"9" Landslide in Qiquan Village, Qijiahe Township, Xia County, Yuncheng City, Shanxi Province

2011From September 8th to June 2nd, 2065 438, there was continuous heavy rainfall in Qiquan Village, Qijiahe Township, Xia County, Yuncheng City, Shanxi Province, and the floors of 9 villagers' houses were protruding and the walls were cracked, with a trend of gradual expansion. On the evening of September 15, technicians from the municipal and county land departments and experts from the 2 14 geological team of Shanxi Geological Exploration Bureau rushed to the scene. On the morning of September 16, they conducted a field survey of hidden danger points, and analyzed that the landslide was in a state of imminent sliding. The leaders of the county party committee and government in Xiaxian immediately organized 1 13 households with more than 340 people to evacuate.

The landslide area is about 4 × 104m2, the average thickness of the landslide is about 10m, and the landslide volume is about 40 × 104m3, with a medium scale. 45 houses were destroyed, along the yellow roadbed 1 1,000 meters, and more than 80 mu of dry land, and the reservoir 1 seat was damaged, resulting in direct economic loss of 45.2 million yuan.

The landslide area belongs to the landform of middle and low mountains, and the terrain fluctuates greatly. The landslide is a round-backed chair with obvious boundary characteristics. It is preliminarily judged that this is a shallow nappe type soil landslide, and the sliding body is mainly composed of Quaternary plastic silty clay with a thickness of 2 ~ 12m. The sliding surface is the contact surface between the Quaternary loose layer and the underlying rock and soil, and the sliding bed is clay or conglomerate, in which joints and cracks are developed.

According to the investigation, the landslide originated in the 1980s. From June 65438 to September 0984, it rained continuously for more than 40 days in this area. The trailing edge of the landslide sank about 3. 0m, leading edge uplift, many houses cracked and collapsed. It can be seen from the drunken forest on the landslide that the landslide has been active for many years, but the amplitude is small, and there have been no incidents such as house collapse.

On 2011September 18, the landslide deformation intensified due to continuous heavy rainfall, which formed a major danger. Due to timely and accurate early warning, rapid emergency response and effective measures, the threatened people moved to avoid danger in time, causing no casualties.

2 Basic environmental background

2. 1 landform

Qiquan Village is located in the southeast of Xiaxian County, south of Zhongtiao Mountain, with high terrain in the north and low terrain in the south. The highest points are located in Xiao Mohe and Yangjiagou in the north of the village, with an altitude of112. The lowest point is at the mouth of Xiaohegou River, with an altitude of 356. 4m, with a relative height difference of 755. 6m。 The terrain in the landslide area fluctuates greatly, mostly in the form of steps. The height of steps is about 5m, and gullies are developed. Small river gullies are the main surface runoff in this area, with steep banks and V-shaped gullies. Villagers cultivate and build houses in gullies and low-lying areas.

2.2 Formation lithology

The exposed strata in the area are mainly Cenozoic and Paleozoic, and the rock and soil are described as follows from top to bottom:

(1) Quaternary Holocene alluvium (Q4al): distributed in modern river valleys, mainly composed of pebbles, with thickness ranging from 0 to 5.0m.. ..

(2) Quaternary residual (Q4cl+dl): distributed on hillsides and some hilltops, mainly composed of silty clay and local stone inclusions, with a thickness of 2.0 ~10.0m.. ..

(3) Tertiary Miocene (N 1): it is distributed in the underground of villages and the top of hillsides, and mainly consists of semi-diagenetic cemented pebbles mixed with mudstone, with a thickness of more than 200.0m.. ..

(4) Permian Upper Shihezi Formation (P2s): distributed in the west of Xiaohegou and south of the village, mainly composed of purple sandstone and mudstone, integrated on the lower Shihezi, with a thickness of about 322.0m.. ..

(5) Permian Upper Shihezi Formation (P 1x): distributed in the west of Xiaohegou and the south of the village, mainly composed of yellow-green and gray sandstone and shale interbeds, integrated on Shanxi Formation, with a thickness of about107.0m..

(6) Permian Shanxi Formation (P 1s): distributed in the east of Xiaohegou, and the rest are buried underground. It is mainly composed of seasonal sandstone, gray and black shale, sandwiched with No.2 and No.3 coals, and integrated on the Carboniferous Taiyuan Formation, with a thickness of about 26.0 meters.

(7) Carboniferous Taiyuan Formation (C2t): distributed in the east of Xiaohegou, and the rest are buried underground. It is mainly composed of gray-black Carboniferous shale, shale with limestone and No.9, 10, 1 1 coal, which is integrated on the Carboniferous benxi formation with a thickness of about 30.0 meters.

(8) Carboniferous benxi formation (C2b): distributed underground, mainly composed of gray bauxite, bauxite and Shanxi-style iron ore, unconformity parallel to Majiagou Formation of Ordovician, with a thickness of about 48.0m.

2.3 Hydrogeological conditions

The landslide area mainly includes loose rock pore water and bedrock fissure water. Pore water of loose rocks is distributed in loose accumulation body, most of which is upper stagnant water with less water. Bedrock fissure water exists in bedrock weathering fissure, and the amount of water is small. The main source of recharge is atmospheric precipitation, which is discharged in the form of springs, and the number of springs changes obviously with rainfall.

3 Monitoring and emergency hedging

In September of 20 10, Yuncheng Land and Resources Bureau conducted a comprehensive training on the prevention and control of geological disasters for the relevant staff of land and resources departments in counties and cities, including inspection, investigation, monitoring and emergency response, and established the "three inspections" system, which clarified the monitoring key points and requirements.

In view of the hidden danger point of landslide geological disaster in Qiquan Village, the county and township land departments adopt the management mode of special person in charge and cadres in charge, and determine the working system of monthly inspection once in non-flood season and twice in flood season, and encrypt inspections when abnormal or dangerous conditions are found. Inspection work mainly includes: signs of ground and building deformation, environmental changes and anomalies, unreasonable engineering activities, etc.

3. 1 Phase 1

On September 3rd, 201/kloc-0, at 9: 00 a.m., Shanxi provincial departments received reports of house deformation, ground uplift, exposed springs, cracks in roads and farmland, and quickly sent experts and village cadres to the scene to check the danger, which was judged as a precursor to landslide according to the training knowledge. After reporting to the leaders of Xiaxian Land and Resources Bureau and law enforcement brigade, nine villagers in danger were immediately evacuated and PVC was adopted. Prevent the upper water from continuing to penetrate into the landslide, and mobilize relevant professionals to monitor cracks, ground heave and house deformation 1 time every 2 hours by using patch method and steel nail method, and report the danger to the county land and resources bureau in real time.

Figure 1 Dew point of spring water in front of landslide

3.2 the second stage

On September 16, experts conducted field investigation and found that the subsidence bandwidth was 2. The extension length is 80m and the sinking depth is 20 ~ 60 cm. The ground of 9 houses in the middle of the slope is uplifted, and the maximum uplift height is 0. 6cm。 The house was severely deformed, and many springs were exposed on the ground. Judge that the landslide is in a state of imminent sliding, delineate the influence range, set the evacuation route and determine the safe-haven location (village Committee and school). It is recommended to organize evacuation immediately. The leaders of Xiaxian County Party Committee, county government and experts from the land department immediately set up the disaster relief headquarters, started the Class IV emergency response to landslide geological disasters, and organized 1 13 households to evacuate more than 340 people under threat. After nearly 7 hours of concerted efforts by the municipal emergency center, county and township transportation, civil affairs, epidemic prevention, public security and other departments, 340 people from 3 households in the landslide-affected area1/kloc-0 were finally evacuated to the safe haven, including 208 people in centralized resettlement and 32 people in decentralized resettlement/kloc-0.

That night, the experts worked out an emergency plan overnight, the contents are as follows:

(1) Two watersheds were built at the rear edge of the landslide, and five PVC pipes were used to discharge rainwater outside the landslide area.

(2) Compacting and backfilling the cracks in cultivated land, paving the cracks on the pavement with plastic sheets to prevent rainwater from continuing to infiltrate.

Fig. 2 Subgrade with staggered trailing edge of landslide

Fig. 3 toe of accumulated slope in front of landslide

(3) Assign special personnel to conduct 24-hour dynamic monitoring on cracks, ground heave and house deformation, report to the headquarters once every hour, and report to the Xiaxian county party committee and government once every two hours.

(4) Contact professional monitoring personnel to rush to the scene as soon as possible to monitor the landslide professionally.

3.3 The third stage

On September 17, the headquarters immediately organized personnel to cover the pavement cracks with plastic sheets, set up a water collection tank and drain the water from it. At that time, the danger became more and more serious, but relief tents, vegetables, oil, noodles, quilts, warm clothes and other relief materials have been transported to Qiquan Village one after another.

Shanxi Provincial Department of Land and Resources attaches great importance to this dangerous situation. After learning of the danger, director Li Jiangong called for instructions many times to ensure the safety of people's lives and property, and sent experts to the scene to guide the rescue. Du Fu, deputy mayor of Yuncheng City and director of the Municipal Bureau of Land and Resources, immediately went up the mountain in the rain to check the disaster situation. At the same time, professional monitoring personnel arrived at the scene and submitted the first monitoring data to the headquarters at 22 o'clock that night: the precipitation continued and the danger was still intensifying.

3.4 the fourth stage

On September 2 1, Yin Yueping, deputy director and chief engineer of the Geological Disaster Emergency Center of the Ministry of Land and Resources, went up the mountain to check the disaster situation and determined that Qiquan Village landslide was a rare nappe landslide in the north, which was in serious danger. It is suggested that the trailing edge of the landslide should be trimmed, the toe of the slope should be controlled by the accumulation of the leading edge, and the secondary disasters should be prevented by proper treatment.

On September 22nd, 2 14 geological team made an emergency survey of Qiquan village landslide.

On September 23, the emergency disposal work was being carried out in an orderly manner, and the danger was basically eliminated. In order to appease the affected people and restore the living order in the disaster area as soon as possible, the headquarters decided to arrange some affected people to go home, and the local party and government departments planned to rebuild their homes for more than a dozen families whose houses collapsed. At the same time, according to the expert's suggestion, the trailing edge of the landslide is cut and the leading edge is piled and rolled.

4 Experience and Enlightenment

First, attach great importance to it and make careful arrangements. Party committees and governments at all levels attach great importance to geological disasters, and careful arrangements for the prevention and control of geological disasters are the premise of doing a good job in the prevention and control of geological disasters. At the beginning of the flood season this year, the Shanxi Provincial People's Government took the prevention and control of geological disasters caused by heavy precipitation as the top priority of government work. Yuncheng Municipal Party Committee and Municipal Government attached great importance to flood control, and organized the departments of land and resources, meteorology, hydrology, water conservancy and other departments to hold an emergency flood control meeting to remind relevant government departments to do a good job in flood control dispatching and geological disaster prevention of mountain torrents in time. In the prevention and control of geological disasters, the Xiaxian county party committee and government have conscientiously achieved the "four in place" of publicity and education, disaster prevention plans, basic work and work responsibilities, laying a good foundation for the successful avoidance and emergency response of this disaster.

Second, extensive publicity and solid work. The solid work of land and resources departments and flood control departments is the key to the prevention and control of geological disasters. (1) Carry out extensive publicity and education for the masses to raise their awareness of disaster prevention and relief. During the flood season this year, the county TV station issued many announcements, mobile phone messages, emergency notices and other ways to vigorously publicize the knowledge of geological disaster prevention and control, and distributed more than 4,000 publicity materials, making the knowledge of geological disaster prevention and control a household name. ② The responsibility for disaster prevention is implemented at different levels. The Office of the Leading Group for the Prevention and Control of Geological Disasters issued a document requesting all township governments and relevant departments to perform their respective duties, make full use of the three-level network for monitoring geological disasters, comprehensively monitor hidden points of geological disasters, especially key areas, and implement round-the-clock monitoring by special personnel, report problems in time, properly handle them and take the initiative to avoid them. ③ The basic work of disaster prevention is in place. A feasible emergency plan has been formulated and a network system of group prevention and treatment has been established, so that disaster prevention work will not be chaotic. Adhere to the 24-hour duty system and make emergency response quickly in case of danger.

Third, group prevention and treatment have achieved remarkable results. Mobilizing the masses to take the initiative to prevent disasters is the basis of doing a good job in disaster prevention. The masses are not only victims of disasters, but also the main body of disaster prevention. Only by mobilizing and organizing can the geological prevention and control work be done well and achieved results. Before the disaster, Yuncheng Land and Resources Department and other relevant departments organized a landslide geological disaster prevention drill while carrying out publicity and education on geological disaster prevention, which played a very important role in the people's active participation in disaster prevention.

(This part of basic information is provided by Shanxi Provincial Department of Land and Resources and edited by Xu Yongqiang.)