In order to actively apply efficient and mature technology, optimize construction technology and improve the scientific and technological support ability of rapid construction. Combined with the engineering practice, our company makes full use of the existing high-quality and efficient construction technology, and this summary of rapid construction technology is jointly compiled by all departments to give play to the supporting and leading role of science and technology in the implementation of rapid construction.
The full text is divided into eight parts, including foundation and underground space technology, concrete technology, reinforcement and prestress technology, formwork and scaffolding technology, electromechanical installation engineering technology, decoration engineering technology, waterproof and thermal insulation technology, prefabricated building technology and so on. The bean workers will share it with you in the next few days for your reference.
What I want to share with you today is the rapid construction technology of underground space, including six major construction technologies.
1. Construction technology of Bailey beam steel trestle for earthwork excavation of deep foundation pit
1. Overview
Today, with the development of buildings in the direction of deep, high and difficult, the construction of underground deep foundation pit occupies a long time limit, especially in the stage of earthwork excavation. How to speed up the earthwork excavation of deep foundation pit is a construction problem that needs to be solved.
The construction period of earthwork excavation is generally 1/3 of the construction period below the ground. It is a simple way to reduce the cost of underground engineering to improve the efficiency of earthwork excavation and reduce the time of earthwork construction. The application of Bailey beam assembled steel trestle in deep foundation pit construction can effectively solve the problem of earthwork transportation and improve excavation efficiency. Bailey beam assembled steel trestle can be reused, which is a green and energy-saving construction technology.
This rapid construction technology has been successfully applied to Hechang Trade Center Project in Quanzhou City, Fujian Province. The earthwork excavation of this project needs to be combined with internal support, and the total construction period is 65,438+000 calendar days. The steel trestle needs to cooperate with foundation pit support and earthwork excavation for 85 days, saving the construction period 15 days.
2. Process flow
3. Key points of operation
3. 1 Pile Foundation Construction of Trestle Column
According to the designed pile type, the pile foundation of the trestle column is drilled by the corresponding pile foundation construction machinery. Common pile foundations of trestle bridge include rotary digging pile, punching pile and hammering pile. In the process of pile foundation construction, the quality control of pile foundation construction should be carried out according to various design pile types to ensure the quality of pile foundation construction. Among them, the length of steel pipe column of trestle embedded in pile foundation construction stage should meet the design requirements, and the steel pipe column should not float, sink, tilt or shift during pile foundation construction, and the allowable deviation of pile foundation should meet the requirements of corresponding pile foundation construction specifications.
3.2 Earthwork excavation
In order to provide the working face of trestle construction, the working face of trestle construction is generally excavated in advance during earthwork excavation. In the process of earthwork excavation, we should control the excavation edge and depth, select a reasonable slope coefficient according to the soil layer, and also reasonably arrange the scope and depth of earthwork excavation according to the principle that the trestle allows subsection construction and the requirements of subsection construction. The depth of earthwork excavation should be controlled within 3m, which can be adjusted appropriately when special geological conditions permit.
In addition to ensuring the safety of earthwork excavation, attention should be paid to protecting the steel pipe column from mechanical damage during excavation, and at the same time, the construction surface of the column should be excavated. The design gradient of common trestle is 8% ~ 12%. During earthwork excavation, excavation should be carried out according to the slope, and the excavation depth should be controlled to provide a reasonable working face for the construction of steel pipe column of trestle.
(1- column; 2- Digging the surface; H1-the maximum height from the excavation face to the top of the column, generally not exceeding 2m; H2-the minimum height from the excavation face to the top of the column, generally not less than 50cm)
3.3 Elevation putright and steel pipe column processing
According to the design drawings, measure the elevation of the steel pipe top on the excavated steel pipe column, and the elevation points should be eye-catching, and each steel pipe column should have two symmetrical points. Gas welding should be used to dismantle the super-long steel pipe column, and the column should be set out according to the size of the main beam in the design drawing, and then the groove and reinforcing plate should be cut and welded on the column.
Limit groove of steel tube column top beam
(1-12 stiffening rib; 2-12 stiffening rib; 3- Crossbeam I40a(2 parallel rows); 4- See the plane mark for the elevation of steel pipe pile top; 5- longitudinal beam)
The deviation of groove forming width and depth should not be greater than 20mm and 5 mm respectively. Before gas welding lofting groove cutting, stay wire and tape measure should be used to check before cutting. In order to ensure the level and elevation of the steel beam after installation, the elevation of the trough bottom formed at the top of each column should be consistent.
3.4 Installation of section steel main girder
Generally, the specifications of steel beams are two I40a parallel beams, which need to be welded together before installation. The installed main girder should be welded and fixed firmly, and the steel surface should be on a slope line.
3.5 Install and fix Bailey beam
The connection between the Bailey plate and the main beam adopts a U-shaped clip welded by 10# I-beam. The longitudinal connection between the berets is connected by bolts, and every two spans of the transverse connection are connected by scissors and tie rods, and the tie rod connection joints are bolts.
Details of connection between beret and secondary beam
(1-8mm thick steel plate U-shaped card; 2- Bailey film; 3- secondary beam)
3.7 Installation of bridge deck
The deck of the traveling bridge adopts 8mm thick patterned steel plate, and the connection between the patterned steel plate and the secondary beam is fixed by arc welding. Patterned steel plates shall be laid in the direction perpendicular to the secondary beam, and a gap of 100mm shall be left between each patterned steel plate, so as to clean up the garbage on the bridge deck. After installation, the panel shall not be warped or deformed.
Details of setting anti-slip strips on the surface of steel plate
(1-8mm thick patterned steel plate; 2-B25 steel bar @300, all over the traffic direction)
3.8 Welding non-slip reinforcement and protective railings
The panel anti-skid strips are designed with B25 steel bars with a spacing of 300mm. Steel bar and steel plate are connected by arc welding, and a welding connection point with a length of 200mm is welded every 300 ~ 400 mm.. The protective railing is made of 16# I-beam and 48×3.5 steel pipe, and the height of I-beam is1.2m.
3.9 Commissioning, Acceptance and Use
After the whole trestle is assembled, it should be put into trial operation to check the connection quality of each connection point and the welding quality of the weld, so as to ensure the safety in construction. Trial operation shall be organized according to the design ultimate load. The trial run starts from empty cars to two full cars, and the number of round-trip trial runs for each trial run shall not be less than 10 rounds. Observe the settlement observation points during the trial operation, and conduct a comprehensive inspection of the quality of each connection point, which will be signed by all parties involved for confirmation, then accepted and put into use. Trial operation is one of the most important steps to test the bearing capacity and safety of trestle, and it shall not be used without trial operation monitoring.
3. Installation of10 horizontal tie rod and bracing
According to the design drawings, when the earthwork is excavated to a sufficient depth, horizontal tie rods between steel pipe columns should be set in time to ensure the integrity of the trestle bottom, and the designed vertical bracing position should be welded in time after the excavation is completed to ensure the stability of the trestle bottom. Horizontal tie rods are generally designed with steel pipes with a diameter of 273×8.0mm, and the bracing is I20a.
3. 1 1 Maintenance and disassembly
During the earthwork excavation and the use of the trestle, the settlement of the trestle should be monitored, and the anti-skid strips, bridge deck connection points and protective railings of the trestle should be monitored. Check and observe the U-shaped clamp connected between Bailey beam and main beam and secondary beam daily, and repair the fallen parts in time. Conduct safety inspection every 3 ~ 5 days to maintain the trestle in time.
After the completion of earthwork excavation, the trestle will be dismantled in time according to the requirements of the later use plan of the project. The demolition sequence is generally antiskid strips and panels → protective railings → secondary beams → Bailey beams → main beams → bracing, horizontal tie rods → steel pipe columns.
Second, GRC cement board instead of brick tire mold construction technology
1. Overview
Traditional side formwork such as foundation beam, independent bearing platform and sump is not easy to dismantle. Generally, digging is done separately, and masonry tire molds are used as templates. However, brick tire mold masonry has a large amount of work, a lot of manpower and a high cost, which is not conducive to ensuring the construction period. In this technology, it is proposed to use GRC cement board instead of brick tire mold construction, which can effectively save costs, save construction period and reduce labor input. GRC is a cement-based composite material. If GRC is used as a permanent formwork, the bonding between GRC and concrete is mainly achieved by the bonding force, mechanical bite force and friction force between concrete and uneven surface of glass fiber reinforced cement slab, which can form a good interface combination with cast-in-place concrete and jointly bear the load. GRC cement slab, as a part of the structure, has good composite effect.
This technology has been successfully applied to the project of Tianjin Beichen Hospital, with a total construction area of about 48505.83m2 Pile foundation and raft foundation are used as the basic structure, and GRC cement board is used to replace the brick tire mold. The construction period is about 3 days shorter than the traditional brick tire mold construction technology, saving 40% of the construction period and 20% of the project cost.
2. Process flow
3. Key points of operation
3. 1 construction preparation
1) The project manager department will organize a professional construction team to conduct technical and safety training before construction. Only after passing the training can they enter the site.
2) The foundation pit (groove) must be excavated in place, and the bottom and side of the foundation pit (groove) should be treated according to the design and specification requirements.
3) Construction survey setting-out has popped up at the scene, and has been accepted and rechecked, and the rechecking procedures have been handled.
4) The piles of soil around the foundation pit and foundation trench are solidified to avoid the collapse of construction earthwork or the sand inclusion polluting the operation surface.
3.2 Cushion construction
After the foundation trench is accepted, the cushion layer of the bearing platform and the ground beam shall be constructed as soon as possible, which is 100mm wider than both sides of the bearing platform and the ground beam sideline respectively.
3.3 Layout of bearing platform and ground beam sideline
When the strength of cushion reaches 1.2MPa, the outer edges of ground beams and pile caps pop out and are used as the installation edges of cement slabs.
3.4 Installation of cement slab
The cement slab is transported to the construction site, hoisted into the foundation pit by tower crane and placed in a relatively flat position. According to the size, the construction site can be manually hoisted and installed. The dug beam and the side of the bearing platform are embedded with large wooden wedges, GRC cement formwork is attached tightly, and the wooden wedges on the side of the beam and the bearing platform are reinforced with large nails. If the cross-section size of the beam and the bearing platform is too large or too high, the wood square can be used for internal support or external reinforcement; At the joint between the beam and the bearing platform, the cement board can be cut into the required size according to the needs of the site. Cement slabs should be connected seamlessly, and they can be reinforced together with wood squares at the side, and their verticality should meet the requirements.
3.5 Cement slab lateral earthwork backfilling and tamping
After the cement slab is reinforced, the cement slab and slope can be filled with 2: 8 lime soil and compacted by layers, but care should be taken not to disturb the cement slab. If there is any disturbance, reinforce it again to ensure that the section size meets the requirements.
3.6 Foundation slab cushion construction
After earthwork backfilling, the foundation slab cushion should be constructed as soon as possible. During the vibrating process, the cushion concrete should try not to touch the cement slab, and it can be repaired manually.
3.7 Joint treatment of bottom pad and cement board
Waterproof plastering should be considered in cement board processing, and rounded corners should be made, so cement board processing board can be set as 20mm lower than the beam height when the scheme is put forward; You can also fillet the corner of yin and yang at the junction of ground beam, cement slab of pile cap and raft cushion. The top of the cement board can also be rounded with a grinder to avoid damaging the waterproof layer.
3.8 Quality acceptance
After the cement board is installed and reinforced firmly, it shall be reported to the supervisor for acceptance after passing the self-inspection by the project department. After being qualified, proceed to the next working procedure-waterproof layer construction, steel bar binding and concrete pouring. Unqualified, rework and reprocess.
Three, diamond wire saw static cutting concrete internal support beam construction technology
1. Overview
Static cutting method is often used to dismantle the concrete inner support beam of deep foundation pit. Compared with traditional pneumatic pick demolition and mechanical gun head demolition, static cutting technology has the characteristics of low noise, less dust, high speed and high efficiency. Compared with blasting demolition technology, it has the characteristics of low vibration, little impact on surrounding safety and simple approval procedures. This method can not only improve the demolition efficiency of concrete inner support beam, but also reduce the pollution to the surrounding environment and realize the purpose of green construction.
The rapid construction technology has been successfully applied to Hechang Trade Center Project in Quanzhou City, Fujian Province. It was originally planned that the construction of each floor structure and the removal of supports would take a total of 45 days, of which it would take 25 days for each support to be completely removed. After using static cutting technology, it only took 14 days to remove the supporting beam in each roadway, saving nearly half of the construction period, and the construction time of single floor area of basement16500m2 only took 25 days.
2. Process flow
3. Key points of operation
3. 1 construction preparation
Before the concrete internal support is dismantled, the replacement structure should be constructed according to the design requirements, and the design strength should be achieved. The construction scheme of cutting and demolition has been agreed and recognized by design, supervision and construction units. The adopted hydraulic control machine and operators enter the site, the temporary water and electricity lines are ready, the crane and forklift are ready, and the bottom support of the inner support beam is unloaded in place according to the requirements of the demolition plan. The usual supporting methods are: when the height difference between the bottom of the inner supporting beam and the structural panel is 600mm, it is supported by sleepers; When the height difference is more than 600mm and less than 2000mm, double-row supporting steel pipe frame is adopted; When the height difference is greater than 2000mm, three rows of supporting steel pipe frames are adopted; Erect the support frame in strict accordance with the plan.
During the construction of the supporting frame, the beam should be divided into cutting sections and arranged. Setting out is based on the capacity of forklift and crane, and it is generally recommended to use 1m3 concrete block.
3.2 waist beam drilling
According to the boundary of the waist beam in the construction section, the hole points shall be measured from the boundary every 2500mm, and the spacing shall meet the requirements of the lifting weight limit, that is, the weight of the cut concrete block shall not exceed the design weight of the forklift and lifting. At the same time, the number of cutters, that is, the cutting cross-sectional area, is guaranteed to be minimum. After the lofting is completed, it is necessary to determine the core sample and take the hole sample to ensure that there is no big deviation from the required size.
3.3 Cutting construction
In general, the cutting sequence of internal support beam in cross section is secondary beam first, then main beam, then internal beam first and then rear beam. At the beginning of cutting, the rope is easy to get stuck or even cut off, which is the result of the original residual stress, deformation and extrusion of the inner support beam. When cutting beams, attention should be paid to forklift transportation of beams. Generally speaking, the cutting line of the middle section of the beam should form inverted characters to facilitate the extraction of the beam section. Otherwise, when the forklift turns or lifts directly, it is easy to cause the risk of concrete blocks falling off when the beam is stuck, which needs to be strictly controlled.
In the process of excavation, it is necessary to strengthen the monitoring of foundation pit and judge whether the support replacement is effective according to the monitoring results. Once the monitoring is abnormal or exceeds the allowable value, stop dismantling the support immediately and find out the reason.
3.4 hanging out
After cutting a certain number of beams, they can be hoisted out of the field. So as to save the cost of the crane and minimize the movement of the crane. At the same time, in order to ensure the construction safety of the crane, generally, the beam section not within the hoisting radius of the crane is transported by forklift, and the balance of the beam section should be controlled by forklift to avoid the beam section hitting the floor. At the same time, it is forbidden for forklift trucks to superimpose beam segments on the floor. Generally, there are post-poured zones in basement structures, so it is necessary to make temporary access slabs with a thickness exceeding 10mm to avoid damaging the floor structure. Forklift passages need to be set in cavities such as elevator shafts and stairwells, and they should be installed in strict accordance with the calculated vertical pole or section steel spacing to ensure the stability of the forklift. Crane should have full-time command when dispatching, and ensure that the driver is not tired. At the same time, each earthwork car transport shall not be overloaded.
The concrete beam blocks are hoisted out.
3.5 Garbage cleaning
In order to quickly remove the cement slurry left by cutting, the number of shippers can be increased, and 3-6 hoppers with the capacity of 1.5m3 will be arranged, and the tower crane will cooperate with vertical transportation and loading. Generally, floors where concrete blocks are transported by forklifts are covered with sacks or geotextiles, and maintenance materials can be cleaned when cleaning.
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