Laying bottom formwork The bottom formwork adopts high-quality bamboo glue formwork of 11 mm. When laying, the formwork shall be firmly hit on the square wood, and the formwork shall be filled with sponge strips. After the design of bottom formwork paving is completed, the exposed sponge strips on the surface of formwork shall be removed, and long square timber must be set under the longitudinal flat-fell seam of bamboo veneer to ensure the quality of formwork flat-fell seam. In order to check the bearing capacity of the support, reduce and eliminate the inelastic deformation of the support and the settlement of the foundation, the support system is preloaded before the formwork is set up. The preloading material is sand bag, and the maximum load is 1.2 times of the design load. It is loaded by stages and preloaded for 48h. During preloading, it spans 5 sections, with 5 points on each section, and is observed for 1 times every 6h. The observation method is to use a level gauge to measure, and the elevation before loading is δ 1, after loading is δ 2, and after unloading is δ 3. According to the observation results, the settlement curve is drawn. Because the foundation treatment adopts local replacement of fill soil, after leveling and compaction, it is compacted by layers with 51cm lime soil, and the compaction degree is over 93%, so the foundation deformation is very small. The 2d observation value is less than 1mm, so it can be ignored. In the later observation, a long downward batten is nailed on the longitudinal (or horizontal) square wood at the observation point, and an upward batten is fixed on the corresponding foundation, and a horizontal line is made at any section where the two battens overlap. After loading, the relative displacement between transverse lines is the elastic-plastic deformation value of the support itself. After preloading, the elevation of bottom formwork can be accurately adjusted through adjustable support. The pre-camber should be considered when setting the elevation. Pre-camber setting should consider the deflection caused by the self-weight of the beam, the elastic deformation and inelastic deformation of the support after loading, the settlement of the support foundation, the anti-camber after tensioning and other factors.