A, before spraying concrete, the uneven part of the slope surface shall be cleaned by pneumatic pick (convex part) or backfilled with mortar rubble (concave part); The surface steel mesh is firmly fixed on the slope wall and meets the requirements of the specified protective layer thickness. Steel mesh can be fixed with steel bars inserted into the soil, and should not be moved when shotcreting.
B steel mesh welding, mesh allowable deviation is10 mm; ; When laying steel mesh, the lap length of each side shall not be less than the side length of a grid.
C the mixture ratio of sprayed concrete should be determined by experiments according to the design requirements, and the maximum particle size of coarse aggregate should not be greater than12mm; ; For shotcrete operation, operators should be trained in advance to ensure that the water-cement ratio and quality of shotcrete meet the requirements; Before shotcreting, mechanical equipment, wind, water and circuits should be thoroughly inspected and put into trial operation; The spraying sequence of sprayed concrete should be from bottom to top, the distance between the nozzle and the sprayed surface should be controlled within the range of 0.8 ~ 1.5m, and the spraying direction should be vertical to the sprayed surface, but one side of the steel bar should be sprayed first, and then the other side should be sprayed to prevent cracks from appearing on the back of the steel bar; In order to ensure that the thickness of sprayed concrete reaches the specified value, a short steel bar can be vertically inserted on the side wall as a sign.
D, in order to strengthen the supporting effect, 3%-5% early strength agent can be added when spraying concrete; After the initial setting of sprayed concrete is 2h, the next working procedure can be carried out, and the maintenance can continue for 5-7d.
For more information about bid writing and improving the winning rate, click on the bottom customer service for free consultation.