I. Overview of the Project:
The retaining wall is located at AK0+ 135, and it is a reinforced concrete slab culvert of1-3.0m. The length of the culvert is 22.5m, and the included angle between the centerline of the culvert and the normal of the road centerline is 0o. The design requires that the bearing capacity of the foundation should be ≥0.25Mpa, and there should be 2 plates of 99cm1and 2 plates of 74cm. The culvert foundation adopts C 15 flaky concrete, and the abutment adopts C20 flaky concrete. The entrance and exit are splayed walls.
Construction preparation:
1. survey setting-out: the survey engineer sets out the retaining wall positioning line and foundation excavation sideline control piles according to the drawings, determines the ground slope according to the geological conditions, sets out the excavation line with lime, and completes the leveling points and pile introduction.
2. Site layout: according to the site conditions, determine the location and direction of the construction access road, the classified stacking site of sand and gravel materials, and the placement position of mechanical equipment and mixing station.
3. Material test and inspection: do a good job in sampling and inspection of raw materials such as sand, stone, cement, construction water and steel bars, and determine the mixture ratio of mortar and concrete.
4. Construction team: The culvert construction team consists of professional construction personnel with rich construction experience in our company, and the team consists of 20-30 people.
5. Housing: The office and living room of the construction team will be rented from private houses nearby.
Second, the construction work and quality requirements:
1, foundation excavation:
(1) inform the supervision engineer before foundation excavation, so as to check and measure the position of foundation plane and the existing ground elevation. No excavation shall be carried out before the inspection and measurement are completed and approved by the supervision engineer. In order to check after excavation, the foundation axis control pile should be fixed outside the foundation pit.
(2) According to the excavation line released by the survey team, clear the trees, turf, roots and other sundries and obstacles in the construction area, and then excavate the foundation earthwork with an excavator. For large boulder and hard rock stratum, manual drilling and blasting are adopted, and excavators cooperate with slag removal for construction. Pay close attention to slope stability during excavation. If cracks are found in the surface soil near the pit, reliable support should be carried out in time and approved by the supervision engineer. When it is about 20cm away from the design foundation elevation, the foundation shall be cleaned by manual excavation.
(3) All materials excavated from excavation, if deemed applicable by the supervision engineer, can be used for backfilling or paving embankment or other methods instructed by the supervision engineer.
(4) The foundation excavation should always maintain good drainage to avoid water damage during the whole excavation construction.
(5) After the foundation pit is excavated to the basement elevation specified in the drawings, if the basement bearing capacity cannot meet the bearing capacity requirements specified in the design, the foundation treatment scheme shall be put forward according to the actual drilling (digging) holes and geotechnical test data, submitted to the supervision engineer for review, and handled according to the supervision engineer's instructions. Before the supervision engineer approves the excavation of foundation pit, concrete or masonry shall not be poured.
(6) After the foundation pit excavation is completed, report to the supervision engineer for on-site supervision and inspection, fill in the foundation inspection form for inspection, and report to the supervision engineer for re-inspection and approval before foundation construction can be carried out.
(7) During excavation and masonry, the pile point should be carefully controlled according to the measurement, and the wall surface and expansion joint should be set up by pulling wires to ensure that the wall surface is smooth, the slope is correct, and the settlement joint is straight without sundries.
(8) Before foundation excavation, the surrounding area shall be drained. After the foundation pit is formed, it should be carefully checked. If it does not meet the requirements of bearing capacity, it should be reported to the supervision engineer for inspection and decision in time, and then handled according to the feasible scheme to ensure that the foundation before masonry finally meets the design standards.
(9) When laying the first floor block of masonry foundation, if the basement is soil, it can be directly laid with mortar; If the basement is a rock stratum, its surface should be cleaned and wetted first, and then laid with mortar.
2, stone masonry and quality requirements:
(1) Stone grade shall meet the requirements of drawings or supervision engineer. Before the stone is used, it should be tested according to the Code for Stone Testing in Highway Engineering (JTJ 054-94) to determine the physical and mechanical indexes of the stone. The ultimate compressive strength of the cube should be ≥30Mpa.
(2) Stone materials should be tough, dense, durable, with appropriate and meticulous texture, uniform color and no weathering, peeling, cracks and structural defects.
(3) Stone materials shall not contain sludge, oil pollution or other harmful substances that hinder the normal bonding of mortar or damage the appearance of exposed surfaces. The transportation, storage and treatment of stone materials should not cause too much damage and waste.
(4) Stone materials should be roughly square, and the upper and lower parts should be roughly parallel. The thickness of the stone is 200~300mm, and the width and length of the stone should be 1 1.5 times and 1.5 ~ 3 times of the stone thickness, respectively. The sharp corners of the stone should be chiseled away. The surface depression depth of all facing stone surfaces perpendicular to the exposed surface shall not exceed 20 mm
(5) In the foundation pit that has passed the acceptance of the supervision engineer, the foundation laying sideline shall be released, and the mortar label shall be laid manually according to the design requirements, and the mortar shall be mixed by machine.
(6) Before laying, each stone should be rinsed with clear water and completely saturated, and the cushion should be clean and moist. All the stones should be placed on the fresh mortar. Before the mortar sets, all joints should be filled with mortar and the stones should be fixed in place. Vertical joint grouting is to grout the side of the stone that has been built, and then press the next adjacent stone; Or after the stones are in place, mortar is poured, and when the vertical joints are filled, they are tamped with flat steel.
(7) Masonry shall be laid in rows and roughly horizontally. Decorative stone should be laid according to the requirements of Ding Yishun. Any horizontal stones should overlap with adjacent stones by at least 80mm, and the mortar joint width should not be greater than 30mm. ..
(8) Pave corner stone and facing stone first, then pave auxiliary stone, and finally pave belly stone. Corner stone or facing stone should be locked with lining stone, and lining stone should be locked with belly stone.
(9) The vertical joints of lining stone and abdomen stone should be staggered, the width of mortar masonry flat joint should not be greater than 30mm, and the width of vertical joint should not be greater than 40 mm. ..
(10) If the stone is loose or the joint is cracked, lift the stone, clean the cushion mortar and joint mortar, and then resurface the stone on the new mortar.
(1 1) Before the mortar is solidified, the jointing depth shall be no less than 20mm. If the conditions do not allow, before the mortar solidifies, the depth shall not be less than 20mm to prepare for jointing in the future.
(12) After the completion of joint or grouting masonry, the maintenance should be strengthened within 7~ 14d according to the cement type and climate.
(13) Masonry shall be built in layers. When laying the upper layer, the lower layer should not be vibrated. It is forbidden to throw, roll or knock stones on the masonry that has been built.
(14) The positioning corner stone of the outer ring shall be flaky with square shape and large size, which shall be alternately bonded with the inner block stone. Upper and lower blocks shall be staggered, and vertical joints shall not overlap.
(15) Larger blocks should be laid on the lower floor. When installing, select blocks with appropriate shapes and sizes, and knock off sharp protruding parts. When the vertical joint is wide, pebbles should be stuffed in the mortar, and pebbles higher than mortar joints should not be used as bedding under the pebbles.
(16) The retaining wall is built in sections according to the design, generally, each section is 10 ~ 15m. At the same time, expansion joints or settlement joints should be set at the basic geological changes. The front slope of the wall between two joints must be the same, and the back slope can be the same or different.
(17) The retaining wall body shall be provided with drainage holes as designed, and the filter layer shall be provided at the entrance of the drainage holes. If the drainage behind the wall is poor or the filler is easy to frost heave, pebble sand with a thickness of not less than 30cm should be filled between the lowest drainage hole behind the wall and the top of the wall 50cm.
(18) The foundation pit at the foot of the wall shall be backfilled and compacted in time, and made into an outward-leaning transverse slope. The filler behind the wall should be filled in layers in time, and the thickness and compaction degree of layers should meet the requirements of the corresponding quality standards of subgrade filler in this section. Large-scale mechanical compaction is prohibited for the filler behind the mortar retaining wall1m.
(19) After the wall is laid to the top surface, the top surface of the masonry shall be leveled with mortar in time to prevent surface water from scouring and infiltration.
3, foundation and wall flaky concrete construction:
(1) The filling amount of flaky shall not exceed 25% of the concrete volume, and the thickness of flaky shall not be less than150 mm..
(2) The compressive strength of flaky is not less than 30MPa and not less than that of concrete. Gravel should be cleaned and washed before use.
(3) Rubble should be evenly placed on the newly poured concrete, with a clear distance of not less than lOOmm. The surface distance of rubble from the wall and foundation shall not be less than 150mm, and it shall not contact with steel bars or embedded parts.
(4) The wall should be set with settlement joints according to the basic geological changes or 4~6m, and poured in sections. Settlement joints are set between sections, with the width of 1-2cm, and asphalt flocs are filled in the settlement joints.
(6) The side formwork and end formwork are supported by steel formwork, and their strength and rigidity should meet the requirements of Technical Specification for Construction of Highway Bridges and Culverts. The dimensions meet the design requirements of the drawings, and the template should be cleaned in advance and coated with engine oil as a release agent.
(7) After all these works are completed, self-inspection shall be carried out according to the requirements of drawings. After the self-inspection is qualified, the concrete can be poured only after it is checked and approved by the supervision engineer.
(8), according to the design requirements of the drawings of concrete label, according to the mixture ratio of the laboratory, using mechanical mixing concrete, concrete pouring with trolley transportation, after concrete pouring, should immediately conduct a comprehensive tamping, tamping concrete, using 50 type internal vibrator vibration.
(9), vibrating must be carried out at the pouring point and the surface of the new concrete, vibrator.
When pouring or pulling out concrete, the speed should be slow to avoid cavities.
(10), the vibrator should be inserted vertically into the concrete, and into the previous layer of concrete, so as to ensure that the newly poured concrete is well combined with the first poured concrete, and the insertion depth is generally 50 ~ lOOmm.
(1 1), the moving distance of the internal vibrator shall not exceed 1.5 times of the effective vibration radius. Avoid contact with steel bars and embedded components.
(12), it is not allowed to use the vibrator to make the concrete flow or transport the concrete for a long distance in the formwork, resulting in segregation.
(13), the sign of concrete vibrating compaction is that the concrete stops sinking, does not bubble, is pulpy and has a smooth surface. Within 1.5~24h after concrete is compacted, it should not be vibrated.
(14), pouring shall be carried out continuously. If it must be interrupted for some reason, the interruption time shall be determined by the test and approved by the supervision engineer. If the interval exceeds the allowable time, it will be treated as construction joint.
(15), the operation on the concrete surface should be meticulous and thoughtful, so that the mortar is close to the template and the concrete surface is smooth, without water bags, airbags and honeycombs.
(16), after the completion of concrete pouring, the surface shall be cured as soon as possible after the slurry is collected, and the water curing shall be maintained for at least 7 days or the days instructed by the supervision engineer.
4. Backfill:
(1), the abutment back fill is required to be sandy soil or gravel soil with good water permeability, which should be compacted and backfilled in layers.
5, test sampling:
During the construction process, random sampling shall be conducted for stone, mortar and concrete according to the requirements of specifications. If the supervision engineer thinks it is necessary, the sampling of stone and pressure test block shall be carried out according to the requirements of the supervision engineer.
Fourth, quality assurance measures
1, quality management and organization
The project department shall set up a total quality management leading group, with the project manager and chief engineer as the deputy team leader, and the members shall be composed of the project quality inspection engineer, work area director, technical director, quality inspector, operator and equipment and materials director of the project department. See the quality inspection organization chart for the quality inspection organization.
Quality inspection organization chart
2, the main mechanical equipment list:
The name of the equipment is called single equipment quantity, and the equipment status table is reserved.
Excavator platform 1 Good Cat 320
Mortar mixer 1 good 250L
Concrete mixer 1 good 350L
Vibrator table 2 is good. Hz6x50
The 4-series walker is good.
Verb (abbreviation for verb) Safety precautions:
1. Construction safety work should implement the policy of "safety first, prevention first", strictly abide by the relevant provisions of Technical Specification for Safety in Highway Engineering Construction (JTJ 076-95), formulate safety system, take safety measures, and be responsible for checking the implementation to ensure construction safety. Conduct safety education and impart safety knowledge to all operators entering the construction site.
2. Set up safety warning signs at the pedestrian passage, and take corresponding safety protection measures for places with potential safety hazards. Various effective protective measures should be taken during construction, such as lighting, dustproof, waterproof and cooling. , to protect environmental sanitation, to ensure the health of construction personnel and production safety.
Six, civilized construction:
1. Strengthen publicity activities, unify thoughts, and enhance the consciousness of civilized construction and site management.
2, combined with the actual situation of this project, a clear division of labor in the intends to implement the civilized construction site responsibility area, formulate corresponding rules and regulations, to ensure that the civilized construction site management rules.
3, reasonable layout of the site, temporary facilities must meet the prescribed standards, so that the site is clean and tidy, roads are smooth, drainage is smooth, signs are eye-catching, and the production environment meets the requirements of standard operation.
4. On-site project overview card, construction organization network card, safety discipline card, safety publicity card, fire prevention notice card, accident record card and construction site plan should be set up completely, with unified specifications, complete contents and eye-catching positions.
5, the construction site adhere to the work is expected to clear, leaving no garbage and sundry, the rest of the spare parts of materials are neatly stacked, and handled in time. Construction waste water is strictly prohibited to be discharged and put in disorder.
6, handle the relationship with the surrounding people in the construction, try to avoid construction nuisance. Control noise during construction to avoid noise pollution.
7, do a good job of construction waste disposal, to avoid environmental pollution.
8, strengthen inspection and supervision, strict requirements, perseverance, make the civilized construction site management really catch results. The leaders of the project team and the management department shall conduct regular and irregular inspections on the civilized construction site, organize a special inspection once a month, score the appraisal, strictly reward and punish, exchange experiences, and check and fill vacancies.
9, strict operating standards, standardized operation.
10, according to the instructions of the owner and the competent construction department, at the same time, listen carefully to the opinions of the resident supervisor, coordinate all aspects, do a good job in safety production and civilized construction, and strive for a safe and civilized construction site.