The towering pillars bear the power of the sky, and the road is like a frame paving. Mo Yan is very rugged here, and he is full of anger and builds a smooth road. In the vast land of southern Gansu, an elevated expressway shuttling between the city and the suburbs is like a winding dragon cruising in the painting, and the traffic network extending in all directions along the line reflects each other, becoming a beautiful scenery for the construction and development of the old revolutionary area.
Aerial view of the project This expressway is an important support project for Ganzhou City to promote the construction of urban energy level improvement action, and after completion, it will further open up inter-regional traffic nodes, greatly facilitate the travel of citizens and promote economic development along the route. Since entering the site, the company's builders have risen to the challenge, promoted the construction of the project with a high starting point and high standards, and strived to build the Gannan Avenue Expressway project into a quality project.
Overall planning and rapid construction boom
The project has a total of 2,949 prefabricated components, and the construction time is only 450 days, and the construction of the prefabricated yard has become the primary link restricting the construction period. At the same time, there are many factories around Gannan Avenue, and the property rights relationship is complex, and the expropriation and demolition work is difficult. "Have a meeting in the evening to summarize the differences in site selection and deploy tomorrow's tasks. On the long road of site selection, Yang Zhan, secretary of the Party branch, led the requisition and demolition team to the "corners" of more than 10 villages along the line, and personally participated in the cost data accounting to ensure that the land cost and transportation distance were optimal. Take the initiative to connect with local ** departments, do a good job in the ideological work of the masses with sincerity, and "break your legs and wear out your mouth" has become commonplace, and promote the smooth development of the expropriation and demolition work with patience and sincerity.
Faced with the problem that the prefabricated yard is only 70 acres in size and the average monthly output is more than 200, Liu Hong, deputy manager of the project, decided to grasp both "time and space": seize the construction progress with the spirit of "white and black, 5+2", overcome the difficulties such as frequent site filling and excavation, no transportation and water transportation channels, and complete the construction work in only one month, so as to realize the rapid entry of machinery and equipment, raw materials and construction teams, and take the lead in construction; Make full use of the limited site to plan 4 long-shaped prefabricated areas, optimize the setting of the area according to the process, implement the fine management at the same time, and adopt the web roof binding fetal tool, the overall hoisting of steel bars and the model system of important parts and other processes to form an efficient assembly line operation and lay the foundation for subsequent large-scale production.
Progress control is a process that runs through the beginning and end, the project starts from the prefabricated components, regularly and quantitatively plans the target node, regularly assigns people to report the progress of the task, and fully supports the resource elements in the process to achieve front-end and back-end linkage control. When it comes to on-site management, project manager Liu Jian has a lot of experience. In the face of the increasingly tight construction period, the project dynamically adjusted the management mode, and the leadership team took the initiative to take the lead, took responsibility for the divisions, and personally supervised and solved the problems found on the site. Regardless of the scorching sun and heavy rain, strictly implement the leadership and safety guarantee system, adhere to the construction site with the responsible attitude of "sweat on a sunny day, mud on a rainy day", so that the task is clear, the investigation is more specific, and the rectification is increased, so as to accelerate the formation of a strong joint force to promote the construction.
The key to reversing the construction period and forcing the schedule is to strengthen the management of the subcontracting team. "Through centralized bidding, on the basis of selecting a strong team, the project implements progress early warning management, through monthly statistics on labor resource input and inspection output value, compares labor costs and actual productivity in the same process, continuously optimizes labor resources, increases assistance to backward teams, and dissuades long-term loss-making teams. The project also ensures that the construction climax is uninterrupted and does not fade through continuous labor competition, with goals and indicators and assessment as the traction. Up to now, the cumulative output value of the project is 124.6 billion yuan, with the highest monthly output value exceeding 100 million.
Overcome difficulties and create innovative high-quality projects
At the lower part of the bridge, rows of prefabricated components are neatly arranged.
1. Be in order until the end of the city. In order to achieve the goal of quality engineering construction, the project has worked "refinement" and strengthened source supervision and process research.
The prefabricated components are installed on the raw material control, and the project uses digital processing equipment for steel bars to accurately cut and cut materials to solve the problems of different lengths, precisions and bending angles of steel bar cutting. Strengthen the inspection of concrete raw materials and factory work performance, standardize the operation of workers, and ensure that there are no defects such as honeycomb and hemp surface. The introduction of automatic intelligent spray curing system, according to the external environment to set different spraying parameters to ensure the quality of concrete curing. In addition, the project also vigorously promotes advanced technologies such as intelligent grouting and intelligent tensioning, chiseling-free hair and slurry stopping, undamaged removal of pile heads, and square grids, so that all kinds of prefabricated components can truly achieve "beauty on the outside and solid on the inside, and consistency on the outside and inside".
Because the prefabricated column adopts the vertical pouring process, the floating slurry on the top of the column is easy to produce cracks after molding. In order to overcome the problem, the project set up a QC team to prevent cracks at the top of the prefabricated column column, and comprehensively optimized the construction plan from the aspects of pier design, materials and technology. When pouring concrete, the top is poured 1-2cm more, and the mechanical chisel is used to chisel it off in the later stage; Improve the design of concrete mix ratio, use the covering geotextile process to strengthen the top surface curing, and reduce the floating slurry; Reinforcement mesh sheets are added at the position of the column lifting point to reduce the force on the concrete hoisting process. After the actual test, the pass rate of the first acceptance of the prefabricated column was increased to 90% in the short term. The group won the third prize of the 2022 QC Group Achievement Award of Hunan Province, which has great promotion and application value.
In view of the problem that the positioning accuracy of the conventional construction method of pier stud assembly is not high, the project has developed a set of precise installation and construction technology, which realizes high-precision control of sleeve and anchor bar through precise positioning processes such as cushion cap embedded steel bar, pier stud embedded grouting sleeve, cushion cap top elevation, pier stud prefabricated segment length, pier stud installation and leveling steel plate; The positioning tooling is connected and fixed with the template bolt, and the embedded parts and the tooling limiting sleeve are reinforced and positioned, so as to effectively avoid the deviation of the embedded parts in the construction process; After the prefabrication is completed, the anchor bolt and sleeve positioning inspection tooling are used for final inspection to ensure accurate installation.
In the precision control of the prefabricated cap beam, the technical team decided to use the metal bellows positioning tooling to install the metal bellows positioning tooling on the bottom plate surface of the formwork also according to the positioning tire frame in the pier stud reinforcement according to the positioning tire frame in the pier stud reinforcement process, and the design and positioning spacing of the tooling are consistent with the pier stud tire frame to ensure that the two components are "hit it off" on the installation and the hole. Under the condition that the bearing capacity of the original pavement foundation meets the requirements, the assembled tower-shaped A-type bracket is used as the installation system, the connection accuracy is higher, and the erection and dismantling cycle is shorter; The use of the slurry baffle hoop and the total station through the steel plate fine-tuning method, the whole process to strengthen the precision control, to ensure that the installation in place at one time, greatly improve the construction efficiency.
In-depth promotion of business management to improve quality and efficiency
The project closely focuses on the goal of "efficiency improvement and value creation", firmly draws the blueprint of big business management to the end, and continues to strengthen the precise control of costs.
The "pavement paving" project adopts the investment and financing model, and the funds are slow to be in place in the early stage, and it is faced with the problem of ensuring the use of steel. After trying a variety of procurement and supply models, the "first chain" model was excavated, relying on the first chain company under Ganzhou Development and Investment, using the cash no account period payment method to purchase materials at a low unit price, and then paying interest at an annualized rate of 9% per year for three years of principal and interest repayment. After accounting, the unit price of steel procurement is about 139 yuan ton lower than the Ganzhou network price, and 550 yuan ton lower than the traditional centralized procurement unit price. Business manager Yang Lei said.
Strengthen the management of progress indicators. The project is supported by the construction of standardized and intelligent beam yards, and through the optimization of the organization and construction, the average monthly production of beam-making pedestals is 4 pieces, the pier columns are prefabricated 6 sections per pedestal per month, the rotary drilling rig is made 3 holes per day, and the work class completes 1 cushion cap every 10 days, which is higher than the production schedule index, while saving about 3 million yuan in the construction cost of the prefabricated site, reducing the formwork configuration and equipment investment of about 30 million yuan, and realizing the double improvement of progress and efficiency.
Strengthen the concept of safety and efficiency. In the face of the high risk of some processes and the low profit of the original plan, the project focuses on optimizing the plan, and insists on reducing costs and increasing profits on the existing basis. The safety risk of the construction pile foundation near the underground pipeline was fully explained, and the two-span small box girder was adjusted to a one-span 60m steel box girder, which increased the contract amount by 4.5 million yuan and increased the profit by 700,000 yuan; On the grounds that the safety risk of the installation of more than 15m pier stud sections across the Daguang Expressway is large, it is changed to a cast-in-place structure, which can timely absorb the box girder of the prefabricated yard and reduce the cost of box girder reversal by 200,000 yuan; As Gannan Avenue is the main road in the urban area, the traffic flow is huge, and the construction cannot be fully enclosed, far beyond the general road use function, after multi-party communication and coordination, more than 300 yuan of repair costs have been incurred so far into the total investment of the project.