Supporting and protective measures for the hottest

2022-09-30
  • Detail

Protective measures for deep foundation pit support

1. Project overview:

this project is the operation steps building of the hydraulic universal testing machine under the understanding of Jiaju Haoyuan green city, with a total area of square meters, the number of floors built is the underground floor, the total height is meters, the construction fire resistance grade is grade, and the design seismic grade is degree. The grade of the construction project is grade, the waterproof grade is grade, the fire resistance class is class I, and the layout is fragmentary

2. Slope of foundation pit

the design mark of the foundation of this project is m, but the existing air elevation is - the foundation pit is used for slope excavation, which should have a stable side slope to prevent collapse and risk of safe construction. It is certain that the excavation and slope should be based on the soil environment, the size of the site and the depth of the foundation pit. At the same time, it should also consider the construction environment, the air load of adjacent roads and slopes, and its slope should be allowed to be 1:1, Is to grade m on each side

according to the geological data, the excavation environment has good soil quality and low groundwater, and the slope excavation is allowed according to the regulations, without support

3. Matters needing attention in rural excavation outside the root

1. To reasonably select the method of foundation pit, we must pay attention to the selection of appropriate mechanical task surface, and consider the appropriate range and elevation of mechanical excavation, so as to prevent over excavation and increase the amount of manual excavation

the excavation method should be reasonably placed and excavated in sections to improve the efficiency of excavation

2. Do a good job in the organization, handling and adjustment of soil excavation. For the continuous construction, do a good job in the organization, handling and adjustment of each link. The progress of soil excavation requires that the construction be stopped in a balanced manner. All vehicles must drive in strict accordance with the specified line and unload the soil to the instigation address

3. When the rural excavation outside the root can affect the adjacent buildings and the pipeline is safely used. There must be reliable means of asylum

4. The upper and lower passages of foundation pit excavation shall be erected

1. A stable and safe doorway shall be erected after foundation pit excavation

2. With the depth of excavation, slowly set up three big things and add protective carved railings and anti-skid strips to prevent staff from falling and chaos when going up and down

3. Set up the upper and lower channels, avoid the reverse rotation radius of the excavator, and avoid the safe interval of the earth moving vehicles

4. Foremen, security inspectors and construction staff often check whether the upper and lower passages are safe and secure. If found, reinforce them immediately

5. When the height of the upper and lower passages exceeds 3M, a platform should be set, and the vertical doorway should not exceed 60

5. There are also big differences between different companies in the technical disclosure of foundation pit excavation

1. This project is a large-scale improved earth excavation, which should be excavated in two layers

2. In order to prevent surface water, construction water, living water and rainwater from invading the foundation pit and scouring the slope to form collapse, drainage treatment should be done before construction

3. According to the geological data, the soil quality and excavation depth are 1:0.0.33. The soil quality of the local pan foundation is relatively good, and no support is set temporarily. After excavation, the method will be determined according to the actual environment

4. Pile materials or park machines and tools near the foundation pit. When bulldozing beyond 2m, the foundation height should not be more than 1.5m, and the spacing between the foundation pit and the accessory buildings should not be less than 1.5. Reinforcement methods should be adopted when required

5. When excavating the edge of the foundation pit, it is not allowed to stop under the slope of the stone or the dangerous building base close to the end of reinforcement. During the operation, attention should be paid to the changing environment of the soil above. If cracks or looseness were found earlier this year, the scene of collapse should be timely sloping or reinforced

6. When the excavation depth exceeds 2, two carved railings (with a vertical spacing of no more than 0.6m and a height of 1.2m) and hanging risk signs must be set, and white marker lights must be hung at night. No one is allowed to rest under deep pits and steep slopes

7. When excavating earth in rainy season, the drainage must be kept unobstructed, and special attention should be paid to the stability of the slope. The construction should be suspended when it rains on New Year's Eve

8. When excavating at night, it should be placed in the section with flat terrain, less construction disturbance and smooth transportation road, and there should be sufficient lighting on the site

9. During mechanical excavation, slope shall be made while excavating, and manual trimming shall be carried out. After meeting the design requirements, stop other homework

10. During earthwork construction, the foreman, quality inspector, safety officer and construction staff should always pay attention to whether there are cracks and landslides on the slope. Once the environment is abnormal, the construction should be stopped immediately, and the construction can be stopped continuously in front of treatment and reinforcement

1. Technical specification for construction of foundation pit support (JGJ)

2. Basic design standard for building foundation (GB)

3. Geotechnical investigation statement (HT)

1. Terrain and geomorphic characteristics of the garden: it was originally located on the hillside, with different steepness and slowness

2. Rural environment outside the root: fine sand, medium sand, fine round gravel soil, silty clay, metamorphosed sandstone

3. Description of aquifer type, permeability and other properties: the main factor affecting the construction of this project is confined water, which is stored in fine sand and fine round gravel soil below. The infiltration coefficient is calculated according to the experienced value of 2m/d

3. The well pipe layout is

the dewatering well adopts reinforced concrete well pipes with an inner diameter of 300mm and an outer diameter of 360mm, including filter pipes (mixed with wires, which can well control the sand content of water when pumping) and well wall pipes (the length of each well pipe is 2.5m)

selection of pumping equipment

QJ submersible pump can be selected. According to the calculation results and design drawdown, a submersible pump with appropriate flow and head is selected. It is proposed to adopt a submersible pump with 32 ~ 50m3/h and head of 26m

at the same time, in order to ensure the safety of adjacent buildings, groundwater recharge should be stopped when required

dewatering construction process

1. Measurement and setting out

according to the basic plan and design scheme given by Party A on site, contact the surrounding environment of the site, measure and set out each well location, and drive wooden piles

2. Hole forming

cz-22 percussion drill is used to complete the well, and the mud wall protection process is used to complete the hole. After the drilling rig is installed in place, check the well location. After it is confirmed to be correct, manually excavate 0.5m deep, bury the wall protection pipe with a diameter of 700mm. After the wall protection pipe is buried, start drilling into the hole, and adopt slurry wall protection to maintain the slurry height in the hole and prevent hole collapse

3. Hoist the well pipe

after passing the acceptance of the on-site technical person, clean the hole with a barrel and hoist the well pipe. The welding between well pipes shall be stable and the verticality shall be guaranteed

4. Well layout

the upper 8.0m shaft wall pipe and the lower 1.0m filter pipe of the dewatering well

5. Gravel filling

fill 1 ~ 3cm gravel filter material outside the well casing, with a gravel filling thickness of 12cm, and fill it to the wellhead

6. Well flushing

the air compressor is used to contact the piston to wash the well, until the well pipe is unobstructed, the water is clean, and the sand content is less than 1/10000, so as to ensure the quality of precipitation

7. Dewatering process control

contact the geological environment of a single well. Dewatering wells without fine sand layer around the well location should be dewatered first to control the amount of sand and ensure that the dewatering construction will not affect the undisturbed soil layout of the bearing layer of the foundation pit

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