Stability Analysis Of Micropile-Slope System Considering Pile Plastic Deformation

Micropile is a type of small diameter drilling pile constructed by strong reinf orcement and pressure grouting with pile diameter between70and300mm and bi g slenderness ratio.There exists less researches about anti-slide mechanism and st ability analysis of micropile structural system which seriously behind constructio n practice. Therefore, it is a frontier pressing task to carry theoretical research on anti-slide mechanism and stability analysis of micropile-slope system.This paper firstly introduces the current research about micropile home and abroad, proposes slope stability numerical method considering pile plastic deformation and studies the anti-slide effect of micropile system independently applied in soil slope and a group of piles structure. In the end, the calculating method of micropile structure is proposed based on FEM. Following achievements are obtained through the study:(1) According to the failure mechanism of micro piles reinforced slope, it gives a new method of safety factor for Micro pile-slope system which base on moment ultimate bearing capacity of micro piles, that is in the micro piles as elastic-plastic materials situation, we use field control variables to achieve strength reduction by finite element of soil slope, and ultimate moment that the bending moment does not exceed is the critical point of the slope safety factor. Analyses calculation results that Micro-piles consider two kinds of elastic-plastic and elastic, it show that the safety factor will indulge in dangerous in the case of micro piles as the elastic material and the safety factor will be more reasonable in the case of micro-piles as the elastic-plastic material.(2) The comprehensive analysis of the micro-pile designed alone is carried out. which mainly consider the effect of the pile spacing, the position of the pile and the incline of the pile on the stability of the slope. The results show that the safety coefficient of the slope decreases with the increase of the pile spacing. At the same time, the plastic zone before and after the pile appears the regionalization. The safety coefficient increases with the decrease of the pile spacing, but the large slenderness of the micro-pile is easy to cause the large horizontal displacement. The bending moment appears the bending moment in two direction, which appears "S". For the arranged location of the pile, the middle of the slope is reasonable.(3) Micro-pile group pile composite structures which is commonly used in engineering, for example,2X2micro-pile group pile, points plus tie beam and without the tie beam both cases. I have established a calculation model to analyze the internal forces and slope stability. The results show that link beam settings can effectively control the deformation of the slope, but limitedly improve the safety factor of the whole slope. Pile body tilted arrangement is conductive to slope stability, and improve safety factor, it has a significant effect to control the slope of the maximum horizontal displacement, and found that the tilted arrangement of the maximum horizontal displacement within a certain distance before the pile, but when we arrange the micro-pile vertically, the maximum horizontal displacement will between the piles.(4)I want to raise a finite element design calculation process which considers the pile elastic-plastic micro pile reinforced slope system. The method can compensate for the deficiencies of traditional methods, and guide on practical engineering.