Safety measures for hoisting reinforcement cage of

Safety measures for hoisting reinforcement cage of rotary excavation pile

I. quality inspection before hoisting

Hayward's contribution to this article is to help the MIT team explain that after the expansion of the material is completed, the person in charge of the production applies to the technology department for inspection, and the quality inspection engineer immediately goes to inspect. The key inspection parts should include whether the following points meet the requirements of technical disclosure:

1. Plum blossom bars shall not be arranged at the designated conduit position Support ribs, etc., shall ensure the space of the conduit position

2. The intersection of two main reinforcements and distribution reinforcement at the main lifting ring position shall be welded on both sides

31. No reaction in operation: the most common is that the rising and falling operation buttons of the beam are unresponsive. From the lifting ring position, the intersection of the first nine distributing bars and the main bars should be welded on both sides, and the closing of the distributing bars should be fully welded

4. The intersection of the three distribution bars and the main bar at the lifting point shall be welded on both sides, and the closing bar shall be fully welded

5. The length of the weld at the closing of the distribution bar at the non lifting point shall not be less than 50% of the lap length

6. In the fabrication process of reinforcement cage, truss reinforcement should be fabricated first, and the truss reinforcement should be fully welded between the upper and lower main reinforcement

7. Ensure that the spacing between main reinforcement and distribution reinforcement is uniform and straight

8. Before lifting the reinforcement cage, ensure that all welding points have been welded, and it is strictly prohibited for the reinforcement cage to fall off due to lack of welding or missing welding during the lifting process

9. During the fabrication of reinforcement cage, ensure that the elevation of main and auxiliary lifting rings is consistent with the disclosure

in addition, the safety officer should conduct a comprehensive inspection of the lifting appliance before each lifting, focusing on the integrity of the steel wire rope, and the hook should have a buckle. Ensure that all lifting appliances meet the specification requirements. Adjust the position of the four fulcrums of the crane to keep the crane on a plane before lifting

II. Construction method

the reinforcement cage is fabricated and hoisted in four sections. After passing the acceptance, the reinforcement cage is hoisted by four-point lifting method. The main lifting point adopts 35t truck crane to lift the reinforcement cage horizontally. When lifting, the crane hook is used to fix the top of the reinforcement cage in four points, and the auxiliary lifting point adopts the auxiliary hook to lift the reinforcement cage from 0.292l to 0.104l in two points. Turn over in the air, loosen the hook of the auxiliary crane, and lift the reinforcement cage into the hole with the main hook of the 35t truck crane vertically, and support it at the orifice with channel steel

III. construction process flow

figure reinforcement cage hoisting construction process flow chart

IV. hoisting configuration parameters

the specification and model of truck crane is qy35k5, the maximum rated lifting weight is 35t, the maximum lifting height is 35m, the longest main boom is 39.6m, and the longest main boom + auxiliary boom is 54.6m. Refer to XCMG group product parameters

v. lifting method of reinforcement cage

1. Clean the site

before lifting and installation, plan the site first, remove the obstacles on the road through the lifting process of the site, ensure the flatness of the road, and organize personnel to clean the operation site to ensure that the road is smooth and clean. At the same time, the hoisting assistant should clean up the short steel head and left welding rod mixed in the finished reinforcement cage to avoid falling hard objects after lifting the reinforcement cage and injuring people

2. Lifting preparation

after the reinforcement cage passes the acceptance, the lifting rigger and the lifting commander must make preparations before the lifting operation: including the technical preparation before the operation, clarify and master the operation content and safety technical requirements, listen to the technical and safety disclosure, grasp the lifting point position of the lifting reinforcement cage and the binding method of the reinforcement cage; Carefully check and implement the specifications, pieces and intactness of tools and riggings required for the operation. The ground where the crane is parked is flat and hard. Steel plates and square timbers are used under the crane legs to increase the stress area of the fulcrum to ensure the stability of the crane during the lifting operation. When working at night, sufficient lighting conditions should be prepared

3. Lifting point location

when lifting the reinforcement cage, two lifting points (located at the top stiffener location) are set on the top for vertical lifting, and one lifting point (stiffener location) is set in the middle of each reinforcement cage for turning over lifting. Set an additional one at the lifting point Φ 20 stiffeners. See the following figure for the specific lifting points of the reinforcement cage:

(1) the setting of the horizontal lifting points of the reinforcement cage: according to the length of the reinforcement cage L, the lifting points should be located at 0.104l, 0.292l, 0.208l

(2) setting of longitudinal lifting points of reinforcement cage: four points are set at the longitudinal lifting points of reinforcement cage. (single amplitude weight: 3.9t, the longest cage length of 27.30m caused by external force P)

(3) the location of the lifting point is: 2.84m+7.97m+5.68m+7.97m +2.84m

the layout of the lifting point is shown in the following figure:

4. Lifting steps of the reinforcement cage

(1) prepare all work before lifting, command the 35t crane to move to the lifting position, the rigger installs the steel wire rope and snap ring on the reinforcement cage, and hang the main hook and auxiliary hook of the 35t truck crane

(2) after checking the installation of the crane wire rope and the stress center of gravity, start the horizontal lifting at the same time

(3) after the reinforcement cage is lifted to 0.3m ~ 0.5m above the ground, check whether the reinforcement cage is stable, and then the main crane slowly hooks up. According to the distance between the tail of the reinforcement cage and the ground, command the auxiliary crane to cooperate in lifting at any time

(4) after the reinforcement cage is hoisted, the main hook is slowly hoisted and lifted, and the auxiliary crane cooperates to maintain the distance between the reinforcement cage and the ground, and finally make the reinforcement cage vertical to the ground

(5) command the rigger to remove the auxiliary lifting point hook on the reinforcement cage, and then stay away from the lifting operation range

(6) command the crane cage to enter the hole and position, the crane rotation should be stable, and pull the traction rope on the reinforcement cage. When lowering, if the reinforcement cage is stuck in the hole, it should be lifted out to check the hole position before lifting, and it is not allowed to enter the hole forcibly

(7) when the reinforcement cage is lowered to the lifting point B, pause and remove the steel wire rope and snap ring of the lifting point B

(8) when the reinforcement cage continues to be inserted downward, when it reaches the lifting point a, pause to put it down, insert the channel steel, fix the reinforcement cage on the top of the pile casing, and then remove the steel wire rope and snap ring of the lifting point a

(9) after the first section of reinforcement cage is hoisted, the second section of cage is hoisted to the orifice, and the main reinforcement is welded. After all the main reinforcement is welded, the stirrup is wrapped and the quincunx spot welding is carried out. After passing the acceptance, it can be lowered at a uniform speed. Hoist the reinforcement cage from the lowest section up in sequence until the whole reinforcement cage is hoisted

(10) when the uppermost reinforcement cage is lowered to the orifice position, temporarily support the reinforcement cage at the orifice with channel steel, measure the top elevation of the pile casing at this time with a level gauge, calculate the length of the hanging reinforcement according to the top elevation of the reinforcement cage, weld the hanging reinforcement on the main reinforcement of the reinforcement cage, then hang the hook on the hanging reinforcement, slowly lower to the design position, insert two parallel channel steel into the top lifting ring of the reinforcement cage, and place the channel steel horizontally on the sleeper, Hang the whole cage on the square timber on both sides of the top of the pile casing to ensure that the position and height of the reinforcement cage are accurate

5. Reinforcement cage splicing

before the reinforcement cage enters the hole, remove the soil and sundries on the reinforcement cage, repair the deformed or moving stirrups, and re weld or bind the welded joints that have been opened. Reinforcement cage 2. When welding according to the shape, material and loading size of the indenter, the upper and lower reinforcement cages must be on the same vertical line, and the lap welding of the main reinforcement adopts single-sided lap welding. Before welding, use a steel wrench to tighten, spot weld to make the two main reinforcements stick closely, and weld the vertical joint. When lifting the reinforcement cage, two welding machines are set on site to weld at the same time, so as to shorten the lifting time of the reinforcement cage. The main reinforcement of the upper and lower reinforcement cages is lap welded, and the welding length of one side is not less than 12D