A, technical preparation before construction

(1) Study the survey report in detail before construction, learn from the owner the details of the foundation pit and buildings, structures, pipelines and roads around the foundation pit, and go through the signing formalities. Special attention should be paid to the relationship between the space occupied by dewatering wells, slope protection piles and soil nails and the underground pipelines or building foundations around the foundation pit to avoid accidents. Before foundation pit excavation, the red line piles and positioning piles of all buildings in the site must be measured and approved by the municipal planning department, and the relevant distance between the underground municipal pipe network facilities around the BenQ trough and the adjacent buildings must be checked.

(2) Level the site: Before the equipment enters the site, level and compact the site roads, yards, well points and pile rows, so as to facilitate the movement of the rig frame in the site and make the rig drill holes smoothly and safely.

(3) Before foundation pit excavation, slope should be placed according to the parameters provided by the construction drawing survey report. Determine the slope of foundation pit excavation, and put the slope according to 1:0.3.

(4) The construction site must have enough lighting for construction at night. Adopt steel pipe frame with a height of not less than 2.5m, and install lighting lamps as required.

Second, the construction machinery and materials preparation

Earthwork excavation adopts mechanical excavation and loading, with dump trucks for transportation, excavators 1 and dump trucks 10.

Third, the construction method

According to the actual situation on site, considering the tight construction period and large engineering quantity, the raft foundation excavation adopts the form of large excavation. Earthwork excavation is supplemented by mechanical excavation, dump truck transportation, manual excavation and soil remediation.

Fourth, the earthwork excavation sequence

1. Earthwork excavation direction: According to the actual terrain, the excavation and transportation will be carried out by relay retreating step by step from south to north and from north to south.

2. Several stages of earthwork excavation: consider unforeseen factors such as foundation pit support construction. The first stage of excavation: excavate 2m from the natural ground layer by layer to 500mm from the basement. (mainly mechanical) Second stage excavation: manually excavate the remaining 500mm layer of the basement. This section of excavation will control the corresponding excavation depth and elevation for different elevation areas at the bottom of the pit.

3. Earthwork excavation and soil nailing wall construction are cross-operated, and the section length is arranged according to soil quality and soil nailing flow operation. The height of each section: the first floor is about 1 250 px from the surface to the first row of soil nails, the height of subsequent layers is the vertical spacing of soil nails, and the height of the last floor from the penultimate row of soil nails to the bottom of foundation pit is 1 250 px. Before the last operation is completed, the next layer shall not be excavated, and the two layers of soil nails shall not be arbitrarily combined.

Five, the rainy season foundation pit drainage measures

According to the design requirements of this project, the influence of groundwater can be considered during foundation excavation and construction. For the influence of surface water and rainwater, dewatering well drainage measures are adopted. In order to avoid the influence of surface water and rainwater on foundation construction in rainy season, drainage measures include surface drainage, drainage in supporting structure and drainage in foundation pit.

1. The upper drainage ditch of the foundation pit is more than 2 meters away from the foundation pit, and the upper edge of the foundation pit is not less than 1.0 meters, and it should be connected with the original waterproof ground as far as possible, and the horizontal roof protection should be flush with the natural ground.

2. Before spraying surface concrete, drainage holes should be set appropriately according to the slope condition, and the drainage holes should be made of 50PVC pipes.

3. Foundation pit excavation needs to ensure that the basement is dry, and drainage ditches and water pits are set at the bottom and around the foundation pit.

Six, earthwork excavation quality assurance measures

1. Earthwork excavation and foundation pit supporting construction are carried out at the same time, and the site is arranged as flowing water construction. Free excavation is allowed in the middle of the foundation pit at a distance of 8~ 10m from the surrounding slope, which is in harmony with excavation in layered operation areas.

2. During earthwork excavation, side wall overbreak or loose soil should be prevented. Mechanical excavation is combined with manual slope cleaning to ensure that the slope is smooth, the slope meets the requirements, and there is no virtual soil on the surface.

3. Earthwork and building materials shall not be piled up within 5m around the foundation pit. Heavy machinery should not work near deep pits. Earth-moving vehicles should try not to drive along the pit. If it is inevitable, it must be accounted for. For heavy machinery, special platforms or deep foundations can be considered.

Seven, the main management measures

1. Technical measures for safety management and protection

Due to the large construction area of this project, a full-time security officer will be set up at the site to be fully responsible for safety production and various safety education activities. The Project Department will organize relevant departments to inspect the site on a regular basis, and organize personnel to rectify the hidden dangers in time to ensure that no major accidents occur.

According to the construction situation in each stage, posters, color codes, signs and slogans are hung at entrances and exits and dangerous areas, and various protective components are in place. All kinds of signs should be hung up and hung in a conspicuous position.

2. The protection of foundation pit:

(1) The underground pipe network shall be proved in earthwork excavation to prevent accidents.

(2) Set up a fence with Ф 48 steel pipe at a distance of 1.0m from the pit edge. It is forbidden to pile up soil, materials and parking tools within 3 meters of the top of the foundation pit. Heavy vehicles are not allowed to stay within 5 meters of the upper mouth of soil nailing wall support. It is forbidden for all construction personnel to climb over the protective railings. Warning signs should be set during foundation pit construction, and red signs should be added at night.

3. The construction personnel outside the foundation pit shall not throw things into the foundation pit, and when passing tools inside and outside the foundation pit, they shall pick them up before putting them down.

4. The personnel under the pit should stay away from the edge of the foundation pit and rest on the slope to prevent carelessness.

5. All construction machinery should obey the command, and personnel should stay away from the construction machinery as far as possible. If necessary, inform the operator first, and then approach after responding.

6. The roads on the construction site are concrete floors and should be kept clear. It is forbidden to pile up materials and equipment.

7. It is forbidden to urinate on the construction site. Intentional violation, aggravated punishment. Construction personnel should save water and put an end to the phenomenon of running water and ever-burning lamps.

8. The installation and use of power lines and facilities on the construction site must be carried out in accordance with the construction organization design, and it is forbidden to connect electricity with any wires. Electric and gas welding operations must be operated by qualified welders, electricians and other professional and technical personnel.

9. All kinds of machinery on the construction site must be parked neatly according to the location specified in the construction site management layout, and maintained regularly. Establish a post responsibility system for all kinds of mechanical operators, so that they can work with certificates, and it is forbidden to operate without a license.

10. Environmental protection measures

In view of the location characteristics of this project, combined with the provisions of our company's management manual and program documents, a leading group for environmental protection work headed by the project manager was established, and a self-system for environmental protection on the construction site was established, and the responsibility was implemented to people. In view of the noise, dust and other pollution caused by on-site production, the following measures are taken to reduce all kinds of pollution and noise nuisance.

(1) Earthwork shall be constructed by a qualified transportation unit, and wheels shall be cleaned by designated personnel at the entrance and exit of the construction site, and the soil on the vehicle shall be compacted or covered tightly. The highest point of earthwork bearing this project shall not exceed 1250px, and the edge shall not exceed 250px. Loading construction muck or other bulk materials shall not exceed the upper edge of the vehicle groove, and it is strictly forbidden to leave it along the way.

(2) Harden the concrete of the construction road. The hardened pavement at the entrance and exit shall not be less than the exit width. A device for washing wheels should be set at the exit, and a special person should be in charge.

(3) Set up temporary sprinkler pipes at the exit of the gate, and set up sprinklers, equipped with sprinkler equipment, and sprinkle water to clean the site in time according to the site conditions to prevent dust.

1 1. Site environmental sanitation management

(1) The construction site shall be arranged by designated personnel to keep the site clean and tidy. Ensure that there is no water on the construction site and vehicles will not appear on the construction site with sediment. Send someone to sprinkle water every day to clean the construction road and beautify the construction site.

(2) Designate a special person to clean the living quarters and office areas every day, to ensure that the living quarters and office areas are clean and tidy, and to ensure that there is no water or dirt.

12. Measures to prevent nuisances

Reasonable arrangement of construction process, as far as possible in the daytime with serious noise pollution.

Eight, earthwork excavation safety measures

1. Before construction, make technical and safety disclosure at all levels. Construction technicians and surveyors should be familiar with the drawings, master the positions and dimensions of on-site survey piles and leveling points, and go through the formalities of pile inspection and line inspection with the on-site builder.

2. When excavating the earthwork of the slope, it is forbidden to cut the toe of the slope to prevent the slope from becoming unstable.

3. The mechanical road should be flat and solid.

4. In the mechanical excavation area, irrelevant personnel are prohibited from entering the site. No one is allowed to stand or do other operations within the working radius of the excavator. When excavating, the loader should be unloaded after the whole machine stops.

5. Excavator operation and vehicle loading should obey the on-site command, and all vehicles must travel in strict accordance with the prescribed route to prevent collision.

6. A protective guardrail with a height of 1.5m must be set around the foundation pit, and temporary stairs should be set in the northwest corner.

7. Before construction, carefully study and analyze the engineering geological and hydrological data of the whole construction area and construction site, the quality and distribution of adjacent buildings or structures, the requirements of digging and abandoning soil, the construction environment and climatic conditions, etc.

8. Before construction, conduct safety publicity and education for all personnel involved in the construction of this sub-project, organize employees to learn safety production operation procedures, and require employees to strictly abide by them in production.

9. During construction at night, the construction project should be arranged reasonably to prevent overbreak or over-paving. The construction site should be illuminated as required, and red light warning should be set in dangerous areas.

10. When using an excavator for construction, no one is allowed to carry out other operations within the scope of work of the excavator, and multi-machine excavation is allowed. The distance between excavators should be greater than 10m, and excavation should be carried out from top to bottom, layer by layer. It is forbidden to dig off your feet first.

1 1. Protective railings/boards should be set around the foundation pit, and personnel should have special ladders up and down, and safety warning signs should be hung.

12. The slope and turning radius of the earth-moving road shall comply with relevant safety regulations.

13. All mechanical equipment must be hung with safety operation cards and safety warning signs.

14. Special types of work must hold relevant certificates.

15. The construction workers standing on the slope of foundation pit are strictly forbidden to frolic with each other, and at the same time, attention should be paid to the safety between the upper and lower working faces.

16. If landslides (such as cracks and sliding) are found during excavation, the construction shall be suspended. When necessary, all personnel and machinery should be evacuated to a safe place, and measures should be taken to deal with them in time.

Nine, emergency measures to prevent collapse accidents

In order to minimize the loss of safety accidents and protect the life and property safety of the company and employees, the emergency plan for safety accidents of the project department is formulated based on the principle of "prevention first, self-help first, unified command and division of responsibilities".

1. According to the requirements of casualty accident reporting in China, after the accident, the project department should report to the company quickly, immediately organize rescue, and protect the scene in time (if you need to rescue the wounded, prevent the accident from expanding, and move the objects on the scene, you must make signs, take photos, and draw the accident scene map), and report the accident step by step within four hours. In case of emergency or special construction site, it can be reported directly to enterprise leaders and government departments so as to implement rescue measures in time.

2. In case of accidents, such as foundation pit collapse, formwork support collapse, object impact, etc., the project department should spare no effort to rescue the wounded at all costs and report to the branch in time. When necessary, request assistance from neighboring countries. The leading group will assign a special person to contact, guide and inform the safety precautions.

3. Before returning to work, conduct a comprehensive inspection, rectification and elimination of hidden dangers.

4. Pay attention to the ways and means of on-site rescue to prevent blind rescue without excluding dangerous factors, so as not to cause harm to others.

5. After the on-site accident, special attention should also be paid to stabilizing employees' emotions and providing preventive education to all employees.

6. Conscientiously implement the "Regulations on the Reporting and Handling of Casualty Accidents of Enterprise Employees" in the State Council, do a good job in the investigation and handling of casualty accidents, and strictly implement the principle of "four passes".