The Research And Application Of Combined Retaining Structure With Large Inclined Angle Anti-lateral Pier

With the further development of urban construction, the basement has become an essential part of new projects. When coping with1-2layers big basement excavation in soft soil zone, existing pit supporting techniques are showing more and more deficiencies, thus to develop a more economical and safer enclosure structure has become very necessary.Present engineering experience and research results show that, batter piles have higher capacity of bearing lateral force. If we can apply these batter piles to supporting project, greatly improvement of lateral resistant performance, lower construction costs and higher security could become truth. On the basis of this idea, we propose a new form of foundation pit support structure-Combined retaining structure with large inclined angle anti-lateral pier。This retaining structure mainly consists of row piles and anti-lateral piers and whose construction process is as follows:first, build the row piles with traditional bored piles, precast reinforced concrete piles or SMW process piles; second, construct batter piles; third, combine the separate erect and inclined piles with coping beams of plates。Due to the strong ability of the resistant for lateral load of the inclined piles, this enclosure structure is characterized by economy, reliability and convenient constructionAccording to the characteristics of the retaining structure, a new piling machinery named Large Inclined Angle Multifunctional Pile Driver, is developed in order to ensure the application of this new technology which can easily complete the construction while existing construction machinery and construction technology are difficult to implement this kind of large dip angle of inclined piles.A three dimensional calculation software named Plaxis3is used to research on the horizontal bearing capacity of inclined piles in the following two aspects which is lateral stiffness and ultimate bearing capacity. In the case of the same pile length, numerical simulation results shows that with the increase of the dip angle, forward batter piles and reverse batter piles have very different manifestations:for forward batter piles, the stiffness increases firstly and then decreases while its ultimate bearing capacity increases all along; for reverse batter piles, the stiffness has a great improve while the ultimate bearing capacity decrease continuously. According to the necessity of engineering practice, further research of inclined piles with the same bottom elevation reveal that unit length of the horizontal bearing capacity of inclined piles also has a decrease trend after the increase at first.A new method to calculate the internal force, deformation and global stability of this combined retaining structure with large inclined angle anti-lateral pier is put forward by improving the traditional theory of retaining structure internal force calculationFinally, the characteristic of economy, reliability and convenient construction of this new retaining structure is proved by its application in a built supporting engineering by comparison with the original design scheme.