1 mud wall protection and slope protection technology, concrete grille
1. 1 general provisions
Before laying, the construction surface shall be arranged with slope according to the design requirements, and then the setting-out shall be measured and the construction control baseline shall be released; The quality ratio of mortar should meet the requirements of strength and construction, and test the test block to ensure the mixture ratio; Masonry is laid by mortar method, and the basic requirements are smooth, stable and dense. The concrete construction shall be carried out according to the requirements of mortar masonry construction specifications.
1.2 construction technology
Before laying mortar, brush the slope, level, compact and put the slope, control the baseline and start the mortar laying construction.
1.3 construction points
Embankment slope protection should be laid in stages from bottom to top after slope brushing, and cutting slope protection should be laid from bottom to top at each stage. Before laying, the slope should be leveled and compacted. Low-lying places can not have concave-convex phenomenon or uneven pebble cushion, and have shortcomings such as uneven slope protection thickness; Masonry surface should be clean, no weathering, cracks and other defects, stone should meet the requirements of the specification. Precast concrete blocks should be prefabricated centrally and uniformly, and slope protection should be shaped in sections before masonry installation. Mortar should maintain proper workability and fluidity, meet the requirements of construction lofting, qualified materials enter the site, and the determined mixture ratio should be maintained. Masonry should be carried out in layers, and each layer of masonry should be grouted, and the masonry should be built with the slurry; Each layer should build by laying bricks or stones corner stone, face stone in turn, and then build by laying bricks or stones abdomen stone; Stone masonry should be selected according to samples, and the edges and corners should be trimmed. After trimming, relatively flat large stones should be selected as face stones. The upper and lower layers of stones should be jointed, and the inner and outer stones should be staggered. Seam width: 2-4cm for vertical seam and 2-2.5cm for flat seam. When the vertical seam width is greater than 5cm, flaky can be filled, mortar first, and then flaky; Masonry should rise in a balanced way, and the height difference and daily masonry height of adjacent sections should not exceed1.2cm; ; The joint surface between masonry should be scrubbed clean, laid in a wet state, and the whole interlayer joint should be laid. Permanent joint, the surface should be flat and vertical; In the process of masonry, water should be sprinkled in time to keep the masonry moist. The curing time of cement mortar masonry is generally 14 days. During the curing period, it is forbidden to knock with a heavy hammer, roll stones, and carry heavy objects on the base surface, which will damage the strength of masonry; Masonry jointing should conform to the external surface, and it is advisable to level off. The jointing mortar is marked as M 10 cement mortar; Before jointing masonry, it should be cleaned and wetted with water, and the mortar should be buried in the joint for 2 cm. Cure in time after jointing.
2 downstream gravel drainage body and concrete slope protection technology
2. 1 gravel drainage body
Gravel drainage ditch at downstream dam foot: Excavator excavates, and the filling materials are directly transported and unloaded by dump trucks at the bank of the ditch, and the excavator lays the materials and compacts them properly. When the drainage body is filled to the top surface, it is finally crushed by a vibratory roller.
2.2 Precast concrete blocks and gaskets
The prefabrication of concrete blocks and partition walls is carried out in the special prefabrication yard downstream of the main dam, and its pouring procedure is: raw material preparation → mixing → clinker transportation → paving and closing → vibrating → surface finishing → maintenance.
1) concrete mixing adopts 1 forced mixer to mix raw materials. When mixing, master the mixing time, which is generally controlled at about 2 minutes (specifically determined by mixing test), so that the fluidity, cohesiveness, water retention and slump of concrete can meet the specified requirements.
2) The concrete transport clinker is transported manually by the tire hopper, transported from the mixing station to the prefabrication point, dumped on the iron plate, and then poured into the mold with a shovel. Pay attention to the continuous, balanced, rapid and timely transportation of concrete from the mixer to the pouring site. In the process of transportation, aggregate separation, slurry leakage, serious bleeding, drying and excessive slump change are not allowed in concrete, and the transportation time should be shortened as much as possible to reduce the number of transshipment. Therefore, it is necessary to ensure that the sum of clinker transportation time and stacking time on the iron plate is not greater than the initial setting time of concrete.
3) The paving and discharging paver pours the clinker into the mold with a shovel, which is slightly higher than the top of the mold and is paved manually.
4) Vibrating, light-receiving, and vibrating workers shall use a flat vibrator as they spread and vibrate, then smooth with wood and iron, and finally compact with light-receiving. The concrete shall be rammed to the maximum possible density, and the vibrating time of each place shall be the time when the concrete no longer sinks obviously, bubbles no longer appear and the concrete begins to pan-grout. At the same time, excessive vibration should be avoided.
5) The time limit for form removal shall be carried out when the concrete strength meets the specified requirements and the surface and edges and corners can be guaranteed not to be damaged by form removal. Damage to concrete and formwork should be reduced when dismantling. Dismantled formwork, supports and accessories should be cleaned, maintained and oiled in time, stored in categories and properly kept.
6) Maintenance and transportation of precast concrete blocks
Concrete curing shall begin at 12- 18 hours after concrete pouring (after initial setting), and the continuous curing time shall not be less than 2 1-28 days. After the strength of precast concrete blocks reaches the age of 28d, they are transported to various construction sites by dump trucks for stacking.
7) Technical requirements for concrete construction
The slump of concrete shall conform to the contract technical specifications or design documents. Technical specifications and design documents are not clear, but should be determined according to the nature of structural parts, concrete transportation, pouring methods and climatic conditions. Time limit for formwork removal: The formwork can be removed only when the concrete strength reaches above 2.5MPa, which can ensure that its surface and edges and corners are not damaged by formwork removal. Special tools should be used to dismantle the formwork to reduce the damage of concrete and formwork. Dismantled templates, supports and accessories shall be cleaned and maintained in time, stored in categories and properly kept. The concrete shall be continuously, evenly, quickly and timely transported from the mixer to the pouring site. During transportation, aggregate separation, slurry leakage, serious bleeding, drying and slump change are not allowed, and the transportation time should be shortened as much as possible to reduce the number of transshipment. For some reason, concrete that has been initially solidified should be treated as waste.
2.3 concrete grating and partition wall slope protection
Downstream slope protection shall be carried out according to the construction sequence of paving the square first and then paving the spacer. After the precast concrete blocks have been cured for 28 days to meet the strength requirements, they will be transported to various construction sites by motor dump trucks. The dam slope is treated manually, and it is not allowed to roll down from the slope, so as to avoid personal safety accidents and precast block fracture. Check the acceptance results of slope cutting again before laying, including whether the control points of foundation surface, coordinate position of control line, elevation and slope ratio are correct. After concrete block masonry, check the flatness ≤ 1cm every 2m feet, and whether the surface compactness meets the design requirements. Check all procedures (drainage ditch, cushion, drainage ditch, etc.). ) under the slope is completely completed. When laying, the control lines in vertical and horizontal directions should be laid from bottom to top, and the straightness and height should be controlled well. Before jointing, check whether there are impurities in the reserved joints between concrete blocks, and fully sprinkle water to wet the laid slopes and reserved joints. Organize welding from top to bottom or from side to side as planned. Cure the jointing mortar in time after hardening, and spray water regularly (twice a day) to ensure that the masonry surface is wet, especially to ensure that jointing is wet. Curing of jointing mortar begins about 10 hour after hardening, and the curing time is 14 days. No peeling and cracks are required on the joint surface.
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