Study On Bearing Characteristics Of Single Pile Under Combined Horizontal And Vertical Loads

With the development of engineering construction,the application occasions of pile foundations are more diversified,and the stress of pile foundations is becoming more and more complex.However,in practical engineering,the load borne by pile foundation was not a single direction load,but a combined load.For example,some wind farms,in addition to bearing the selfweight and vertical load of the superstructure,usually bear the horizontal load generated by waves,earthquakes and wind.However,the traditional calculation methods don’t have considered the interaction between horizontal load and vertical load.Therefore,the research on the bearing characteristics of the single pile under horizontal and vertical combined load could provided a basis for pile foundation design in the future,and has certained engineering significance.Based on a wind power construction project in Ye County,Pingdingshan City,this paper studies and analyzes the bearing characteristics of a single pile under horizontal and vertical combined load by using the methods of theoretical analysis,field test and numerical simulation.The main research contents and results were as follows:(1)By combing and analyzing the research status,bearing characteristics and calculation methods of a single pile under horizontal vertical combined load,the research results of pile foundation stress characteristics under horizontal vertical combined load were summarized.(2)Through the field test,the vertical bearing capacity of a single pile under the pre-applied horizontal load on the pile top was studied.The pre-application of horizontal load on the pile top increases the settlement of the pile top and weakend the vertical bearing capacity of a single pile.In addition,the pre-application of horizontal load on the pile top could promoted the exertion of pile end resistance but has little effect on the transmission law of pile axial force.The horizontal load on the pile top affects the vertical bearing performance of a single pile by reducing the exertion of the friction resistance on the upper part of the pile body,but its influence depth decreases gradually from below the ground.In this paper,the influence of the horizontal load on the pile side friction was mainly within 11 m below the ground.(3)Based on the field test,the horizontal bearing capacity of a single pile under the pre-applied vertical load on the pile top was studied.The pre-application of vertical load on the pile top reduces the horizontal displacement of the pile top and improved the horizontal bearing performance of a single pile.In addition,the pre-application of vertical load on the pile top reduces the maximum value of pile bending moment under the same horizontal load but doesn’t affected the distribution law of pile bending moment.(4)The bearing characteristics of a single pile under a combined horizontal and vertical load inhomogeneous clay layer were studied by numerical simulation.The preapplied horizontal load on the pile top weakened the vertical bearing performance of a single pile,and the pre-applied vertical load on the pile top improves the horizontal bearing performance of a single pile,but there was an optimal vertical load,which maked the lifting effect most significant.On the other hand,increasing the elastic modulus of soil around the pile,increasing the friction coefficient between pile and soil,and increasing the pile diameter could improved the vertical and horizontal bearing performance of a single pile,but the improvement degree of a single pile bearing performance by different influencing factors was not consistent.