Retaining wall construction technology
1. Basic measurement and setting out
According to the design drawings, measure and place the plane position of the retaining wall according to the center line and elevation points of the wall and vertical elevation. Accurately determine the main axis and starting and ending points of the base of the retaining wall, the location of the expansion joints, and whether the connection at each end is straight, and add the ground elevation of each point of the retaining wall according to the actual needs of the construction stakeout, and set construction level points on the foundation. The axis and wall lines pop up on the surface.
2. Foundation pit excavation
(1) The retaining wall foundation pit is excavated with an excavator, and the bottom is brushed manually with the excavator. The size, shape and burial depth of the foundation shall be constructed in accordance with the design requirements. If any discrepancies with the design conditions are found after foundation excavation, the design should be adjusted according to the actual situation. and report to relevant departments.
(2). The foundation excavation is an open-cut foundation pit. When excavating in soft ground or steep slope base sections, the foundation pit should not be penetrated throughout the entire section. Instead, the trench hopping method should be used to excavate to prevent the upper part from losing its foundation. stable. When the base soil is gravel soil, gravel soil, sandy soil, clay soil, etc., it should be leveled and compacted.
(3) When excavating a foundation pit with an excavator, there should be a dedicated person to direct the excavation. Over-excavation is not allowed during the excavation process to avoid disturbing the original soil of the base.
(4) When brushing the bottom of the foundation pit, a 10-degree reverse slope (that is, low inside and high outside) should be reserved. The function of the reserved bottom slope is to prevent the extrusion force of the soil inside the wall from causing the retaining wall to move upward. Slide outside.
(5) When the earthwork excavated for the foundation pit is stacked at the site, enough good soil for backfilling must be left; the excess earthwork should be transported away at once to avoid a second time of bad luck.
(6) When discarding soil beside the foundation trench, the slope should be ensured to be stable. When the soil quality is good, the pile of soil beside the trench should be 1.2 meters away from the upper edge of the foundation trench, and the height should not exceed 1.5m.
(7) Any soil foundation pit shall not be exposed, disturbed or soaked for a long time after being dug to the elevation, which may weaken the bearing capacity of the foundation. Try to avoid over-excavation of the foundation. If there is over-excavation or looseness, it should be tamped down. After the excavation of the foundation pit is completed, the lines should be set out for re-inspection to confirm that the position is correct and signed by the supervision engineer before foundation construction can be carried out.
3. Mortar mixing
(1) The mortar is mixed mechanically. The feeding sequence should be to pour sand and cement first, and finally add water. The mixing time should be 3~5min, not less than 90s. Mortar consistency should be controlled at 50mm~70mm.
(2) The mass ratio should be used in the preparation of mortar. The mortar should be mixed and used to maintain an appropriate consistency. Generally, it should be used within 3 to 4 hours. When the temperature exceeds 30°C, it should be used within 2 to 4 hours. Use it within 3 hours. Mortar that segregates or bleeds should be re-mixed before masonry, and mortar that has solidified must not be used.
(3) In order to improve the workability of cement sand, inorganic plasticizers or organic plasticizers such as microfoaming agents with saponified rosin as the main component can be added. The dosage can be Test confirmed.
(4) Mortar test blocks: 2 sets of cube test blocks (6 blocks) need to be made for each workbench shift. If the mortar mix ratio changes, the test blocks should be made accordingly.
4. Expanded foundation pouring
(1) After excavation and treatment of the foundation trench, check the size and elevation of the foundation, and submit it to the supervision engineer for acceptance. Before pouring, check the bottom of the foundation pit. Whether the reserved slope is 10 (that is, the inside is low and the outside is high). The function of the reserved slope is to prevent the wall from sliding outward due to the extrusion force of the soil inside the wall. After passing the acceptance, pour the cushion layer
(2), lay out the wires to expand the foundation, and before setting up the formwork, lay out the wires between the bottom and top edges of the foundation to control the slope of the retaining wall.
(3) Formwork support: The template is made of 15mm thick coated smooth multi-layer wood board with 50×100 wooden squares on the back. The formwork is required to be neatly spliced, horizontally and vertically, and the construction process must be straightened both horizontally and vertically for inspection. Vertical stitching needs to be staggered, and the staggered stitching position is half the length of the template. During operation, correct and reinforce in order from bottom to top to ensure that the construction position is flat and does not leak slurry.
(4) Pouring: Use a vibrator to vibrate when pouring to prevent honeycombs, pitted surfaces and other phenomena that affect the quality and appearance.
A deformation joint is set up every 10-15m, and the deformation joint is isolated with a 30mm thick polystyrene board. It is required that the isolation must be complete and complete without gaps to ensure complete separation of each section of the retaining wall.
5. Flat stone wall masonry
(1). Laying out: After the foundation construction is completed, measure and stake out the wall, and use a total station to find the control line of the retaining wall. And based on the basic measurement and stakeout control points, the inner and outer edges of the wall and the positions of each expansion settlement joint were measured to check whether the connection at each end is straight.
(2) Foundation corners and junctions should be built at the same time. Temporary breaks that cannot be built at the same time but must be left in place should be left diagonally.
(3) When laying the foundation, the large gaps between the stones should be filled with mortar first and then with gravel blocks. It is not allowed to place gravel blocks first and then fill them with mortar or dry filling. Gravel block method.
(4) The thickness of the foundation mortar joints is 20mm~30mm, the mortar should be full, and there should be no mutual contact between the stones.
(5) Before masonry, the dirt on the stone surface should be cleaned and moistened with water. During masonry, wires must be hung on both sides of poles or templates. The outer wires should be straight and neat, and the slope should be tapered layer by layer. The internal wires should be roughly smooth to ensure that the dimensions of each part of the masonry meet the design requirements. The bottom surface of the mortar masonry should be paved with horizontal mortar. , vertical joints should be filled with grout, and there should be no gaps or vertical joints running through them. When the masonry work is interrupted, the pores of the stone layer can be filled with mortar. When re-laying, the surface should be carefully cleaned and sprinkled with water to moisten it. The segmented positions of the working section should be at expansion joints and settlement joints, and the horizontal joints of each section should be consistent.
(6) When the foundation is completed, backfill immediately and compact it in layers with a small machine, leaving a slight slope outward on the surface to prevent water from seeping into the foundation.
6. Regulations and requirements for wall masonry
General regulations:
(1) In order to control the slope of the inner and outer sides of the wall, before masonry , first nail the slope frame with pine boards, and the slope is controlled according to the design drawings of each section. After the slope frame is made, stand it at both ends of the masonry section, and pull small lines for masonry.
(2) The masonry sequence should be carried out in layers. The bottom layer is extremely important. It is the cornerstone of the above layers. If the quality of the bottom layer does not meet the requirements, it will affect the above layers. When building masonry in layers, the corner stones should be placed first, followed by side stones or facing stones, and finally the belly stones should be filled.
(3) Therefore, the retaining wall in this section is long. In addition to being layered, the masonry must also be built in sections according to the design requirements of the drawings. When masonry is constructed in sections, the section locations should be located at deformation joints or expansion joints, and the horizontal joints in each section should be consistent. The height difference between adjacent masonry buildings should not exceed 1.2m. The installation position of the seam plate should be accurate and firm, and the material of the seam plate should comply with the design requirements.
(4). When the design height difference of adjacent retaining walls is large, the high wall section should be built first. The height of continuous construction of retaining walls should not exceed 1.2m every day. The wall must not shift or deform during masonry construction.
(5) When building a retaining wall, the width (thickness) of the masonry should meet the design requirements, and the position of the hanging wire should be corrected frequently during the masonry construction.
(6) The bottom surface of the masonry should be paved with horizontal mortar, and the vertical joints should be filled with grout and compacted. There should be no empty joints or through vertical joints. When the masonry is interrupted, the gaps in the stone layer should be filled with mortar. When re-laying, the surface of the stone layer should be cleaned and moistened with water. The working seams should be left with diagonal stubble.
(7). The exposed surface of the retaining wall should have a jointing groove with a depth of 10mm~20mm, and the jointing should be jointed according to the design requirements.
(8). Layered stone masonry consists of 2 to 3 layers of stones to form a working layer. The horizontal joints of each working layer should be roughly flush, and the vertical joints should be staggered and cannot be connected.
(9) For the outer ring positioning rows and corner stones, choose square stones with relatively large sizes, and connect them with the inner layer of bricks in alternating lengths. The upper and lower layers of stones should also be staggered. Arrange to avoid overlapping vertical joints, and the width of the joints should generally not be greater than 4cm.
(10) Larger blocks should be used in the lower layer, with the wide side of the stone facing downwards. There should be mortar between the stones and no direct contact. When the vertical joints are wide, they can be Gravel blocks are stuffed into the mortar, but small stones are not allowed to be used as backing pads under the blocks.
(11). The stones in the masonry should be matched in size, staggered with each other, tightly connected, and equipped with various small stones for squeezing and filling joints. Small stones can be used when squeezing. The hammer knocks pebbles into the cracks.
(12) The embedded drainage pipe should be located accurately. Drainage holes should be provided every 2 meters, the water seepage should be appropriately dense, and the upper and lower drainage holes should be staggered.
(13). The outward cross slope of the drainage hole is 3, and the height of the bottom drainage pipe from the ground is 30cm. The water inlet is filled with graded gravel filter layer for treatment.
Masonry requirements:
(1) It is advisable to use 2 to 3 layers of stones to form a working layer, and the horizontal joints of each working layer should be roughly leveled. The vertical joints should be staggered and not penetrate each other; large-sized flake stones should be selected to build the lower part of the masonry; larger and squarer flake stones should be used at the outer edge of the corner to alternate with the inner blocks.
(2) For positioning rows and corner stones on the outer circumference of the wall, stones with flat surfaces and larger sizes should be selected first. When mortaring, the lengths should be alternated with the inner stones, and the upper and lower layers should be vertical. The joints should be staggered and the joint width should not be larger than 4cm. Large stones should be used for the lower layer in layered masonry. The shape and size of each stone should be appropriate. If the vertical joints are wider, small stones can be stuffed, but small stones higher than the mortar layer cannot be used under the stones. When arranging, the stones should be staggered, seated firmly and tightly, and the sharp protruding parts should be knocked out.
(3). Stones with flat surfaces should be selected for the exposed areas of masonry. Make the masonry surface neat and tidy, and do not use small stones as inlays.
(4). The stones in the masonry should be matched in size, staggered, and firmly interlocked. The larger and more square stones should face downward with their wide sides, and mortar should be filled between the stones. It must be dense and must not be built dry.
(5) Pointing: Pointing can prevent harmful gases, wind, rain, etc. from corroding the interior of the masonry, extend the service life of the structure, and provide a beautiful decorative appearance. The retaining wall joints in this sub-project shall be constructed using concave joints. The cement mortar of 1:1.5~1:2 should be used for pointing joints, and it should be embedded into the joints for about 2cm. Before pointing, the joint grooves should be cleaned, rinsed with water and moistened, and then an appropriate amount of cement slurry should be applied in the joints.
The pointing joints should maintain natural joints after construction, and there should be no blind joints, missing joints, cracks, or weak bonding. The horizontal seams and vertical seams of the surviving gray seams should be of the same depth, intersecting, dense and smooth, the overlaps should be smooth, the external corners should be square, the internal corners should not be straight up and down, and there should be no missing or blind seams. The gray seams should be neat, with smooth corners, consistent width, no burrs, and no hollowing or falling off.
7. Wall back filler
1. Wall back filler can only be backfilled when the strength of the masonry mortar reaches above 70. And gravel soil with good water permeability should be given priority for filling. If it is really difficult to use impermeable soil, the filter layer and weep holes must be prepared and synchronized with the masonry. The back of the water-immersed retaining wall should be filled with materials with good water stability and water permeability.
2. The backfill on the back of the wall should be evenly spread and leveled, and a cross slope of not less than 3 should be set layer by layer. Compact layer by layer. It is strictly forbidden to use expansive soil and high plasticity soil. The compaction thickness of each layer should not exceed 20cm. A compaction test should be conducted according to the rolling equipment and filler properties to determine the filler layer thickness and the number of rolling passes to provide correct guidance. construction.
3. When compacting, care should be taken to prevent the wall from being affected by large impacts. Within 1.0m of the back of the wall, frog-type tamping machines, internal combustion tamping machines, and hand-operated vibrating machines should be used. Rollers, vibrating plate compactors and other small compaction machines are used for crushing.
V. Construction Progress Plan
1. Construction Period Plan
The planned construction period of the rubble retaining wall project is 49 days. According to the construction period requirements, on-site survey data and overall project The construction plan and the specific construction period of the rubble retaining wall project are as follows:
(1) The foundation pit excavation construction is scheduled to start on March 20, 2009 and will be completed on April 26, 2009.
(2) The pouring construction of the expanded foundation masonry is planned to start on March 25, 2009 and will be completed on May 5, 2009.
(3) The wall masonry construction is planned to start on March 30, 2009 and be completed on May 12, 2009.
(4). The filling construction behind the wall is planned to start on April 2, 2009 and be completed on May 18, 2009.
Retaining wall construction period plan
March 2009 April 2009 May 2009
30 10 20 30 10 20
Foundation pit excavation
Extended foundation formwork and pouring
Wall masonry
Filling behind the wall
2. Construction period guarantee measures
The construction team is required to formulate a thorough construction progress plan, improve the construction management organization, reasonably arrange each process, organize and coordinate the construction operating procedures of each team, and decompose the construction period goals to each team and implement them one by one. Team managers often go deep into the construction site to investigate whether the measures to complete the plan, labor, materials and mechanical equipment configuration can meet the construction requirements, and check the completion status of the project to be aware of it; analyze and find the reasons for failure to complete the indicators, and formulate remedies Measures should be taken, and the construction plans of each team should be balanced and adjusted before implementation, and construction delays should not be caused by human factors. Increase the intensity of fines and penalties, overcome the procrastination style, open up the working surface to implement parallel flow operations, achieve orderly and balanced production, do a good job in the management of the entire construction process, strengthen predictability, and make the planning arrangements realistic. Finally, the equipment should be in place, Materials and personnel are in place, so that construction site management is institutionalized, standardized and scientific, and we strive to strictly follow the construction plan to ensure the construction period.
1 Management staff 4 6 Surveyors 1
2 Technicians 3 7 Concrete workers 10
3 Carpenters 2 8 Electricians 2
4 Masonry 40 9 Security personnel 4
5 Warehouse management 1
Construction instruments and equipment configuration table
Serial number name unit quantity remarks
1 GTS-102N electronic total station 1, full station positioning measurement
2 J-2 theodolite station 1, full station positioning and setting out
3 DS3 leveling station 2, elevation control measurement
4 50m steel tape measure 3 for line measurement
5 Camera department 1 collect picture information
6 Camera station 1 engineering photography
Machinery Equipment Table
Machine Name Specifications Unit Quantity Remarks
Excavator DCH225 Unit 1
Bulldozer Unit 1
Dump Truck Hongyan Vehicle 2
Concrete mixer platform 2
Mortar mixer platform 1
Vibrator platform 2
Submersible pump φ100 platform 2
6. Precautions for safe and civilized construction
During the excavation process, if a landslide occurs, take immediate measures. If the landslide is large, use rubble to tightly build it. Due to the high groundwater level at the site, a sump pit was excavated for centralized pump drainage. The earth and stone excavated for the foundation shall be lifted and transported manually, and the stacking location shall not be less than 1.5m from the edge of the foundation trench.
1. Establish and improve a safe and civilized reward and punishment system, establish a civilized construction style, and create safe production practices.
2. Implement the management regulations of relevant superior departments on production safety and civilized construction, clarify job responsibilities, organize regular safety and civilized inspections, and conduct "three-level" safety education for construction personnel entering the site.
3. Machinery operators must be trained and certified to work. They are not allowed to gamble or drink alcohol after get off work. They must take a break and work fatigue is strictly prohibited. In particular, they must be wary of sliding down the slope when rolling the edge protection soil. The commander must stand 5m away from the machine to prevent being hit by the machine.
4. Strengthen the management of construction electricity, adopt the three-phase five-wire system for all power supply, and adopt the principle of one machine, one gate and one leakage protector for the switch box. Cables in the work area and living area should be installed and spliced ??by professional electricians. It is strictly prohibited to pull the wires privately. Construction cables are either elevated or buried underground in plastic pipes. It is strictly prohibited to use open flame electrical appliances such as electric stoves. All lines must be equipped with air protection switches to prevent electric leakage and the lines can be disconnected immediately.
5. Improve the safety disclosure and safety acceptance system. Safety technical disclosures should be made to operators before the start of each sub-project. Machinery, electrical equipment, safety protection facilities, etc. should be subject to special acceptance before they are put into use. .
6. Smoking is strictly prohibited in warehouses and other places, especially fireworks near flammable materials; oil tanks must be kept away from living areas, covered with sand, and clearly visible warning signs set up.
7. Set up eye-catching signs or warning lights in the construction area to prevent non-operators from passing through.
8. Corresponding labor protection equipment must be worn when working. It is strictly prohibited to wear slippers into the construction area.
9. Organize meaningful cultural and sports activities to give employees a positive cultural life mood; at the same time, keep the living area clean and green.
10. Danger Point Analysis and Control Measures
Operation
Project Danger Point Control Measures
Soil
Stone
Square
Foundation
Earthwork
Mechanical operations 1. According to the engineering specifications, groundwater level, construction machinery conditions, and progress Requirements and other reasonable selection of construction machinery; 2. Do not work under dangerous rocks or boulders or close to unreinforced dangerous buildings; 3. The excavator should be at a certain safe distance from the slope to prevent collapse. causing a rollover accident.
Ultra-deep, steep walls, water gushing, and slippage 1. Steps or supporting ladders should be dug up and down the deep foundation trench, or slopes should be opened, and anti-slip measures should be taken. It is prohibited to step on the upper and lower supports and the edges of the foundation trench. Safety railings should be installed; 2. When the foundation trench is deep, slope protection methods should be adopted to prevent the slope from loosening due to water loss or ground water erosion and infiltration affecting the stability of the slope.
In order to ensure the safety of the supporting structure in support engineering and dewatering equipment and operations, the following measures should be taken: (1) Before earth excavation, a detailed earth excavation plan should be prepared. It can only be implemented after approval by the design unit; (2) The principle of supporting first and then digging should be strictly followed; (3) Earth excavation should be carried out in layers, sections, and symmetrically to ensure that the supporting structure is evenly stressed; ( 4) Excavating machinery is prohibited from directly pressing over the support rods of the supporting structure. When it must cross, the bottom of the support rods should be filled with earth and elevated with walkway boards; (5) It is strictly forbidden to pile a large amount of load on the foundation trench during excavation.
7. Quality Assurance Measures
1. Technical organizational measures to ensure project quality
(1) Establish a quality management system that combines clear-cut responsibilities, rights and interests Responsibility system, earnestly carry out comprehensive quality management, ensure that everyone bears the burden of quality and have indicators on everyone's shoulders, and at the same time grasp the construction site, supervise and manage the entire construction process of the entire project, eliminate common quality problems, and make quality management superior. new level.
(2) Strengthen technical management, conduct written technical explanations for each process, the person making the briefings, and the recipients will sign on the written form, clarify responsibilities, organize each team leader to learn the technical specifications, and make every operator familiar with them. Quality acceptance criteria. Organize construction strictly according to design requirements.
(3) Quality management organization structure
2. Quality control points and specific measures for major sub-projects
(1) Carefully prepare construction plans and operation guidance written and implemented so that the entire process of project quality can be controlled.
(2) Carry out joint review of drawings, technical briefings and technical training, and organize relevant personnel to study carefully the new technologies and new processes that are promoted and applied. During construction, process monitoring should be strengthened to ensure no rework.
(3) Establish a quality management team to handle on-site quality problems in a timely manner, accumulate original data, and organize and summarize on schedule.
(4) The construction workers will monitor the work on site and provide the information to the quality inspectors and technical department in a timely manner, which will be processed in a timely manner by the technical supervisor.
(5) The quality of each sub-project shall be strictly implemented in the "Three Inspection System", and each team and team shall be responsible for the scheduled, fixed-point, and positioning construction work, and check the quality level at all levels. Each process should be self-inspected, mutually inspected, and reported to the supervision engineer after passing the quality inspection. Only after passing the inspection can the next process be carried out to avoid rework. Strictly abide by relevant construction technical specifications and quality assessment standards to lay a solid foundation for excellent projects.
3. On-site material quality management
(1) There is a hardened 300m2 space with a distance of 8m from the red line on the right side of the entrance gate to the fence for the storage of gravel, sand and other materials. , and a cement warehouse was built on the hardened ground for the storage of cement, and the rubble was neatly stacked along the foundation trough. After the materials arrive at the site, they are stacked and stored in categories strictly in accordance with the locations designated by the project department, and eye-catching signs are set up.
(2) Strictly control the quality of incoming materials. Unqualified materials are not allowed to enter. In accordance with specification requirements, all indicators of incoming materials are inspected by batch, on time and by manufacturer. Incoming inspection and inspection are carried out when all materials enter the site. For materials that require secondary inspection such as sand and stone, samples are taken and sent to the laboratory for testing as required, and unqualified products are removed from the site.
4. Technical review and acceptance of concealed projects
(1) For construction content that is highly technical and has a significant impact on the quality of sub-projects, it will not be implemented until it is officially started or Before the next process of construction, technicians and quality inspectors must conduct technical reviews and keep records.
(2) After the excavation of the foundation trench is completed, the next step of construction can only be carried out after the signature and approval of the supervising engineer and the relevant acceptance unit.
5. Quality management objectives
Continuously enhance the quality awareness of each team and ensure project quality into all aspects of the construction process. To build confidence in creating high-quality projects, the one-time pass rate of the project is required to be 100% and the excellent rate is 97%.
6. The operating mechanism of the quality system is shown in the diagram below.
Quality system organization and coordination quality supervision information management system
Audit and evaluation
Schematic diagram of quality system operation mechanism
8. Environmental protection measures
1. Strengthen the environmental education of all employees and migrant workers, pay attention to environmental protection, and conduct civilized construction.
2. During construction, nearby trees and water and electricity facilities that should not be removed should be protected.
3. Strengthen the supervision of dust, noise, waste gas, and sewage at construction sites, inspect, assess, reward and punish them together with civilized construction sites, and take measures to eliminate pollution from dust, waste gas, and sewage.
4. Protect and improve the environment of the construction site, prevent water and soil erosion, and carry out comprehensive management.
5. Carry out publicity and education work, take effective measures to control man-made noise and dust pollution, and adopt technical measures to control dust, sewage and noise pollution.
6. Strictly follow relevant labor protection rules and regulations. Take protective measures for construction workers engaged in noise, dust, etc. work and shorten their working hours appropriately.
7. Sewage and garbage must be properly disposed of. Sewage must be sprayed regularly and sediments must be cleaned. Garbage must be piled up in a centralized manner and transported to designated garbage dumps regularly.
8. It is prohibited to burn linoleum, rubber, plastic, leather, trees, dead grass, various packaging bags and other substances that produce toxic, harmful smoke and odorous gases at the construction site.
9. During the construction process, avoid damaging the farmland drainage and irrigation system. If there is a conflict with the farmland drainage system, temporary water pipes should be buried and temporary canals should be dug to ensure that the drainage, irrigation and drainage systems are uninterrupted. They should be cleaned and restored in a timely manner after completion. .
10. All kinds of construction machinery and materials are neatly placed in the prescribed places.