The Analysis On Displacement Of Pile-Anchor Supporting System In Deep Excavation

The combined support of row pile prestressed anchor is a new-style supporting structure in recent years. It takes good advantage of the charactristics of the pile and the pressed archor, making supporting structure load reasonably and the construction of excavation safe and reliable. Now, the technique has been used widely in the foundation project with narrow site and complicated surroundings. However, because of the insufficience of the theory, the calculation model on the premise of many assumptions cannot sufficiently reflect the interaction between the supporting structure and the soil. Furthermore, the foundation monitoring data is extremely short of, so to calculate the displacement and deformaction of the supporting system accurately is still a problem at present. Adopting methods combined of theoretical analysis, numerical simulation and prototype observation, Using the monitoring data of construction field, and considering the interaction among many factors, this thesis speads out the following research on the horizontal displacement of the retaining pile, surrounding soil and the building settlement.(1)Put forward a calculation method of the displacement of the excavation pile-anchor structure which considering a variety of effect factors. To make the pile into vertical multi-span continuous beam and treat the anchor as the elastic support. The stiffness coefficient is contacted by these of the anchor in active area and passive zone. To consider the effect of the anchor prestress to the displacement of the retaining pile, and then develop a displacement method equation to calculate the mutual work among the pile,the anchor, the soil. Finally, the displacement of the supporting structure is calculated. On the basis of above theoretical analysis, develop a displacement calculation model of the retaining structure of multi-pivots anchor, and make use of relevant calculation procedures made by Matlab 7.0.(2)On the basis of analying and summarizing the calculation methods of the excavation surrounding ground settlement, make use of the exponential carve fitting the deformation method of the ground settlement to calculate the ground settlement of project instance, analyze and compare the calculated and measured values, and test the correctness and the suitability of this method.(3)Using the large finite element analysis soft-ware ADINA, considering the nonlinear of the soil and the principle of foundation excavation by steps,according to the particular project and the construction procedure of the foundation excavating, a 3-D finite model is developed to analyze the numerical values. Finally, the change law and effect factors of the displacement of the pile and the settlement of the soil in the process of excavating are found out.(4)Taking the deep excavation of Zhengzhou Kai-Lin Building as the background, to make a field monitoring scheme, monitor the horizontal displacement of the pile top and the surrounding building settlement in the process of excavating, and analyze the measured value. Finally, get the law of the horizontal displacement of the pile-anchor retaining structure and the surrounding building settlement, and give pieces of advice on the . deformation control of deep excavation.