＂Empty heaven and earth＂ locks ＂evil dragon＂, and China’s geological disaster early warning ability opens up a big move
Our reporters Wu Xiaoying and Xie Jiao
"Do you know how to walk the dragon?" The giant sitting opposite asked.
The afternoon sun shines through the glass, making this lab full of coffee aroma warm and comfortable. However, the geological expert’s words are inseparable from the collapse of the earth. "In the past, there was an old saying in the countryside, that is, when the dragon passed, the mountain collapsed! Many fellow villagers have to ask their husbands for feng shui and dragons before repairing their houses. In fact, it is to see if there will be geological hazards in the site selection of building houses. The so-called dragon walking is a geological disaster such as large-scale mudslides. "
The State Key Laboratory of Geological Disaster Prevention and Geological Environment Protection of Chengdu University of Technology, where Professor Ju Nengpan is located, is to find out these geological "evil dragons", "lock" their breeding changes and try not to let them cause people and property damage.
On February 17, 2019, a landslide occurred in Group 9 of Longjing Village, Xingyi City, Guizhou Province. The automatic monitoring system deployed in this laboratory issued a red warning 53 minutes in advance, and finally achieved "zero casualties" and "zero losses" for on-site personnel.
In 2017, they also successfully warned the loess landslide in Heifangtai, Gansu Province several hours in advance.
The geological "evil dragons" that once sneaked underground and violently raged have gradually emerged and been monitored in front of China’s increasing scientific and technological level.
Why is it difficult to trace the "dragon" in the mountains?
China is one of the countries with the most serious geological disasters and the most threatened population in the world, and nearly 300 thousand hidden dangers of geological disasters have been identified.
At 6 o’clock on June 24, 2017, Xinmo Village, Diexi Town, Mao County, Aba Tibetan and Qiang Autonomous Prefecture, Sichuan Province. Before dawn, the rock behind the village collapsed and the whole village was covered in an instant, killing 10 people and losing 73 people.
Pei Xiangjun, a professor at Chengdu University of Technology, presided over the investigation of the cause of the accident. He confirmed to reporters that the mountain next to Xinmo Village was the epicenter of the Diexi earthquake of magnitude 7.5 in the 1930s, and this landslide was the "sequela" of the earthquake. After more than 80 years of development, after a light rain that did not cause disasters, it changed from quantitative to qualitative, leading to the overall landslide.
According to records, Diexi earthquake was an extremely terrible disaster. In that earthquake, Diexi ancient city fell vertically into Minjiang River. The earthquake also caused serious "internal injuries" to nearby mountains and rivers. The landslide in Xinmo Village shows that the development time of geological disasters exceeds cognition, and it is extremely slow but never stops.
Why did you fail to find this hidden danger after many times of danger removal? Pei Xiangjun analyzed that the cliff was steep and the landslide was 1250 meters higher than the affected village, so there was no way for human beings to drill. Dense vegetation blocks the surface, so it is difficult to find traces of disaster development by traditional geological exploration methods.
"Geological disasters are like beasts hidden in the mountains. It’s hard for you to see them or stab them." Yan Xiangjun said.
On August 14th, 2019, between Lianghong and Aidai Station in chengdu-kunming railway, tens of thousands of high rock masses suddenly collapsed, causing 17 people to lose contact, and no traces of geological disasters were found beforehand. Similar situations lead to the interruption of chengdu-kunming railway almost every year.
"There have been many catastrophic geological disasters in China recently, which are characterized by high position and high concealment. It is difficult for traditional investigation methods to find hidden dangers in advance." Xu Qiang, executive deputy director of the aforementioned State Key Laboratory, said that this is also the difficulty of the current geological disaster prevention and control.
Innovation and change of geological survey technology
"The mountain must be the bone of heaven and earth, and the heaven and earth in the town are giants. Such as man’s back and Xiang Liang. Give birth to a four-legged dragon … … There is a dragon in the high mountain, but it is distorted in the flat ground. Pingdilong rises from the high pulse, and rises from the star peak to the low point. "
These are not imaginary languages in tomb-robbing novels, but are from the book "Shake the Dragon Classic" in the Tang Dynasty. From today’s perspective, it is the geological structure and fold characteristics that predecessors have summarized.
Jiangyuan civilization in the upper reaches of the Yangtze River came from ancient times and left many traces in Sichuan. Yingpanshan prehistoric site, more than 5000 years ago, is located near Maoxian county. This large-scale central settlement site where the Yellow River civilization meets the Yangtze River civilization cleverly avoids three nearby earthquake fault zones.
Jian Chen, an archaeological expert from Chengdu Institute of Cultural Relics and Archaeology, believes that after several strong earthquakes and geological disasters in the past 5,000 years, the Yingpanshan site is basically intact, with only a slight landslide on the northern slope. This shows that the ancients had clear disaster avoidance theory and rich disaster avoidance practice in engineering site selection.
Nowadays, with the development of geological science, people have a professional identification and description of the development of geological disasters, that is, to explore the development degree of geological structure through engineering methods, that is, drilling sampling analysis.
At the top of Zheduo Mountain, a drilling rig kept roaring, and the designed drilling depth was 1090 meters, which was used to detect Zheduotang fault. According to Liu Zhijun, an expert from China Railway Second Hospital, the Zheduotang fault is an active fault, which has great influence on the construction. It is necessary to use a deep-hole drilling rig to reveal its material composition and properties. The survey of a 100-kilometer target requires thousands of wells with different depths.
Drilling exploration can obtain rich data, but it is not comprehensive to grasp the large-scale geological changes. Especially in the Hengduan Mountains and the Qinghai-Tibet Plateau, which have changed greatly, sometimes when a hole is drilled one meter further, the data obtained are completely different.
China’s geological survey technology has reached the crossroads of innovation and change.
From the ground to space, technology locks the "dragon"
If a single sample can’t be seen clearly, multiple samples will be sampled; If the single sample is unclear, just zoom in. With the popularization of high technology, mankind has ushered in a new era of aerospace exploration.
Chengdu University of Technology puts forward an integrated method of "satellite remote sensing+UAV mapping+drilling analysis", which first divides the risks of areas that people can’t reach; Then, through satellite remote sensing detection and drone mapping, vegetation is automatically "peeled off" on the three-dimensional terrain, the surface deformation amplitude is monitored, and the risks are identified and then put into the traditional engineering geological exploration means for detailed investigation.
From the early warning practice in Xingyi, Guizhou and Heifangtai, Gansu, it can be seen that this technology has been able to count down the geological disaster warning for 53 minutes.
In the monitoring video of Xingyi landslide in Guizhou, a dark mountain wall completely collapsed in the distance, and 53 minutes before that, the early warning alarm had sounded to inform the nearby personnel to evacuate, and there were no casualties. The process was completely under control.
This technology is also introduced into the field of railway construction. Liu Xiaohui, an employee of China Railway Second Hospital, personally experienced the iterative upgrade of surveying and mapping equipment: "In the past, surveying and mapping went up the mountain and down the deep ditch, relying on step by step. Sometimes, in order to measure a benchmark, I set out early in the morning, cut a big bamboo at a designated place, erect a measuring pole and then drive back. It is already night at the foot of the mountain … … Now realize ‘ Empty world ’ Integrated measurement, GPS, Beidou, aerial survey and drone are all involved in the measurement. "
The new technology has also been applied in engineering exploration such as Chongqing-Kunming high-speed railway. In addition to introducing and innovating new technologies such as high-resolution space remote sensing, unmanned aerial vehicle (UAV) survey and cross-hole electromagnetic tomography, China Railway Second Hospital also innovated relevant theories of karst geology suitable for high-speed rail project construction and constructed risk assessment methods. Many academicians have appraised that this complete set of technology is at the leading level in the world.
Looking for dragons in the ground, looking at dragons in the air, and locking dragons with technology. China’s geological disaster early warning capability has already made a big move.