Foundation pit support engineering is a high-risk technical field in the construction industry. Although the incidence of foundation pit accidents nationwide has been decreasing year by year, such incidents still occur from time to time. Improper design and substandard construction quality remain the primary causes of these accidents. Ensuring environmental safety and engineering safety, enhancing support technology levels, controlling construction quality, and reasonably reducing project costs are fundamental principles that technical and management personnel in foundation pit engineering must adhere to. A notable functional characteristic of foundation pit support is its dual role: not only creating conditions for underground structure construction 
and ensuring construction safety, but more importantly, protecting surrounding environments from harm. The environmental protection requirements of foundation pit support are particularly prominent in urban areas. Therefore, construction units, supervision agencies, design and construction teams, as well as engineering regulatory departments should pay close attention. As a temporary measure for underground structure construction, foundation pit support completes its purpose once the underground structure is built. Given the short service life of support structures, the loads considered during design generally do not require long-term application. If the support structure remains in use after excavation for an extended period, load variations may occur over time, along with changes in material properties and the surrounding environment. To prevent neglecting these conditions—such as load variations, material performance changes, and environmental shifts caused by prolonged use of support structures—designers should clearly specify the service life of support structures in design documents to avoid exceeding design specifications. The design of support structures must ensure a minimum one-year service period, which takes into account both the construction timeline of the main underground structure and seasonal variations affecting the support system. Throughout the year, changes in groundwater levels, climate, and temperature can significantly alter soil properties and structural performance. Since actual construction seasons may differ from design projections, even projects requiring less than one year of support should maintain year-round functionality. For most construction projects, this service period meets the requirements for main underground structures. However, for projects with special construction timelines, the support period should be extended accordingly while considering load-bearing capacity and structural durability. As a temporary measure for underground foundation construction, foundation pit support must protect both the excavation area and surrounding environment. Beyond meeting structural demands, these supports must safeguard environmental safety. The design and construction of foundation pit support systems prioritize two key functions: primarily preventing excavation hazards to the surrounding environment, which constitutes the primary objective of such structures. Secondly, the project must ensure construction safety for its main structure by providing normal working space and environment for underground structure construction, along with designated areas for material storage and transportation, as well as road conditions. It should isolate groundwater and surface water inside and outside the foundation pit to guarantee normal construction of underground structures and waterproofing works. Measures to prevent collapse accidents include:
1. Develop construction plans and specialized safety measures in accordance with building safety technical standards and specifications.
2. Conduct dewatering work and implement protective measures before foundation pit excavation.
3. Load various construction materials at specified distances around foundation pits (trenches), slopes, and pile holes.
4. To ensure formwork stability, install vertical columns as required and add horizontal supports and shear braces both longitudinally and transversely along columns.
5. Set up restricted area barriers and warning signs around demolition sites, assign dedicated personnel for supervision, prohibit unauthorized access, and demolish buildings sequentially from top to bottom. Multiple-story simultaneous demolition and excavation are strictly prohibited.
6. Maintain minimum distances of 1.5 meters between all construction machinery and foundation pits (trenches), slopes, or pile holes based on equipment weight, support requirements, and soil conditions.
7. Conduct comprehensive site inspections and maintenance during rainy seasons and winter thaw periods to ensure unobstructed drainage before resuming work.
8. During mechanical excavation, workers must not enter the machinery’s working area for cleaning or slope adjustment operations.
9. The lifting equipment should be repaired, maintained and checked regularly, and overload and violation of regulations are prohibited.
Post time: Jul-24-2025