catalogue
1, project overview 1
2, construction technology, process plan 1
2. 1 foundation treatment
2.2 Full House Support Construction 1
2.3 Bearing Installation 6
2.4 Template Installation 7
2.5 Reinforcement Installation 7
2.6 concrete construction 8
3, construction quality assurance system and measures 9
3. 1 Quality Assurance Agency 9
3.2 Quality Assurance Measures 9
3.3 Quality Assurance System 12
4, safety assurance system and measures 13
4. 1 safety assurance system 13
4.2 Safety Protection Administration 13
4.3 Safety Assurance Measures 13
5, civilized construction and environmental protection 15
1, project overview
The continuous beam DK 105+708. 19 of Zhanghe Bridge is located in Xinyi Village, Huolonggang Town, Yijiang District. The superstructure design adopts (40.6+64+40.6)m three-span one-link prestressed concrete continuous beam. The construction technology of hanging blue cantilever casting is adopted for continuous beams. The cast-in-place box girder is 7.6m long, 6m wide at the bottom, 12.2m wide at the top and 2.8m high. C50 concrete is 95. 1m3, and its weight is 251.94t.
2, construction technology, process plan
Geology is silty clay soft plastic (OK), σ= 120KPa, with a layer thickness of 4m; Silty clay is hard plastic (plastic), σ= 150KPa, layer thickness 15m. The original ground is about 13- 14m away from the bottom of cast-in-place beam. The cast-in-place section of DK 105+708. 19 continuous beam is constructed with full support.
2. 1 foundation treatment
After the pile cap construction is completed, the pile cap shall be backfilled and compacted in layers. Under 1m 184# pier, the original ground shall be compacted by layers of undisturbed soil, with the thickness of each layer not exceeding 30cm, and the rest shall be compacted by layers of crushed stone soil. 18 1# pier, the ground shall be rolled first, and then the gravel soil with a thickness of 50cm shall be replaced. The scope of foundation treatment is the plane outline of cast-in-place section plus one meter working face. Testers shall conduct compaction test on the treated foundation to ensure that the bearing capacity of the foundation is not less than 120KPa. After replacement, 20cm thick C 15 ordinary concrete is poured on the foundation surface. The drainage slope of 2% is set horizontally, which is combined with the external temporary drainage system to ensure that the foundation is not soaked by rain during construction. The elevation of the top surface of the replacement foundation is determined according to the elevation of the beam bottom and the adjustable height of the bottom support and jacking of the bowl buckle bracket.
2.2 Mantang Support Construction
0+0 bracket installation
After the foundation treatment is completed, the cast-in-place section full-house support is erected, and the bowl-shaped 48*3.5mm steel pipe support is adopted. Under the web, the vertical rod spacing is 30×60cm (horizontal× vertical), and the cross bar spacing is120 cm; . The spacing between vertical poles under the bottom plate is 60×60cm (horizontal× vertical), and the spacing between horizontal poles is120 cm; ; The vertical pole spacing under the wing plate is 90×60cm (horizontal× vertical), and the cross bar spacing is 120cm. Template using bamboo veneer.
Bending a horizontal pole step from the first floor and the top floor shall not exceed 60cm, that is, the amount of bottom support and top support shall not exceed 30cm. Shear braces are horizontally and vertically arranged on the bracket, and the angle of shear braces is 45 ~ 60. A protective fence with a height of 1.5m is set around the top of the support and inspection ladder, and a safety net is hung. In order to enhance the stability of the full-house support, a cable wind rope is set around it.
Full house support arrangement is as follows:
Support calculation
According to the drawing analysis, the cast-in-place box girder is 7.6m long, 6m wide at the bottom, 2.8m wide at the top, 95. 1m3 C50 concrete at the height, and weighs 251.94t.. For the sake of safety, the maximum cross section of the beam is taken for analysis. The main structural dimensions of the section are: beam height 280cm, bottom plate thickness 60cm, top plate thickness 60cm, bottom plate width 600cm and web plate width 95cm. Construction load P =2.5kpa, vibrating load P =2kpa, and other temporary facilities P = 1kpa. Take 26KN/ m3 for concrete, then:
P-wing =9.9kpa, P-top and bottom =3 1.2kpa, and concentrated load at web, top plate and bottom plate: f = 72.8kPa..
Calculate the load combination under the bottom plate = 45kpa.
Calculate the load combination σ p abdomen under the web = 95kpa.
Calculate the load combination σ p wing under the wing plate =19.4kpa.
2.2.2. 1 bamboo veneer calculation
E bamboo =5× 103Mpa [σ] bamboo =24MPa. Take 1mm wide slats as the calculation unit, and bamboo plywood δ= 15mm.
Plywood:
According to the calculation of load force under the web, the calculated span of bamboo plywood distribution beam is set to 10cm (net spacing).
σ= M/W =(ql2/ 10)/W = 2.5 MPa & lt； [σ]=24Mpa (available)
In order to ensure the overall stability, the bottom plate is also arranged in this way.
According to the calculation of load force under the wing plate, the calculated span of bamboo plywood distribution beam is set to 20cm (net spacing).
σ= M/W =(ql2/ 10)/W = 2. 1 MPa & lt； [σ]=24Mpa (available)
2.2.2.2 square timber calculation
2.2.2.2.1Longitudinal square timber under bamboo veneer
The longitudinal beam spacing between the web and the bottom plate is 20cm, the longitudinal beam spacing between the wing plates is 30cm, and the span is calculated at L = 0.6m The square timber is Korean pine I =10cm *10 *103/12 = 833.3cm4, whichever is the web.
σ= M/W =(ql2/8)/( 10 * 102 * 10-6/6)= 7.7 MPa & lt； [σ]= 12Mpa (available)
Conclusion: It meets the requirements.
2.2.2.2.2 Jacking up the horizontal square timber.
Select 10cm* 10cm Korean pine, I =10 *103/12 = 833.3cm4 calculated at the bottom, with a span of 60cm:
σ= M/W =(ql2/8)/( 10 * 102 * 10-6/6)= 7.2 MPa & lt； [σ]= 12Mpa (available)
Calculated by web, the span is 30cm:
σ= M/W =(ql2/8)/( 10 * 102 * 10-6/6)= 3.9 MPa & lt； [σ]= 12Mpa (available)
Calculated by wing plate, the span is 0.9m:
σ= M/W =(ql2/8)/( 10 * 102 * 10-6/6)= 7. 1 MPa & lt； [σ]= 12Mpa (available)
Force calculation of φ 48× 3.5 mm bowl buckle steel pipe support in 2.2.2.3;
The profile features are A=489mm2, I= 12. 156cm4, W=5.078cm3, I =1.578cm. ..
The arrangement of web uprights is: 30cm*60cm* 120cm (horizontal distance * vertical distance * step distance), then λ = L/I = 76.
The arrangement of the bottom vertical pole is: 60cm*60cm* 120cm (horizontal distance * vertical distance * step distance), then λ = L/I = 76.
The arrangement of wing vertical rods is: 90cm*60cm* 120cm (horizontal distance * vertical distance * step distance), then λ = L/I = 76.
Conclusion: Bowl-buckle steel pipe support meets the requirements.
Calculation of foundation bearing capacity in 2.2.2.4;
The structural load of bottom formwork and internal formwork is 5KN/ ㎡, the dead weight of steel pipe support (calculated by 14m height) and the construction live load is 5KN/ ㎡, so the web is the most unfavorable. Taking the web as an example to calculate the load combination, the axial force transmitted from the superstructure to the top surface of the foundation is n = 1.2 * [(2.8 * 26+5) * 0.
+ 1.4 * 5 * 0.6 * 0.3 = 19.25 kn
Then: p = n/ab =19.25/0.6/0.3 =107 kpa.
C 15 concrete surface contact stress:
Silty clay soft plastic in design drawings (available) σ0= 120KPa. The foundation treatment method is to remove the undisturbed soil on the surface to the hard surface, level and roll it, then lay 20cmC 15 concrete, and then set up supports. For the backfill part of foundation pit, the bearing capacity shall not be less than 120KPa, and the tester shall check whether the bearing capacity requirements are qualified through compaction test.
Support preloading
Preloading purpose
In order to test the stability and safety of the support, eliminate inelastic deformation and elastic deformation when the support is erected, obtain the pre-camber reserved for actual construction, ensure the linear shape of the bridge after completion, and preload the support.
2.2.3.2 preloading method
Simulated compaction method and large nylon bag sand compaction method are adopted, each bag weighs about 0.8 tons. The crane with electronic scale is used for weighing, and it is directly hoisted to the formwork at the top and bottom of the support for preloading. Before preloading, check the weighing scale of the crane and calculate the mathematical relationship between the digital display data of the crane and the actual weighing data.
In order to prevent the bottom die from being damaged when heavy objects are pressed, after the erection of the longitudinal and transverse beams of the support and the bottom die is completed, a layer of striped cloth is spread on the bamboo veneer of the bottom die, and a precompressed sand bag is hung on the striped cloth, and the striped cloth is removed after preloading. When hoisting, no one is allowed to stand under the sandbag to prevent the sandbag from suddenly falling and hurting people.
The method of five-level loading and five-level unloading is adopted. During preloading, the stacking position of sand bags should be basically similar to the actual load distribution of the beam, and the upper part of the web is concentrated. The preloading weight shall be 120% of the beam weight, and the preloading weighing sequence shall be 20%-50%-80%-100%-120%.
Through the settlement observation of observation points, after the first loading, observe once every 2 hours, continuously observe the settlement twice, and then carry out the second loading. When the standing time after loading to the design load is not less than 1 day or the deformation value before and after loading is not more than 2mm, the structure is considered to be stable and can be unloaded. Unloading to 100%, standing, measuring and observing for 3 times. When the difference between the last two measurements shows that the rebound is stable, unload the next stage and measure it, and so on until the unloading is completed.
Layout of observation points in 2.2.3.3
At least two layers of observation points are arranged vertically, that is, the top surface of the foundation and the bottom surface of the formwork are arranged respectively, and the upper and lower observation points correspond to each other one by one. The plane layout of observation points should be determined according to the area and shape of the loading area, and the layout should be reasonable and representative. According to the actual situation, measuring points should be added at the changes of key points such as foundation and beam weight. The observation points shall be numbered in sequence, corresponding to the observation records one by one, and the layout diagram of observation points shall be drawn.
Along the longitudinal direction of the beam, the L/2 and L/4 parts of the beam end, the side of the bearing platform and the span are taken during preloading, and the observation section is set with the bearing termination part. Three observation points are arranged on each section, with the bottom of two webs 1 and the middle of the beam 1. Draw a drop line from the top of the bracket, set a drop ball at the end of the vertical line, measure the relative distance between the drop ball and the observation point, and get the deformation of the bracket.
Observation frequency and records in 2.2.3.4.
Level and double-sided tower ruler are used for observation. Comparing the last observation data with the observation data before preloading, the total settlement of the support is obtained. Compared with all the measured values when unloading is completed, the elastic deformation value can be obtained.
After the preloading of the support is completed, the data recorded on site should be sorted out and analyzed, and the comprehensive deformation of the support and foundation can be obtained. According to the measured data and analysis results, the settlement-time curve is drawn. According to the observation records, the preloading settlement results are sorted out, and the pre-arching height of beam bottom plate and cantilever is controlled by adjusting the top support elevation of bowl buckle bracket.
2.3 bracket installation
After the bearing pad stone reaches 50% of the design strength, the spherical bearing can be installed. Spherical bearings are assembled in the factory, and pre-deflection is reserved according to the design requirements.
Before installing the bearing, check the connection of the bearing, roughen the surface of the bearing seat stone at the bearing position, remove the sundries in the reserved anchor bolt holes, install the template for grouting, and soak the surface of the bearing seat stone with water.
After the bearing is installed in place with a crane, the bearing is supported with a concrete wedge, so that a gap of 20-30mm is left between the bearing plate and the top surface of the abutment cushion stone, and non-shrinkage high-strength cement mortar is poured into the bottom of the bearing by gravity grouting.
When grouting, grouting shall be carried out from the center of the bearing to the periphery until the grouting material completely fills the gap between the template and the base plate of the bearing.
After the grouting material is finally set, dismantle the formwork and concrete wedges at four corners, check whether there is slurry leakage, fill the slurry leakage if necessary, fill the gap after the wedge pulls the slurry, tighten the anchor bolts of the lower bearing plate, and dismantle the connecting bolts of the upper and lower bearing plates in time after the concrete pouring of the beam body. After installation, the bearing should be inspected, and the exposed surfaces of embedded plates and anchor bolts should be painted in time to avoid rust.
2.4 template installation
Large pieces of bamboo plywood and square timber are used for the outer and bottom molds, and plywood is used for the end mold and the inner mold. When installing the side formwork, lift it with a 25t crane and put it in place directly. The connection position between the bottom of the side die and the bottom die is pre-drilled. After the side formwork is installed in place, hold the electric drill to drill holes on the side formwork, and connect the side formwork and the bottom formwork closely through bolts. The formwork is fixed vertically and horizontally with brackets, and the elevation of the formwork is fine-tuned. The templates on both sides are fixed with the ejector rod through the pull rod. The pull rod is made of 25 # finish rolled rebar, and the ejector rod is made of steel pipe with jacking. Adjust the size and elevation of the formwork and reinforce it. After the binding of the bottom plate and web reinforcement of the continuous beam is completed, assemble the internal formwork. There is no bottom die for the internal model, and 40cm square inspection holes are reserved on the web according to the vertical height of 50cm and the horizontal spacing of 100cm for assisting concrete vibrating.
2.5 steel bar installation
The overall reinforcement of continuous beam is bound, and the installation sequence is as follows: binding the bottom plate and web reinforcement (including positioning reinforcement and floating reinforcement, etc.). ) → Install the longitudinal corrugated pipes on the bottom plate and web, and bond the corrugated pipes with black tape or colored plastic tape → Install the vertical prestressed tendons and embedded parts (anchor pad, drainage pipe, exhaust hanging basket embedded parts, etc. ) → Tie the steel bars at the bottom of the roof → Install the longitudinal corrugated pipes at the bottom plate and top plate in turn → Tie the steel bars at the top of the roof.
When the beam rebar collides with the prestressed rebar, the beam rebar can move or bend properly. The tail of the binding wire should not extend into the protective layer, and the thickness of the protective layer should be controlled by the concrete pad with the same label as the beam concrete. The reinforcement at the bridge deck drainage hole can be moved appropriately, and spiral reinforcement and oblique cross reinforcement are added for reinforcement. After the roof steel binding is completed, the protective wall, vertical wall and embedded parts of catenary foundation shall be embedded in the corresponding positions. According to the characteristics of the hanging basket, all kinds of embedded holes of the hanging basket are arranged at the same time. The position of the embedded holes depends on the structure of the hanging basket, mainly including the back anchor hole, the outer sliding beam hole and the inner sliding beam hole. According to the design requirements, comprehensive grounding arrangement and connection shall be carried out, and embedded parts such as bridge deck drainage pipes, ventilation holes and inspection holes shall be buried.
Steel bars must be accepted according to specifications before use, and raw materials and welding tests should be carried out in batches. It can only be used after passing the test.
Galvanized metal corrugated pipes are used for longitudinal prestressed pipes, 90× 19mm flat galvanized metal corrugated pipes are used for transverse prestressed pipes, and iron pipes with an inner diameter of 45mm are used for vertical prestressed channels. Anchor pads are fixed on the head formwork according to the design requirements to ensure that they are perpendicular to the channels. Before pouring beam concrete, the longitudinal pipes should penetrate into the plastic support pipes to prevent the holes from leaking and blocking, and the support pipes should be pulled out during pouring and before the final setting of concrete. Transverse prestressed reinforcement should be penetrated first, and the pipeline should be kept unblocked before concrete pouring and final setting. Vertical prestressed reinforcement and tunnel are installed and positioned at the same time. The position of prestressed channel is first set on the bound steel skeleton and positioned with tic-tac-toe steel. The spacing between straight segments is not more than 80 cm, and the spacing between curved segments is not more than 40 cm, which are arranged along the longitudinal direction of the channel. Bellows are fixed and positioned with 8 steel bars. In order to prevent the corrugated pipe from burning when the steel bars are welded, steel plates are placed on it for isolation. The joints are connected by corrugated pipes with slightly larger caliber, and the outside is fastened with black tape.
2.6 concrete construction
Continuous beam concrete is mixed centrally in the mixing station (DK 102+700), transported horizontally by concrete tanker and vertically by concrete pump. The strength grade of concrete is C50.
From the beam 1/4 to the end and mid-span direction, it is poured symmetrically, so as to eliminate the influence of the deformation of the mid-span bracket on the concrete and prevent the vertical cracks in the mid-span concrete. Concrete shall be poured in layers with a thickness of 30cm, and the upper concrete shall be poured before the final setting of the lower concrete.
The box girder is thin and the steel bars are dense, so it is difficult for concrete to enter the mould. The method adopted is to set a string tube on the bottom plate of the web to prevent the concrete from falling freely and colliding with the steel pipe. Chord pipes on the bottom plate pass through the skylight on the top plate, and the top plate directly enters the formwork.
The concrete is cast in one step, and the pouring sequence is as follows: the bottom plate is laid first, and then the web plate and the top plate are poured. In order to prevent the vibration of anchor, groove and other reinforcement parts from being false, the vibration of web concrete is checked by using the inspection hole of internal model.
After the completion of concrete pouring, when the concrete reaches the final setting, it will be covered with non-woven geotextile, and the concrete will be maintained according to the winter construction plan.
When the side formwork is removed, the concrete strength should reach more than 60% of the design value; The temperature difference between the concrete core and the beam surface, inside and outside the box, and between the surface and the environment should not be greater than 65438 05℃, and attention should be paid to the integrity of the edges and corners of the beam.
3, the construction quality assurance system and measures
In order to ensure the construction quality, control one by one from the process, and ensure a qualified rate of 100%, a perfect guarantee system and measures are specially formulated.
3. 1 Quality Assurance Agency
3.2 Quality assurance measures
3.2. 1 raw material quality control measures
Raw materials shall be purchased and managed by special personnel according to technical quality requirements, and handover records shall be carefully made between purchasing personnel and construction personnel.
After raw materials enter the site, the varieties, specifications, quantity and quality certificates of raw materials shall be inspected and accepted, and sampling and reinspection shall be conducted according to relevant standards. Only qualified raw materials can enter the site. Unqualified raw materials shall be removed from the site according to relevant regulations.
After raw materials enter the site, a raw material management account shall be established in time, and the raw material management account shall be filled in correctly, truly and completely.
Cement and mineral admixture are stored separately in bulk boxes. Bagged powdery materials should be stored in a special warehouse during transportation and storage, and should not be piled up in the open air, and special attention should be paid to moisture prevention.
Coarse aggregate shall be purchased, transported, stacked and graded according to technical requirements.
Establish raw material stacking places and clear signs that meet the production of the factory. When stacking raw materials, there should be stacking boundary signs to avoid misuse.
3.2.2 Engineering Survey Control
The construction lofting method and construction survey scheme shall be approved by the supervision engineer, and the measuring instruments shall be calibrated and verified. Establish a strict technical management system for construction measurement inspection, review and audit. The surveying industry should establish strict technical management systems such as calculation, review, audit and technical responsibility, and surveyors should implement the signature verification system of observation, recording, forward-looking and backward-looking in the surveying industry, and implement self-inspection, mutual inspection and special inspection. 100% recheck the calculated data of field measurement and field observation records to ensure that the original records and calculations are correct.
3.2.3 Concrete Engineering Quality Assurance Measures
Mixing quality control: Forced mixer, electronic metering system, real-time moisture content monitoring system and high-performance concrete mixing are adopted to meet the requirements. Determine the slump, expansion, bleeding rate and air content of the mixture to ensure good workability and pumpability.
Concrete transportation conditions: the transportation road is smooth and smooth, and a special concrete truck matching the production and pouring capacity is selected.
Quality of concrete pouring: Before concrete pouring, carefully check the position, quantity and fastening degree of the cushion blocks of the reinforced protective layer, and assign special personnel to repeatedly check to improve the quality assurance rate of the thickness and size of the reinforced protective layer. Concrete pouring shall be carried out continuously by layers, and no construction joints shall be left at will.
Quality of concrete vibrating: plug-in vibrator can be used for concrete vibrating. When vibrating, formwork, steel bars and embedded iron pieces shall not be collided. Concrete vibrating should be carried out according to the pre-specified technology and method. When pouring concrete, it should be vibrated evenly and densely in time. The vibrating time of each point shall be subject to the surface flooding or foaming, generally not more than 30s, so as to avoid over-vibration. In the process of vibrating concrete, strengthen the inspection of formwork support stability and joint tightness to prevent slurry leakage. After concrete pouring, carefully compact and smooth the concrete surface, and it is forbidden to sprinkle water when plastering.
Quality of concrete curing: After concrete is vibrated, moisture-retaining measures shall be taken in time to cure concrete. When the newly poured concrete has exposed surface, the exposed surface should be leveled first, then covered with geotextile, and watered in time to keep moisture. After the concrete is dismantled, it will be cured with plastic sheets later (winter construction will be carried out according to the approved winter construction plan).
3.2.4 Concrete Durability Assurance Measures
The most important technical measures to ensure the durability of the structure are to prepare high-performance concrete that meets the durability index and working performance requirements, control the quality of concrete raw materials and operating procedures such as mixing, transportation, pouring and vibrating, strengthen the moisture, heat preservation and curing process of concrete, and strengthen the management of handling, storage and protection to prevent structural cracking.
3.2.5 Quality assurance measures for pouring continuous beams
The supporting system is designed according to the construction load and structural requirements to ensure that its strength, stiffness and overall stability meet the standards and meet the requirements of various working conditions.
According to the bridge and construction load, the pre-camber is reserved to keep the appearance alignment of the beam consistent with the design. Strictly control the flatness and joint of continuous beam model to ensure the smooth appearance of concrete.
Strengthen concrete vibrating. Peripheral personnel to check whether the template is loose, and tap the template to check whether the concrete is dense.
3.3 Quality Assurance System
4, safety guarantee system and measures
4. 1 safety guarantee system
Adhere to people-oriented, strengthen project safety management, meet the standards of equipment quality and personnel quality, and form a horizontal to vertical safety production guarantee system.
4.2 Safety Protection Management Organization
Under the leadership of China Luqiao Ning 'an Railway Engineering Command, the second part of the project established a safety joint control contact mechanism with the supervision company, Ning 'an Company and relevant departments.
Establish a safety production Committee with the project manager as the team leader, the deputy project manager and chief engineer as the deputy team leader, and the leaders of relevant business departments of the project manager as members; The shelf team should set up a safety leading group accordingly to form a safety management organization system. Take construction safety, personal safety, equipment safety, flood season safety and dam safety as the primary responsibilities, sign safety guarantee responsibility letters at different levels, strictly abide by the relevant laws, regulations and technical standards of safety production, establish and improve the safety production management system, hold regular safety work meetings, and solve problems in time when found. Make a safety plan, do a good job in safety training, eliminate hidden dangers of accidents and nip unsafe factors in the bud.
4.3 Safety guarantee measures
4.3. 1 Safety measures for aerial work of continuous beam
4.3. 1. 1 During the construction of aerial work project, reliable safety protection measures must be taken, and aerial work safety facilities must be installed in strict accordance with the design and in accordance with the provisions of Safety Regulations for Railway Engineering Construction. Aerial work personnel must wear safety belts and set up protective nets and other anti-falling facilities.
4.3. 1.2 The personnel engaged in aerial work shall have a physical examination regularly or at any time, and shall not engage in aerial work if there is any disease unsuitable for climbing. Patients with hypertension and cardiovascular and cerebrovascular diseases are prohibited from working at heights. It is forbidden to work high above the ground after drinking. Aerial work personnel shall not wear slippers or hard-soled shoes. The required materials shall be prepared in advance, and the tools shall be put in the tool bag.
4.3. 1.3 ladders for aerial work shall not be padded without gears, and two people shall not get on and off the same ladder at the same time. When ladders are used in passages (or platforms), fences should be set up. Contact between aerial work and the ground should be handled by special personnel or equipped with communication equipment.
4.3. 1.4 When aerial work is carried out at night, there must be sufficient lighting equipment. In case of strong winds above level 6, aerial work should be stopped to ensure the personal safety of construction personnel.
4.3. 1.5 It is forbidden to transport objects by hanging basket.
4.3. 1.6 The outer side of the protective frame is covered with a double-layer green dense mesh safety net enclosure.
4.3.2 Construction electricity safety measures
The line adopts three-level leakage protection and two-level grounding connection; The system of "one machine and one brake" is implemented, and a special switch box is equipped. The electrician shall be responsible for locking all switch boxes and power distribution cabinets on site; Regularly check and maintain electrical lines and equipment to prevent leakage and short circuit; Measures such as using safe voltage and Class III electric tools.
4.3.3 Safety measures for support construction
(1) Before preloading, the bracket structure shall be inspected in detail to ensure that the bracket is installed firmly and stably before loading.
(2) Pay attention to safety during construction. Safety technicians shall guide the construction at the site, and there shall be special personnel to command when loading (unloading) goods. The loading capacity should not be too high, and the sandbags should be stacked smoothly to prevent the sandbags from collapsing or falling.
(3) In the process of preloading construction, technicians must guide the construction on site. If there is any abnormality during preloading, stop loading immediately and analyze the reasons. After troubleshooting, the construction can continue.
(4) after the completion of preloading, sandbags must be