Research On Earthquake Dynamic Experiment Of Micropiles Supporting Structure

Many west places of our country are in high earthquake intensity areas and seismically active areas,The issue of slope stability that is caused by earthquake is a important issure.The research of slope engineering seismic design is a urgent problem as our country is carrying out the strategy of “Western Development”and “the Belt and Road”. The micropile which is a flexible structure is a new structure of convenient construction and environment less impact,and that exist fine ductility. The micropiles can achieve a bending deformation and absorb a lot of energy and avoid brittle failure under earthquake action.So the micropiles are widely used in rescuing the earthquake.The issure that research on dynamic experiment of Micropiles is a important issure in slope engineering seismic design. The issure that research on the micropiles’ internal force characteristic under earthquake can lay a foundation of research on strengthening slope retaining structures’ seismic behavior and accelerate the issure of national earthquake prevention and disaster reduaction.This graduation thesis mainly depends on the natural science foundation of Gansu province and the scientific project of transportation construction in Qinhai province.The subject is 《 The landslide evaluation methods of earthquake and the research of new retaining structure of slope》 and 《Research on landslide treatment and slope prevention under Yushu earthquake in Qinhai province》.The herringbone micropiles and parallel micropiles is this graduation thesis’ s object. The graduation thesis researches the deformation features of slope and the earth pressure distribution,the internal force distribution,the deformation features of herringbone micropiles and parallel micropiles by large-size shaking table test and dynamic numerical simulation.The thesis draws a conclusion that the seismic bearing capactity and the anti-deforming capacity of herringbone micropiles is stronger than parallel micropiles. In addition, the graduation thesis utilizes seismic theory in hand to researche seismic design of micropiles.The main research conclusions are as follows:(1)The slope’s deformation begins with tensioned cracks in trailing edge of slope under earthquake,and The slope have more tensioned cracks than shearing cracks under earthquake.Tensile failure is a main failure modes of slope under earthquake. The horizontal earthquake action has a big effect on slope deformation.(2) The horizontal earthquake action has a big effect on earth pressure and internal force of micropiles.The Vertical earthquake action has a little effect on earth pressure and internal force of micropiles when the vertical earthquake peak acceleration is less than 0.4g, The Vertical earthquake action has a big effect on earth pressure and internal force of micropiles when the vertical earthquake peak acceleration is 0.4g or the vertical earthquake peak acceleration is more than 0.4g.(3) The hillside earth pressure of two kinds of micropiles is a “K” shape in the upper of sliding surface and inverted trapezoidal distribution under the sliding surface and the hillside earth pressure of sliding surface is max. The middle earth pressure of herringbone micropiles is trapezoidal distribution in the upper of the slip middle mass and a “K” shape under the slip middle mass. The middle earth pressure of parallel micropiles is trapezoidal distribution. The riverain earth pressure of herringbone micropiles is trapezoidal distribution. The riverain earth pressure of parallel micropiles is a “K” shape in the upper of sliding surface and inverted trapezoidal distribution under the sliding surface and the riverain earth pressure near the pile top is max. The hillside sliding surface earth pressure of herringbone micropiles is larger than parallel micropiles. The middle and riverain sliding surface earth pressure of herringbone micropiles is less than parallel micropiles.(4)The bending moment of two kinds of micropiles is a “S” line under earthquake. The shearing force of two kinds of micropiles is a “〉” shape under earthquake. The axial force of two kinds of micropiles is that one pile is tension and the other is pressure under earthquake. The bending moment of herringbone micropiles are greater than parallel micropiles. The shearing force of herringbone micropiles are less than parallel micropiles.The axial force of herringbone micropiles are less than parallel micropiles. The top displacement of herringbone micropiles are less than parallel micropiles.(5) The micropiles seismic calculation should consider vertical earthquake when the fortification intensity is more than nine.The seismic design of micropiles should enhance micropiles’ seismic concept design and increase micropiles’ seismic ductility.