1 Introduction
A landslide geological disaster occurred in Dapo Street, Dapo Township, Rong'an County, Liuzhou City, Guangxi Zhuang Autonomous Region, at 2:30 a.m. on June 19, 2014, with the central geographic location of 109°31′16″E, 25°09′07″N. There are 2 landslides***, located at the top of the artificial cut slope of the mountain on the west side of Dapo Street and the river bank below the east side of Dapo Street, one of which is 120m wide, 7.5m long and 6m thick, with a volume of 5,400m3, and a main slip direction of 123°; the other one is 70m wide, 25m long and 2m thick on average, with a volume of 3,500m3, and a main slip direction of 95°. Two landslides **** caused 8 buildings of 2 to 4 floors on Dapo Street were damaged, 1 motorcycle repair store slid into the river, the direct economic loss of about 300,000; due to the timely evacuation, avoiding casualties of 173 people in 39 households. In accordance with the "Geological Disaster Prevention and Control Regulations", its disaster is small.
2 Overview of geological disasters
2.1 Geological environmental conditions
(1) topography and geomorphology
The landslide is located in the tectonic denudation of hilly geomorphology area, where the peak elevation of the hill is 256m, the relative difference in elevation of 76m, the natural slope of the mountain slope 25 ° ~ 45 °, the growth of vegetation is lush, the coverage rate is greater than 90%. The middle and lower part of the hill is the street of Dapo Township, with the ground elevation of 180m, and the construction of buildings on both sides of the street has formed an artificial slope with a height of 24-36m and a slope of 56° on the west side, while the dumping and filling of soil on the east side has formed an artificial slope with a height of 22m and a slope of about 50°. At the foot of the slope is the Dapo River, with a riverbed elevation of 158m, a riverbank slope height of 15-22m, an average slope of the bank slope of about 45°, and the river flowing from east to west.
(2) Stratigraphic lithology and its engineering geological characteristics
The area where the landslide is located is covered by the Quaternary slope residual gravel soil, with a thickness of 3~5m and a gravel content of about 40%~50%, which has a loose structure and good water permeability, and the soil is prone to landslides and collapses along the contact surface between residual layer and bedrock. Lower Cambrian Qingxi Formation ( ) yellow-brown mudstone, muddy sandstone, weak water resistance, easy weathering, low mechanical strength, fresh rock dry compressive strength of 26.6 ~ 192MPa, softening coefficient of 0.25 ~ 0.94.
(3) Geological structure
According to the regional data, the landslide is located in the nuclear part of the Dapo - Yayao dyke, which has large changes in the inclination angle of the rock strata, and is composed of Cambrian It is composed of Cambrian strata, axial NE, 38km long and 18km wide. the regional rock yield is 140°∠68°.
(4) Hydrogeological conditions
The groundwater in the area where the landslide is located mainly consists of fissure water of clastic rock, which is stored in sandstone fissures and mainly receives recharge from the atmospheric precipitation, and is discharged from the bottom of streams and gullies, the side of the ditches and other places to form gully springs, etc. The flow rate of springs is 0.3L/min during the dry season. Spring flow in the dry season 0.3L / s, groundwater runoff modulus is generally 6 ~ 6L / s.km2, water abundance.
2.2 Geological Hazard Characteristics
Guangxi Rongan County, Liuzhou City, Rongan County, Dapo Street landslide consists of two landslides, which are located on the top of the slope above the back of Dapo Street and on the river bank below it, of which:
H1 landslide: located on the top of the man-made cut slope, with the side slope height of 24-36m and the slope gradient of 56°, and the slope residue gravel soil in the upper 4-5m, and the lower part of the strongly weathered The upper 4-5m of the slope is slope residual gravel soil, the lower part is strongly weathered mudstone and muddy sandstone, the width of the slide is 120m, the length of the slope is 7.5m, the thickness is 6m, the volume is 5400m3, the main direction of the slide is 123°, the slide is dominated by the slope residual soil, and the slide surface is the contact surface of soil and rock. The back edge of the landslide along the ridgeline produces nearly north-south arc-shaped cracks, crack width 0.1 ~ 0.8m, under the wrong 1m; the front edge of the many times produced small-scale avalanche slip, there have been nearly 800m3 of soil and stone from the top of the slope avalanche slip and down the foot of the slope of the impact on the houses, *** caused by the large slope street 8 2 ~ 4-story building damage, the slide has been piled up to some of the houses of the third floor.
H2 landslide: located in the river bank below the Dapo Street, the landslide width of 70m, slope length of 25m, an average thickness of 2m, volume of 3,500m3, the main slip direction of 95°. The leading edge of the slide was washed by the river, most of the slide has been slid into the river, a small amount of the slide piled up on the slope. The landslide caused 1 motorcycle repair store at the top of the slope to slide into the river.
2.3 Analysis of the causes of geological hazards
According to the field investigation, the occurrence of landslides is dominated by natural factors, followed by man-made factors, and is the result of the combined effect of natural and man-made factors. Among them:
H1 landslide: the upper part of the slope of the mountain where the landslide is located is the slope accumulation soil of 4-5m thick, and the underlying bedrock is mudstone; in 1997, the construction of Dapo Street cut the slope to build a house to form an artificial slope with a height of 24-36m and a slope degree of 56°, which changed the natural state of the slope, cut through the soil-rock contact surface, and formed the high and steep proximity surface, which created spatial conditions for the formation of landslides and collapses. June 18, 2014 sudden rainfall, in about 3 hours or so rainfall nearly 200mm, rainwater infiltration, resulting in rapid saturation of the soil body, soil strength reduction, self-weight increase, in addition, due to the mudstone water insulation, rainwater infiltration to the strongly weathered mudstone after seepage along the soil-rock contact surface, so that the friction of the soil-rock contact surface decreases to produce sliding.
H2 landslide: Dapo Street construction process cut slope excavation of the abandoned soil near the river bank landfill, the formation of 22m high, slope 50 ° or so of the artificial side slopes, easy to slide along the original topography of the slope produced landslides, avalanches; coupled with the place for the bend of the Dapo River, the river scouring is more intense. 18 June 2014 sudden rainfall, resulting in the river water level soaring, flooding strong scouring of the riverbank, erosion foot of the slope, triggering the sliding of the riverbank slope generated
3 Geological disaster inspection and monitoring
According to the meteorological warning information, starting from June 17, 2014, under the influence of the tropical high pressure and low-altitude shear line and other factors, there will be a strong rainfall process in most areas of Guangxi Zhuang Autonomous Region, with locally heavy rain or torrential rain. The Department of Land and Resources of the Autonomous Region, together with the Meteorological Bureau and Hydrological Bureau of the Autonomous Region, utilized various early warning and forecasting information platforms to issue timely yellow warning forecasts of geologic disaster risks to cities and counties throughout the region, and Dapo Township in Rong'an County, Liuzhou City, is one of the yellow warning areas of geologic disaster risks this time. According to the geological disaster early warning and forecast information of land and resources departments, the Party committee and government of Dapo Township, Rong'an County, Liuzhou City, started the geological prevention and control work in a timely manner according to the predetermined geologic disaster prevention and control plan, and held a meeting of all cadres and workers to urgently deploy the prevention and control of geologic disasters in the whole township and all preventive and responsive work such as flood relief, and required all relevant responsible persons, monitors and residents threatened by geologic disasters to strengthen the rain, river water conditions and Geological disaster-prone areas and hidden danger points of the duty and inspection, monitoring and other work, all efforts to do a good job of prevention and response work. Under the influence of heavy rainfall, the accumulated rainfall in Dapo Township, Rong'an County, Liuzhou City, reached 195mm in 48 hours until 16:00 on June 18, and at 2:30 a.m. on June 19, a resident in the geologic hazard-prone area of Dapo Street heard the sound of the wall at the back of his house being smashed, and immediately got up to look at it, and found that the back wall was smashed by a small piece of mud collapsing on the back hillside, and realized that it might be a precursor of a landslide on the back hillside. He realized that it might be a precursor to a landslide on the back slope, so he immediately informed his neighbors who were affected by the landslide and reported it to the local land and resources department. The local land and resources department inspection and monitoring group strengthened monitoring, to 6:00 am on June 19, the back edge of the landslide body on the hillside crack widening, the front edge of the soil accelerated sliding, is a landslide accelerated sliding phenomenon, inspection and monitoring group immediately reported to the head of the party committee and government of Dapo Township, the township party committee and the Government immediately started the landslide geohazard emergency response, in accordance with the plan of the organization of the government of the township of Dapo staff and the police station police officers to the scene to carry out emergency disposal. At 10:00 a.m. on June 19, the mountain sliding, according to the Liuzhou City, the main leaders of the instructions, Rong'an County Party Committee, the county government quickly organized a rescue team rushed to the scene of the disaster, together with the Dapo Township Party Committee, the government and other key people in charge of the composition of the front-line command department forward command, go all out to carry out emergency rescue work, emergency, orderly organization of the affected residents to evacuate, and properly do a good job of resettlement work. Due to timely warning, monitoring in place, decisive decision-making, strong measures, Rong'an County, Dapo Township successfully avoided the occurrence of 39 households of 173 people casualties, and all the affected people have been properly resettled.
4 Geological disaster avoidance and resettlement
The main measures taken in the emergency response to the "6.19" landslide geological disaster in Dapo Street are:
(1) Do a good job in advance to prepare for geologic disaster prevention and response
Since the beginning of the flood in 2014, the autonomous region has convened a flood control and drought relief television and telephone work conference, comprehensively strengthened flood control and drought relief, and strengthened flood prevention and relief. The autonomous region held a TV and telephone work conference to comprehensively strengthen the flood control and disaster prevention response work. on May 18, in Nanning City, the autonomous region held a flood control and rescue exercise to enhance the ability of all levels to deal with emergencies during the flood season. on May 28, the regional government emergency response office, the Department of Land and Resources and the Qinzhou Municipal People's Government jointly held the 2014 Geological Disaster Emergency Avoidance and Disaster Relief Exercise in Pubei County, and organized the municipalities and counties to watch the live broadcast on TV, with innovative The way to effectively improve the level of flood prevention and disaster response around the timely strengthening of the vast number of cadres and masses in our region before the flood season awareness and knowledge of geologic disaster prevention and control.
(2) strengthen the monitoring of geological disasters, early warning and forecasting work
In the Dapo Township occurred "6-19" landslide geologic disaster, according to the Rong'an County rainfall weather process, the autonomous region of land and resources departments in a timely manner to the cities and counties issued a yellow warning of the risk of geologic disasters information. Rong'an County government received the warning information, timely organization of land and resources departments and meteorological departments to strengthen emergency coordination and liaison, do a good job of real-time monitoring of rainfall and forecasting, according to real-time monitoring of rainfall and forecasting information for short-term prediction of geologic hazards, and the possibility of occurrence of geologic hazards of the time, location, the scope of disaster and the degree of impact of the prediction; and at the same time, require the government of the township of Dapo to strengthen the duty of emergency response, strengthen the Rong'an County on June 18th, there was widespread heavy rainfall, Rong'an County through the rural weather warning loudspeaker repeatedly issued weather forecast information and real-time rainfall information, which was released at 7:26 on June 18th, Dapo Township 2 hours of rainfall amounted to 62mm, 16:00 on the 18th more than 195mm, Dapo Township Party Committee, the government immediately organized staff to strengthen inspection and monitoring, and informed the whole township people to do a good job of preventive response. June 19 early morning, the affected people found the omens of geologic disasters, the local land and resources departments of geologic hazards technicians to the scene to inspect the deformation of the back of the mountain cracking, by strengthening the monitoring of the emergence of dangerous situations after the danger of the rapid report of the danger of the Dapo Township Party Committee, the Government, to provide the necessary basis for scientific decision-making. For the successful avoidance of danger to fight for the valuable evacuation time.
(3) Formation of front-line command department in charge of geologic disaster emergency response
After the occurrence of the disaster, the Party committee and government of Dapo Township started the geologic disaster prevention and control plan in a timely manner, and organized cadres and workers to take the trombone and notify the threatened people to evacuate to the safe area quickly from door to door; the main leaders of Rong'an County also rushed to the scene at the first time to start the emergency response to the geologic disaster according to the plan, and set up the geologic disaster emergency rescue and rescue team. The main leaders of Rong'an County also rushed to the scene in the first time, and started the geologic disaster emergency response according to the plan, and set up the geologic disaster emergency rescue and relief headquarters, with the secretary of the county party committee as the commander. Other county leaders as deputy commander, the establishment of monitoring group, security group, rescue group, resettlement group, logistical support group 5 emergency rescue group, each group leader by l county leaders, members of the relevant departments and bureaus composed of leaders, the emergency response team in accordance with their duties to immediately carry out disaster relief and rescue work. Monitoring group is responsible for investigating and verifying the danger, organizing monitoring and predicting the development trend and potential threat of geological disasters, delineating the danger zone, and setting up four monitoring piles at the cracks of the landslide body, and implementing round-the-clock monitoring and early warning on the changes of the landslide body; the security group is responsible for the traffic control of the important sections of the geologic disaster location, maintaining the traffic order and security order at the scene, and pulling the cordon in the danger zone, setting up warning signs, and closing the danger zone with wooden boards. The security team is responsible for the important road traffic control at the place where the geological disaster occurred, maintaining traffic order and site security order, pulling warning lines, setting up warning signs in the dangerous areas, closing the dangerous areas with wooden boards, arranging 24-hour guards, and forbidding people to go in and out of the area; the rescue team is responsible for the rescue and rescue of the residents affected by the disaster and the health rescue, and under the guidance of the experts, excavating drainage ditches in the mountains at a distance of 3m above the cracks of the back edge of the landslides, filling in the compacted cracks of the landslides, and covering the body of the landslides with colorful strips of cloth to stop the surface water from seeping into the cracks and to reduce the seepage of the rainwater and the ground water and to play a role of blocking the slip; The resettlement group is responsible for the transfer and resettlement of the threatened people and important properties, taking the family and friends, the establishment of temporary resettlement sites and other ways to resettle the affected people; logistical support group is responsible for the repair and restoration of power, communication facilities in the disaster area, the distribution of relief supplies, and other logistical support work. The emergency response team under the unified command, give full play to its role, coordinated and orderly organization of rescue work, so that the threatened 39 households 173 people successfully escape.
(4) seriously grasp the post-disaster disposal work
After the disaster, Rong'an County Government entrusted the geological disaster technical support unit Guangxi Geological Environment Monitoring General Station to put forward the landslide emergency disposal technology program, and timely convening of special meetings. On the large slope township "6-19" landslide emergency disposal of geological disasters program was discussed, and finally determined the implementation of the slopes to remove the landslide potential program, quickly commissioned professional and technical companies responsible for cleaning and engineering supervision. Program scientific, reasonable, commissioned by the company's strong professional and technical, good reputation, post-disaster follow-up work in a short period of time in an orderly, timely and solid advancement, hidden danger is also expected to be fundamentally eliminated.
5 Experience and inspiration
(1) Leadership attention is a prerequisite
After the occurrence of the danger, the city and county governments and relevant departments attached great importance to. The city's main leading comrades made important instructions, county leaders forward command, the units quickly responded to the landslide site to organize and carry out the evacuation of people, hidden dangers, victims resettlement and other work, to ensure that the lives and property of the people in the landslide hazardous area safety.
Rong'an County leading cadres strongly support the work of geological disaster prevention and control. Every year, the county government held a special meeting on the prevention and control of geological disasters; issued a document to clarify the focus of prevention, the annual flood season county leaders are led to the key hidden danger points to check and supervise the clear implementation of preventive responsibilities and preventive measures.
(2) publicity and training is the foundation
Rongan County focus on geologic disaster prevention and control publicity and training. Each year, nearly 70,000 yuan for geo-hazard publicity and training funds, through radio and television, newspapers and magazines and other media to widely publicize the knowledge of geo-hazard prevention and control, and to take advantage of the "Earth Day", "Land Day", "March 3" and other festivals to take a variety of forms. "and other festivals to take a variety of forms of geohazard prevention and control knowledge propaganda; annual distribution of more than 10,000 copies of publicity materials, more than 1,200 copies of the card, in the geohazard-prone areas, important disaster sites and highway routes to set up a warning sign 260, so that knowledge of geohazard prevention and control really do into the "point"! "
Announcement
Each year before the flood season, Rong'an County Government organizes professional and technical personnel from the land and resources department to carry out geological disaster prevention and control knowledge training for 12 township cadres, village cadres, principals of primary and secondary schools, monitors and other relevant personnel in the county, combined with the type of geologic hazards in the county characteristics, in plain language to the masses of cadres and masses of geologic hazards prevention and control knowledge to enable them to master the classification of geologic hazards and the various types of The county government also organizes annual training courses on land and resource management, which are organized by the land and resource management department of the county. The county government also organizes land and resources and other relevant departments to go deep into the county's important geologic disaster sites, targeted emergency drills to carry out emergency geologic disaster avoidance, so that the masses can really grasp and use the knowledge of geologic disaster prevention and control, and constantly improve the ability to save themselves and each other from geologic disasters and the level of self-rescue.
(3) The group survey and group defense is fundamental
The Rong'an County government has always attached importance to the group survey and group defense work, and has always taken it as an important means to monitor the danger. Every year, the Liuzhou Municipal Government and the county government, the county government and township government, township government and village committees and monitors signed a working certificate of responsibility, the responsibility for the prevention and control of geologic hazards decomposition and implementation. Form a horizontal to the edge, vertical to the end of the work pattern. Rong'an county government invests more than 200,000 yuan each year to establish and maintain the operation of the county's group monitoring and prevention system, and at present *** implement 307 geologic disaster monitors, implement the management of subdivided areas, covering all the geologic disaster prone areas and hidden danger points in the county's 12 townships, to ensure that the annual flood season when the investigation, inspection and verification work is carried out effectively. When encountering disasters and dangers, can timely up and down linkage, give full play to the role of group monitoring and prevention, effective prevention and reduction of geologic disasters caused by casualties and property losses.
(4) Geological disaster early warning in time is the key
Timely and accurate geological disaster early warning information played an important role in this successful risk avoidance, in the autonomous region, the city of the two levels of geologic disaster forecasting and warning information platform issued by the early warning information, Rong'an County, arranged for people to carry out the collection and collation of geologic disaster forecasting and warning, and encountered extreme meteorological conditions, and in a timely manner through the SMS platform to send the early warning information to the whole country, the whole country, and the whole country. In 2014, more than 21,000 pieces of meteorological warning information on geological disasters have been issued. At the same time, the meteorological department of the autonomous region installed 14 rural meteorological warning loudspeakers in 12 townships of Rong'an County, releasing real-time meteorological warning and forecasting information; the land and resources department of the autonomous region installed 4 sets of geologic disaster automatic monitors in important geologic disaster hidden spots, such as Dabang Tun of Futian Village of Ya Yaoyao Township, and Erwo Tun of Liangbei Village of Dongqi Township, Rong'an County, to carry out real-time and effective monitoring in a scientific way, so as to let the general masses know and prepare early for the meteorological warning information. Meteorological warning information early understanding, early preparation, early detection of geologic disasters, early stop, early treatment, maximize the loss of geologic disasters will be reduced to a minimum.
(5) Geological disaster emergency plan is a guarantee
Rong'an County, according to the townships and townships of the actual situation of geologic disasters in a timely manner to adjust the county leading group of geologic disaster prevention and control work, the introduction of the "Rong'an County Emergency Response Plan for Emergencies in Emergencies of Geologic Disasters", "Rong'an County Geologic Disaster Prevention and Control Program", and the corresponding modifications to improve the townships and villages and townships of the hidden disaster prevention and prevention plan, strict implementation of the geologic disaster Inspection, duty, rapid reporting and other systems to effectively ensure that after the discovery of dangerous situations, the county party committee, the county government can start the emergency response in a timely manner, in accordance with the emergency plan to carry out emergency response work in an orderly manner, so that "the hands have a plan, the heart does not panic.
(6) Scientific disposal of geological disasters is the focus
In the process of heavy rainfall, the Rong'an County Party Committee and the county government require all townships and relevant functional departments to strengthen the geologic disaster emergency watch, strengthen the inspection and monitoring of geologic disaster hazardous areas, geologic disaster prone areas; according to real-time monitoring of rainfall and forecast information for short-term real-time early warning of geologic disasters; in the rescue and relief process, the decision-making is decisive, scientific disposal, and the rescue and relief work is carried out in an orderly manner. In the process of rescue and relief, the decision-making is decisive, scientific disposal, the rescue team under the guidance of experts, from the back edge of the landslide fissure 3m above the mountain to excavate drainage ditches, fill and abandon the landslide fissure, cover the landslide body with colorful strips of cloth to prevent surface water from seeping into the fissure, to reduce the infiltration of rainwater and surface water, to play a role as a barrier to the slippery; the establishment of four monitoring stakes in the landslide body fissure, the implementation of the change of the body of landslides all day round-the-clock monitoring and early-warning; the Dangerous areas to pull the cordon, set up warning signs, maintenance of traffic order and site security order, with wooden boards closed to the dangerous areas, arrange for 24-hour guards, strictly prohibit the entry and exit of people; take the family and friends, set up temporary resettlement sites and other ways to resettle the affected people; regularly informed of the disaster disposal situation and accelerate the progress of the reconstruction, take the initiative to communicate with the disaster victims to stabilize the ideological and emotional well-being of the victims and so on are all scientific and effective geologic disasters. Emergency response measures.
(7) Communication innovation is the highlight
Rongan County also makes reasonable use of modern network media, the use of cell phone WeChat to establish a "rural Rongan" WeChat group, bringing together the county, township and township levels of the government's leading cadres and the main person in charge of the relevant departments, not only to strengthen the usual business communication and contact, and effectively realize the information ***sharing, innovation, and the development of a new way of communication. Information **** enjoy, innovative information communication methods, but also in the disposal of sudden geological disasters can better play the timeliness, more convenient on-site command in a timely, scientific and effective way to take strong, more perfect disposal measures.