Bian Xiao sorted out the relevant contents of masonry retaining wall through the architectural knowledge column of the encyclopedia website "Building Network" of the construction industry. The basic situation is as follows:
According to the relevant information compiled by Certificate Network, the construction technology of masonry retaining wall is as follows:
A, construction equipment:
Each construction section must be equipped with portable mixer, water pump, iron plate, scale and other basic mechanical facilities. Trolley, shovel, hoe, spade, tile hammer, hand chisel, spirit level, jointing strip, shoulder pole, sloping gantry, etc. According to the construction needs, provided by the labor service cooperation team.
Second, the material requirements:
Stone used in the project should be uniform, hard, not easy to weather, no cracks, and surface stains should be removed. The shape of the sheet is not limited, but the thickness of the middle part shall not be less than 15cm. Ordinary portland cement should be used, different types of cement should not be mixed, and expired cement is strictly prohibited. The fine aggregate is made of hard and durable natural yellow sand, the particle size is below 5mm, and the silt content of sand is not more than 3%.
Third, safety measures
Construction personnel must wear safety helmet and protective gloves. High slope construction should have protective ropes, slings and warning signs. In the construction process of turquoise removal, there should be a special person to command. When repairing the slope manually, we should pay attention to the potential risks such as landslides and landslides, and make corresponding adjustments in time to avoid unnecessary safety accidents. The electrical operation on the construction site should be operated by full-time electricians according to the specifications. Check the leakage of equipment and wires used in the operation area, and repair them immediately if problems are found. Operators of electrical equipment must wear qualified labor protection clothing and standard insulating gloves. Rainy, snowy or humid weather is not suitable for using electrical equipment in the open air. The electricity facilities on the construction site should be equipped with leakage protection devices. The switchboard at the construction site shall be protected from rain and snow. Grounding protection should be provided outside the metal shell of electrical equipment. All kinds of lines on the switchboard should be numbered and marked with the purpose. During the maintenance of distribution lines, a warning sign "No closing, manned operation" should be hung. Stop, someone must be in charge of power transmission.
When carrying stones, attention should be paid to the coordination of steps, and the construction sidewalk should have sufficient width and strength to ensure transportation safety. In the process of manual drilling, it is necessary to prevent the stones from collapsing and injuring the operators. When operating the mixer, you should abide by the operating rules, and it is forbidden to operate illegally.
Fourth, the construction preparation
The construction site requires three links and one leveling, and the quality indexes of cement, yellow sand and stone pass the laboratory sampling inspection; On-site construction machinery and equipment can meet production requirements; Operators, construction team leaders and technicians have accepted technical disclosure. According to the requirements of the drawings, the survey and setting-out work has been completed. For masonry with slope requirements, a self-made groove should be set. Cement and sand used for construction should be classified and piled up, and cement should be waterproof and moisture-proof. Masonry mortar shall be determined by the tester according to the design requirements and the actual situation of site materials, and written on the sign.
Five, the basic measuring unreeling
According to the design drawings, the coordinate points of the four corners of the foundation are accurately set out with the total station, and the main (horizontal) axis, starting and ending points and settlement joints of the retaining wall foundation are accurately determined. According to the actual needs of construction lofting, the original ground elevation of each point of retaining wall is measured with a level to determine the excavation depth of foundation pit. Set the construction leveling points, pop up the axis and wall line at the bottom of the foundation pit, and lead the axis and wall line out of the operation section.
Six, foundation pit excavation
Dredge the ground drainage system before foundation pit excavation. It is forbidden to overbreak when excavating the excavator, so as not to disturb the undisturbed soil of the basement. 20cm shall be reserved for digging to the design basement, and artificial brushing shall be adopted for finishing, so as to ensure that the basement is smooth and the geometric size and elevation of the basement meet the requirements. Base brush 10% reverse slope (i.e. low inside and high outside) to prevent the retaining wall from sliding outwards due to the squeezing force of the soil in the wall. Ensure slope stability during excavation, and use artificial shallow hole blasting in case of stones. The plane size of basement excavation should be widened by about 50cm compared with the design size; The slope of foundation pit wall should be based on geological conditions, foundation pit depth and construction method, and the corresponding slope ratio should be adopted. If the foundation excavation is different from the design, it should be reported to the relevant departments and the design should be adjusted according to the actual situation. After the foundation pit is excavated to the design elevation, the bearing capacity of the basement should be checked, and the foundation construction should be carried out immediately after being checked by the supervision engineer. When the earthwork excavated in the foundation pit is piled up in the site, enough good soil must be reserved for backfilling; Excess earthwork should be transported away at one time to avoid secondary transshipment. When the soil is abandoned at the edge of the foundation pit, the pile of soil at the edge of the pit should be 1.2m away from the upper edge of the foundation pit, and the height should not exceed1.5m. Any soil foundation pit should not be exposed, disturbed or soaked for a long time after being dug to the elevation, so as to weaken the bearing capacity of the basement. After the foundation pit excavation is completed, pay-off and reinspection shall be carried out, and the foundation construction can only be carried out after the position is confirmed and signed by the supervision engineer.
Seven, mortar foundation
1, before laying, the stone surface should be cleaned and watered, the vertical poles on both sides of the foundation pit should be hung up, the lateral line should be straight and flat, and the slope should be closed step by step.
When you lay the foundation, you should sit in the mud first, and then hit the stone.
3, the foundation settlement joint setting requirements with the wall.
4. After the foundation slurry is laid, the foundation pit shall be backfilled by layers with permeable materials, compacted by layers with small machinery, and the surface shall have a slightly outward slope to prevent water from infiltrating into the soaked base.
5. The foundation grouting process is basically the same as the wall grouting process.
Eight, mortar mixing
1. Masonry mortar is labeled M7.5. In order to ensure the actual configuration strength of mortar, the ingredients shall be prepared according to the strength requirement of not less than 8.7Mpa, and the construction mixture ratio shall be prepared according to the weight, and mixed by small mixing machinery. If P.O32.5 cement is used, the design mixture ratio of mortar should be cement 1: sand 5. 1, and the water content should be adjusted according to the water content of sand. Mortar mixing and feeding sequence is dry mixing of sand and cement, and then wet mixing with water, and the wet mixing time shall not be less than 45s. Mortar should be used when mixing, maintaining a proper consistency (30-50 mm), and should generally be used within 2 hours. Mortar with segregation and bleeding should be re-stirred before masonry, and mortar that has been overtime or solidified shall not be used. Mixed mortar shall be transported to the masonry site by hand dump truck and stacked on clean iron sheet. It is forbidden to pile it on the ground.
2. The testers of the project department should not only distribute the mortar ingredient list to the mortar construction site, but also perform the responsibility of "opening appraisal". The so-called "unpacking appraisal" is to check whether the cement, sand and mixing water meet the specifications in the ingredient list at the construction site; Check whether the mixing quantity of each plate meets the requirements. The sand should be put into the handcart and weighed, and unweighed sand should not be directly shoveled into the mixer hopper. It is advisable to mark the horizontal line with ink on the car to convert the weight into volume, which is beneficial to the construction convenience.
Nine, mud wall
1. Before laying, samples shall be released as designed. In order to control the slope inside and outside the wall, before masonry, the slope frame should be nailed with pine boards, erected at both ends of the masonry section, hung with horizontal lines, and laid by stages and layers by grouting method. The subsection position is located at the settlement joint, and the horizontal joints of each subsection should be consistent. Before paving, the flaky should be watered and wetted, and the dirt on the stone surface should be washed clean. Layered masonry takes 2-3 layers of stones as a working layer, and the horizontal joints of each working layer are roughly leveled, and the vertical joints of different horizons should be staggered accordingly and cannot be penetrated.
2. Each layer of masonry should be grouted before masonry. The thickness of grouted stone should make the stones tightly connected when they are extruded for masonry, and the masonry mortar should be dense and full. Positioning stone (corner stone) and facing stone should be large-sized stone with relatively neat surface. When laying in layers, corner stone, back stone or face stone should be laid first, and then belly stone should be laid. Peripheral fixed blocks should be staggered with inner blocks, mortar should be laid at the joints of positioning stones, and pebbles should not be embedded.
3. When laying abdominal stones, the stones in the masonry should be matched in size, the joints between the stones should be staggered and the mortar should be dense. There shall be no direct contact between stones without mortar, and mortar shall not be laid after the stones are dry-filled. The flaky is not suitable for upright use, and the sharp protruding part should be knocked off when laying. In general, larger stones are made of large surfaces. However, when grouting flaky, it is necessary to use the natural shape of flaky to connect the large and small masonry together alternately. Except that the stones on the bottom layer should face down, the stones on the top don't have to face down, so they are staggered and closely matched. At the same time, when laying the lower stone, we should consider how to connect the upper stone, and leave gaps in the stone building process to ensure the depth of 2 cm, which is conducive to jointing. The width of flat seam and vertical seam is not more than 20mm, and small stones can be knocked into the jam with a small hammer in the wider seam, but the stones should be wrapped with mortar. Before the mortar solidifies, scrape the joint mortar to a depth of not less than 20mm to prepare for jointing in the future.
4. Mortar rubble should be embedded in the slope by 0.2m to prevent the influx of surface water. When the design elevation difference of adjacent retaining walls is large, high wall sections should be built first. When the masonry is interrupted, the gaps in the masonry stone layer should be filled with mortar. When the masonry is resumed, the surface of the stone layer should be cleaned and watered, and the working joints should be left with oblique stubble.
5. When the mortar is close to the design height, the top should be paved with relatively flat stones, leveled with cement mortar, and the slope of horizontal running water on the top surface is 2%. Check the plane position, section size and slope of masonry at any time in the process of masonry to ensure the appearance and internal quality of masonry.
6. The masonry retaining wall shall be provided with drainage holes with the spacing of 2 ~ 5m, and round PVC pipes with the diameter of 10cm shall be installed in the holes. The position of the preset drainage hole should meet the design requirements, and the outward cross slope of the drainage hole is generally 3%. The upper and lower drainage holes should be staggered, and the height of the bottom drainage hole from the bottom should be 30cm. Settlement joints of masonry should be set according to design requirements. Generally, a settlement joint is set every 10 meter (corresponding to the foundation settlement joint). Each settlement joint should run vertically through the whole masonry section, with a width of about 2 cm. Joints shall be filled with asphalt cotton wool, and the depth of filling shall not be less than 20cm.
Ten, mortar specimen production
Each workbench class produces two groups of standard health specimens for self-inspection and one group of standard health specimens for supervision and sampling, and one group of specimens consists of six test blocks. When making, the mortar is divided into two layers (about 40mm for each layer) and put into the test mold coated with release agent, and each layer of mortar is compacted evenly for 25 times with a tamping rod (steel bar with a diameter of 20mm and a length of 200mm, and the bottom surface is machined into a plane). After the second layer is compacted, insert it several times along the mold wall with a spatula to make the mortar 6-8 mm higher than the mold wall. 0.5- 1 hour after the specimen is formed, scrape off the remaining mortar with a spatula, and level the surface for site coverage and maintenance. Generally, after demoulding for 24 hours and indicating the construction site and date, it will be sent to the construction unit and the resident office laboratory for standard maintenance.
XI。 Gypsum process
After the completion of retaining wall masonry, the top of the wall shall be plastered with plastering mortar no less than 10, and the plastering thickness is generally 20-30 mm ... The cross slope of flowing water at the top of plastering layer shall be 2%. The setting requirements of settlement joint in plastering section are the same as those in wall, and plastering shall be carried out after the settlement joint on the top surface is completed. After plastering, use C30 cement mortar to tick off the running water on the top surface. The plastering width should be 2cm beyond the top side of the wall, commonly known as "wearing a hat". The "hat" should extend downward along the wall and be integrated with the wall. The thickness of the hat is 6cm.
Twelve, pointing process:
The mortar rubble retaining wall should be slotted and true, and it is forbidden to slot. After jointing, the outline of the stone cannot be hidden, and the exact position and width of the real joint should be clearly visible. Before the joint, the joint depth should be not less than 20mm, and the joint width should be the real width of the joint. Do not meet the requirements should be reworked. After fully cleaning and wetting the qualified joints, tick off the joints with mortar (mixed with fine sand) with a higher grade than masonry mortar. The height of joint surface is slightly lower than that of masonry by 2-4 mm, and the surface of jointing mortar should be smooth and level. After jointing, the masonry is chiseled and clearly visible. Using ink in concave joints can increase aesthetic feeling.
Thirteen. Backfilling of wall
When the mortar strength reaches more than 70%, the filler at the back of the wall can be backfilled to ensure the stability of the wall. Permeable materials shall be used for layered backfill and compaction. If the waste of foundation pit meets the requirements, priority will be given, and the maximum loose thickness of backfill layer is not more than 20cm. The drainage hole behind the wall is provided with a gravel filter layer wrapped by double waterproof geotextile. According to the space of the working face, choose the appropriate compaction machinery, and pay attention to avoid the impact of compaction on the wall. Close to the back of the wall 1.0m, small compaction machinery such as frog rammer, internal combustion rammer and walking vibratory roller will be used for rolling.
XIV. Health
After the completion of masonry, it should be covered with straw bags or geotextiles in time, and often sprinkled with water to keep it moist. The curing period is generally not less than 7 days. Collision and bearing should be avoided during health maintenance.
Anti-freezing and heat preservation measures should be taken for low temperature construction in winter.
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