Landslide (collapse) type and case analysis in Shenzhen

As of December 25, the number of landslide accidents in Shenzhen was changed from 76 to 75. Tian Zeming, the first survivor, was trapped for 67 hours and saved. The Shenzhen City landslide accident strikes the dregs around the city. Behind every ever-expanding city, there may be a building rubbish mountain. Beijing, Nanjing, Jinan and other cities all have similar situations.

A spot of concrete pouring collapsed, horrible excavation site!

“11.20” Special Major Collapse Accident at Gaoyangzhai Tunnel Entrance of Hubei Enshi Yiwan Railway (35 deaths)

Hunan Phoenix Bridge collapsed (36 deaths)

How to solve this problem is what the local government needs to think about. How to ensure the safety of people's lives is not only the responsibility of the government, but also the citizens themselves should have security emergency knowledge in this area. Let's take a look at the types of collapse accidents and their case studies.

Collapse accident characteristics

1. Basic Concepts Collapse accident refers to accidents caused by collapse of buildings, structures, stacks, and landslides. It is suitable for collapse due to improper design or construction, and collapse accidents such as earthwork, gravel, etc. For example, when a building collapses, a scaffold collapses, a formwork frame collapses, a mobile operation platform collapses, a dumping platform overturns, earth and stone collapse when digging trenches, pits, and holes, and the wall collapses. It does not apply to accidents caused by explosions or explosions.

2. Environment, industry and features of collapse accidents
1) The main environment: It usually occurs during construction operations and the use of various types of equipment and facilities.
2) Major industries: Most of them are concentrated in construction, bridges, road excavation and construction of related enterprise houses, repairs, demolition, and warehouse storage.
3) Collapse features: This type of accident is caused by collapse (collapse) of a large number of objects, a wide range of operations, often injuring many people with serious consequences, and is a major or major personnel casualty accident.

Collapse accident case

1. After the accident
Section xx highway K20+440-K20+910 is an excavation section for road cuttings, and a company with x provinces, roads and bridges is under construction. Among them, the area where the accident happened is on the right side of the K20+750-K20+757 line. In this design, there is no anti-slide pile or anchor rod for the slope protection in the design. Instead, a skeleton above the first platform is used for protection and the lower part is 4m high. 1.2m, 1: 0.25 slope C20 stone concrete retaining wall.
At 6:50 on October 26, 2006, six workers from the Luqiao First Company team dismantled the stencil according to the piece of stone concrete retaining wall section arranged on the right side of the K20+750-K20+757 line that was completed on the 24th. At 7:06, about ten cubic meters of earth and rock slopes suddenly collapsed, resulting in the backing of the template steel tube inside the retaining wall. The Yang Moumou, Hou Moumou, and Cao Moumou who were under construction were buried. At 8:10, the on-site personnel dug three people out and sent them to nearby hospitals. Yang Moumou and Hou Moumou were rescued and died at 9:20 and 9:40 on the same day because they were buried for too long. Cao some cracks in the ribs, causing general safety responsibility accidents.

2. Analysis of the cause of the accident
1) Direct Causes (1) Poor soil quality, loose soil, fractured rock mass, poor combination between layers, joint direction of the rock piece and the line are parallel, which is not conducive to the stability of the slope, and sudden looseness and collapse of the rock and earth is the cause of the accident. direct cause.
(2) The hazard identification of the team at the scene is not comprehensive, and the hidden trouble investigation and rectification is not in place. If the soil of the slope is not effectively reinforced and protected, and the sideline of the slope is not observed, the blind organization personnel will enter the danger. Site clean-up site construction is the direct cause of the accident.
2) Indirect causes (1) Improper rescue methods. When the accident occurred, the personnel were buried between the retaining wall and the mountain that was poured two days ago. The distance between them was less than 1m. When rescued, the rescue personnel entered the excavation from both sides of the 7m-long retaining wall, which greatly delayed the best time for rescue and caused the injured to bury it for too long. At the time, there was an excavator less than 50m from the site. The on-site commanders did not decisively use the excavator to pull down the 4m high retaining wall to rescue the buried personnel. Improper rescue measures are the main cause of casualties.
(2) Corrugated slab concrete retaining wall formwork supporting steel pipe, no support plate is set on the support surface of the cutting slope, but is supported directly on the cutting slope surface by an adjustable support, and at the same time there is no vertical and horizontal connection between supporting steel pipes to form As a whole, the failure of the design of the retaining wall formwork support system is an important cause of accidents.
(3) There is a weak link in the construction organization of the project. In the case of poor geological conditions, unstable slope, and no specially designed protection and treatment measures, the foundation trench is excavated too long and the retaining wall slab concrete is not stratified. Pouring is an important cause of accidents.

3. Accident conclusion This is a responsibility accident

4. Improvement measures (1) Strengthen leadership and strengthen construction site management. Strictly follow the principle of “Four not misses” to conduct a safety re-education for all construction personnel, organize the study of laws, regulations, standards, and regulations concerning safe production, and focus on strengthening safety technical knowledge, support for retaining walls, and special safety for demolition. The technical disclosure and relevant operating procedures are studied to enhance the operator's safety awareness and self-defense capability.
(2) People-oriented, strengthen safety education, raise the awareness of safety of all operators, further strengthen the implementation of safety production responsibility system and safety inspection system, improve the safety management system, define safety responsibilities, and form a horizontal-to-edge, vertical monitoring network .
(3) Thoroughly do a hidden trouble investigation work. Where there may be a collapsed part, measures must be taken to adopt a reinforcement or unloading plan to eliminate the dangerous source.
(4) In the case of a good soil structure during excavation, the back formwork should be eliminated and the soil form should be used to reduce the risk of mold removal.
(5) Loose soil at the time of excavation. Under the condition of ensuring safety, the back stacks the straw bag stacking with sand and gravel instead of the template to reduce the risk of demoulding.
(6) For excavation construction, take one excavation and the length is not more than 7m when the soil quality is good, and the soil quality is not more than 5m when it is poor.
(1) The concrete shall be placed at a height of not more than 2m at a time, and shall be filled at the back in time.
(8) Continue to strengthen safety inspections in the construction process, forecast in advance, advance control, and further improve the accident emergency plan system, improve the ability to respond to emergencies, and reduce accident losses.