Earthwork excavation of deep foundation pit is an important part of building engineering, and it is the premise for all subsequent processes to proceed smoothly. Therefore, it is necessary to strengthen the construction management of earthwork excavation of deep foundation pit, ensure that the errors generated in the project are within the specified range, ensure that the construction data are consistent with the scheme data, and analyze the specific problems. This paper analyzes and discusses the common problems and construction technology of deep foundation pit construction in housing construction engineering, hoping to provide reference for relevant employees.
Keywords: building construction; Deep foundation pit construction; Problems; construction technique
It is an era of electronic information. Science and technology are on the rise every day, and all walks of life are affected by it. Housing construction enterprises are no exception. They integrate science and technology into the construction and constantly improve the existing construction technology. Because the world population has been rising but not falling, it has caused land shortage in many cities, and the concept of residential construction has gradually changed to high-rise buildings, which has invisibly increased the depth and difficulty of foundation pit construction. This is the most basic and important step in order to bear the foundation pit of dozens of high-rise buildings. However, as far as the current construction level is concerned, there are still some common problems that need further analysis and research.
1 Construction Status of Deep Foundation Pit in Housing Construction Project
The construction of deep foundation pit engineering is related to many factors, such as the hydrogeological conditions of the construction site, the surrounding site conditions, the underground conditions around the foundation pit, the installation position of underground pipe network and so on. Compared with similar projects, the risk of deep foundation pit project will be higher, its construction site will be narrower and the construction period will be longer. In case of severe weather such as rainstorm or strong wind, these variable factors will have certain influence on the stability of deep foundation pit. Divided into several adjacent sites for construction, the main construction procedures include foundation pouring concrete, digging and water saving. These processes often influence and contain each other, thus increasing the difficulty of coordination. With the rise of building height, the deep foundation pit needs to be dug deeper and larger, and sometimes the width and depth will extend to more than several hundred meters, which also increases the difficulty of supporting system. Deep foundation pit excavation is generally carried out in hard soil layer, because soft soil layer will cause settlement and displacement, which will adversely affect the construction of underground pipelines and surrounding buildings in the future.
2. The main problems in the current deep foundation pit construction
2. 1 excavation and support problems
The deep foundation of most housing construction projects is excavated by large mechanical equipment. However, often due to the slope repair can not meet the overall design requirements, there will be under-excavation or over-excavation. In the actual excavation construction process, the construction management personnel failed to fulfill their responsibilities and the technical disclosure was unclear, which led to the different excavation heights in different places and the poor operation level of workers operating mechanical equipment, which made the slope flatness after excavation unable to form a regular state. When repairing the slope manually, the surface can only be slightly trimmed, and the next construction process-initial spraying-is carried out without strict inspection, which is easy to cause over-excavation and under-excavation after retaining the soil.
2.2 The design and actual construction conditions are quite different.
The construction of mixing pile is usually an essential step in deep foundation pit construction, but many constructors are not clear about the cement dosage and can't master the accurate dosage, which often leads to insufficient cement dosage, which reduces the strength of foundation pit support and affects the quality of the whole construction. The main reason for all this is that the construction unit did not strictly follow the construction drawings in order to complete the engineering quantity early, and the supervision of construction materials was not strong, so it was easy to cut corners. Most construction managers only pay attention to small interests and give up long-term interests. This short-sighted vision will bring great potential harm to construction projects. Generally speaking, before a three-dimensional space structure is formed, the construction is mainly adjusted according to the original plan of the plane structure, so as to better achieve the established space construction effect.
2.3 Deep foundation pit slope trimming operation is difficult to control.
Compared with other types of construction projects, the construction of deep foundation pit is more difficult. The operation mode of coordination, thinking and cooperation between human and mechanical equipment is the most commonly used construction method in construction enterprises at present. Large-scale excavation construction needs huge mechanical equipment to complete, and then the edge of the excavation part is more finely constructed and carefully handled by hand. But in real life, mechanical equipment often can't grasp the exact excavation depth, either too deep or too shallow, and sometimes even expand the excavation area a lot. In addition, because the mechanical equipment can't grasp the excavation depth, the slope rectification quality can't be effectively guaranteed. However, without the help of machinery, it is difficult to complete the excavation work only by manpower, and there are many human factors. Due to these factors, deep foundation pit excavation can not be carried out smoothly.
In view of the main problems existing in deep foundation pit at present, the corresponding construction technology analysis is put forward.
3. 1 Strengthen the organization and management of the excavation construction process.
During the whole excavation process, reasonably and carefully arrange the construction position, time and time of retaining and supporting, protect the excavated part as much as possible, greatly shorten the exposure time without supporting, and minimize the time and scope of soil disturbance, so as to fix its own displacement to a certain extent and play a fixed role with the excavated soil. Effectively controlling the construction sequence and progress of earthwork excavation, combined with the correlation between excavated soil and excavated soil, is conducive to controlling the soil movement of supporting structure. In order to better understand the movement of supporting structure and soil around foundation pit, it is necessary to strengthen the detection of excavation process.
3.2 Strengthen the connection between design and actual situation.
When designing a deep foundation pit, we should first pay attention to the reasonable planning of excavation depth and waterproof measures, and then design some subtle excavation work in detail. In the early stage of construction, we should fully understand and control the details of each link, because some details are more complicated. Under normal circumstances, based on relevant technologies, supervise the whole team in strict accordance with technical standards and construction design and construction. In addition, construction personnel should carefully choose technology and equipment and strictly abide by the company's articles of association. In order to better understand the construction of deep foundation pit, we can take photos or investigate the surrounding buildings or land, and analyze the whole construction site in detail with the detailed information of the construction area and the results of geological exploration, thus greatly narrowing the gap between design and practice. For example, when dealing with soft soil, the excavation requirements should be strict, and the depth and speed should be grasped. Otherwise, it will easily lead to unbalanced construction, which will lead to a downward trend in soil stability and hardness, and in serious cases, it may lead to soil landslide. This will not only hinder the timely completion of the project, but also damage the quality of the building. Therefore, use various modern channels to strengthen the understanding of the construction site and conditions, and strengthen the gap between the design and the actual situation, so as to better carry out the construction.
3.3 Strengthen the treatment and control around the deep foundation pit.
Under normal circumstances, choose to carry out excavation work in dry water or less rainy weather. Most construction projects will be affected by water, so when choosing the construction area, the investigation of groundwater level is a priority factor, and certain waterproof measures should be taken during construction to avoid being infringed by it. The slope of deep foundation pit is the most susceptible area to water. In order to ensure the safety and stability of building construction, the method of blocking first and then pumping is usually adopted to solve the problem, so as to reduce the occurrence of soil sliding around the foundation pit. The treatment of deep foundation pit slope is a very complicated process, but it is essential in the whole construction process. In order to excavate a deep foundation pit with suitable size, we can excavate a foundation pit with smaller size than planned with mechanical equipment first, and then trim its slope with manpower, so as to achieve the required flatness, excavate the most accurate deep foundation pit and reduce the drop.
4 conclusion
To sum up, although the problems existing in the construction of housing deep foundation pit are not very difficult, they are related to the quality and safety of the whole building project. Therefore, we should vigorously analyze the problems existing in deep foundation pit, formulate detailed construction technical scheme to solve them, and strengthen the technical assessment and supervision of construction personnel. Only by continuous progress and improvement can we ensure the quality of construction projects and enhance the market competitiveness of enterprises.
refer to
Guo Ying. Research on the Construction Technology of Deep Foundation Pit of Building [J]. Science and Technology and Enterprise, 20 13( 1 1).
[2] Mo Zilun. Discussion on common problems and construction technology of deep foundation pit construction in housing construction engineering [J]. Theoretical research on urban construction, 20 12(24).
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