Paper Keywords: high-rise building quality control and safety Abstract: Due to the particularity of high-rise building engineering quality and safety, the author from the perspective of further strengthening quality and ensuring safety, combined with some experience in practice, to talk about some personal views for peer reference.
1 Key points of high-rise building construction control
1. 1 Strength control of high-rise buildings
The strength control of high-rise buildings mainly refers to the strength of concrete, and there are strict specifications and standards according to the building requirements. Therefore, in order to ensure building quality and improve efficiency, several control points in building construction are very important and cannot be neglected. The content is as follows:
① Selection of proportion. Before the project starts, it is generally required to do the mixture ratio test at the statutory testing institution according to the design requirements, which will be carried out during the actual construction. However, according to the actual situation of the project and the original situation of the site, the proportion of laboratories should be adjusted to ensure the practical universality of the proportion of laboratories, which requires corresponding measures to strengthen the control of raw materials in actual construction.
② Strict maintenance system. (1) There should be a maintenance plan for mass concrete, and there should be a special person in charge, and there should be enough understanding of maintenance from the subjective consciousness. Measures such as personnel, water source and coverage should be considered in the maintenance plan, and major key details should not be omitted. (2) Strengthen the supervision of maintenance period. Take effective measures to track records, find problems in time, and ensure the effectiveness of maintenance.
(3) Strengthen the concrete strength evaluation. According to the Standard for Evaluation of Concrete Strength (GBJ 107), the concrete strength should be tested and evaluated in batches.
1.2 survey control of high-rise buildings
(1) axis control
① Axis control in foundation construction. The foundation construction of high-rise buildings is generally deep foundation pit construction. According to the field axis control points, lead the axis control points to 5m outside the axis, set gantry piles and protect the axis control piles. Use theodolite to guide the axis into the foundation pit, use 50m steel tape to set out the pile position, bearing platform, foundation beam and soil in each part, then nail the axis pile around the foundation pit, and strictly control the setting-out size of each detail by using the method of matching the stay wire with a small steel ruler.
②? Axis control of structure construction above 0. 00. A high-rise building? During the construction of structures above 0.00, due to the synchronization of scaffolding and construction layer, some reference points from the periphery cannot be measured, so the internal control method is often used. Are you online? +/-0.00 After the axis of structural construction review is correct, the line of sight of theodolite shall prevail, and the longest vertical and horizontal axis of a floor shall be offset by 2m, and several pieces of 200mm shall be embedded. 200mm？ 10mm steel plate, mark the control axis or main axis control point on the steel plate: when the second floor and above are constructed. Based on the first floor, set 200mm at the corresponding position of each floor. 200mm square hole, use laser instrument to measure the lower control points, and then use theodolite and steel tape to correct the axis, and release the axis and detail dimension line of each layer. When the laser instrument is used to guide the measurement, the correction of laser instrument facula must also be considered to reduce the error caused by facula.
(2) Control of verticality
① Controlling verticality is the foundation and one of the key links to ensure the quality of high-rise buildings. In order to control the verticality of the building, the positions of the four corner columns of the building should be determined according to the column network layout of the building. When installing the quadrangular column template, pop up the thickness line along the outer layer of the column, erect the template, add support, and measure the verticality of the column with messenger wire; After the verticality is guaranteed to be 100%, the formwork shall be aligned with the outer line for reinforcement, support and concrete pouring.
(2) In the process of verticality control, the laser instrument weighting hammer is used for double comparison to increase the verticality accuracy. At the same time, the vertical measurement error of high-rise buildings can be minimized by combining internal and external control. When installing corner wall column formwork on the second floor and above, the verticality of corner wall column formwork shall be determined by messenger wire method. After positioning, supporting and strengthening two or more corner wall columns around, on this basis, two hanging plates are nailed on the outer sides of the upper and lower openings of the corner wall column template along the vertical and horizontal directions, and lines are hung on the upper and lower openings of the template to control the external wall column and the corner wall column to be on the same axis and verticality.
(3) Control of elevation lines
(1) At least four holes (usually led by at least three high-level) on the precontrol axis of each floor shall be used for elevation positioning, supplemented by multi-level elevation sum check, and then supplemented by level leveling to check whether these four points are on the same horizontal plane, so as to ensure the accuracy of elevation.
(2) The accuracy of elevation of four holes needs to be improved, and the elevation of holes may lose its benchmark function due to formwork, pouring and loading during construction. To ensure the reliability of the putright point, strengthen the formwork support of the hole, and control the floor thickness of this part with steel bars with a diameter of 12 to ensure the accuracy of elevation.
(3) In the four corners of the building, where conditions permit, check points of storey height and cumulative storey height should be set up, and the position should be affixed on each floor for inspection to prevent the cumulative error from being too large. In the process of checking the elevation at all levels, it is necessary to realize that the four-hole control points at all levels and the external height check points are above the same level to confirm the accuracy of the elevation, so as to achieve the purpose of elevation control.
3 crack control
From the design point of view, there are the following measures to control building cracks:
① Strengthen basic investigation. For complex foundation, after foundation trench excavation, comprehensive drilling and exploration should be carried out, and construction should be carried out after the weak parts are exposed and reinforced; ② Reasonable setting of settlement joint. Make it freely settle to prevent cracks, and the width of settlement joints should be set according to the requirements of specifications; (3) Set up post-pouring belt and expansion strengthening belt reasonably, and take corresponding measures to compensate concrete shrinkage; (4) The design chooses the one with good ductility. In the design of floor steel bars, in order to improve the ductility of the combination of floor concrete and steel bars, Grade I and II steel bars with relatively low strength and good ductility are superior to Grade III steel bars with relatively high strength and low ductility, especially cold-rolled ribbed steel bars.
From the construction point of view, the measures to control building cracks mainly include:
① Strictly control the slump of concrete. The greater the slump, the more water, the greater the drying shrinkage and settlement of concrete;
(2) Before pouring concrete, the formwork shall be soaked in water. In columns, beams, wall panels and other variable cross-sections should be cast in layers.
(3) when pouring concrete in dry and windy weather or summer, shrinkage cracks are easy to occur. The secondary plastering should be carried out after the initial setting of concrete and before the final setting, and the early curing of concrete should be strengthened, and the surface should be covered with sacks and straw bags and kept moist;
(4) Within two years after the completion of concrete pouring, keep the relative humidity in the empty room basically consistent with the outdoor relative humidity, and not less than 85%. This requirement can be achieved by opening windows frequently, and it is best to sprinkle water regularly to increase humidity where conditions permit;
⑤ Reasonable arrangement of roof insulation construction. Because there is a time interval between the completion of the construction of the roof structure layer and the completion of the operation layer, the roof construction should try to avoid the high temperature season.
2. Building safety
2. 1 Improve the safety awareness of construction personnel in an all-round way.
We should firmly establish the policy of putting safety in production first. With professional safety knowledge as the content and rewards, laws and regulations as the means, the safety awareness of construction personnel is enhanced, the self-safety prevention ability of construction personnel is continuously improved, and the relationship between responsibility, right and benefit in safety production is clarified, so as to achieve the best construction safety benefits.
It mainly includes: strengthening the daily training of professional safety knowledge and technology, educating with typical safety cases and accident lessons, and carefully analyzing and discussing against laws and regulations. Publicize safety laws and regulations one by one in the safety education publicity column. Actively organize all kinds of managers to attend good safety lectures and visit commended projects. By attaching importance to personnel management, establishing mechanism and perfecting system, the safety of construction enterprises is created.
2.2 Clear the person responsible for production safety of the construction project.
In the construction, it is clear that the project manager is fully responsible for safety control and formulates the key points of safety management. In order to define the commitment and goal of construction safety, it is necessary to work out the project safety plan, establish the responsibility system for production safety and improve the safety guarantee system. The project department should establish a responsibility system for production safety, and decompose the safety responsibility objectives into posts and implement them to people. According to different construction projects and conditions, reasonably organize financial and material resources to ensure construction and production safety.
2.3 Pay special attention to safety management before and during construction.
Engineering construction safety comes from the production process and must be based on? Mainly? Preparation before construction and supervision and management during construction. Before construction, it should be carried out step by step. The first is to do a good job of investigation before construction.
Investigate and record the topographical and geomorphological features of the site, find out the factors that may cause potential safety hazards in time, and formulate safety technical measures and site safety warnings according to the site records and design documents. Carry out safety education, implement safety technical training and assessment, and make safety technical disclosure. What should be followed in construction? Construction according to the drawings? , fully understand and master the requirements of design documents and the content of safety technical measures. Do a good job in the acceptance of various safety protection and stress support systems. Especially well supports, scaffolding and various supports. The unloading platform and other parts that bear constant live load should be built according to the mode of safety calculation. Grasp the whole construction dynamics, and timely discover and correct illegal operations and behaviors.
2.4 adhere to the six basic principles of safety management
To manage production and safety at the same time and adhere to the purpose of safety management, we must implement the policy of putting prevention first and insist on? Siquan? Dynamic management, safety management focuses on control, and it is developed and improved in management.
3 Conclusion
In modern high-rise building construction technology, safety construction is the main part of construction. How to ensure construction safety is an important part of production management of construction enterprises. The object of safety management is the state management and control of all people and things in production, and safety management is a dynamic management. With the more and more extensive application of new technologies, new materials and new processes, construction enterprises must constantly improve their own technology and management level in order to create better benefits.
refer to
[1] Cheng Yongshuang talks about construction control of high-rise buildings, Shanxi Architecture, 0 1, 2009.
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