Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel(CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the ...Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel(CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the underlying untreated stratum. Due to the changing permeability property of CFG piles, the whole consolidation process of the composite ground with CFG piles was divided into two stages, i.e., the early stage(permeable CFG pile bodies) and the later stage(impermeable pile bodies). Then, the consolidation equation of the composite foundation with CFG piles was established by using the Terzaghi one-dimensional consolidation theory. Consequently, the unified formula to calculate the excess pore water pressure was derived with the specific solutions for the consolidation degree of composite ground, reinforced area and underlying stratum under instant load obtained respectively. Finally, combined with a numerical example, influencing rules by main factors(including the replacement rate m, the treatment depth h1, the permeability coefficient Ks1, Kv2 and compression modulus Es1, Es2 of reinforced area and underlying stratum) on the consolidation property of composite ground with CFG piles were discussed in detail. The result shows that the consolidation velocity of underlying stratum is slower than that of the reinforced area. However, the consolidation velocity of underlying stratum is slow at first then fast as a result of the transferring of effective stress to the underlying stratum during the dissipating process of excess pore water pressure.展开更多
CFG pile has been widely applied as one of the common ground treatment techniques. As a concealed work, the construction quality of pile foundation not only relates to the success of the project, but also concerns the...CFG pile has been widely applied as one of the common ground treatment techniques. As a concealed work, the construction quality of pile foundation not only relates to the success of the project, but also concerns the benefits of thousands of hot, seholds. Only strengthening the supervision and management during the construction and strictly designing and specifying CFG pile can ensure the construction quality of CFG pile. But most researches focus on operating mechanism and theoretical analysis, and there are fewer researches about the construction of CFG pile. The real construction of CFG pile has no specified operation and lacks of the construction guidance, which not only causes great problems and has great influence on the intensity of CFG pile, but also makes the real pile body have great difference from the design requirements. Therefore, the study on construction of CFG pile in the paper has great significance.展开更多
In 2011, in order to speed up the transformation of urban and state-owned industrial and mining shanty towns, the municipal party Committee and municipal government added five new industrial and mining shanty towns tr...In 2011, in order to speed up the transformation of urban and state-owned industrial and mining shanty towns, the municipal party Committee and municipal government added five new industrial and mining shanty towns transformation projects, including the industrial and mining shanty towns in Mentougou District of Beijing Coal Group with a total construction area of 380,000 square meters. Shanty town renovation mainly replaces the original shanty residential area with modern high-rise buildings. Mentougou area is located in a mountainous area with complicated strata, which makes the construction of high-rise buildings meet new geotechnical engineering problems and puts forward higher requirements for geotechnical engineering design and construction in this area. The proposed site for a shanty town renovation project in Mentougou District of Beijing Coal Group is located on the north side of Dayu South Road and the east side of Heishan Street in Mentougou District of Beijing. Including 6 residential buildings and 1 underground garage. According to the vertical design of the site and building and the engineering geological characteristics of the project, the author puts forward a more optimized design of foundation pit support and construction scheme of foundation treatment. Combining with the design and construction experience in the area, the problems in the design and construction process, such as the complex surrounding conditions of the site, different elevation of the building floor, the difficulty in forming holes for piles and anchor rods in gravel soil layers, and the design and construction engineering problems of large-diameter CFG piles, are solved. In this paper, the problems encountered in the design, construction and engineering inspection of foundation pit support and foundation treatment are discussed in detail. Through exploration, research and analysis, a more reasonable design, construction and engineering inspection scheme is proposed, which can be used for reference by similar projects in the future.展开更多
基金Project(51378197)supported by the National Natural Science Foundation of China
文摘Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel(CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the underlying untreated stratum. Due to the changing permeability property of CFG piles, the whole consolidation process of the composite ground with CFG piles was divided into two stages, i.e., the early stage(permeable CFG pile bodies) and the later stage(impermeable pile bodies). Then, the consolidation equation of the composite foundation with CFG piles was established by using the Terzaghi one-dimensional consolidation theory. Consequently, the unified formula to calculate the excess pore water pressure was derived with the specific solutions for the consolidation degree of composite ground, reinforced area and underlying stratum under instant load obtained respectively. Finally, combined with a numerical example, influencing rules by main factors(including the replacement rate m, the treatment depth h1, the permeability coefficient Ks1, Kv2 and compression modulus Es1, Es2 of reinforced area and underlying stratum) on the consolidation property of composite ground with CFG piles were discussed in detail. The result shows that the consolidation velocity of underlying stratum is slower than that of the reinforced area. However, the consolidation velocity of underlying stratum is slow at first then fast as a result of the transferring of effective stress to the underlying stratum during the dissipating process of excess pore water pressure.
文摘CFG pile has been widely applied as one of the common ground treatment techniques. As a concealed work, the construction quality of pile foundation not only relates to the success of the project, but also concerns the benefits of thousands of hot, seholds. Only strengthening the supervision and management during the construction and strictly designing and specifying CFG pile can ensure the construction quality of CFG pile. But most researches focus on operating mechanism and theoretical analysis, and there are fewer researches about the construction of CFG pile. The real construction of CFG pile has no specified operation and lacks of the construction guidance, which not only causes great problems and has great influence on the intensity of CFG pile, but also makes the real pile body have great difference from the design requirements. Therefore, the study on construction of CFG pile in the paper has great significance.
文摘In 2011, in order to speed up the transformation of urban and state-owned industrial and mining shanty towns, the municipal party Committee and municipal government added five new industrial and mining shanty towns transformation projects, including the industrial and mining shanty towns in Mentougou District of Beijing Coal Group with a total construction area of 380,000 square meters. Shanty town renovation mainly replaces the original shanty residential area with modern high-rise buildings. Mentougou area is located in a mountainous area with complicated strata, which makes the construction of high-rise buildings meet new geotechnical engineering problems and puts forward higher requirements for geotechnical engineering design and construction in this area. The proposed site for a shanty town renovation project in Mentougou District of Beijing Coal Group is located on the north side of Dayu South Road and the east side of Heishan Street in Mentougou District of Beijing. Including 6 residential buildings and 1 underground garage. According to the vertical design of the site and building and the engineering geological characteristics of the project, the author puts forward a more optimized design of foundation pit support and construction scheme of foundation treatment. Combining with the design and construction experience in the area, the problems in the design and construction process, such as the complex surrounding conditions of the site, different elevation of the building floor, the difficulty in forming holes for piles and anchor rods in gravel soil layers, and the design and construction engineering problems of large-diameter CFG piles, are solved. In this paper, the problems encountered in the design, construction and engineering inspection of foundation pit support and foundation treatment are discussed in detail. Through exploration, research and analysis, a more reasonable design, construction and engineering inspection scheme is proposed, which can be used for reference by similar projects in the future.
