The sin of design
Civil Engineer
Another design institute has suffered!
The connection between the retaining wall and the steel structure was not clarified in the design documents, and the design intent and design documents were not explained to the construction unit and the supervision unit before construction, resulting in a reduction in the quality of the construction project at the source.
The cause of the collapse of the wall
Civil Engineer
Through the on-site inspection, testing and identification of the collapsed wall and expert demonstration, it is comprehensively determined that the factors that cause the overall collapse of the outer retaining wall of the plant are mainly internal causes and inducements.
1. There are congenital defects in the engineering quality of the outer retaining wall of the plant, and there are serious safety hazards.
It is mainly manifested in: first, the structural column, ring beam and parapet of the perimeter retaining wall are not effectively connected with the main steel frame; second, the height-thickness ratio of the perimeter retaining wall and the typical column spacing of the structural column do not meet the requirements of the specification (2); third, the concrete compressive strength of the foundation beam of the perimeter retaining wall, and the steel lap anchorage of the structural column and the window lintel do not meet the requirements of the code. As a result, the out-of-plane stable bearing capacity of the periphery retaining wall itself is much lower than the gravity load, and it cannot be kept stable, which is the internal factor that causes the overall overturning and collapse of the wall.
2. There are no fire protection measures for the main steel structure of the plant, which fails to delay the heating process of the steel structure.
After testing and identification, there is no fire protection coating on the surface of the main steel structure of the plant, which does not meet the design requirements, resulting in the rapid thermal expansion of the steel frame under the fire state, and the outward tilt of the wall caused by the uneven heating of the inner and outer sides of the outer wall, the use of the steel structure beyond the design conditions and the technical transformation, etc., are important inducing factors for the overall overturning and collapse of the wall.
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According to the report, at about 18:36 on August 5, 2023, a fire broke out in Jiangxi Zhongnan Environmental Protection Equipment Co., Ltd., Ganzhou Economic and Technological Development Zone, with a fire area of about 700 square meters, and the retaining wall on the northeast side of the plant collapsed during the fire fighting battle, resulting in the death of 2 fire rescue personnel, 15 fire rescue personnel were injured, and the direct economic loss was more than 670 yuan. After the accident, in accordance with relevant laws and regulations, the provincial government set up a "8.5" general fire accident investigation team (hereinafter referred to as the accident investigation team) of Jiangxi Zhongnan Environmental Protection Equipment Co., Ltd. in Ganzhou Economic and Technological Development Zone, led by the Provincial Emergency Management Department, the Provincial Fire and Rescue Corps, the Provincial Public Security Department, the Provincial Department of Housing and Urban-Rural Development, the Provincial Department of Industry and Information Technology, the Provincial Federation of Trade Unions and the Ganzhou Municipal People's Government. The accident investigation team invited the Provincial Commission for Discipline Inspection and the Provincial Supervision Commission to intervene in the accident investigation in a timely manner. After investigation, it was determined that the "8.5" general fire accident of Jiangxi Zhongnan Environmental Protection Equipment Co., Ltd. in Ganzhou Economic and Technological Development Zone was a production safety liability accident caused by serious violations of laws and regulations by relevant enterprises, non-implementation of main responsibilities, and failure of local governments and their relevant departments and units to perform their duties. 1. Basic information of the accident (1) The situation of the plant where the fire started. The fire plant is located at No. 25, Pingfengling Road, Ganzhou Economic and Technological Development Zone, and the property right unit is Jiangxi Sumitomo Fuji Elevator Co., Ltd. (hereinafter referred to as Sumitomo Elevator Company). The plant is a three-span portal steel frame light house steel structure, single-storey (partial 2 floors), 198.2 meters long, 80.3 meters wide, and 11 meters high (the middle span was upgraded to 13.5 meters before the accident). 1. Plant construction. The construction of the fire plant started in May 2018, and the name of the construction project is "Jiangxi Sumitomo Fuji Elevator Co., Ltd. Annual Output of 4,500 Elevator Production Project - Plant". The construction unit is Sumitomo Elevator Company, the design unit is Jiangxi Provincial Co-construction Engineering Design Institute Co., Ltd., the design is a class E plant, the design fire resistance level is Class II, the drawing review unit is Ganzhou Xinzhu Construction Engineering Construction Drawing Design Review Co., Ltd., the construction unit is Ganzhou Dongxin Construction Engineering Co., Ltd., and the supervision unit is Ganzhou Zhengdong Engineering Construction Supervision Consulting Co., Ltd. The plant construction project obtained the planning permission for construction land in November 2017, the construction project planning permit in May 2018, the construction project construction permit in October 2018, the fire protection design record in November 2018, the project was completed in August 2019, with a built-up area of about 16,000 square meters, and the completion acceptance record was completed in June 2020.
2. Plant leasing. After the completion of the plant, the elevator company did not use the plant for its annual output of 4,500 elevators for the production project, but successively leased the 1# and 2# workshops to Jiangxi Zhongnan Environmental Protection Equipment Co., Ltd. (hereinafter referred to as Zhongnan Environmental Protection Company), and leased the 3# workshop to Ganzhou Saikewell Technology Co., Ltd. (the company provided part of the 3# workshop to the partner Jiangxi Lixinda High-tech Equipment Co., Ltd. for free use).
3. Renovation of plant heightening. According to the production demand, Zhongnan Environmental Protection Company put forward the requirements for plant heightening to Sumitomo Elevator Company. On March 15, 2023, Sumitomo Elevator Co., Ltd. applied to the Ganzhou Economic and Technological Development Zone Bureau of the Ganzhou Municipal Bureau of Natural Resources for the change of planning permission for plant heightening and renovation in the form of an application letter. On March 17, 2023, the Ganzhou Economic and Technological Development Zone Bureau of the Ganzhou Municipal Bureau of Natural Resources replied to Sumitomo Elevator Co., Ltd. to adjust the height of the second span plant from 11 meters to 13.5 meters. On April 28, 2023, Sumitomo Elevator Co., Ltd. and Jiangxi Changding Construction Engineering Co., Ltd. (hereinafter referred to as Changding Engineering Co., Ltd.) signed a construction contract for the construction of Sumitomo Elevator Company's plant heightening and renovation project, which is to increase the steel structure of the G-D/1-22 axis area (2# workshop) by 2.5 meters. In July 2023, Hu Mouqi, the legal representative of Changding Engineering Company, handed over the heightening renovation project to his cousin Long Mousheng, and then Long Mousheng found Xiong Mouhua to convene personnel for renovation construction. (2) The course of the fire. At about 15 o'clock in the afternoon of August 5, 2023, according to the construction arrangement of the "Plant Renovation Project", Xiong Mouhua, the construction team leader, led 10 construction personnel such as Zhang and Li to work in different locations in the 2# workshop in 4 groups. Among them, Zhang and Li Mouping carried out gas cutting and installed overhead crane track operations at the G-axis position in the factory. From 16:46 to 16:53, Zhang used an air cutting gun to cut screws and angle irons on the G-14 steel column, and adjusted the size of the bolt hole. At about 18:36, Xiong Mouhua, who was checking the construction situation in the workshop, found that the PPR tank (tank height of about 4 meters) located in the PPR tank (about 4 meters high) located under the north side of the 2nd column (G axis) in the northeast to southwest direction and the 14th (G-14) steel column in the northeast to southeast direction of the plant was on fire.
(3) Fire emergency response and assessment. 1. The initial extinguishing of the fire. At about 18:36, Xiong Mouhua immediately shouted for help after discovering the fire. The on-site construction personnel tried to extinguish the fire, and first used the hobby lifting platform to carry people to extinguish the fire, but due to the deep tank tank, the fire extinguisher could not be sprayed to the root of the flame, and the fire extinguishing was ineffective and the fire gradually increased. At about 18:39, employees of Zhongnan Environmental Protection Company operated an overhead crane to try to transfer the PPR tank around the fire site, but failed due to the large fire. At about 18:41, the employees of Zhongnan Environmental Protection Company connected the portable fire hose in the workshop and handed it over to the fire extinguishing personnel on the lifting platform of the curved arm truck to extinguish the fire, but due to the insufficient water output of the portable fire hose, the fire extinguishing was still ineffective. At 18:42, employees of Zhongnan Environmental Protection Company used their mobile phones to call 119 to call the police. At about 18:49, due to the ineffective fire extinguishing at the scene, the fire was out of control, and the on-site personnel were evacuated one after another. 2. Fire fighting and rescue situation. At 18:42, the command center of the Ganzhou Fire and Rescue Detachment (hereinafter referred to as the detachment) received the alarm and successively dispatched 4 brigades, 5 fire stations, 4 full-time government fire brigades, 23 fire trucks, and 95 fire rescue personnel to the scene for disposal, and the detachment's full-service command headquarters was dispatched. At 18:49, the Ganzhou Economic and Technological Development Zone Fire and Rescue Brigade (hereinafter referred to as the brigade) led 5 vehicles and 20 people from the Jintan Avenue Fire and Rescue Station to the scene, immediately organized the evacuation of personnel, and set up 2 water cannons at Gate 1 and Gate 3 of the plant to control the fire. At 18:52, 4 vehicles and 20 people from 4 government full-time fire brigades under the brigade arrived at the scene one after another, and a water cannon was added to Gate 1 to control the fire. At 19:02, the fire spread further. The detachment's Yingbin Avenue special service station reinforcements 5 vehicles and 22 people arrived at the scene, and added 1 mobile water cannon and 1 water cannon at Gate 3 to control the fire, and used high-spray trucks to suppress the fire from a high position. At 19:12, the outer wall on the northeast side of the plant collapsed outward in an instant (the length of the collapse was about 175 meters), and the on-site safety officer immediately issued an emergency evacuation order, but because there was no warning of the collapse, 17 commanders and fighters could not avoid danger and were injured or buried by the collapsed wall. The brigade quickly set up 3 search and rescue teams to carry out rescue, and 5 vehicles and 20 people from the Hongqi Avenue Fire and Rescue Station and Special Service Station that arrived one after another immediately joined the search and rescue operation. As of 19:28, 16 injured people were rescued and sent to the hospital for treatment (one of them died after resuscitation). At 19:30, there was still 1 full-time government firefighter who was buried, and the detachment's full-service command arrived at the scene and re-established two search and rescue teams to carry out search and rescue under the cover of water cannons. At 19:40, 2 vehicles and 6 people from the Shixingling Fire and Rescue Station in Rongjiang New District arrived at the scene and used a high-spray truck to control the fire at a high level in the east corner of the plant. At 19:43, one full-time government firefighter who was buried was rescued and immediately sent to the hospital for treatment (died after rescue efforts). At 19:45, the on-site command decided to set up 2 mobile guns on the northeast side of the plant for long-range strikes, 1 fire extinguishing robot on the northwest side, and 2 high-spray trucks on the southwest side to cool the roof of the plant. At 19:50, 2 vehicles and 7 people from the Ganxin Avenue Fire and Rescue Station arrived at the scene and rotated as a reserve force. At 23:50, the fire was completely extinguished. (4) Casualties and losses. The fire accident itself caused no casualties, but the collapse of the parapet wall on the northeast side of the plant killed 2 fire rescue personnel and injured 15 others (1). According to the statistics of "Statistical Methods for Fire Losses" (XF185-2014), the direct economic loss of fire is more than 670 yuan. 2. Analysis of the cause of the accident (1) Identification of the cause of the fire. According to the results of on-site investigation, on-site test, and evidence extracted from the fire scene, combined with witness testimony and video analysis, the factors of spontaneous combustion, residual fire, electrical fault, and fire caused by the production process were ruled out. The comprehensive determination of the cause of the fire is: during the elevation and renovation of the steel structure of the 2# workshop (G-D axis of the plant) leased by Zhongnan Environmental Protection Company, the gas cutting operators carried out unlicensed illegal thermal cutting operations in the area above the fire point, and the high-temperature metal slag that fell from the splash ignited the PPR tank and other combustibles placed in the 1# workshop (G-K axis of the plant) immediately below the working face, causing a fire.
(2) Analysis of the causes of wall collapse. Through the on-site inspection, testing and identification of the collapsed wall and expert demonstration, it is comprehensively determined that the factors that cause the overall collapse of the outer retaining wall of the plant are mainly internal causes and inducements. 1. There are congenital defects in the engineering quality of the outer retaining wall of the plant, and there are serious safety hazards. It is mainly manifested in: first, the structural column, ring beam and parapet of the perimeter retaining wall are not effectively connected with the main steel frame; second, the height-thickness ratio of the perimeter retaining wall and the typical column spacing of the structural column do not meet the requirements of the specification (2); third, the concrete compressive strength of the foundation beam of the perimeter retaining wall, and the steel lap anchorage of the structural column and the window lintel do not meet the requirements of the code. As a result, the out-of-plane stable bearing capacity of the periphery retaining wall itself is much lower than the gravity load, and it cannot be kept stable, which is the internal factor that causes the overall overturning and collapse of the wall. 2. There are no fire protection measures for the main steel structure of the plant, which fails to delay the heating process of the steel structure. After testing and identification, there is no fire protection coating on the surface of the main steel structure of the plant, which does not meet the design requirements, resulting in the rapid thermal expansion of the steel frame under the fire state, and the outward tilt of the wall caused by the uneven heating of the inner and outer sides of the outer wall, the use of the steel structure beyond the design conditions and the technical transformation, etc., are important inducing factors for the overall overturning and collapse of the wall.
(3) Causes of casualties of fire and rescue personnel. 1. There are major safety hazards in the building structure. There is a hidden danger of insufficient stability of the collapsed wall, and there are serious structural safety hazards in the masonry perimeter retaining wall structure due to the non-strict implementation of relevant national specifications in design and construction (1). At the same time, a reinforced concrete ring beam is set up at an elevation of 3.3 meters and 9.8 meters above sea level of the collapsed wall, and the huge gravitational potential energy produces a strong destructive force when it collapses, causing serious damage to fire rescue personnel and vehicles. 2. The overall overturning and collapse time is short and the harm is great. The time for the masonry perimeter wall of the brick-concrete structure to collapse in the event of a fire is less than one-third of the normal fire-resistant design requirements, and it is difficult to predict in advance. The masonry perimeter wall near the K-14 steel column on the northeast side of the plant suddenly overturned outward, driving the adjacent walls with a span of 175 meters to instantly overturn and collapse within 3 seconds.
3. The combat operation surface of fire fighting is limited. The circular lane on all sides of the fire plant is only the northeast lane to facilitate the operation of fire fighting vehicles, the lane is about 12m wide, which is the closest to the fire area, and this operation face is equipped with five entrance and exit openings to facilitate quick internal attack. The width of the lane in other directions is narrow, the distance to the area of fire is increased several times, and there are three entities that do not catch fire. There are a number of cars parked on all lanes, and there are polypropylene, steel frames, finished plastic buckets and other items on the northeast side of the fire extinguishing operation to occupy the road and pile up, resulting in the limited development of fire rescue vehicles, and the vehicle parking position is close to the outer parapet wall of the plant, and it is impossible to reserve enough safety distance.
3. The main problems exposed by the accident (1) Relevant enterprises 1. Jiangxi Zhongnan Environmental Protection Equipment Co., Ltd. As the lessee of the burning plant and the controlling shareholder of Sumitomo Elevator Company, first, he has a weak sense of safety and engages in PPR in the Class E plant Second, the main responsibility for safety production is not implemented, the safety education and training and hidden danger investigation system are not implemented, the emergency plan is not formulated and the drill is carried out, the on-site safety management is chaotic, and during the construction of the plant heightening and transformation, the production site is not properly separated from the fire prevention and the combustibles at the operation site are not cleaned up, and the production is still organized and the construction unit is allowed to carry out the hot work in violation of regulations; the third is to organize production in violation of regulations, and the production is illegal in the new production plant without obtaining the industrial product production license。 2. Jiangxi Sumitomo Fuji Elevator Co., Ltd. As a fire plant construction (property rights) unit, the first is not to conscientiously fulfill the primary responsibility of the construction unit for the quality of the project, and entrust the project supervision task to the Zhengdong supervision company that has an equity relationship with the construction unit, resulting in the on-site construction supervision workflow in the form, and arranging personnel without relevant qualifications to participate in the on-site management of the design, construction and supervision units. The second is to change the use of the plant at will, lease the Class E plant to the unit of Class C production process to engage in production operations, and do not sign a safety management agreement with the three tenants, fail to coordinate and manage the safety production and fire protection work in a unified manner, and fail to conduct regular safety inspections. Supervise and rectify hidden dangers, especially in the case of knowing that there are cracks in the outer walls of the plant, not to deal with them, and let the risks and hidden dangers exist for a long time; This eventually led to a fire and a collapse of the wall. 3. Jiangxi Changding Construction Engineering Co., Ltd. As the construction unit of the plant heightening and renovation project of Sumitomo Elevator Company, the main responsibility for production safety was not implemented, the safety production management organization was not established, the safety production responsibility system and safety production rules and regulations for all employees were not established and improved, and the safety production education and training and assessment were not organized, and the safety management was seriously lacking; the plant heightening and renovation project did not prepare the construction organization design, did not arrange full-time safety management personnel, did not establish a fire safety responsibility system, did not formulate an emergency plan, and did not organize targeted fire drills; in violation of regulations, Long Mousheng, who had not obtained the qualification certificate of the constructor, was arranged to be the person in charge of the project, and Zhang Mousheng, who had not obtained the qualification certificate for special operations, was hired, Li Mouping and 6 personnel carried out electrical welding fire operations, and did not clean up the combustibles at the operation site, resulting in fire accidents. 4. Ganzhou Dongxin Construction Engineering Co., Ltd. As the construction unit of the plant project construction project of Sumitomo Elevator Company, it allowed others to undertake the project with the company's qualifications, failed to carry out construction in accordance with the design drawings and relevant technical standards, resulting in serious quality and safety hazards in the construction project, and failed to arrange personnel with the qualification of construction engineer to serve as the project leader and participate in the completion and acceptance of the plant. 5. Ganzhou Zhengdong Engineering Construction Supervision Consulting Co., Ltd. As the supervision unit of the plant construction project of Sumitomo Elevator Company, the project supervision was a mere formality, and the project supervision failed to perform its obligations in accordance with the supervision contract, and appointed a person who did not have the supervision qualification to be responsible for on-site supervision; the actual construction person in charge and the construction personnel without professional qualifications were appointed to be responsible for the construction of the project, and the construction process was not carried out according to the drawings. Coordination and management, failure to carry out regular safety inspections, supervise and rectify hidden dangers, especially in the case of knowing that there are cracks in the outer walls of the plant, not to deal with them, and allowing the risks and hidden dangers to exist for a long time; Zhongnan Environmental Protection Company implements unified and coordinated management of production operations, and neglects to supervise the construction unit's arrangement of personnel who do not have the corresponding qualifications to enter the site for hot work. This eventually led to a fire and a collapse of the wall. 6. Jiangxi Provincial Co-construction Engineering Design Institute Co., Ltd. As the design unit of the Sumitomo Elevator Company's plant construction project, first, the design documents did not meet the requirements of the specification, the Sumitomo plant construction drawing design documents issued were not strictly controlled, the connection between the retaining wall and the steel structure was not clarified in the design documents, and the design intent was not explained to the construction unit and the supervision unit before construction. Explain the design documents, resulting in the reduction of the quality of the construction project at the source; the second is that the company's electronic signature management is chaotic, and the personnel on the construction drawing design documents issued by the company are all using the seal without their consent, and arrange the personnel who do not meet the requirements to participate in the completion acceptance of the plant, and the management documents such as the completion acceptance record form are replaced by signatures. 7. Ganzhou Xinzhu Construction Engineering Construction Drawing Design Review Co., Ltd.
As the design drawing review agency of Sumitomo Elevator Plant Construction Project, the construction drawing review was not strict, and the construction drawing design did not meet the requirements of relevant standards and specifications was not found, and a qualified opinion was issued.
In addition, the accident investigation team handed over to the discipline inspection and supervision organs for further investigation and handling of clues discovered during the investigation of the accident and other clues on problems existing in the performance of duties by public officials of local party committees and governments and relevant departments.