Zhong Da Consulting Bianxiao Company sorted out the relevant regulations of foundation pit collapse through combing the relevant contents. The main contents are as follows:
Construction enterprises should conscientiously follow the Standard for Safety Inspection of Building Construction JG59-99, strengthen enterprise safety production and safety management, comprehensively strengthen safety training and education, and improve employees' safety awareness, responsibility awareness, technical level and safety quality; Carry out construction and operation in strict accordance with the technical specifications for construction issued by the Ministry, increase investment in safety protection facilities, do not simplify safety protection measures at will, put an end to carelessness and reckless risks, and conscientiously do a good job in safety production disclosure; Strengthen the use and management of labor protection articles, and severely deal with illegal operators. Through strict production safety management, the "five major injuries" in construction are reduced to the lowest point, and construction safety is effectively guaranteed.
Main measures to prevent foundation pit collapse:
1 Before foundation pit excavation, possible accidents should be predicted to prepare for foundation pit rescue and reinforcement:
(1) Implement the personnel of the emergency rescue team and clarify the responsibilities;
(2) Establish the information feedback system of foundation pit monitoring;
(3) Ensure the source and transportation of back pressure materials;
(4) Prepare necessary water plugging and plugging materials and equipment;
(5) Prepare steel bars, cement, sand, woven bags and equipment for reinforcement;
(6) Know the location of underground pipeline valves.
2. When cracks appear around the supporting structure ground, they must be blocked with clay or cement mortar in time.
3. If the deformation of the supporting structure of the foundation pit is large, measures such as unloading or cutting the top of the slope, stopping digging in the pit, appropriately increasing the support or anchor rod, and piling sand bags to back pressure the bottom of the pit can be taken.
4. If the foundation pit wall leaks water and soil flows, the ground or roads outside the pit will sink, buildings will tilt or pipelines around the pit will break. Measures should be taken to deal with leakage, such as stopping dewatering and digging in the pit, and quickly pouring plugging materials (such as quick-setting cement slurry, chemical slurry, resin material, etc.). ); In severe cases, the excavation of foundation pit and reinjection water in the pit should be stopped immediately to balance the water level inside and outside the pit, close the pipeline valve in this section, block the leakage with clay and concrete, and treat the leakage of water-stop curtain with cement slurry, chemical slurry and other materials. If necessary, make waterproof curtain before continuing the construction.
5. If the foundation pit excavation causes quicksand, piping or pit bottom uplift instability, the dewatering and excavation in the pit should be stopped immediately, and the back pressure of backfilling sand bag, soil bag or riprap should be adopted, and the dynamic water pressure should be balanced by reinjection. Effective methods (such as grouting, passive area reinforcement, etc.) after piping and quicksand stop. ) be adopted.
6. When the deformation of the foundation pit supporting structure exceeds the allowable value or the instability precursor appears, the following measures shall be taken immediately.
(1) When the deformation of the supporting structure exceeds the allowable value, but it is relatively small, and there is no obvious large deformation, the internal support, anchor rod and anchor cable should be added to the deformed part in time, and the monitoring frequency should be increased.
(2) When the deformation of the supporting structure is too large, indicating instability and obvious inclination, diagonal braces can be immediately added between the pit bottom and the pit wall to make it stable.
(3) When the supporting structure inclines inward or loses stability due to insufficient pile burial depth, earthwork excavation should be stopped immediately, and sand bags should be piled up in front of the supporting structure or short piles should be driven in the passive area for reinforcement.
(4) When the soil around the pit is seriously deformed and the deformation rate continues to increase, it should be regarded as a precursor to the overall sliding instability of the foundation pit. Backfill the foundation pit with sand bags or other materials immediately, and properly handle the foundation pit after it is stabilized.
(5) When the deformation of the foundation pit is in a critical state, the normal construction operation should be stopped immediately, the workers should be evacuated from the dangerous area, and emergency measures should be taken to reinforce it.
(6) When the buildings around the foundation pit are seriously cracked and inclined, people should be evacuated immediately, and the surrounding buildings should be reinforced or demolished after the foundation pit support and surrounding soil are stable.
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