What are the key measures to ensure the flatness of the formwork when installing the Waterstop Bolt?

What are the key measures to ensure the flatness of the formwork when installing the Waterstop Bolt? 

In the process of installing the Waterstop Bolt, it is necessary to use the combination of "precise positioning, uniform stress, and auxiliary reinforcement" to avoid deformation and tilt of the formwork due to improper screw installation. 

1. Before installation: accurately plan and position and lay a flat foundation Unified lay-off positioning: According to the construction drawings, pop up the "screw positioning line" on the surface of the formwork on both sides - according to the design spacing (usually 30-50cm, determined by the pressure on the concrete side) to pop up the transverse and longitudinal parallel lines to ensure that the hole position of each Waterstop Bolt fully corresponds to the formwork on both sides (deviation ≤ 2mm), so as to avoid forcibly pulling the formwork when threading the rod due to the misalignment of the hole, causing local bulge or tilt. Matching the formwork and support specifications: the formwork should be stiff and flat surface (such as bamboo rubber board, steel formwork) to avoid warped and damaged formwork; At the same time, the wooden square (usually 50×100mm) behind the formwork should be straight, the steel pipe support (Φ48×3.5mm) should be not bent, and the wooden square spacing and steel pipe spacing should be set strictly according to the design requirements (wooden spacing ≤30cm, steel pipe spacing ≤60cm) to provide uniform support for the formwork and prevent the formwork from being locally dented when the screw is stressed.

2. During installation: control the force balance to avoid formwork offset Symmetrical threading and fastening: When threading the Waterstop Bolt, it should be carried out gradually from the middle of the formwork to both sides to avoid uneven force on the formwork caused by concentrated threading on one side. When fastening the nut, the "symmetrical tightening" method must be used - first screw one side of the nut to a slight force, then screw the other side of the nut, and repeatedly alternate until the force on both sides is balanced (it can be judged by observing the fit between the template and the wooden square). Control the tightening force: Use a torque wrench to tighten according to the design torque (usually determined according to the diameter of the screw, such as the torque of the Φ12 screw is about 25-30N·m), to avoid excessive force causing the screw to bend, local pressure deformation of the formwork, or too little force causing the formwork to loosen; After fastening, check the surface of the template with a ruler (2m length) to ensure that the flatness deviation is ≤ 3mm. Install auxiliary positioning parts: For large areas of formwork (such as basement exterior walls), "positioning struts" (steel bars or steel pipes with the same wall thickness) can be installed between the formwork on both sides of the Waterstop Bolt, and 1 screw can be set every 2-3 screws to prevent the spacing deviation of the formwork due to its own weight or external force extrusion before pouring; At the same time, at the top, bottom and corners of the formwork, an additional "oblique support" (steel pipe and ground are 45°-60°) are added to enhance the overall stability of the formwork and avoid warping of corners.

3. After installation: comprehensive inspection and adjustment to eliminate hidden dangers of flatness Point by point inspection and correction: After the installation is completed, use a 2m ruler to check the flatness along the lateral and longitudinal sections of the formwork, loosen the corresponding screw nuts for the parts where the deviation exceeds the standard, adjust the position of the formwork or wooden support and re-tighten; at the same time, check the joint of the formwork, if the joint is misaligned due to uneven force on the screw, it is necessary to install a "layering" at the joint and supplement the screw to ensure that the splicing is flat. Pre-pressure test (optional): For important waterproof structures (such as pool walls), the formwork can be pre-pressed before pouring (use a jack or heavy object to apply equivalent concrete side pressure), observe the deformation of the formwork, and if there is a local depression, reinforce the screw and support in the corresponding area in time to ensure that the formwork can withstand the pressure of the concrete side without obvious deformation during pouring. In short, the core of ensuring the flatness of the formwork is to "make the formwork evenly stressed and the support stable" - to ensure the symmetry of the screw force point through precise positioning, to avoid local force overload through symmetrical fastening, and to enhance the overall stiffness of the formwork through auxiliary support.