Analysis For The Bearing Characteristics And Application Of Folded Linear Secant Pile

With the continuous reduction of urban land space,the underground space left for the construction of foundation pit projects is becoming more compact,and the surrounding environment of foundation pit projects is also more complicated.In terms of the northwest region,the underground soil conditions are relatively well,and most of the foundation pit projects are pile-anchor retaining structure,but in recent years,the secant pile has been used as a relatively new type of foundation pit retaining structure.In the current process of designing the secant pile,it is designed according to the conventional row-and-row retaining structure,Ignoring the contribution of the pile body to the overall bearing characteristics of the structure,the design scheme is relatively conservative.In this paper,with the foundation of the linear secant pile structure,this paper puts forward the folded linear secant pile based on the controlling of occlusion angle.In this paper,using the equivalent stiffness method to calculate the equivalent length,axial stiffness and bending stiffness theory about the folded linear secant pile,and simulate the load-bearing characteristics of the folded linear secant pile with the Plaxis2 D analysis software.The main research contents and results are as follows:(1)It is believed after theoretical calculation that when the equivalent stiffness method is used for calculation,with the occlusion angle increasing the moment for the inertia of the element pile for the calculation unit will change,resulted the continuous reduction of the equivalent length of the calculation unit,The equivalent thickness increases,the axial stiffness value decreases,and the bending stiffness increases continuously.After numerical simulation with engineering cases and considering the occlusion angle,it is found that the bending moment of the pile is continuously reduced,and the maximum lateral displacement of the pile is continuously reduced,which is more favorable to the engineering design.Therefore,the author believes that the folded linear secant pile is better than the common linear secant piles.(2)This paper takes the foundation pit of a bridge pier in Lanzhou as the engineering background.After numerical simulation,it is considered that the bite angle of folded linear secant pile is not as large as possible.When the occlusion angle of the pile is between 25° and 35°,its bending load bearing characteristics are optimal.In addition,in this paper,the occlusion angle of the pile is used as a quantitative model to simulate and contrast the bearing characteristics of the pile under different pile diameters.The results show that the maximum horizontal displacement of the folded linear secant pile is less than that of the linear secant pile,so the folded linear secant pile retaining structure is more suitable for foundation pit projects where the surrounding environment of the foundation pit is more severe.(3)In the calculation of the equivalent "T" beam reinforcement bar of the meat-load pile,whether it is linear or folded linear,the effect of the element pile has greatly increased the area of the compression area of the "T" beam.After contrast the three different scheme: Pile retaining and supporting(without consideration of the element pile),the linear secant pile(considering the element pile),the folded linear secant pile(considering the element pile and the Angle of occlusion).The results show that the design scheme of the design of the folded linear secant pile is superior than the other two design schemes,with the minimum bending moment of the pile and The minimum reinforcement amount of the pile and the more safe for supporting structure...