At all times and in all countries, there are both good quality projects and poor quality projects. There is no denying that some ancient wisdom was really rare at that time, but the research on various aspects of engineering in ancient times was certainly not as systematic and in-depth as in modern times. So there is no comparability.
The consequences of man-made buildings against natural forces. Let's lengthen the timeline and see where the life span of man-made buildings is, even if you can carry 100 nuclear bombs, a hundred years? Two hundred years? Even if you dare to blow again, do you dare to say that the Three Gorges can coexist with the sun and the moon? The life of the Three Gorges is there. The final best result of the Three Gorges Project is artificial blasting in dry season. But no one can guarantee foolproof before death, in case it is an unbearable disaster.
There is no objection to the construction of super dams, and you can choose to build them in deep mountains and forests. We should not choose to build in the upper reaches of densely populated cities, which is the basic common sense of human hedging! This is the main reason why everyone opposes it!
1. The project has a design life when it is designed. The Three Gorges is not an ordinary reservoir project, and its design life itself is more than 500 years (500 years is the data I have learned, supplemented by accurate data). If you insist on blowing, I can't help it.
The Three Gorges was not built there and put on the grass. As long as human society is still running, it will not stop repairing and maintaining the dam. And don't underestimate human engineering technology, not to mention the continuous progress of human technology.
The Three Gorges is a gravity dam. Even if the dam breaks in a thousand years, it will not be thousands of miles away. Is this the only water conservancy facility in the whole Yangtze River? )
Any large-scale project has risks. What we should do is to reduce risks through reasonable design and avoid risks through constant maintenance, rather than avoiding risks. I agree with you that the technical demonstration and construction process should be more cautious, but as soon as it arrives? It is safe to die before death. Suggest manual blasting? ? Like many bridges, the design life is only 20 or 50 years, so it will not be used? Will human society not repair and maintain these bridges? Should these bridges be artificially bombed when the traffic flow is low now? Any large water conservancy building will be overhauled regularly. Maintenance can be carried out in stages, not that the Three Gorges Dam must be overhauled together when there is no water, but that it can be partially overhauled by some methods when there is water.
What's more, the material is not reinforced concrete as you think, but special concrete. Many experts and scholars have demonstrated such a project as the Three Gorges, and no one is a fool. The Three Gorges was built only for the sake of superficial scenery. In your opinion, the Three Gorges is actually a time bomb that will explode at any time to generate electricity (make money). However, there were two schemes at the time of scheme demonstration, and it was for flood control (protecting downstream cities) that this scheme was determined. In order to prevent flood, the first priority is safety, and the operation of the dam is very complicated. There are many very accurate measuring points in the Three Gorges, and its deformation will be monitored and maintained regularly. Structural health test? Dujiangyan also needs to be disconnected for maintenance every few years.
In order to ensure that concrete is soaked in water, there are special academicians who have done dry-wet cycles on concrete materials (in fact, as long as water conservancy projects are involved, they will do experiments and research on dry-wet cycles and freeze-thaw cycles). You do think of some problems, but designers and scientists are not fools, they also think of these problems. Some of your problems may have been solved long ago, but for some reason, you don't understand, just judge. Is it a little arrogant?
Dujiangyan has been the capital for thousands of years, and the Chengdu Plain has not been hit by floods. Do you dare to say that Dujiangyan has no flood control capacity? Before the construction of Zipingpu Reservoir, the flood did cause damage to Dujiangyan, but this damage was repaired every year in the annual maintenance, and the problem was not serious. If you know the operation principle of Dujiangyan, you will know the flood control function of Baokou and Sha Fei weir. The difference between dry season and rainy season is the way of Dujiangyan flood control, which is completely different from the principle of the reservoir now.
In fact, the life span of cement is different from that of living things, that is to say, it can reach the strength I need within this fixed number of years. After this period of time, the strength will slowly decline, rather than die instantly. Secondly, concrete can also be repaired. In some places, due to the influence of natural environment, the strength may begin to decline before reaching the fixed number of years, so it can be strengthened and improved with appropriate technology. The difference between the Three Gorges and Chernobyl is that the problems of the Three Gorges will be encountered in advance, such as dry-wet cycle and freeze-thaw cycle, and the construction can only begin after the research is completed. Chernobyl is driving ducks to the shelves, and the nuclear reactor inside is much more fierce than water. However, the Three Gorges must be reinforced repeatedly. As long as the reinforcement can still be used, it will be maintained and reinforced, just like Dujiangyan.
It is almost impossible to store water to generate electricity, prevent floods and disasters without spending money. Almost anything important has advantages and disadvantages. If you only think about the benefits and don't bear the results, you can only accomplish nothing. Human beings want to develop, starting from the earliest slash-and-burn farming, that is, to fight against heaven and earth, instead of waiting for natural evolution and the redemption of the gods. The road for mankind is to destroy the primitive nature and create a new customized ecosystem for mankind. This is the fate of mankind, that is, when it will perish on this road, and it was doomed from the first day when primitive people picked up tools.
No one can be sure whether his judgment is the most comprehensive. Therefore, this kind of winning project is better to do less. For example, water flow can take away a lot of upstream heat. Whether this thing exists or not is unknown. We are limited by our own senses, and we are doomed not to fully understand the whole world, so it doesn't mean that there will be no problems in the future, and there may be some problems lurking now. This heat refers not to the temperature, but to the heat contained in the water. If a large amount of water flows into the sea, is the heat in the water taken away, and we intercept it, which will inevitably affect the heat distribution in all parts of the whole basin, right? What kind of result this will cause is actually impossible to demonstrate. The scope of influence is too large.
Personally, the main reason why the Three Gorges has been criticized is that people don't understand water conservancy. It is taken for granted that they should store water in flood season and release water in dry season according to the requirements of the public, but they don't know that the Three Gorges only impounded some floods in flood season. Take this year's flood as an example. What they didn't see was that when the Three Gorges Reservoir put 60,000 into storage, it might release 36,000. Even in the case of a large downstream flood peak, in order to control the flow at around 20,000, the impounded part has not been taken into account by the public.
There are two problems that people have not thought deeply about:
1 If there were no Three Gorges, wouldn't there be floods? In fact, if there were no Three Gorges, all the upstream water (including the part impounded by the Three Gorges now) would be discharged and then superimposed with the downstream water, and the disaster in the downstream would be more serious.
The dam itself is safe. The flood control limited water level of Three Gorges 145, normal water level 175 and dam elevation 185. The meaning of flood control limited water level can be referenced, which means that the water level of the Three Gorges Reservoir is usually controlled at around 145 in flood season, and the flow is determined according to the incoming water in flood season and the downstream hydrological conditions. At this time, it also needs to be considered. In fact, flood control in the Three Gorges flood season is not power generation, nor is flood control unconditionally controlled. Dujiangyan has no reservoir and does not need to store water, so the public will not be harsh, and its own project has indeed achieved the tasks of flood diversion, flood discharge and sediment discharge perfectly; There are reservoirs in the Three Gorges, which can store water and drain water. It is wrong not to follow the requirements of the public.