Analysis Of Uplift Performance Of Stiffened Micro-pile

Micropiles have merits of higher speed for construction, less occupancy for construction,and higher bearing capacity, and greater adaptation to any type of soils.It is widely used in tower base, ancient building protection and slope stability, etc.Stiffened micro-pile in design for resistance to pull out pile can hold concurrently do compressive strength of pile, this makes it have great advantage in foundation of minitype soaring tower (Bear tension and compressive load alternately)Because of Stiffened micro-pile diameter small, length-diameter ratio of pile is larger, belong to Elongated pile,stiffness of pile is low. And the resistance of tension piles skin friction concentrated in the lower part,along with the stiffness of pile reduced gradually,also skin friction gradually play from the top to the bottom increasingly obvious, the bearing capacity of pile endpoint department is difficult to play when it reach limit bearing capacity of Elongated pile. Second high-pressure grouting can significantly improve performance of foundation, it can improve bearing capacity of pile foundation. Because the length-diameter ratio of micropiles is larger, pile skin friction is larger, in the process of load transfer from the top to bottom of the pile, the pile will crack from top to bottom when pile axial force achieve a certain value limit, it will further increase the pile body deformation. While making pile body relative displacement of the pile-soil become larger, lower pile-soil relative displacement smaller. micropiles is easy to crack when it bear larger load,this will further enlarged micropiles deformation.It is different to traditional micropiles, stiffened micro-pile with pipe steel or form steel piles instead of traditional reinforcing cage, It is can effectively decrease the pile deformation, meanwhile, improving the bearing capacity of pile resistance to pull.On the basis of summarizing the predecessors'research, simulation analysis of the influence of bearing capacity of micropile length, rigid materials,grouting soil by FLAC3D program.Through the experimental study and numerical simulation predecessors we can found that rigid materials can limit micro cracks of pile body development, reducing pile deformation, easy to pile load transfer from top to bottom; Grouting soil and rigid materials work together make micro-pile uniform trend of axial force, it is beneficial to pile skin friction and body, improve stiffened micro-pile capacity.