Computation Theory And Application For Micro-Piles Based On P-y Curves

Micro-piles are used in sphere of post-earthquake repair, deviation rectification and reinforcement of the old building foundations,etc, and its application history is over half a century. Though micro-piles are widely used in actual engineering, as a type of piles, its functions in bearing horizontal load did not get to play. In the 1980s, China started tests and researches on micro-piles, although there are many application examples, and good effects are achieved, little application researches have been conducted in slope engineering, and theory system has not formed. Application and development of micro-piles are trapped by hysteretic design theory of micro-pile to some exent,so theoretical research on micro-piles is highly necessary, the paper mainly focuses on the design theory of micro-piles under lateral load.(1) The application and development status of micro-piles at home and abroad are introduced, and the existing micro-piles are classified in detail, the mechanism of skid resistance, applicable conditions and characteristics of various micro-pile structures are summarized; which leads to the 3×11 micro-pile composite structure discussed in this paper.(2) The exsiting calculation theory of p-y curves and the characteristics of the micro-pile composite anti-slide structure are analyzed, based on which the calculation method of the micro-pile composite structure basing on p-y curves is put forward, including the determination of the p-y curves for different soils, and the calculation method for internal force of piles,etc.(3) Experimental research on 3×11 micro-piles composite structure connected by frame beam is conducted through indoor model test according to similarity theory, the mechanism of skid resistance and stress characteristics of the composite structure are researched, the regularity of structural internal force and the possible failure modes are explored. Furthermore,comparative analysis is made on the theoretical and experimental results basing on p-y curves.(4) The model of micro-pile frame structure is analyzed using numerical analysis software Midas,and the theoretical result,the model tests results and the simulation result are compared,the reasonable result is drawed,which proves the reasonableness and the validity of the theoretical methods to some extent.