous efforts to be wasted, and may even kill the construction workers. And buried in it, the transportation around here is very inconvenient.
The underground cavity detector uses geological radar to emit electromagnetic waves. When the electromagnetic waves encounter unfavorable geological bodies underground, they will produce strong reflections. After the receiving and acquisition system, they are presented in the form of images on the computer system. By analyzing these images, suspicious points are screened out. During the measurement process, interfering factors such as small holes are eliminated, and then the confirmed holes are verified to finally determine their location and size.
The young man also followed Qi Yanliang to search, and finally discovered the location of the underground cavity. The corresponding relationship between the location of this cavity and the river is that the location below the river near the bank of the cavity should be the entrance.
Dai Zhao said: "This should be the entrance, so bring the construction machinery truck over and drive out the shield machine inside."
The construction machinery truck drove over again. The boy liked the car very much and was very curious. Every time it drove out, some novel large-scale construction machinery and equipment would always come out of it. What came out this time was a cylindrical construction machine.
This is an earth pressure shield machine, also known as a soil-cutting closed type or soil-pressurized shield. There is a full-section cutting cutterhead at its front end, and a sealed cabin for storing cutting soil behind the cutting cutterhead. A long cylindrical screw conveyor is installed at the lower part of the center line of the sealed cabin, and an entrance and exit are provided at one end of the conveyor. The so-called earth pressure balance means that the cut soil and muddy water in the sealed cabin fill the sealed cabin and have an appropriate pressure to balance the earth pressure on the excavation surface to reduce disturbance to the soil and control surface settlement. This kind of shield is mainly suitable for clayey soil or silt sand soil with a certain degree of cohesiveness. There are now new types of earth pressure balance shields that add water or mud, which can be applied to a variety of soil layers.
The basic principle of earth pressure balance shield is that the cutterhead cuts the soil layer, and the cut soil enters the soil cavity. While the soil in the soil cavity is balanced with the pressure of the excavation surface, it is excavated by the screw conveyor in the soil cavity and installed. The earth-discharging device at the earth-discharging port performs continuous excavation in a state where the amount of excavation and the amount of advancement are balanced.
Qi Yanliang drew a line at both ends of the river, which happened to pass through the cavity that he could detect with his detector. On the shore, he deduced that this should be the original entrance location. Dai Zhao ordered the shield machine to start digging from here. Because the cavity below has been excavated, the shield machine only needs to be mounted on the trailer and driven forward without excavation work. Then it reaches the place close to the other side of the river, and then excavates. The excavation task at the original exit location continues to be completed.
Qi Yanliang said: "There is sand and mud down here, so can the excavation task here be completed? Is the tunnel down here strong?"
Dai Zhao said: "There should be no problem. This kind of shield machine is suitable for use in this soft sand environment. Moreover, the tunnel below has been completed and reinforced. There is no need to re-build and Reinforcement.”
The excavation surface stabilization mechanism of the earth pressure balance shield can be divided into two types according to geological conditions. One is suitable for clay soil layers such as silt, clay, etc. with small internal friction angles and easy flow; the other is It is suitable for sand, gravel, etc. that have a large internal friction angle, are not easy to flow, and have high water permeability.
The Earth Pressure Balance Shield is more suitable for advancing in weak alluvial soil layers, but when advancing in gravel layers or sandy soil layers, the characteristics of the Earth Pressure Balance Shield can also be exerted after adding appropriate soil.
The shield machine dug out the entrance, and the mud was transported outside and piled on the bank of the river. After the shield machine went down, everyone used a booster to push it onto the trailer. The trailer drove in the relatively wide tunnel below, and finally arrived at We reached the location below the other side of the river, where the passage was not completed, and the shield machine continued to dig. The excess soil was piled on both sides of the tunnel. Finally, the shield machine finally came out from the exit position, and both ends of the tunnel were opened. The construction vehicles were built one by one, passing through the tunnel under the river.
