Study On Horizontal Bearing Characteristics Of I-shaped Concrete Core Composite Cement-soil Pile

Concrete core composite cement-soil pile is a type of pile composed of precast rigid core pile and flexible cement-soil pile.This pile type integrates the advantages of both,not only low cost,green environment protection,but also can give full play to the strength of the material itself in the limit state.Based on the concrete core composite cement pile,this paper breaks the tradition of taking round pile and square pile as the cross section of the core pile,takes the special-shaped i-shaped precast concrete pile as the core pile,and puts forward a new pile type--i-shaped concrete core composite soil-cement pile.At present,the research on the composite pile mainly focuses on the vertical bearing characteristics,but the horizontal bearing characteristics are less studied.Through indoor scale test and ABAQUS finite element simulation analysis,this paper discusses the horizontal bearing characteristics of the composite pile under different influencing factors.The main contents are as follows:(1)The distribution of displacement,bending moment and rotation angle of I-shaped concrete core composite cement pile under horizontal load is analyzed by indoor model test.The results show that the critical load and ultimate load of the composite pile perpendicular to the flange are 52.4% and 54.7% larger than those perpendicular to the web.Under the same load,the horizontal displacement perpendicular to the flange direction is smaller than that perpendicular to the web direction.In the case of constant vertical load applied to the pile top,the horizontal displacement of the composite pile is reduced and the horizontal bearing capacity is improved compared with that of the composite pile without vertical load.(2)The effects of different width-to-height ratios,different vertical loads and different section types on the horizontal bearing characteristics of the composite pile are analyzed.The results show that five kinds of composite piles with different ratio of width to height are simulated by finite element method the ratio of the horizontal bearing capacity in the strong and weak directions of composite piles can be determined as an exponential growth relationship with the aspect ratio.According to the requirements of the horizontal bearing capacity in the strong and weak directions,the reasonable size of the core pile section can be designed.Through the establishment of the pile-soil model under different vertical loads,the calculation shows that under the same horizontal load,the pile The horizontal displacement of the top will decrease with the increase of the vertical load,and the influence is mainly obvious in the later stage of the horizontal load.Generally speaking,the vertical load on the top of the pile plays a favorable role in the horizontal bearing capacity of the composite pile;the horizontal bearing capacity of the square pile and the circular pile with the same volume as the I-shaped special-shaped core pile is designed and compared,and the results show that the Ishaped pile is the composite of the core pile The horizontal bearing capacity of composite pile in strong axis direction is about 30% higher than that of square pile and circular pile.It has certain bearing advantage to use this I-shaped special-shaped pile as core pile.(3)Based on the m method of single pile with horizontal load,the calculation method of horizontal bearing capacity of i-shaped concrete core composite cement pile is given,and the rationality of the calculation method is verified by combining the results of test and numerical simulation,so as to guide the engineering application.