The principles for determining the construction sequence are as follows:
(1) Off-site, on-site, off-site from far to near;
(2) First the whole field, then the single event, and the whole field starts with leveling the soil;
(3) Underground first, then above ground, and underground first deep and then shallow;
(4) Pipelines and road works should be dried before supporting, drainage should be downstream first, and other sources should be downstream first.
1. Off-court and backcourt are preferred.
For some projects related to the inside and outside of the site, such as road engineering and pipeline engineering, the construction should start from the outside and then gradually extend into the site. In this way, some completed parts can be used, and the construction is extremely convenient. The correct construction sequence can make the equipment needed for road construction directly transported to the construction site through the main road. As the road extends to the site, some existing roads can be used, thus ensuring the smooth supply of equipment needed at the site, not only giving full play to the benefits of new projects, but also solving transportation problems economically and striving for construction time.
2. First the whole competition, then the individual competition.
It means to complete the whole site project first, and then complete the independent buildings and structures. The so-called full-site project refers to those public projects related to the construction of multiple projects or users, and the operation surface covers the whole construction site, such as site leveling, various pipeline and cable trunk lines, railways, main roads in the field, etc. [ 1]
3. First underground, then above ground.
This is an important principle that any project construction must strictly follow. The so-called underground first, then on the ground, that is to say, in construction, the project below zero elevation is completed first, and then the part above zero elevation is completed. From the whole construction site, projects below zero elevation generally include the following tasks: laying underground pipe network, building special lines, railways and highways in the site. In underground engineering construction, in addition to observing the above sequence, we should also implement the principle of deep before shallow, that is, do deep before shallow. When the construction is carried out step by step, only after the completion of the project below zero elevation, the construction of the above-ground project will be carried out. Underground engineering will be carried out in accordance with the procedure of deep first and then shallow, which is technically strict and generally the most reasonable in many cases.
4. Pipelines and pipeline projects shall be dried first, then branched, drained first, then downstream, and other sources first.
Managing the construction sequence of the first trunk line and the second branch line in the road can make the completed part of the project play a role quickly. If branch roads and pipe roads are built first, because these pipe roads are not connected with main pipelines, trunk roads and trunk roads, the benefits of the project will not be fully brought into play, the water in the upstream waterways will not be supplied, the water in the sewers will still not be discharged, and there is no source of gas, steam and electricity, so the roads will not be fully utilized. The construction of pipeline road engineering must first complete the main road, and the road will gradually lead to the site from the connection with the nearby main road.
Generally speaking, these principles mentioned above are not allowed to be disturbed. If it is disrupted, it will cause confusion, which may damage the quality of the project, increase the project cost, form waste and delay the construction period. In short, it will cause less delay. Of course, according to the above construction sequence is not completely mechanical. First of all, due to different construction conditions, it may be necessary and reasonable to change one of the above construction sequences under special circumstances. For example, in the filling area, pipes can be laid first. Secondly, following the above sequence does not mean that all pending projects must be completed before the sequential pending projects can be carried out. It is possible or even necessary for construction projects to be continuously interleaved. What is important here is to master a reasonable overlapping boundary. This reasonable overlapping boundary also varies with different conditions. The general principle is that the work of the latter link can only be started after the necessary working conditions are provided in the previous link, and the start of the latter link should not affect the work of the previous link, nor should it affect the continuity and smooth progress of its own work.
Basis for determining construction sequence
1. According to the construction sequence agreed in the contract, key projects, difficult projects, projects that control the construction period and projects that have great influence on the follow-up are determined to start first;
2. Determine the construction sequence according to the design drawings or data requirements;
3. According to the requirements of construction technology, construction specifications and operating procedures, determine the construction sequence;
4. Determine the construction sequence according to the requirements of the overall construction organization and management of the construction project;
5. Determine the construction sequence according to the actual situation of construction machinery and construction site;
6. Determine the construction sequence according to the status of local resources and outsourced resources;
7. Determine the construction sequence according to the geological, hydrological and local climate changes of the construction project and the degree of influence on the construction project.
According to the above points, the reasonable construction sequence can be determined dynamically, and the construction progress can be accelerated without increasing resources.
The construction sequence includes spatial sequence and time sequence. The arrangement of these two sequences is influenced by many aspects. Only by analyzing the specific situation of specific projects and mastering its changing rules can the arrangement be reasonable.
The so-called spatial order refers to the construction sequence of the same project content (like a division or subdivisional work), that is, the direction or flow direction of construction. The construction of any project must start from a certain place and then move in a certain direction. Sometimes, this order is influenced by the engineering structure or construction technology, and it is often relatively fixed.
The so-called time sequence refers to the construction sequence of different project contents (such as different subprojects in a unit project). In a unit project, the construction of any sub-project and its adjacent sub-projects is always suitable for construction first, and the others are suitable for construction. Due to the requirements of construction technology, some of them are often fixed. In addition, some have great flexibility because the construction sequence is not limited by technology. For example, the foundation of any building or structure must be treated before it can be used as a superstructure; As far as structure and decoration are concerned, the structure is always done first, and then the decoration is done. This is a fixed construction sequence that any project must follow. Even in the case of three-dimensional intersection parallel flow operation, from the perspective of the whole building object, all the work goes hand in hand at a certain time, but from a local point of view, the basic order of foundation, upper part, structure and decoration has not changed. However, in addition to this unchangeable sequence, other structural sequences can be considered from different angles and arranged differently. At this time, we should start from the following points; (1) is technically reasonable, which can ensure the quality and facilitate the construction and finished product protection; (2) Economical, reduce material consumption, and avoid planing and repair; (3) Fast progress, creating construction conditions for subsequent processes, making full use of the working face, and organizing parallel construction as far as possible.
Factors determining the construction sequence
When determining the construction sequence, the following factors should generally be considered:
(1) Follow the construction procedures.
(2) Conform to the construction technology. For example, the construction sequence of precast reinforced concrete columns is shuttering, binding steel bars and pouring concrete, while the construction sequence of cast-in-place reinforced concrete columns is binding steel bars, shuttering and pouring concrete.
(3) Consistent with the construction method. For example, the construction sequence of single-storey industrial workshop hoisting project, if the method of block-by-block hoisting is adopted, the construction sequence is hanging column → hanging beam → hanging roof system. If the comprehensive hoisting method is adopted, the construction sequence is: the first internode hanging column, beam and roof → the second internode hanging column, beam and roof → the last internode hanging column, beam and roof.
(4) According to the requirements of the construction organization. Such as the overall arrangement of indoor and outdoor decoration engineering construction sequence, according to the order stipulated by the construction organization.
(5) Consider construction safety and quality. When the roof adopts three-felt and four-oil waterproof layer construction, the exterior wall decoration is generally arranged at the back. In order to ensure the quality, it is best to arrange stair plastering after the upper decoration project is completed.
(6) Consider the climatic conditions of the day. In winter indoor construction, glass should be installed first, and then other decoration works should be done.