Application And Study Of Cut-off And Reinforcing Soil Nail Wall In Deep Foundation Pit Of Soft Area

In recent years,with the development of city construction,more and more high-rises and municipal projects appear in Beijing, Shanghai and Guangzhou,and so on, such as Jinmao high-rise. Deep foundation Pites are necessary for these super high and great buildings. But foundation pit is the importment parts of the whole project quality, cost and period. Doubtless, foundation pit system decides the success or failure of whole project.Since 1990's, composite soil nail wall has been studying in Beijing , Shenzhen, Xiamen, Shanghai, and so on. Especially, CENTRAL RESARCH INSTITUTE OF BUILDING & CONSTRUCTION OF MMI proceeded systems research and development on composite soil nail wall series, designed and constructed some type projects in Shenzhen. MINISTRY OF CONSTRUCTION and Government of Shenzhen generalize composite soil nail wall as an important technology, which make composite soil nail wall and project application on a new stage. The paper aims at providing some guidance for cut-off and reinforcing soil nail wall application, and offering a few commonplace remarks by way of introduction so that others may come up with valuable opinions about the study and development of cut-off and reinforcing soil nail wall.As a kind of composite soil nail wall, this paper mostly studies application of cut-off and reinforcing soil nail wall in deep foundation pit of soft area. Firstly, it enter on the soil nail wall concept, and briefly introduce status of soil nail wall in civil and external, difference between soil nail wall and Soil Reinforcement, difference between soil nail and anchor bar, shortcoming and merit of cut-off and reinforcing soil nail wall. Secondly, analysed by FLAC software cut-off and reinforcing soil nail wall, and explain the difference among cut-off and reinforcing soil nail wall, support system without prestressing and suopport system without cement concrete pile, present action mechanism of cut-off and reinforcing soil nail wall from synthesis action among cement concrete mixing piling, anchor bar and soil nail. Thirdly, focus on difference with design of soil nail wall, because cement concrete mixing piling and anchor bar participate the action. Sum up and supplement design of cut-off and reinforcing soil nail wall. Fourthly there are many paroxysmal incidents during construction, because cut-off and reinforcing soil nail wall mostly apply in high-level and soft area. Measure dealing with these incidents decides success or failure. This paper put forward some measures correspond to instances base on concrete project. Finally, the soil nail force analysis through the present field-stretching test is not true of force analysis under order. This paper attempt to put forward method about bond stress base on force analysis and cohesive stress distributed law of soil nail under order, and program correspond to idea, and supplement the field stretching test.