What are the conditions of building foundation pit support, it is necessary to immediately alarm and

When there are cracks and slippage around the perimeter.

Supporting measures should be taken for excavation of foundation pit under the following circumstances:

It does not meet the technical and economic requirements because the amount of slope excavation is too large.

There are buildings nearby and cannot be sloped for excavation.

The slope is in loose and saturated soft soils that are prone to loss of stability.

Sites with abundant groundwater and not suitable for well-point precipitation.

The exterior wall of the underground structure is a load-bearing continuous wall of reinforced concreted earth.

Set up the precipitation of tube wells to facilitate the excavation personnel and machinery operations and soil loading and unloading transportation. The top layer is excavated with a long-arm excavator, and a small loader is used in the pit during the excavation process to push the earthwork away from the excavator to the working range of the excavator.

Foundation pit excavation includes catenary pillar pit, steel column foundation pit, cable pit excavation, etc. According to the excavation method, it can be divided into manual excavation and mechanical excavation.

When excavating foundation pits in soft soil areas, the following provisions should also be met:

1. Before construction, it is necessary to do a good job of ground drainage and lowering the groundwater level, and then it can be excavated, and the precipitation work should continue until the backfill is completed.

2. The road of construction machinery should be filled with gravel or gravel of appropriate thickness, box or tip drainage, etc., and the groundwater level should be lowered to the bottom of the foundation pit, and the tool-type roadbed should be laid if necessary.

3. When excavating adjacent foundation pits, the construction sequence of deep and shallow or simultaneous construction should be followed, and the foundation should be done in time.

4. When excavating the foundation pit on the dense group of piles, the soil should be excavated symmetrically after a period of time after the pile is driven. When excavating foundation pits near dense pile groups, measures should be taken to prevent the displacement of the pile foundation.

It seems to look at the geological conditions, and generally more than 800 will have to be supported.

What safety inspections should be carried out in foundation pit support? Hello, happy to answer your <>

Pro-construction safety inspection standards: 1. The main contents of construction safety inspection should include: safety management, civilized construction, scaffolding, foundation pit support and formwork engineering, "three treasures" and "four mouths" protection, construction electricity, material hoist and external elevator, tower crane lifting and hoisting and construction machinery and tools.

As a basis for evaluating the safety production situation of a construction site. 2. The items of safety management inspection should include: safety production responsibility system, target shouting management, construction organization design, branch (sub-item) engineering safety technology disclosure, safety inspection, safety education, pre-shift safety activities, special operations with certificates, industrial accident handling and safety signs.

3. The items of civilized construction inspection should include: on-site fencing, closed management, construction site, material stacking, on-site dormitory, on-site fire prevention, comprehensive management of public security, construction site signage, living facilities, health care and first aid, and community service. 4. Scaffolding inspection includes six kinds of scaffolding safety inspections, including cantilevered scaffold inspection, portal scaffold inspection, hanging scaffold inspection, hanging basket scaffold inspection, and attached lifting scaffold safety inspection.

5. The safety inspection of foundation pit support is the safety evaluation of foundation pit support engineering at the construction site. The items to be inspected should include: construction plan, edge protection, pit wall support, drainage measures, pit side load, upper and lower passages, earthwork excavation, foundation pit support deformation monitoring and operating environment.

6. The safety inspection of formwork engineering is the safety evaluation of formwork in the construction process. The items to be inspected should include: construction plan, support system.

Ten contents of column stability, construction load, formwork storage, support and dismantling formwork, formwork acceptance, concrete strength, transportation road and working environment. 7. The "three treasures" and "four mouths" protection inspection is the inspection of the use and protection of safety helmets, safety nets, safety belts, staircases, elevator shafts, reserved holes, pit openings, passage entrances, balconies, floors, roofs, etc. 8. The inspection of the electricity consumption of the construction site is the evaluation of the temporary electricity consumption of the construction site.

The items to be inspected should include: external power protection, grounding and zero protection system, distribution box, switch box, on-site lighting, distribution lines, electrical installations, transformer and distribution devices and electricity files. 9. The inspection of material hoist (gantry, well frame) is the evaluation of the design, production, erection and use of material hoist.

The items to be inspected should include: frame production, limit safety device, frame body stability, wire rope, floor unloading platform protection, hanging basket, installation and acceptance, frame, transmission system, contact signal, winch operation shed and lightning protection. 10. The inspection of external elevators (dual-purpose elevators for people and goods) is the evaluation of the safety status and use management of external elevators on the construction site.

The contents of the inspection should include: safety device, safety protection, driver, load, installation and disassembly, installation and acceptance, frame stability, contact signal, electrical safety and lightning protection. 11. The tower crane inspection is the inspection of the use of the tower crane.

Items to check.

Answers]: a, b, c, d

When one of the following situations occurs, the danger alarm shall be carried out immediately, and emergency measures shall be taken for the protection objects in the foundation pit support structure and the surrounding environment:

1) The monitoring data reaches the cumulative value of the monitoring alarm value;

2) The displacement value of the foundation pit supporting structure or the surrounding soil suddenly increases significantly or the foundation pit appears quicksand, pipe gushing, uplifting, sinking or serious leakage;

3) The support or bolt system of the foundation pit support structure is too deformed, buckled, fractured, relaxed or pulled out;

4) Serious sudden cracks or deformation cracks that endanger the structure of the surrounding buildings and the surrounding ground;

5) Sudden and obvious increase in the deformation of the surrounding pipelines or cracks, leaks, etc.;

6) According to the local engineering experience, there are other situations that must be alarmed. p471。

1. Supporting structure: (1) Supporting structure forming quality reputation; (2) Whether there are cracks in the crown beam, support and enclosing purlin; (3) Whether there is a large deformation of the support and column; (4) Whether there is cracking or leakage of the waterproof curtain; (5) Whether there is subsidence, cracks and slippage of the soil behind the wall; (6) Whether there is soil, quicksand, and pipe gushing in the foundation pit.

2. Construction conditions: (1) Whether there is any difference between the soil conditions exposed after excavation and the geotechnical investigation report; (2) Whether the length of the excavation section and the thickness of the layer are consistent with the design requirements, and whether there is ultra-long and ultra-deep excavation; (3) Whether the discharge of surface water and groundwater at the site is normal, and whether the foundation pit dewatering and recharge facilities are operating normally; (4) The ground load around the foundation pit, whether there is an overload of the pile.

3. The surrounding environment of the foundation pit: (1) whether the underground pipeline is damaged or leaked; (2) Whether there are cracks in the surrounding buildings (structures); (3) Whether there are early cracks and subsidence of bridges on the surrounding roads (ground); (4) The construction of adjacent foundation pits and buildings (structures).

4. Monitoring facilities: (1) The datum point and measuring point are in good condition; (2) whether there are any obstacles that affect the observation work; (3) The integrity and protection of the monitoring components.

5. Other inspection contents determined according to design requirements or local experience.

Answers]: a, b, d, e

When the base is in danger of staring at the pit support body, 1 can be takenThe foundation pit support body is reinforcedThe back pressure of the soil within the passive zone in the pit is 3Outside the pit, a deep well is set up to dewaterDig the pit pure rules and the outer soil for unloading.

When the foundation pit support construction and use time exceed the design service life, the foundation pit safety assessment should be carried out, if necessary.

It is very important to carry out a safety assessment of the foundation pit, especially when the foundation pit support construction or the service life exceeds the design service life. The foundation pit file support construction and the service life of the foundation pit exceeding the design service life may cause potential safety hazards to the surrounding environment and buildings, so safety assessment is necessary. The following factors should be considered when conducting a foundation pit safety assessment:

1.Stability and safety of foundation pit support structure;2.The integrity and reliability of the supporting structure of the foundation cavity pit;3.

The service life and remaining life of the foundation pit supporting structure;4.Monitoring data and deformation of foundation pit supporting structure;5.Environmental impact and safety risks of foundation pit support structures.

According to the results of the foundation pit safety assessment, corresponding measures need to be taken when necessary, such as reinforcing the supporting structure, repairing the damaged parts, and cleaning up the surrounding environment to ensure the safety and stability of the foundation pit. At the same time, for foundation pits that exceed the design service life, demolition or redesign and construction should be considered.

There are two situations in which excavation foundation pit support measures are taken: first, foundation pit support, dewatering engineering excavation depth of more than 3m (including 3m) or although not more than 3m but the geological conditions and surrounding environment are complex foundation pit (groove) support, precipitation engineering. Second, with the forest earthwork excavation project to serve the excavation depth of more than 3m (including 3m) of the foundation pit (groove) of the earthwork debate mu excavation project.

More than a certain scale of the danger of the greater sub-project scope: 1, deep foundation pit engineering (1) excavation depth of more than 5m (including 5m) of the foundation pit (groove) of earthwork excavation, support, precipitation engineering. (B) although the excavation depth does not exceed 5m, but the geological conditions, the surrounding environment and the underground pipeline are complex, or affect the foundation pit (groove) of the adjacent building (structure) safety of the earthwork excavation, support, dewatering engineering.

In the above two cases, we must do a special plan for the safety of deep foundation pit support, and there should be a qualified foundation pit support design adopted by the drawing review department, and the latter is more than a certain scale, and the special safety plan must be approved by the expert group.

1. The excavation of the foundation pit should be based on the requirements of the design of the foundation pit support structure, and the detailed construction of supporting piles, crown beams and waist beams, anchor cables and anchor rods, mixing piles and jet grouting piles, and earthwork excavation plans should be formulated.

2. The ground around the boundary of the foundation pit should be hard-ground and set up a drainage ditch, and water leakage and seepage should be avoided from entering the pit wall and soil, and frequent inspections should be made to find that the drainage ditch or the ground is cracked, and measures should be taken to remedy it in time.

3. During the construction, it should be proofread with the geological data provided in the geotechnical engineering survey report, and the design unit should be notified when the geological data is quite different from the actual situation, so as to make corresponding adjustments and changes in time.

4. Before the construction of the supporting pile, it should be found out whether there are underground obstacles of the underground pipeline, and if there is, the pipeline should be displaced, and the abandoned underground pipeline and underground obstacles should be removed.

5. The anchor cable should first carry out the uplift acceptance test and confirm the tension lock, and the design pull-out force can be met before the excavation can be constructed.

6. It is strictly forbidden to put materials and vehicles around the foundation pit. When stacking materials and vehicles outside the perimeter of the foundation pit, the stacking around the perimeter of the foundation pit shall not exceed 20 kpa.

7. The northeast side of the foundation pit is adjacent to the pedestrian tunnel, and two rows of 600 (local 800) concrete bored piles have been constructed on both sides of the tunnel. Attention should be paid to avoiding the existing piles when constructing anchor holes for anchor cables adjacent to tunnels to ensure the safety of pedestrian tunnels.

8. In the process of foundation pit excavation, do a good job in the channel layout of excavation machinery and vehicles, the sequence of excavation and the arrangement of the surrounding soil pile, and measures should be taken to prevent collision with the support structure, engineering piles or disturbance of the undisturbed substrate soil.

8. If the foundation pit is over-excavated, and the excavation depth exceeds the design depth, it must be agreed by the designer, and the foundation pit support needs to be re-checked for safety before it can be carried out.

9. The excavation of the foundation pit should be closely coordinated with the foundation construction of the main structure. When excavated to the design foundation pit bottom elevation, the cushion should be poured in time to seal the bottom and carry out the bottom plate and foundation construction.

10. In the process of excavation and anchoring, inspection and observation should be carried out by a special person, and when an abnormal situation occurs, the excavation should be stopped immediately, and the cause should be immediately investigated and measures should be taken to continue digging.

11. The construction of the supporting structure should be carried out in strict accordance with the principle of combining dynamic design and information construction.