Analysis on safety technical measures of shotcrete in alleys of 9# track.
I. Overview of the Project
1, construction site: 9# track lane
2. Construction content: 9# track roadway bolting and shotcreting, paving and pouring ditches.
3. Engineering quantity: sprayed concrete length 1363m, sprayed concrete thickness 100mm, sprayed concrete strength C20, sprayed concrete (cement: yellow sand: crushed stone) volume ratio1:2. The dosage of accelerator is 3 ~ 5% of cement dosage, and the water-cement ratio is 0.46. The cement grade is P.O42.5R, the yellow sand is medium coarse sand, the stone particle size is 5- 10 mm ... The total width of the ditch is 500mm, the total depth is 400mm, and the bottom and wall thickness of the ditch casting are 100mm. After the ditch is poured, the net width is 300mm and the net depth is 300mm. 9# track alleys hardened length 1363m, thickness 100mm. The concrete of trench foundation is C20, and the mixing ratio is: cement: water: sand: stone-1: 0.56: 2.03: 3.35438+0. P.042.5R ordinary portland cement is used as the cement, and the grain size of medium and coarse yellow sand and gravel is16-31.5mm2. ..
Attachment: Section Support Diagram of 9# Track Lane
Second, the construction preparation
1. Before shotcreting, all shotcreting personnel must take part in operation training and examination. Those who fail the exam are not allowed to take part in homework. They must attend the next round of training and can't take up their posts until they are qualified. After taking leave, you must train and make up lessons, and you can't go to work until you pass the exam.
2. Clean up the construction site, connect the gas and water pipelines, open the gas and water supply valves, check the air pressure and water pressure, and check whether the feng shui pipeline is leaking, leaking and unblocked. Deal with problems in time.
3. The feng shui pipeline in the roadway should be simply bandaged to prevent the pipeline from being soiled by shotcrete. The road signs and measuring points in the roadway should be well protected to prevent gunite from covering up.
4. Before spraying concrete, the standard line must be hung, and the number of hanging lines shall be determined according to the site conditions.
5. Before spraying concrete, connect the feng shui pipeline and the power supply of shotcrete machine in advance.
6. Prepare shotcrete materials before shotcrete, and put them in order.
7, shotcrete machine is installed in the roadway section with good support.
8, check whether all the bolts in the roadway are qualified, no problem rear can shotcrete work.
9, check whether the shotcrete machine is in good condition, with or without air leakage, etc. No problem, and then spray work.
10, check whether the feng shui pressure meets the requirements, the wind pressure is controlled at 0. 1-0. 12Mpa, and the water pressure is controlled at 0.25Mpa.
1 1. Transport line protection and signaling: The rail transport line has complete "one slope and three gears" devices, and the signaling device is clear, sensitive and reliable.
12. shotcrete material: 425# cement: 5-8mm stones: medium coarse sand: deep well water.
13, manual mixing is adopted, and the mixture ratio meets the requirements.
14. Machining groove template: the specification is 300mm high ×6000mm long. Use cross braces in the middle. The length of the cross brace ensures that the overall width of the template is 300mm, and each end is welded with a template card with a width of 50mm.
Third, the construction scheme
1 and 9# track alleys before shotcreting, two sides and low roots must be brushed together, and the uneven floor should be leveled. Available pneumatic pick, hand pick. During construction, coal gangue is loaded manually.
2. Spray concrete first, then pave the ditch, and proceed simultaneously from outside to inside. Spray concrete for 50m in a cycle, and then spray concrete; Foundation laying and trench pouring shall be carried out in sections, every 6m is a cycle, and foundation laying shall be completed once in the whole section.
3. During the construction of the drenching section, the method of intercepting water and diverting water should be adopted to eliminate it, and it should be carried out in sections.
4. The building materials are transported to the construction site by harvesters, and then mixed evenly by hand according to the mixture ratio.
Fourth, the construction technology
Process flow: hanging the bottom to clean the roadway floor → spraying concrete → ditch formwork stabilization → ditch irrigation → laying the bottom → leveling the concrete surface → dismantling the formwork → maintenance → cleaning.
1, undercover, ask for help. Construction technology:
According to the actual situation, adjust the slope of the roadway, brush and expand the underexcavated parts on both sides of the roadway to ensure that the specifications of the roadway meet the design requirements and level off. When the bottom is lifted, the coal gangue can be transported out by manual loading.
2, shotcrete construction technology
(1) Wash the roadway side. Before spraying concrete, wash the roadway dust with pressure water to ensure the cohesive force between concrete and the top of roadway and the quality of sprayed concrete.
(2) When starting the machine, supply gas first, and then send electricity, water and materials. When stopping the machine, stop the material first, then stop the machine, stop the water and stop the wind.
(3) When spraying concrete, the distance between the nozzle and the sprayed surface should be kept between 0.6 ~ 1.0m, and the nozzle and the sprayed surface rotate vertically in a spiral shape, with the moving radius of 100 ~ 200mm, and should be carried out in the order of supporting first and then jacking.
(4) The shotcrete hand should adjust the water-cement ratio according to the spraying effect, and the spraying effect is best if the concrete is shiny and does not flow. If the concrete flows, the water-cement ratio should be reduced, and if the concrete is dry and dull, the water-cement ratio should be appropriately increased.
3, vertical form removal construction technology:
Erect the processed template in the dug hair ditch, measure the size when stabilizing the template, then fix the outside of the template, and fix it with a cross wedge in the middle. Then pour. After pouring, keep the surface of the poured formwork and mortar free of any movement and damage. After the concrete strength reaches the demoulding time, the formwork in the ditch can be removed, and then pour 100mm thick concrete according to the thickness of the ditch bottom.
4, pouring construction technology:
Building materials are transported to the construction site by ground harvesters, then mixed with water according to the mixture ratio, and then paved manually. Use pneumatic vibrator to strengthen vibration, and the vibration time should be uniform and sufficient. The concrete surface will be submerged, there will be no bubbles, and the concrete will no longer sink. Pouring must be done while vibrating and tamping. Then according to the relationship between the waist line and the permanent bottom plate, the concrete surface is roughly leveled; After vibration tamping, it will be rolled by self-made 1.5m long towed roller; Smooth the surface with a wooden trowel. Then according to the provisions of the maintenance, maintenance time of not less than 7 days.
Verb (abbreviation of verb) construction requirements and quality standards
(a), shotcrete construction
1, sprayed concrete should be mixed in strict proportion. The content of accelerator is generally 3% ~ 5% of the cement weight, which can be appropriately increased at the position of water spraying and mixed with the loading.
2, before spraying concrete, carefully according to the center line to find the outline, and adopt hanging line injection. Ensure the coating thickness, surface flatness and foundation depth.
3. When spraying concrete, spray it for 30 ~ 50 mm at first, and then spray it into a driveway after solidification. Whether it is primary spraying or secondary spraying, the sprayed rock surface must be washed with pressurized water before spraying, and the floating dust must be washed off.
4. The spraying work must be carried out in sequence, so that the foundation is sprayed first, then the wall is sprayed, and finally the top is sprayed. At the same time, we should abide by the principle of concave first and convex later.
5. If there is a sprinkler at the top of the roadway, it should be sprayed from the periphery to the middle first, and then the water gushing will be concentrated by using the aqueduct to ensure the spraying quality.
6, after shotcrete roadway to regular maintenance, each class water again, maintenance time of not less than seven days.
7. In order to ensure the quality of sprayed materials, the cement should be the products of regular manufacturers, and the sand and gravel should not contain sundries and dirt. It is forbidden to use expired and deteriorated cement and accelerator.
8. Wash the sand and gravel with water before mixing, and wet mix the materials. The mixture is used up on duty in case of failure. Injection rebound rate shall not exceed15%; When spraying concrete, the existing traverse points and observation points of delamination instrument must be protected in advance, and spraying coverage is strictly prohibited.
9. The over-excavation, under-excavation and over-excavation parts shall meet the design requirements by shotcrete filling according to the design specifications. First, uncover the anchor net at the underexcavated parts on both sides, find enough design specifications, re-anchor and lay the anchor net, and then carry out shotcrete construction.
1 1, quality requirements
(1) The mixture ratio of sprayed concrete and the content of accelerator must meet the design requirements, and the strength of sprayed concrete must meet the design requirements.
(2) Clear width requirement: the distance from the center line to any side is 0 ~+ 150 mm, and 0 ~+ 100 mm is preferred.
(3) Clear height requirement: the overall height of roadway is 0 ~+ 150 mm, which is qualified, and 0 ~+ 100 mm is excellent.
(4) The allowable deviation value of surface flatness is ≤ 50 mm. ..
(5) Allowable deviation value of foundation depth ≤ 10%.
(2), ditch pouring construction
1. Set the processed template in the dug capillary ditch, measure the size when stabilizing the template, then fix the outside of the template, and then pour it after fixing it with a diagonal wedge in the middle.
2. After pouring, keep the surface of the poured formwork and mortar free of any movement and damage. After the concrete strength reaches the demoulding time, the formwork in the ditch can be removed, and then concrete with a thickness of 100mm can be poured according to the thickness of the ditch bottom.
3, 50m after each shotcrete lane, laying a ditch, ditch is located in the right direction of roadway.
4. Dig a horizontal diversion ditch at each water outlet point of the roadway floor, and lead the water from the water outlet point to the ditch on the right side of the roadway (the size of the diversion ditch is 100㎜× 100㎜, and the length is determined according to the position of the water outlet point on site), and fill the ditch with stones with a particle size of not less than 40㎜ as the filter layer.
5. The thickness of trench wall shall not be less than 000mm, the allowable deviation of trench width is 30 mm, the allowable deviation of depth is 30 mm ... The allowable deviation from waist line to gully edge is 20 mm. ..
6, quality requirements
(1) The allowable deviation of the center line is 50 mm.
(2) The allowable deviation of depth is 30mm. (3) The allowable deviation of width is 30mm.
(4) The allowable deviation of wall thickness shall not be less than the design 10 mm. ..
(3), the foundation construction
1. raw material control: cement must have factory certificate. Cement, sand and stone must be sent to the laboratory designated by Party A for raw material test before use. It is forbidden to use damp, caked and expired cement. Coarse aggregate with impurity content exceeding the specified amount must be cleaned. According to the specification requirements, the mixture ratio of materials should be tested on site and adjusted in time. The water content of sand and gravel should be determined, and the water cement ratio should be adjusted in time.
2, strictly control the water cement ratio of concrete.
3, concrete mixing time shall not be less than 3 minutes, to ensure uniform mixing.
4, concrete summer-planting surface must be cleaned before pouring, to ensure that there is no dirt, debris.
5, the floor must be clear to the hard bottom, in order to carry out concrete laying;
6, template before each use, must clean up the template, brush oil.
7, paving, pouring construction must use vibrator for vibrating.
8. During the pouring process, the leading cadres and technicians shall supervise the whole construction process. 9. Before the concrete surface is solidified, pedestrians are not allowed to walk on it.
10, quality standard
Quality requirements: The surface of the concrete floor with subbase should be smooth, the allowable deviation of subbase thickness is 30mm, the local convexity and concavity are not more than 30mm, the slope is subject to the waist line, and the surface flatness is 10mm.
1, when spraying concrete, the line must be hung to ensure that the spraying thickness is not less than100 mm.
2. Clear width: the width should not exceed the designed 50 mm ..
3. Clear height: the distance from the waist line to the top and bottom plates should not exceed the designed 50 mm ..
4, spray layer thickness is not less than 90% of the design.
5. The allowable deviation of surface flatness is 50.
I believe that after the above introduction, everyone has a certain understanding of the safety technical measures of shotcrete in the alleys of 9# track. Welcome to Zhong Da for more information.
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