Study On In-situ Test And Numerical Analysis On Pile And Anchors Retaining Of Deep Excavation

With the development scale of the high-rise buildings, subway projects, municipal projects and the underground space, Foundation works have increased drastically for nearly 10 years.Pile-anchor supporting structure also has been widely used as an important supporting structure with the advantages of strong adaptability. The design theroy, work mechanism and characteristics of pile and anchors retaining in deep excavation was presented in this paper.Taking a deep excavation situated in Guangzhou downtown as the research background, data from the deformation monitoring of the support systems of the deep excavation were analyzed in the paper, and a series of displacement-time curves of the deep excavation were obtained and discussed to decrease the effects of deep excavation deformation on the adjacent buildings and roads.By establishing three-dimensional numerical model of the pile and anchor retaining structure, FLAC3D numerical calcualated method was adopted in conditions of supporting with or without cable. Analysis by comparing them indicated: pile and anchors retaining played an important role in deformation controlling. Furthermore, the stress state of cable and pile of supporting structure was also monitored, and the calcualated results of displacement were compared with data got by in-situ tests, which agree well with each other in both figure and value.As we know, the breakage of pile and anchors retaining is gradual and the construction of deep excavation is dynamic, the author established the RBF and BP prediction model based on artifical neural network theory, and compare with each other. According to the limited deformation data and the program, we could predict the future deformation and its developing trend of deformation in deep excavation for the later construction and forecast the possible dangers in time. The precision of the model was validated by engineering examples.FLAC 3D program can simulate the characteristics of all kinds of soil material and the reciprocity between soil and retaining structure, such as soil nailing, cable, top beam, retaining pile, etc.In the design of retaining and protection of foundation excavation, FLAC numerical analysis method with artificial intelligence predictions can be used to solve some difficult problems which defeat the methods proposed by codes.The results of them are helpful to optimize the design of retaining and protection project and to supervise its construction.