Research On Displacement And Software Development Of Pile-anchor Retaining Structure In Deep Foundation Pit

In recent years,with the rapid advancement of urbanization in China,a large number of people have flooded into cities,resulting in more and more urban land use and increasing trffic pressure.The number of high-rise and super-high-rise buildings in urban is increasing day by day,and the construction of subways is also imperative.Accompanied by more and more the number of deep foundation pit engineering,the scale is bigger and bigger,the depth is deeper and deeper.Deep foundation pit engineering is regional,and its supporting forms are various.It is necessary to adapt the measures into local conditions and choose the appropriate form of support.For the characteristics of loess in the northwestern region,the prestressed bolt support structure of row piles is a common form of support.At present,the research on deep-pit excavation pile anchored structures has become more mature,and the calculation theory is also varied.The direction of research and analysis has also shifted from the calculation of bearing capacity stability to displacement control design.There are many methods for calculating the displacement of the pile-anchor retaining structure in deep foundation pits,but most of them are cumbersome and complicated.In view of this situation,this paper adopts a combination of theoretical analysis and numerical simulation,then proposes a relatively simple displacement calculation method.It provides a reference for the study of displacement control of deep foundation pits with pile-anchor retaining structures.The main research contents are as follows:(1)Based on the existing displacement calculation method of pile-anchor retaining structure,and the influence of the movement of pile-anchor support structure on earth pressure,the non-Ultimate earth pressure theory is introduced,and the calculation theory of this paper is proposed,namely incremental iterative theory.According to this calculation theory,the calculation formula for calculating the displacement of the pile body is deduced,and the calculation program is compiled.Combined with the engineering example,the results of pile displacement calculated by the incremental iteration method are compared with those calculated by the simulation software Plaxis,and the rationality of this calculation method is verified.According to the idea of displacement control of pile-anchor retaining structure in deep foundation pit,a simple method for the displacement control of pile-anchor retaining structure is proposed.(2)The numerical simulation software Plaxis was used to analyze the influence of various design parameters on the displacement of the pile-anchor retainingstructure in deep excavation.After the cohesion of the soil was removed from the soil parameters,other soil parameters had a significant impact on the displacement of the pile.In addition,the overload value of the top of the foundation pit and the prestress of the anchor rod also had a great influence on the displacement of the pile.Meanwhile,the overall impact of the rest of the parameters is small,and even little or no impact.(3)Based on the Matlab GUI,a simplified calculation program for the deep-pit excavation pile-anchor retaining structure is constructed.The program is mainly divided into a main interface,a parameter setting interface,a model generation interface,and a calculation and analysis interface.The four modules is relatively concise in the design and clear in the functions.Through the calculation of specific projects,the rationality of the calculation software is verified.