Research Rigid Pile Composite Foundation For Expressway Research On Bearing Characteristics Diseases

Since the establishment of the Xiongan New Area,To promote the development of male Xiongan New Area,improve the demand of the highway,in central Hebei Province,Rongwu highway as a contact Beijing-Tianjin-Hebei Region began to build high-speed channel,due to the project scope distribution along a lot of soft soil layer,the project’s construction process has to face in the deep soft soil foundation in the process of the construction of a highway,as a new type of foundation treatment technology,Rigid pile composite foundation has become one of the most commonly used measures to deal with soft soil foundation in the process of expressway construction.Based on the actual working conditions of Rongwu expressway,the working characteristics of rigid pile composite foundation are analyzed through field experiment combined with numerical simulation.The main research results and contents are as follows:(1)By referring to the relevant literatures of rigid pile composite foundation,the progress of theoretical research,engineering practice,numerical simulation and laboratory test at home and abroad is summarized,and the shortcomings of the existing theories are briefly analyzed.The reinforcement mechanism and load transfer mechanism of rigid pile composite foundation are introduced.(2)In the field experiment,the pile top pressure,soil pressure between piles and grid strain of rigid pile composite foundation are monitored by embedded pressure box and flexible displacement meter.It is found that the pile top pressure,soil pressure between piles and grid strain increase with the increase of filling height.After filling,the pile-soil stress ratio decreases with the increase of pile spacing.Under the same pile spacing,the pile-soil stress ratio at the center of embankment is the largest,and the pile-soil stress ratio at the shoulder is the smallest.(3)In the field experiment,the settlement amount and total settlement amount in the reinforced area of rigid pile composite foundation were monitored by the embedded settlement instrument of 14 m and 30 m.It was found that:(a)the settlement amount in the reinforced area accounted for 20%-30% of the total settlement amount,and the settlement mainly occurred in the lower layer;(b)After the completion of the filling,the settlement growth rate in the post-construction monitoring period is 10%-20% of that of the subgrade filler;(c)After the pile reinforcement,the uneven settlement in the reinforcement area is effectively controlled.(4)The ABAQUS software was used for numerical simulation,and the analysis found that:(a)Settlement rates at various points on the surface of the foundation were different,with the largest settlement rate at the line in the subgrade and the smallest settlement rate at the shoulder.(b)The maximum horizontal displacement occurs at the foot of the slope;(c)The pile axial force increases with the increase of the filling height.At the same filling height,the pile axial force at the center of the roadbed is the maximum,and the pile axial force at the shoulder is the minimum.(5)The influence factors of rigid pile composite foundation are analyzed by ABAQUS software.It is found that:(a)the increase of pile length,pile modulus and grid modulus will increase the pile-soil stress ratio and pile axial force,and reduce the settlement of composite foundation;(b)The increase of cushion thickness and the installation of pile cap will reduce the upper load borne by the pile.