Proruption! Hunan a construction site foundation pit collapse accident, the scene was buried!

       On February 3, a foundation pit collapsed at a construction site in Buyi Street, Lengshui River, Hunan province, where collapsed stones and soil buried part of the site below. Lengshuijiang Emergency Management Bureau learned that a number of departments have been on the scene to deal with. The person in charge of the Buxi sub-district office said that the preliminary investigation of the cause of the collapse is the construction of the stone wall above the prison, no casualties were found, the specific cause of the accident in further investigation.

Cautions

       Foundation pit support is to ensure the safety of the underground structure construction and the surrounding environment of the foundation pit. Generally, the foundation pit support project is temporary, and the safety reserve of the support structure is relatively small and the risk is high. At the same time, due to the complex construction technology of foundation pit support engineering, involving a wide range, many changing factors, and frequent accidents, is the most difficult point in the construction project, but also the key to reduce the project cost and ensure the quality of the project.

       Foundation pit support construction unit should pay attention to the following matters during the construction process:

       1、Under the excavation of foundation pit in soft soil, high groundwater level and other complex sites, it is easy to produce diseases such as soil slip, foundation pit instability, pile displacement, pit bottom uplift, serious water leakage of support structure, soil flow and damage, which pose a great threat to the safety of surrounding buildings, underground structures and pipelines.

Foundation pit support construction

       2、In order to do a good job in foundation pit support engineering, we must do a good job in the whole process of excavation and support, which includes the whole process of survey, design, construction and monitoring work.

       3、The foundation pit support project includes many closely related links, such as retaining support, waterproof, precipitation, excavation and so on, and the failure of any link may lead to the failure of the whole project. At the same time, the foundation pit construction of adjacent sites, such as piling, precipitation, excavation and other construction links, will have mutual influence and restriction, increasing the inducing factors of accidents, so attention should be paid to every detail in the construction.

       4、The construction cycle of the foundation pit support project is long. From the excavation to the completion of all the projects below the ground, there are many random factors affecting the safety, and the occurrence of accidents is often sudden, so the emergency plan should be made.

       5、The foundation pit shall be excavated and supported according to the sequence and parameters specified in the design, and shall be layered, segmented, time-limited and balanced excavated.

Foundation pit support construction

       6、The foundation pit supporting structure shall excavate the lower earthwork only after the concrete meets the design strength and the anchor rod (cable) and steel support are prestressed according to the design requirements. Advance excavation and overexcavation are strictly prohibited.

       7、In the process of construction, it is strictly prohibited to collide with equipment or heavy objects to support, waist beam, bolt and other foundation pit supporting structures, nor to place or hang heavy objects on the foundation pit supporting structure.

       8、When removing the supporting structure, it should be removed from bottom to top according to the order of foundation pit backfill, and filled with the demolition. Reinforcement measures should be taken when necessary.

       9、When the foundation pit support adopts internal support, the construction should be conducted in the order of first support, first support and then disassembly. The sequence of disassembly and replacement should meet the requirements of the design conditions, and should be combined with the monitoring results of the internal force and deformation of the site supporting structure.

       10、The inner support shall be removed symmetrically after the inner beam, plate, column structure and the concrete meet the strength of the design requirements.

       11、After the excavation and support, the construction of underground structure and installation should be carried out in time. During the construction process, the stability of the pit wall should be checked at any time. The bottom of the foundation pit should be full of bedding layer and close to the envelope structure. At present, there are more and more high-rise buildings, and many construction projects involve deep foundation pit projects. If the design or construction of deep foundation pit engineering is not paid attention to, major collapse accidents may occur.

——Source: Construction safety technology

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