With the rapid development of science and technology and construction industry, various advanced construction technologies emerge in an endless stream in current construction projects, creating favorable conditions for modern construction projects and playing an inestimable role in promoting social development. In the current construction projects, the construction technology of foundation pit support is a common construction technology. With the application of this technology in modern architectural engineering, it not only effectively improves the quality and efficiency of foundation pit construction, but also effectively saves the engineering cost. It is for this reason that the construction technology of foundation pit support is favored in current construction projects. In order to further improve the level of foundation pit supporting construction technology in construction engineering and promote the development of construction industry, it is not only of great significance but also urgent to increase the analysis and research on foundation pit supporting construction technology in construction engineering.
Keywords: construction engineering; Foundation pit; Support; build
In the construction of building engineering, foundation pit engineering has always been one of the important parts that people pay attention to, especially the construction of deep foundation pit, which has an impact on the overall success or failure. The construction of deep foundation pit directly affects the stability and safety of high-rise buildings, and also ensures the smooth development of the whole construction project. For deep foundation pit support engineering, the interaction between design and construction needs to be considered. Join hands? , to ensure the quality of foundation pit support. With the development trend of the construction industry, foundation pit construction is also developing in the direction of large scale, large width and large depth, which also makes the construction more difficult and longer. Therefore, we need to pay attention to the construction technology of foundation pit support to ensure the safety of foundation pit construction.
Ensure that the quality is not affected.
1, the characteristics and present situation of foundation pit engineering in construction engineering
1. 1 The foundation pit is dug deeper and deeper.
Perhaps the land is too expensive, perhaps it is more convenient to apply, or perhaps the urban planning and regulations have forced the building to develop underground. In the past, basements on the first and second floors were not common even in big cities. But now basements on the third and fourth floors are very common in coastal cities, and there are basements on the fifth and sixth floors.
1.2 The geological conditions of construction engineering are too poor.
Due to the influence of geology and environment, the geological conditions of construction projects are getting worse and worse, and many of them can meet the actual standards, especially in some coastal economic development zones.
1.3 The surrounding environment of the foundation pit is too complicated.
Because high-rise buildings and super-high-rise buildings are generally located in cities with relatively dense buildings and dense populations, and they are close to municipal roads. However, the original building structure is too old, and underground pipelines and underground T: pipelines are densely distributed. Therefore, during the construction of foundation pit, we should not only ensure sufficient stability, but also consider that the surrounding buildings are not affected.
1.4 excessive foundation pit support technology
Foundation pit support, such as steel sheet pile, precast pile, manual digging pile, internal support, underground continuous wall, various pipes, piles, plates, braces, walls, etc. All of them are combined with anchor rods for joint support, in addition to anchor nail walls and other aspects.
2. The reasons of foundation pit support in building engineering.
2 1 When designing the supporting structure, the physical and mechanical parameters of the soil are not selected properly.
The earth pressure that the foundation pit supporting structure can bear will directly affect the safety of the building structure, but considering the geological conditions, we can't accurately calculate the earth pressure. So far, Rankine Company and Coulomb Company have been used. When choosing the physical parameters of soil, I need to consider many aspects, especially after deep foundation pit excavation, cohesion, moisture content and internal friction angle may change. Therefore, it is difficult to accurately calculate the actual bearing capacity of the supporting structure. If there is no accurate value of physical and mechanical parameters of foundation soil, it will have a serious impact on the design results.
2.2 When taking soil from the foundation pit. Not complete enough
Before the calculation of foundation pit supporting structure, it is necessary to analyze and sample the foundation soil layer to obtain reasonable physical and mechanical indexes and provide reliable design basis for supporting structure. Generally speaking, within the scope of deep foundation pit excavation, drilling sampling must be done well and carried out according to the requirements of national codes. In order to minimize the cost of 1_ range and the workload of drilling, it is also necessary to avoid excessive drilling. Therefore, the soil samples taken are incomplete and random. Moreover, considering the complexity and variability of geological structure, the obtained soil samples can not accurately reflect the actual properties of soil layers in this area.
2.3 The spatial effect of foundation pit excavation is not comprehensively considered.
According to the measured data of foundation pit excavation, when will the horizontal displacement around the foundation pit move to the inside of the foundation pit? 374? Wait, it's usually big in the middle and small on both sides. Moreover, the instability of deep foundation pit slope usually occurs in the middle of the side length. It can be seen that deep foundation pit excavation is an empty question. In the traditional design, the foundation pit supporting structure is treated according to the plane strain reason. For some slender foundation pits, this assumed plane strain is in line with the actual requirements, but if it is a rectangular or rectangular deep foundation pit, the difference is great.
2.4 There are differences between the design and calculation of the actual hand and the supporting structure.
At present, the design and calculation of deep foundation pit supporting structure still adopts the limit equilibrium theory, but ignores the fact that the actual stress situation of deep foundation pit supporting structure is relatively complicated. From the practice of building engineering, theoretically speaking, it is safe to design the safety factor according to the limit equilibrium theory, but it will be destroyed in some cases; Although the safety factor of some supporting structures is relatively low, it can not even meet the design requirements, but it can meet the actual construction requirements. In the deep foundation pit supporting structure, the limit equilibrium theory belongs to a static design, but after the soil is excavated, it belongs to a dynamic equilibrium state. As time goes on, the strength of the soil will also decrease, so there will be some deformation. So this is also a point that cannot be ignored in the design.
3. Construction technology of foundation pit support in building engineering
3. 1 Foundation pit support design
In the design of foundation pit support, we should consider the actual site construction requirements, and make a reasonable, rigorous and scientific scheme in combination with the important coefficient and safety grade of foundation pit side wall. Therefore, we need to pay attention to: First, we need to make full use of new concepts and technologies, and analyze specific affairs, instead of copying the previous design concepts. In today's design field, there is no authoritative and recognized calculation formula for deep foundation pit supporting structure, which is still in the exploration stage. Compared with other fields, the design of deep foundation pit supporting structure needs to break the tradition and guide the juice cleaning system through on-site monitoring; Second, study the supporting structure theory and material test, so practice is the only truth test standard. Only a large number of experimental studies can support the correct theory. Compared with many developed countries, there is still a big gap in the supporting structure of experimental deep foundation pit in China. However, with more and more high-rise and super-high-rise buildings springing up in China, although domestic designers have mastered the first-hand R data, they have not been able to form a corresponding theory due to the lack of scientific experimental data, which also needs our attention; Third, when designing the supporting structure, we should know how to innovate, be brave in innovation and actively explore new ideas. In the construction of deep foundation pit supporting structure, it is often necessary to combine all the elements, which requires us to explore better calculation strategies and new design ideas.