What Are Landslides?

Landslides refer to a certain portion of rock and soil on the slope of a mountain slope, which is subject to gravity (including the gravity of the rock and soil itself and the dynamic and static pressure of groundwater), and generates shear displacement along a certain weak structural surface (band) to move to the slope as a whole. The role and phenomenon of the downward movement. Commonly known as "walking the mountain", "falling the mountain", "floor sliding", "slippery" and so on. Is one of the common geological disasters.

Landslide

The intensity of landslide activity is mainly related to the scale of the landslide, the speed of the landslide, the distance of the landslide, its accumulated potential energy, and the functions it produces. Generally speaking, the higher the position of the landslide body, the larger the volume, the faster the moving speed, and the longer the moving distance, the higher the landslide activity intensity and the greater the harm. Specifically, the factors affecting the intensity of landslide activity are:

(1) Terrain. The greater the slope and height difference, the greater the landslide position energy, and the higher the landslide speed. The openness of the terrain in front of the slope has a great influence on the magnitude of the slip distance. The more open the terrain, the greater the slip distance.

(2) Lithology. The higher and more complete the mechanical strength of the rock and soil that make up the landslide body, the fewer landslides tend to be. The rock and soil properties that make up the landslide surface directly affect the level of landslide speed. Generally speaking, the lower the mechanical strength of the landslide surface, the higher the speed of the landslide body.

(3) Geological structure. The more developed the geological structure that cuts and separates the slope, the larger and larger the scale of landslide formation.

(4) Predisposing factors. The stronger the external factors that induce landslide activity, the greater the landslide activity intensity. For example, landslides induced by strong earthquakes and heavy rains are mostly high-speed landslides.

Induced Factors Affecting Landslide Activity Time and Its Regularity

The landslide activity time is mainly related to various external factors that induce the landslide, such as earthquakes, cooling, freezing and thawing, tsunami, storm surge and human activities. There are roughly the following rules:

(1) Simultaneity. Some landslides are active immediately after being affected by the trigger. When strong earthquakes, heavy rains, tsunamis, storm surges, and unreasonable human activities occur, such as excavation and blasting, a large number of landslides will appear.

(2) Hysteresis. Some landslides occur slightly later than the time that induces the factors. After rainfall, snowmelt, tsunami, storm surge and human activities. This kind of lag is most obvious in rainfall-induced landslides. These landslides occur mostly after heavy rain, heavy rain and long continuous rainfall. The length of the lag time is related to the lithology, structure and rainfall of the landslide . Generally speaking, the looser the landslide body, the more developed the fissures, and the larger the rainfall, the shorter the lag time. In addition, landslides that occur after artificial excavation of slope feet, after loading and reservoir storage and drainage also fall into this category. The lag time of landslides caused by human activities is related to the intensity of human activities and the original stability of the landslides. The greater the intensity of human activity and the lower the stability of the landslide body, the shorter the lag time.

Inducing factors affecting the spatial distribution of landslides and their laws

The spatial distribution of landslides is mainly related to geological factors and climate. The following areas are usually prone and frequent areas of landslides:

(1) Bank, river, lake (reservoir), sea, ditch bank slopes, canyon areas with large terrain differences, mountainous areas, railways, highways, and slopes of engineering buildings. These zones provide favorable landform conditions for landslide formation.

(2) Among geological structural belts, such as fault zones,

(1) Establish a geological hazard monitoring and early warning system project. Establish a monitoring team combining professionals and group surveys and group defenses, set up professional team-based monitoring networks for important geological hazards, set up group surveys and group defenses as main points for other geological disasters, and guide and regularly inspect with professional teams Combined monitoring sites, real-time monitoring of geological disasters in mountainous areas through professional monitoring systems, mass monitoring and prevention monitoring systems, and information systems, prevent geological disasters for the government and relevant departments, protect people's lives and property, and prevent and reduce disasters. Implementation provides scientific basis and technical support.

(2) Establish expert analysis system for mountain geological disasters. After a landslide is in danger, the local government s geological disaster prevention and control headquarters will convene a meeting of experts in the field of disasters and related experts to analyze the information collected by the monitoring and early warning system, determine the status and early warning level of the landslide, and estimate the impact of the surge. Scope, forming consultation opinions for local government decision-making reference.

(3) Determine the issuing department of early warning information and regulate the form of issuing early warning information. The "Emergency Response Law of the People's Republic of China" stipulates that when natural disasters, accidents, or public health events that can be warned are about to occur or the probability of their occurrence is increasing, local people's governments at or above the county level shall, in accordance with relevant laws and administrative regulations. Issue the corresponding level of alert and procedures prescribed by the State Council, decide and announce that the area concerned enters the early warning period, and report to the people's government at the next higher level, if necessary, report it to the next level, and report to the local garrison and neighboring or related areas that may be harmed People's Government Bulletin. Therefore, the early warning information should be clearly issued by the local government in a formal form, and each department should take corresponding measures according to the early warning level issued by the local government.

(4) Establish a linkage mechanism. The landslide disaster prevention and relief work involves all aspects of monitoring, early warning, disposal, and disaster relief. It requires all units, departments and departments to perform their duties and cooperate closely. Only under the unified leadership of the local government, all relevant units cooperate and take the initiative to act Only by actively responding can we minimize or reduce the losses caused by landslides. ^[2]

Different types, different properties and different characteristics of landslides will show different anomalies before sliding. Signs of a landslide are shown. In general, there are the following:

(1) Before the big slide. At the foot of the leading edge of the landslide, there is a phenomenon of spring water resurrection that has been blocked for many years, or there is a sudden abrupt spring dryness, a sudden abnormality in the well water level, and the like.

(2) In the landslide body. Horizontal and longitudinal radial cracks appear in the front, which reflects that the landslide body is pushed forward and blocked, and it has entered the state of sliding.

(3) Before the big slide. At the foot of the leading edge of the landslide body, the soil appears to be uplifted, which is a significant phenomenon of landslide pushing forward. There is a cracking rock or being squeezed by shearing. This phenomenon reflects deep deformation and fracture. Animals are very sensitive to this and have abnormal reactions.

(4) Before the slip. Small collapses and relaxations will occur in the surrounding rock mass. If there is long-term displacement observation data in the landslide body, before the large slide, both the horizontal displacement and the vertical displacement, there will be an accelerated change trend. This is a clear sign of Linhuan. The cracks at the trailing edge of the landslide sharply expanded, and hot or cold wind emerged from the cracks. Before the landslide, the animals in the range of the landslide body were frightened and the plants were abnormal. For example, pigs, dogs, and cows are terrified and do not fall asleep. Withered or skewed trees. ^[1]

Basis for judging the stability of landslides

After the landslide, if you observe the landslide body from a macro perspective in the field, you can roughly judge its stability according to some external signs and characteristics.

Sign of stabilized landslide body

(1) The back wall is high, covered with trees, no scratches can be found, and it is very stable.

(2) The landslide platform is wide and flattened, the soil is compact and there is subsidence.

(1) Power mobilization. According to the situation of the scene, the lighting, anti-chemical rescue, emergency rescue, logistic support and other consumption

Landslides not only cause casualties and property damage within a certain range, but also pose a serious threat to nearby road traffic. ^[2]

(1) Artificial respiration. Before performing artificial respiration, first remove the dirt from the patient's mouth, remove the movable dentures from the mouth, then tilt the head back, lift the lower jaw, and unband the pine top to avoid affecting the thorax movement. The artificial rescuing rescuer is located on the side of the patient's head, holding the patient's jaw with one hand to lean back as much as possible, and tightening the patient's nostril with the other hand to prevent air leakage, and then take a deep breath and quickly breathe the air into the patient's lung Inside. Immediately after blowing, leave the patient's mouth, and loosen the hand that blows the nose, so that the blown-in gas will be naturally discharged, and at the same time, observe whether the chest of the patient is undulating. Adults can inhale repeatedly about 16 times per minute and children 20 times per minute until the patient can breathe on their own.

(2) Cardiac massage. If the patient's heartbeat stops, he should perform cardiac massage at the same time as artificial respiration. If two people are rescued, one person presses the heart 5 times and the other inhales 1 time, alternately. If rescued by a single person, press the heart 15 times and blow 2 times alternately. When pressing, the patient should lie supine on a solid bed or floor, with the head tilted back. The rescuer is located on the side of the patient's lying side with his hands overlapping and his fingertips facing upwards. Two horizontal fingers), apply force vertically and evenly, and pay attention to add your own weight. Press your arms vertically and press down the sternum for 3 to 5 cm, then relax to allow blood to flow into the heart, but the root of the palm should not leave the chest wall. Adult patients can press about 80 times per minute with short, powerful movements and continuous. Generally, after breathing for 1 minute, check the patient's breathing and pulse once, and then check it every 3 minutes until the effect is achieved. ^[3]

At 4:00 on July 17, 2014, due to the continuous heavy rainfall, a sudden landslide in the Dakuo Formation of Dakuo Village, Heitu Township, Zhijin County, Guizhou Province, caused an estimated 14,000 cubic meters of landslide, causing 8 people to be buried. As of 10:00, the search and rescue team has searched and rescued two injured people, and the remaining 6 are still in intense search and rescue.

At about 14:45 on July 17, 2014, a landslide occurred at K774 + 600m of National Highway 213 (near Shidaguan Township Chaoxian Station), and the amount of landslides reached more than 3,000 square meters. Of the 19 wounded, 6 of them have been transferred to Chengdu Huaxi Hospital. Nine vehicles were found to have been smashed, including one truck, seven trolleys and one pickup truck.

At 18:40 on July 17, 2014, a landslide in Maoxian County, Sichuan, killed 10 people and injured 19. Fan Tianyong, director of the Deyang People's Hospital, a member of the Deyang Medical Experts Group trapped in the landslide, was hit by a flying stone. His chest and abdomen were seriously injured. He was killed after rescue.

The Deyang medical expert team was on their way to aid Tibet and was preparing to replace the last batch of aid teams. As a result, they encountered a landslide on the road. Fan Tianyong has been identified by Deyang as dying from work.
At 19:53 on July 17, 2014, the road collapsed in Shidaguan Township, Maoxian County had been rushed through, and vehicles in the past could pass unilaterally. ^[5]

At 11:30 on April 21, 2016, a landslide disaster occurred next to Liuxiu Village Primary School, Fushi Town, Rong'an County, Guangxi Province. At that time, boulder rushed into the classroom, causing the school's classrooms in the first and second grades of the school to collapse. In this disaster, 21 elementary school students were injured in varying degrees ^[6] .

At about 5 am on May 8, 2016, a landslide occurred in Kaishan Township, Taining County, Sanming City, Fujian Province, causing an office building at the Chitan Hydropower Plant to be collapsed and a project site accommodation shed to be buried. At present, 39 people have lost contact and 2 have been killed ^[7] .

At 5:45 on the morning of June 24, 2017, a sudden landslide in Xinmo Village, Diexi Town, Mao County, Sichuan, with a volume of 18 million cubic meters. The mountain collapsed, causing a river blockage of 2 kilometers and more than 100 people buried.