Study On The Trapezoidal Cross-Section Vertical Pre-Stressed Anchor Anti-Slide Pile

In recent years,large-scale landslides have appeared continuously on the bank slope of the Three Gorges Reservoir,which is mainly caused by the instability of the bank slope resulting from the periodic immersion of the reservoir water.However,the conventional anti-slide pile structure being applied to control the newly formed landslide caused by flood damage can't produce an ideal result.To this end,this paper,based on the National Natural Science Foundation of China project,"Study On The Landslide And Disintegration Mechanism Of Dangerous Rocks In The Limestone Area"(Project No:51378521),and the major project of the Chongqing Municipal Science and Technology Commission,"Study On The Destruction Mechanism Of Soil-like Bank Slope During The Operation of The Three Gorges Reservoir"(Project No.:CSTC2013JJB005),and the authorized team invention patent "isometric trapezoidal section vertical prestressed a nti-slide pile"(Patent No.:CN104878770A) and through theoretical analysis and model test,systematically studies the new technology of the trapezoidal section vertical prestressed anchor cable anti-slide pile for controlling the large-scale landslide disaster in a reservoir bank slope.The main results achieved in this study are as follow:(1)The stress characteristics of the trapezoidal section vertical prestressed anchor cable anti-slide pile in the rigid or elastic mode are analyzed.The internal force and deformation calculation methods for the trapezoidal pile's under-load sections and embedded fixed sections under the parabolic load are analyzed.The related influencing factors of internal force and deformation are also analyzed.At the same time,this paper proposes a calculation method for trapezoidal diffusion angle and derives the formula for calculating the width of the trapezoidal anti-slide pile.(2)This paper analyzes the value range of the trapezoidal pile structure size,determines the calculation method of the sectioning line of the trapezoidal pile section,proposes two vertical prestressed structure layout forms of the trapezoidal section vertical prestressed anti-slide pile,and derives related calculation for mulas for parameters,such as structural reinforcement amount and reinforcement ratio respectively.At the same time,key construction techniques such as the top and bottom of the anchor cable and the acoustic tube are constructed in this paper.(3)With indoor models and 3D simulation model test,this paper analyzes the mechanical properties and the failure form of the trapezoidal section vertical prestressed anti-slide pile,proposes the law for the influence of the pile side angle change on the soil arching effect between piles,determines the value range for the safety factor of the trapezoid anti-slide pile,and derives the calculation formula for the failure surface.At the same time,the normal anti-slide pile model test with the same parameters was performed,and the results were compared with that for the trapezoidal piles.(4)This paper proposes the existence theory and failure mechanism for "double soil arch" of trapezoidal section vertical prestressed anti-slide pile,analyzes the characteristics of the influence different pile side angles have on "double soil arch",create the calculation model for "double soil arch",derives the calculation formula for reasonable pile spacing,analyzes the influence of pile side angle on pile spacing and the designed value range of pile side angle,and determines the optimal angle value for the "double soil arching effect".(5)Two groups of piles designed with double-row trapezoidal piles and double-row ordinary piles respectively were applied to the landslide control project for the Three Gorges Reservoir,and the application effects and the engineering costs of the two designs are compared from the economic perspective.The practicability and the economic value of the trapezoidal section vertical prestressed anchor cable anti-slide pile are furthur analyzed.The main innovations are as follow:(1)The trapezoidal section vertical prestressed anchor cable anti-slide pile is a new technology for controlling large-scale landslide disaster on the reservoir bank slope.It is a new type of stressed structure with independent intellectual property rights.In past researches,the trapezoidal vertical prestressed structure has not been studied.This paper studies this new technology for controlling flood damage landslide.(2)This paper proposes the theory of "double soil arch" for trapezoidal section vertical prestressed anchor cable anti-slide pile,analyzes the under-load characteristics and force transmission mechanism of "double soil arches",and demon strates key technical issues,such as the existence conditions,the failure mechanism and the reasonable pile spacing for "double soil arches".(3)Using a analysis method that combines indoor model destructive tests and 3D soil arching effect model tests with theories,this paper reveals the deformation and failure law for the trapezoidal section vertical prestressed anchor cable anti-slide pile,and analyzes the law for the influence of soil arching effect between piles of a trapezoidal anti-slide pile.(4)This paper establishes the calculation and design method for the trapezoidal section vertical prestressed anchor cable anti-slide pile,and solves core technical problems like the force calculation and structural design for a trapezoidal anti-slide pile.