[(Division) Irrigation and Water Conservancy Construction Scheme] Construction Scheme of Division or Subdivision Project

Land reform in low mountains and hills of Yuyangguan and other two towns in Wufeng County.

Niuzhuang 1 project of the third bid section of construction project.

(irrigation and water conservancy)

Construction methods and techniques

Niuzhuang 1 Bid Section of the third bid section of the reconstruction project of low hills in Yuyangguan and other two towns in Wufeng County.

Engineering Project Department

20 13 February

Irrigation and drainage of agricultural ditches

First, the construction technology

The construction of the channel project is carried out according to the following procedures: survey and setting out → excavation of foundation trench → foundation cleaning, leveling and tamping → C20 concrete floor pouring →M7.5 mortar ditch building → interface treatment → maintenance.

Second, the foundation trench excavation

1. According to the actual situation on site, mechanical excavation and manual cooperation are adopted for slotting.

2, according to the requirements of design drawings and measurement positioning center line, according to the trench excavation size, play a good gray line.

3. When mechanical excavation is adopted, detailed disclosure shall be made to the mechanical driver. Disclosure content generally includes excavation section, pile location, existing underground structure, construction technology and safety requirements, etc. , and appoint someone to cooperate with the driver. The cooperating personnel should be familiar with the relevant safety operation procedures of mechanical excavation, and cooperate with the surveyors to measure the elevation and width of the trough bottom, and put the slope in time to prevent overbreak and steep slope.

4, mechanical excavation, should ensure that the soil structure at the bottom of the tank is not disturbed and destroyed, excavation should be about 20cm above the design elevation of the bottom of the tank without digging, using artificial bottom cleaning (machine digging).

5. When manually cleaning the trench, the elevation and width should be carefully controlled, and the soil structure at the bottom of the trench should be protected from damage. The distance from the edge of the pile to the edge of the trough should be determined according to the means of transport.

6. Silt is excavated manually and transported to the designated spoil ground by rubber-tyred vehicle.

Third, the concrete formwork

1, template installation

Template uses wooden template, according to the design size, customized supporting template.

Template engineering quality requirements

2, concrete engineering

(1) All subbase surfaces shall be smooth and free of humus, turf, branches, sundries and garbage. Should be deleted. Without the acceptance and signature of the supervision engineer, the foundation preparation work shall not be carried out for the lining construction of floor concrete.

(2) The trench bottom should be built on the old soil layer, and the overbreak part should be compacted and backfilled with crushed stone soil layer by layer according to the specification requirements, with the density reaching 95% or higher. Both sides of the drainage ditch are built with mortar.

(3) C20 ordinary concrete is used for the ground of the channel, and the concrete is mixed by a mixer. After concrete is mixed, it should be poured into the warehouse within 45 minutes. When pouring concrete, the loose soil layer should be excavated for the soil foundation, and sundries should be removed. Before pouring, gravel should be used as the bottom and compacted. For rock foundation, fresh rocks, loose rocks and protruding edges and corners should be removed, dirt, dirt and sundries should be removed, and surface washing should be cleaned with clean water. You can't pour it until it is dry. When pouring concrete, an expansion joint should be left every 10 meter. The poured concrete must be vibrated and compacted by a vibrator, and the curing time after concrete pouring shall not be less than 14 days.

Fourth, culvert construction

(1), C20 concrete is used for the bottom plate of culvert and C25 concrete is used for the top plate. ② Before culvert construction, the elevation of culvert bottom must be re-measured to check whether the design elevation meets the actual needs and whether it meets the drainage and irrigation functions of the original ditch.

(3) During the construction, when the thickness of the overburden at the top of the culvert is less than 0.5m, it is forbidden for any heavy machinery or vehicles to pass through.

(4) When laying out pipe culvert construction, pay attention to the total length of culvert, the configuration of pipe joint and the accurate position of wing wall hole.

⑤ Culverts should be arranged in strict accordance with the design. When the culvert axis deviates from the original ditch, attention should be paid to the smooth connection between the hole and the original ditch to ensure the normal function of the culvert.

Five, drainage channel quality control standards

1, guaranteed project

(1) The quality of raw materials for channel engineering must meet the design requirements, and the mixture ratio of mortar and concrete should be determined through experiments.

(2) The number of settlement joints of the channel must meet the design requirements, and the bottom, wall and settlement joints of the channel must be treated according to the design requirements.

2. Allowable deviation items

The plane position, section size, longitudinal slope and surface flatness of the trench bottom high line shall meet the requirements in the following table:

List of allowable deviation of drainage ditch inspection items

Grouting masonry construction method

I. Process flow

According to the actual situation, the construction shall be carried out in accordance with the principles of foot protection first, slope protection later and coping. The mortar masonry project of this project shall be constructed according to the following procedures: foundation earthwork cleaning-foundation construction-masonry-performance cleaning-plastering.

Second, the main component project construction method

2. 1 foundation soil cleaning

The base surface cleaning scope includes slope surface and step surface, and the top boundary should be 30 cm ~ 50 cm outside the design base surface sideline. In order to avoid man-made damage to the cleaned foundation soil, the unqualified soil and sundries on the slope protection surface must be removed, and the pits, grooves and ditches within the base of the embankment should be backfilled according to the requirements of embankment filling.

After the base surface is cleaned and leveled, it shall be submitted for inspection in time. After the acceptance of the foundation surface, we should pay close attention to the construction. If the construction can't be carried out immediately, the base surface should be protected, rechecked before returning to work, and cleaned again if necessary.

2.2 foundation soil rolling

Plane vibrating equipment is proposed for surface vibration of slope protection base. Found the local "spring"

Timely deal with quality problems such as "soil", smooth interlayer, hollow interlayer, loose soil layer or shear failure, and pave new soil after inspection.

2.3 Masonry structure

2.3. 1 raw materials

1) Masonry stone shall be accepted on site, and the masonry material shall be solid and fresh, without weathered peeling layer and cracks. There is no dirt, rust and other impurities on the stone surface, and the color of the stone used on the surface should be uniform. The stone density should be greater than 25kN/m3, and the compressive strength should be greater than 60MPa. Stone shape specifications are complete, rubble should be massive, and the minimum weight should not be less than 25kg. Rubble with specifications less than the requirements can be used for caulking, but its dosage shall not exceed 10% of the weight of masonry here. Stone should be angular and smooth, its length should be greater than 30cm, the minimum side thickness should be greater than 20cm, the exposed surface of stone should be chiseled, and the elevation difference of masonry surface should be less than 5mm.

2) Sand: site acceptance of sand materials. Quality requirements: material diameter is 0. 15 ~ 5 mm, fineness modulus.

2.5 ~ 3.0, the maximum particle size of sand for mortar masonry is not more than 5mm, and the maximum particle size of sand for mortar masonry is not more than 2.5 mm

3) Cement and water: the variety and strength grade of cement meet the requirements, and the arrived cement should be stored separately according to the variety, strength grade and factory date. It is forbidden to use cement with water caking. The standard of water is that all water suitable for drinking can be used and should not affect the strength growth of concrete and mortar. The pH value of water is insoluble and soluble, and the chloride content meets the specification requirements.

4) Mortar

1) The dosage of mortar must meet the requirements of strength and workability specified in the construction drawings, and the dosage must be determined through experiments. When the dosage of cementing material needs to be changed during construction, the test should be carried out again.

2) When mixing mortar, ingredients shall be made in strict accordance with the ingredient list determined by the test.

The allowable weighing error shall meet the following requirements: cement 2%, sand 3% and additive 65438 0%.

3) Stirring time: Mechanical stirring shall not be less than 2 ~ 3min.

4) Cementitious materials should be used with mixing, and the allowable intermittent time of cementitious materials should be determined through experiments or selected with reference to the following table. When segregation or bleeding occurs during transportation or storage, it shall be re-stirred before masonry, and initial setting mortar shall not be used.

5) When the average daily temperature in winter is lower than 3 ~ 5℃, it is not suitable for masonry. When the temperature is not lower than 0℃, the strength grade of cement mortar should be appropriately improved, and the masonry temperature of clinker should be kept not lower than 5℃. In order to prevent freezing injury, heat preservation measures should be taken.

Mortar masonry

(1) General requirements

Mortar masonry shall meet the following requirements:

1) Before laying, the dirt on the stone outside the masonry should be washed clean, and the masonry surface should be kept wet when laying;

2) The layered masonry is laid by mortar sitting method, and the thickness of mortar laying is 3 cm ~ 5 cm, which increases with the increase of mortar laying and masonry. Masonry joints should be filled with mortar, and the mortar in masonry joints should be compacted with flat iron. Before grouting with mortar, it is forbidden to pile up stones;

3) The upper and lower masonry should be staggered; The exposed surface of masonry should be smooth and beautiful, and a gap of about 4cm deep should be left for jointing treatment. Horizontal seam width should not be greater than.

2.5cm, vertical seam width should not exceed 4 cm;

4) Masonry stops for some reason, and the mortar has exceeded the initial setting time, so the mortar strength should be achieved.

2.5MPa before continuing the construction and before continuing the masonry, the scum on the surface of the original masonry should be removed; Vibration of the lower masonry should be avoided when laying;

5) The mixture ratio and working performance of mortar shall be determined by experiments according to the design label, and specimens shall be randomly taken at the masonry site during construction.

6) Before paving mortar, the stone should be wetted with water to make its surface fully absorbed, but no residual moisture is allowed. When laying, the masonry method of lateral vertical stone and middle core filling shall not be adopted. Mortar should be full, and large gaps between stones should be filled with mortar first, and then embedded with gravel or flaky. It is not allowed to use the construction method of paving macadam before filling mortar or dry filling macadam blocks, and the stones should not touch each other.

7) When the lowest temperature is between 0℃ and 5℃, attention should be paid to the surface covering protection during masonry operation. When the lowest temperature is between 0℃ and 30℃, masonry should be stopped. In case of rainstorm, the warehouse surface without canopy should immediately stop construction and properly protect the surface. After the rain, the accumulated water should be removed first, and the parts washed by the rain should be treated in time.

(2) Operating requirements

1) grouting (grouting): cement mortar is used as the cementing material, and the grouting thickness is 1.5 times the design thickness, so that there is a certain sinking space for the stone after installation, which is beneficial to the mortar joint. Build by laying bricks or stones one by one, and adjust carefully during operation to ensure that the mortar is dense, so as not to form a cavity. Rubble masonry, mortar thickness of about 8cm, is to cover uneven surface.

2) Placement of stone: On the surface of masonry with slurry, place the cleaned and wet (or saturated dry surface) stone, and hit the stone surface with a hammer to make the slurry begin to overflow to a certain extent. The joint width between stone materials should be strictly controlled, and cement mortar should be used for masonry, generally 2-4cm.

3) Vertical joint grouting: After the stone is in place, vertical joint grouting shall be carried out in time and vibrated (inserted) for compaction. After compaction, the joint surface sinks slightly, which can be filled when the upper joint is laid with slurry.

4) Vibrating: the width of cement mortar joint is small, and manual tamping insertion method is adopted, which is commonly used.

Tamping tools include steel tamping, bamboo tamping or special tamping steel plate.

5) Secondary masonry time: After paving the pavement for 24 ~ 36h per unit (depending on the temperature, cement type and strength grade), it can be cleaned and washed to prepare for the paving of the next layer.

(3) The quality of masonry shall meet the following requirements:

1) leveling: the same elevation should be roughly leveled, and the height difference between adjacent masonry should be less than 20 ~ 30 mm ..

2) Stability: The stone must be placed stably, with the big face down, and shaken or knocked properly to make it stable.

3) Densification: direct contact of stones is prohibited. Mortar for seat joints and vertical joints should be full and dense, and the mortar should be evenly spread. After the vertical joints are filled with mortar, they should be compacted until the surface is submerged.

4) Staggered joints: In the same masonry layer, adjacent stones should be laid alternately, and there should be no straight joints along the flow direction. Upper and lower adjacent stones should also be staggered and overlapped to avoid vertical straight seams. If necessary, it can be laid regularly.

(4) Maintenance

The exposed surface of masonry shall be maintained in time between 12 ~ 18h after masonry, and the exposed surface shall be kept moist frequently. The curing time of cement mortar masonry is longer than 14d. In winter, the hydration reaction of cement is slow and the initial setting time is prolonged. Generally, masonry is not suitable for sprinkler maintenance, but thermal insulation and anti-aging measures such as covering sacks, straw bags, straw curtains, plastic films and boiler heating are adopted.

2.3.3 Common quality faults of masonry engineering and preventive measures

(1) Slurry masonry is not dense

1) phenomenon: there are dog holes or cracks in the paved parts, and the mortar is not full when opened.

2) Reasons: A, the mortar is not fully filled; B, mortar joint width is not enough; C, there is no layered horizontal build by laying bricks or stones.

3) Preventive measures: (a) Grouting method is adopted for construction, and the grouting between two stones is full; (b) Laying in layers with overlapping inside and outside; (c) Arrange full-time quality inspectors to conduct on-site inspection in each masonry operation area to ensure the quality assurance progress and be responsible for the end. Make on-site records, and investigate the quality inspector's responsibility if there is any problem.

2.3.4 Masonry quality inspection

1) The masonry strength must meet the requirements of construction drawings.

2) Check the density and porosity of masonry. For masonry with dam height below 1/3 and masonry with dam height below 5 ~ 10m, at least one group shall be dug for each block. For masonry with dam height above 1/3, the number of test pits shall be determined by the supervisor and the contractor through consultation. The measured density and porosity must meet the construction requirements.

3) Joints shall be dense, without overhead and slurry leakage. Water pressure test should be carried out at the parts with anti-seepage requirements to detect the water absorption rate of the unit.

4) The joint width of masonry surface meets the specified requirements.

2.3.5 Cement mortar plastering

1) The plastering mortar should adopt fine sand and a small water-cement ratio, and the water-cement ratio should be controlled between 1: 1 ~ 1: 2.

2) Ordinary Portland cement with P42.5 or above shall be used for the anti-seepage mortar.

3) Plastering mortar must be mixed separately, and it is forbidden to mix with masonry mortar.

4) After plastering is completed and the mortar is finally set, the masonry surface should be scrubbed clean and covered with soaked materials for at least 21d.. During curing, water should be sprayed frequently to keep the masonry moist and avoid collision and vibration.

2.3.6 filtration and drainage engineering construction

1) Before laying the filter layer, the foundation surface shall be excavated and leveled. For some low-lying parts, it should be filled with the same soil material as the foundation surface or the first filter material of the filter layer.

2) The laying of the filter layer shall meet the following requirements:

(1) Before paving, the site should be well drained, piles should be set up, and sufficient filter materials should be prepared;

(2) The thickness of filter materials with different particle sizes must meet the design requirements;

(3) According to the requirements of the design structure layer, it shall be laid layer by layer from bottom to top, with clear layers, and shall not be mixed with each other, and shall not be dumped along the slope from a height.

3) When paving in sections, the joint level shall be clear, and there shall be no dislocation, omission and interlayer mixing.

4) In the section where the filter layer has been laid, the upper masonry shall be laid in time, and trampling is strictly prohibited.

5) Paving should be stopped in snowy days, and it is forbidden to mix frozen soil, ice and snow into materials when returning to work after snow.

Three. Quality control and acceptance

3. 1 quality control

1) Check the construction operation and quality of masonry, and see if it conforms to the provisions of relevant specifications;

2) Check whether the deformation joint construction and water stop structure production meet the design requirements;

3) The strength evaluation of cement mortar specimens should meet the requirements of corresponding specifications;

3) unit engineering division, in which the mortar masonry is divided into a unit every 50 meters ~ 100 meters of embankment length;

concrete work

This project adopts self-mixed concrete.

I. Operating conditions

1, when the task list is issued, it must include the project name, location, location, quantity, various technical requirements for concrete (strength grade, retarding and special requirements), site construction method, production efficiency (or time limit). Handover lap requirements, as well as the content of coordination between the supply and demand sides, are issued together with the notice of construction mixture ratio.

2. The test run of the equipment is normal, and the number of concrete transport vehicles meets the requirements.

3, the material supply is sufficient, especially the specified cement varieties have enough reserves or follow-up supply is guaranteed.

4. All materials shall pass the inspection and meet the use requirements.

5, mixing station, cast site and transport vehicles with walkie-talkies as a reliable means of communication.

6. The weather meets the operation requirements.

Second, the production of self-mixed concrete

1, according to the mixture ratio to determine the amount of each plate (tank) of various materials, should be weighed.

2. Loading sequence: generally, stones are loaded first, then cement is loaded, and finally sand is loaded. When admixture is needed, it should be added together with cement.

3. The shortest time of concrete mixing should be determined according to the requirements of construction specifications.

Third, concrete transportation.

1. Concrete will be transported by trolley at the site.

2. After the concrete is discharged from the mixer (machine), it shall be transported to the pouring site in time, and the duration shall not exceed the initial setting time. During transportation, it is necessary to prevent concrete segregation, cement slurry loss, slump change and initial setting.

3, concrete transportation road should be flat, if there is uneven, should be paved bridge fang.

Fourth, concrete pouring

(1), before pouring concrete, the cast-in-place template must be blown clean, and the wooden mold needs to be watered and wet. When pouring concrete, use a flat vibrator to vibrate. To grasp the time, the concrete surface level will no longer sink, no bubbles will appear, and the surface will be covered with mortar.

(2), at any time according to the elevation control line stay to check the flatness, with 2-4 m aluminum alloy poles.

Scrape the surface flat, then rub it flat with a wooden trowel, and rub it for more than two times before the initial setting of concrete to prevent the concrete surface from drying and cracking.

(3) In order to ensure that the cast-in-place concrete is smooth and consistent, the cast-in-place concrete should be leveled and rubbed twice before initial setting, and pulled out along the grain with a big brush.

Verb (abbreviation of verb) concrete maintenance

Generally, the method of covering, watering and storing water is adopted for plane structure concrete, which is not only economical, but also can keep the concrete in suitable mild and humid conditions for cement hydration for a certain period of time, so as to ensure the growth of concrete strength. The vertical structure adopts the method of brushing curing liquid to form a film on the surface of concrete, which isolates the contact between concrete and air, seals the evaporation of water in concrete, completes the hydration of concrete, and makes the concrete reach the design strength before the film breaks. In winter construction, all exposed parts of the concrete surface can be tightly covered with plastic film and straw curtain to ensure that there is condensed water in the film and sufficient strength growth temperature. After concrete pouring, the natural curing time is generally 12h, and the concrete surface shall be kept moist within 7d, and the impervious concrete shall be cured at least 14d.

Six, finished product protection

(1) The protection of finished concrete products has a direct impact on the appearance and durability. Therefore, the finished product must be protected.

(2) After concrete pouring reaches a certain strength (when the test block with the same conditions reaches 65438±0.2 MPa), the foreman can proceed to the next procedure. Before the next process, the board surface should be protected. In addition, when pouring concrete, the scattered concrete should be cleaned in time to prevent secondary pollution. (3) When the concrete does not reach 65438±0.2 MPa, it is forbidden to trample on it. When the formwork is dismantled, protect the corners with angle iron or old bamboo formwork to prevent falling corners.