Research On Bearing And Deformation Mechanism Of Inclined Pile Under Horizontal Load

Because of its good horizontal bearing performance,inclined pile is gradually applied to foundation reinforcement engineering and foundation pit support engineering.At present,the research is mainly carried out on sandy soil foundation,and the research on bearing performance and construction in soft soil area is less.In this paper,the deformation,stress characteristics and bearing mechanism of inclined foundation pile and inclined retaining pile under horizontal load are analyzed by field test and finite element simulation,which can provide reference for the design of inclined pile.Then,the pile driving resistance is analyzed by field test,and the empirical formula of pile driving resistance of inclined pile under static pressure in soft soil area and the matters needing attention in related application are put forward.Finally,the feasibility of the application of inclined pile is discussed through an application case.The main conclusions are as follows:(1)The horizontal bearing performance of inclined pile is closely related to the properties of foundation soil.In soft soil foundation,whether inclined pile combination or single pile,the bearing performance of negative inclined pile is better than positive inclined pile,and the bearing performance is negatively correlated with the inclination angle,which is similar to the law of horizontal displacement of pile top in sandy soil foundation;The Q-S curve is the rising stage of the parabola with the opening upward,and the slope of the curve increases gradually with the load increases.The deformation of pile body is similar to that of vertical pile,and there is influence depth.The worse the bearing capacity is,the deeper the influence depth is;The negative inclined pile is easy to produce reverse bending at the lower part of the pile body;When the positive inclined pile is subjected to the horizontal load of the pile top,the magnitude and position of the maximum bending moment and axial force of the pile body have little correlation with the inclination angle,but have a positive correlation with the load,and the position of the maximum load increases slightly to the pile bottom,about L / 3 from the pile top;The maximum bending moment and axial force of negative inclined pile are negatively correlated with the inclination angle,and the change with load is similar to that of positive inclined pile;The resultant force of side friction of pile body is upward for positive inclined pile and downward for negative inclined pile,which is related to the bearing performance;When the negative inclined pile is subjected to the horizontal load on the top of the pile,the soil on the back side of the pile rises and the loading side sinks.The influence range on the horizontal plane is in the shape of "8",and the bearing performance is positively correlated with the influence range;The positive inclined pile is characterized by the settlement around the pile.The greater the inclination angle is,the greater the settlement is.The rest are similar to the negative inclined pile.(2)The inclined piles combination with the same inclination will play a synergistic role under the same load at the same time,and the deformation is relatively similar,but the deformation is larger than that of a single pile,and the superposition effect can not be ignored.So when carrying out the pile bearing capacity test with the unexcavated foundation pit project,it is necessary to interval an appropriate distance to eliminate the mutual influence;The pile deformation of inclined pile combinations with different inclination angles under the same load is similar,the pile deformation under the opposite load is reduced compared with that under the single load,and the bearing performance of different inclined pile combinations with the same included angle is different under the same load.(3)The inclined static pile pressing method needs to check whether the pile bending moment meets the requirements under the conditions of different pile length,inclination,density and clamping position.This paper puts forward the control formula for the selection of equipment and pile type for the first time;The penetration resistance of oblique static penetration test is generally 1 ～ 2 times that of traditional test,and the law of pile pressing force is similar to it;The static pressure construction of inclined pile not only can construct large angle inclined pile,but also has the advantages of safe,efficient and high precision.It has good effect and great prospect when applied to urban geotechnical engineering support.