A brief discussion on common safety production problems at construction sites and key points in remediation techniques?

Common production safety problems at construction sites and technical points for rectification

1. Safety management

1. The signatures of relevant personnel of the special construction plan should be authentic and valid, and their opinions should be clear. After approval by the supervision unit, the special construction plan can be effectively implemented into actual operations.

2. The enterprise safety inspection is in place, and the questions raised can list the safety hazards existing on site according to the sub-items of the "Construction Safety Inspection Standards" (JGJ59-99) or the "Municipal Engineering Construction Safety Inspection Scoring Method" , and there are project department rectification responses and enterprise review records.

3. Personnel must undergo safety education before taking up their posts. In particular, teams and teams should be briefed on safety precautions before taking up work every day. Special workers must hold certificates before taking up their posts.

2. Civilized construction

1. The construction site must implement closed construction, and the height of the hard fence shall not be less than 1.8m. "Five signs and two pictures" (project overview sign, management personnel list and supervision telephone number sign, safety production system sign, fire protection system sign, civilized construction system sign, site general plan, and safety sign layout plan) are set up at obvious places at the main entrances and exits. Entrances and exits are marked with the business name or logo. In construction areas such as municipal roads and pipelines in non-urban areas, gates should be set up at obvious entrances and exits (the gates should be marked with the company name or company logo), and passages should be left and hard fences should be set up where there are pedestrians and vehicles. Warning lines such as colorful flags and ribbons can be set up in other areas.

2. Hard floors should be installed at the entrance and exit of the construction site gate, the main road in the working area, the main road in the living area, around the building, and where mechanical materials are stored, and a 20×20cm drainage ditch should be set up. Earthwork should be piled centrally or transported externally.

3. The construction area should be clearly separated from the office and living areas, and corresponding isolation measures should be taken. It is strictly prohibited to use gas stoves, rice cookers and other appliances in staff dormitories, and it is strictly prohibited to live in kitchens, work areas, simple rooms, etc. The staff canteen must be kept clean.

4. Set up safety warning signs at the construction site at main construction parts, operating areas, dangerous areas and main entrances and exits. In addition to protective facilities and safety signs, red light warning lights should also be set up at night at various openings and pits near access roads at the construction site.

5. A fire management system must be established at the construction site. Buildings and other places should be equipped with fixed firefighting facilities or mobile firefighting trucks. High-rise buildings should be equipped with firefighting pressurized water pumps and firefighting water source pipes with specified diameters.

3. Scaffolding

1. The I-beams, channel steels, steel plates, anchor bars, wire ropes, etc. used in the cantilever frames should have raw material factory certification documents and performance test reports. The layout of the steel sections and embedded parts of the cantilever frame must have a plan. After the embedded parts are embedded, there should be an acceptance record signed and approved by the safety officer, project technical leader, and professional supervision engineer.

2. The foundation of the floor-standing scaffolding is hardened and drainage ditches are set up around it. The vertical poles should be placed vertically and stably on the metal base, concrete floor, concrete prefabricated blocks, pads or steel beams. Sweeping poles should be connected vertically and horizontally. The design of the corner beams should be clearly stated in the plan.

3. The construction load on the working layer should meet the design requirements and must not be overloaded. Formwork supports, cable wind ropes, delivery pipes for pumping concrete and mortar, etc. are not allowed to be fixed on the scaffolding; hanging lifting equipment is strictly prohibited. Scaffolding shall not be mixed with unloading platforms, derricks, etc.

4. Scaffolding should have rigid wall parts. Flexible wall parts cannot only have tie bars but no support. The number of wall-connecting parts should meet the requirements, and appropriate remedial measures should be taken after removal during the painting stage. The scissor braces should be set continuously from bottom to top to the top step of the scaffold. The scissor brace should be effectively fixed to the extended end of the crossbar or vertical pole that intersects with it. Horizontal diagonal braces should be provided at both ends of straight-shaped and open-shaped scaffolding.

5. The outer frame of the scaffolding shall be fully enclosed every 3 steps as well as the bottom, working layer and overhanging layer of the cantilever frame. If the clear distance between the vertical poles and the wall in the scaffolding body is greater than 20cm, stand plates or internal railings must be laid, and the arc-shaped main body of the scaffolding should be protected at both ends.

IV. Three Treasures and Four Ports

1. Scaffolding should be one step higher than the working level, or reliable protective measures should be taken. Safety protection at high-altitude working points should be synchronized with the main construction. conduct.

2. Staircases, elevator shafts, reserved openings, balconies without railings or railings, around balconies, around awnings and eaves, around roofs and floors without external scaffolding, and around water tanks and Guardrails, boards or nets must be installed around water towers, municipal engineering inspection wells and caissons (during construction). After the completion of the project, supporting manhole covers should be installed in time at the inspection wells and caissons.

3. Protective railings must be installed on the fifth edge. The protective railings consist of upper and lower horizontal bars and railing posts. The height of the upper bar from the ground is 1.0-1.2m, and the height of the lower bar from the ground is 0.5-0.6. m. For roofs with a slope greater than 1:2.2, the protective railings should be 1.5m high and a safety net should be hung. When the length of the crossbar is greater than 2m, railings must be added; dangerous parts along the edge such as water supply and drainage trenches, bridge projects, and mud pools should be effectively protected.

4. The edge protection of various vertical transportation and unloading platforms must be in place. The sides should be fully enclosed with 1.2m high double protective railings and safety nets, or 1.2m high-definition color steel plates should be used to fully seal the platform mouth. Safety doors or movable protective railings with kick protection should be installed. The bottom plate of the unloading platform is required to be laid with hard boards such as wooden boards and steel plates with a thickness of more than 4cm, and is equipped with anti-slip strips. It is strictly prohibited to use only moso bamboo scaffolding pieces. The supporting points and upper tie points of the cantilevered steel platform must be located on the building and shall not be set on construction equipment such as scaffolding. The diagonal tie rod or steel wire rope should be structurally provided with two front and rear lanes on each side, and each of the two lanes should be used for single lane stress calculation.

5. Safety helmets must be worn correctly when entering the construction site. Protective sheds must be erected in places where there is a risk of being struck by high-altitude objects, such as the entrance and exit passages of floors, around hoists, steel bar processing, mixing operations, and winch cabs. The height of the shed roof should not be less than 2.5m, and a second floor should be erected on the roof (the direction of the main ribs of the scaffolding pieces should be vertical , the distance is greater than 30cm). Personnel working at heights must wear seat belts.

6. Scaffolding operations should be covered with scaffolding sheets layer by layer. The foot and limb pieces need to be tied firmly, with no less than 4 binding points. The outside of the scaffolding must be closed with qualified dense-mesh safety net. The main bamboo bars of the bamboo leg pieces are laid vertically in the direction of the longitudinal horizontal poles.

7. When working on municipal structures, caisson formwork, steel bar making, concrete pouring, etc. with a height greater than 2 meters, platforms, guardrails and walking steps with a width greater than 60cm should be installed.

5. Formwork support frame

1. Before the construction of formwork support, a special construction plan must be prepared, and it can only be implemented after being approved, signed and stamped by the technical director of the enterprise. The construction plan includes the formwork Support calculation, size arrangement, assembly and disassembly procedures and targeted safety measures, etc.

2. Special plans for tall formwork support systems with a height exceeding 8m, a span exceeding 18m, a total construction load greater than 10KN/m2, or a concentrated line load greater than 15KN/m must be organized with experts for demonstration.

3. It is strictly prohibited to use wooden supports. Formwork supports should use qualified steel pipes and fasteners, and steel support materials that are severely corroded, deformed, broken, desoldered, or loose in spirals must not be used.

4. The erection of formwork supports shall be carried out strictly in accordance with the requirements of the construction plan. The vertical pole foundation, verticality of the poles, vertical and horizontal sweeping poles, two-way horizontal poles, scissor braces, etc. shall be inspected to ensure that they meet the requirements of the construction plan. . Brick pads shall not be used under formwork support poles. The vertical poles of the formwork should be connected, and it is strictly prohibited to extend them through horizontal poles. The overlapping length of vertical poles must reach 1m, and three or more overlapping fasteners must be used. It is strictly prohibited to mix formwork and scaffolding. The support mode of setting up rods on both sides of the beam and not using the center rod at the bottom of the beam should be adopted.

5. Before dismantling the formwork, a targeted safety technical disclosure must be made, and both parties must complete the signature procedures. After the template is set up, acceptance inspection should be organized and the acceptance form should be filled in carefully and the content should be quantified. Only after passing the acceptance inspection can you enter the next process and keep the acceptance record on file. Formwork removal approval procedures must be followed.

6. The reserved holes and edges on the formwork surface should be protected for safety.

Formwork support should be carried out according to the prescribed operating procedures, and the next process should not be carried out before the formwork is fixed. It is strictly prohibited to climb up and down on the connectors and supports, and it is strictly prohibited to install or remove the formwork on the same vertical surface above and below. For formwork with complex structure, installation and disassembly should be carried out strictly in accordance with the measures of construction organization design.

VI. Foundation Pit

1. Before foundation pit operations, a special construction plan should be prepared as required. The construction plan must be approved, signed and stamped by the technical person in charge of the enterprise before it can be implemented. Special design for foundation pit construction where the excavation depth exceeds 5m (inclusive) or where the depth of the basement with more than three floors (inclusive) does not exceed 5m (inclusive) but the geological conditions, surrounding environment and underground pipelines are extremely complex, must be subject to corresponding It will be implemented after the design by the qualified unit and the construction drawing review unit will review and organize experts to demonstrate.

2. The distance between the accumulation of soil, materials and machinery around the foundation pit and the construction of mechanical equipment from the edge of the foundation pit and the stacking at the edge of the pit should comply with the requirements of the design and construction plan, and overloading is strictly prohibited.

3. When excavation of foundation pit, a detailed monitoring plan should be prepared according to the design requirements, including monitoring items, alarm values, monitoring points, monitoring cycles, records and information feedback, etc., and the plan should be strictly followed implementation.

4. When excavation of foundation pits, the construction plan must be strictly followed. The order and method of excavation must be consistent with the design working conditions, and follow the principles of "grooving support, supporting first, digging first, and dividing." The principle of “layer excavation and over-excavation is strictly prohibited”.

5. Drainage ditches should be set up on the ground around the boundary of the foundation pit to avoid water leakage and seepage into the pit; when dewatering outside the pit is used, measures must be taken to prevent dangerous settlement of adjacent buildings.

6. There must be dedicated passages for workers to get up and down during foundation pit construction. The passages must be structurally strong and reliable, and their number and location must meet the construction requirements and comply with relevant safety protection regulations.

7. During foundation pit construction, 1.2m high railings and safety nets must be used for closed edge protection. The distance between the edge protection railing and the edge of the foundation pit shall not be less than 50cm.

8. The tensile bearing capacity of anchor rods should be tested according to regulations (the number of tests under the same conditions should not be less than the total number of 1 and should not be less than 3).

9. The slope of the soil nail wall, soil nail spacing, and grouting volume must meet the design requirements. The upper soil nail grouting and shotcrete surface layer must reach 70% of the design strength before excavation of the lower earth and lower soil. Nail construction.

10. The surrounding enclosure of the caisson in municipal pipe jacking construction must be equipped with fixed hard isolation on three sides and a movable isolation that can be opened and closed on one side, and be equipped with warning signs and warning lights.

11. Toxic and harmful gases must be detected before construction of caissons and pipe trenches, and measures such as ventilation and oxygen supply should be taken.

12. When the caisson sinks in silty clay or silt, preventive measures must be taken to prevent the caisson from suddenly sinking or soil intrusion; during pipe jacking operations, the groundwater level is high or the groundwater level is high. When there is quicksand, safety protection measures should be taken. If any abnormality is found, the operation should be stopped immediately to eliminate danger.

7. Construction electricity

1. A three-level power distribution and a second-level leakage protection system must be implemented. The distance between the distribution box and the switch box should not exceed 30m, and the horizontal distance between the switch box and the fixed electrical equipment it controls should not exceed 3m. The control box and switch box should be set up separately. When power and lighting are combined into the same distribution box, power distribution should be separated, and the power switch box and lighting switch box must be installed separately. Each electrical equipment must have a dedicated switch box and a safe height above the ground. It is strictly forbidden to use the same switch box to directly control more than one electrical equipment (including sockets).

2. TN-S zero protection system must be implemented. The cable must contain all working core wires and the core wires of the protective neutral wire and protective wire. Cable lines requiring three-phase four-wire power distribution must use five-core cables. The metal shells of electrical equipment, lamps, and lamp brackets must be electrically connected to the protective neutral line.

3. Cables should not be pulled or connected indiscriminately. They should be laid overhead or buried. It is strictly prohibited to install them openly, drag them anywhere, or tie them to scaffolding at building entrances and exits, reinforced floors, easily damaged and corroded floors, etc. In the structure of the facility, it is strictly prohibited to use bare metal wires for binding, and it is strictly prohibited to use flowery wires and sheathed wires. It is strictly prohibited for the incoming and outgoing wires of the electrical box not to be located on the bottom of the box.

4. When the provisions in Articles 4.1.2 and 4.1.4 of the "Technical Specifications for Temporary Electricity Safety at Construction Sites" (JGJ46-2005) are not met (safety distance from overhead lines) , insulation and isolation protective measures must be taken, and eye-catching warning signs should be hung.

5. The distance between indoor and outdoor 220V lamps at the construction site shall not be lower than 2.5m and 3m respectively. For lighting in relatively humid places or where the height of the lamp from the ground is less than 2.5m, the power supply voltage should not be greater than 36V; in humid places it should not be greater than 24V; in conductive ground, water, and metal containers, it should not be greater than 12V.

6. Damaged, unqualified, or mismatched electrical appliances must not be used in the distribution box to prevent live parts from being exposed. It is strictly prohibited to use the reverse switch. Mobile electrical boxes used in pile foundations, municipal projects, etc. must be set on fixed supports and must not be placed directly on the ground.

7. If cranes, tic-tac-toe frames, scaffolding, etc. in the construction site are outside the lightning protection range of adjacent buildings and structures, lightning protection devices should be installed on the top, four corners of the frame, and the end of the boom. , Lightning rod height is 1-2m.

8. Construction machinery and equipment

1. Construction machinery and equipment must have production licenses, product quality certificates, installation, use and maintenance instructions, supervision and inspection certificates and other documents , defects must be repaired and acceptance procedures must be performed when entering the site.

2. The material hoist is not allowed to use bilateral discharging, and one machine can only supply materials to one building. A safe distance must be maintained between any part of the tower crane and overhead transmission lines. If the distance is smaller than the safe distance, effective protective measures must be taken. When operating multiple towers, measures must be taken to ensure that the distance between any close parts (including hoisted objects) between two machines shall not be less than 2m.

3. Mechanical transmission devices and cutting parts should have protective covers. The use of multifunctional woodworking machinery is strictly prohibited. The mixer hopper and tower crane hook are insured. Vertical transport machinery is equipped with emergency power-off measures for the driver. The derrick elevator has interlocking self-falling doors and anti-fall devices; the cage door should have an electrical or mechanical interlocking leveling stop device.

4. The foundation of vertical transportation machinery must be constructed in accordance with the product instructions, engineering quality technical specifications and special construction plan requirements. The supervision unit shall witness the sampling and production of test blocks, and the installation can only be carried out after the foundation acceptance check. The foundation construction and acceptance conditions must be There is a written record, and the installation unit and the construction general contracting (using) unit sign and take responsibility respectively.

5. The installation and disassembly of vertical transportation machinery must be prepared by the installation and disassembly unit (climbing is the user unit), which must be approved by the unit’s technical director and submitted to the general construction contractor (use www.fdcew.com) It can only be implemented after review and approval by the unit and the supervision unit; the construction general contractor (usage) unit and the installation and disassembly unit must sign a contract contract and a safety production responsibility letter; the installation and disassembly unit must perform safety technical disclosure and signature procedures for the operating personnel. Installation, disassembly and maintenance units (including manufacturers) must be carried out by professional teams that have obtained professional contracting qualifications for lifting equipment installation projects, and should be supervised by technical personnel and safety personnel.

6. The acceptance of vertical transportation machinery must be supervised and inspected by an inspection and testing agency with corresponding qualifications. It must be inspected and passed by the construction general contracting (using) unit and the installation and disassembly unit (including the manufacturer), and must be reported to the project The local construction administrative department or the construction safety supervision and management agency shall register. If the registration is not completed, it shall not be put into use. When in use, the acceptance qualification plate, maximum lifting capacity plate, driver induction plate, safety warning sign and operating procedure plate should be hung. Passenger and freight elevators must meet relevant specifications and standards, and the instructions clearly specify the conditions for passenger use before they can be used, and a sign limiting the number of people must be hung.

7. The attachment device of the vertical transport machinery frame to the building structure (if the usage conditions exceed the manufacturer's instructions, an installation and construction plan must be prepared) must comply with the requirements of the instructions or construction plan, and the attachment device of the frame must not be connected to the scaffolding , the end is fixed with pins to resist torsion and welding is prohibited. When the free height of the tower crane exceeds the specifications in the instruction manual, a wall-mounted device must be installed. Cable wind ropes are used to assemble and disassemble the lifting frame body, and rigid connecting rods are used to put it into use. When the cable wind rope height is less than 20m, there is one group (4 pieces), and when the height is 20-30m, there are two groups.

The ground anchor should use no less than 2 steel pipes (Φ48-53) set side by side (perpendicular to the force direction of the steel wire rope), with a spacing of not less than 0.5m, a driving depth of not less than 1.7m, and cable wind rope anti-slip measures on the top of the pile.

8. Vertical transport machinery operators should be trained and certified to work. When encountering strong winds, gusts, rain, snow and fog, assembly, disassembly, lifting and transportation operations are not allowed. When out of service or when the driver leaves the machine, the power supply should be cut off and locked, and the ladder cage lowered to the ground. It is strictly forbidden to lift heavy objects or leave the ladder cage suspended in the air for a long time. It is strictly forbidden for anyone to stay, work or pass under the cage, boom and heavy objects. Lifting heavy objects should be tied steadily and firmly, and no scattered objects should be stacked or hung on the heavy objects. Parts that are easily scattered should be fixed with a cage fence before being lifted. Objects marked with binding positions should be bound according to the markings and then lifted. The driver's position should have good visibility, and windows should use sunscreen films and no curtain stickers. There should be obvious level signs on the outside of the rack or on the unloading platform door. The passenger and freight elevator has a floor call display contact signal. The tower crane commander should use semaphores or walkie-talkies.

9. During municipal pipe jacking construction, small cranes and other lifting equipment must be used to lift pipes and excavated materials. Simple single-pole winch lifting equipment is not allowed.

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