Numerical Research On The Interaction Between Abutment,Slab And Soil Of Seamless Bridge

The setting of expansion joints and device in the bridge engineering can meet the requirements of bridge deformation,but the expansion device damaged easily in the long-term exposure to the environment.Moreover,its maintenance and replacement cost a lot of manpower,material resources and financial resources,still has not been worked out satisfy the deformation and economic and durable expansion device,therefore bridge experts put forward the concept of seamless bridge.At present,the application of seamless bridge has been very common all over the world.However,due to the complexity of structure-soil interaction,the design calculation of seamless bridge is still based on experience,and no mature design standard has been formed.In this Thesis,ABAQUS was used to carry out numerical simulation for the interaction of integral abutment,slab and soil.In addition,the new Z-shaped slabs proposed by Professor Chen Baochuan’s team in Fuzhou University were studied,and the model calculation and comparative analysis were carried out between the new Z-shaped slabs and the traditional slabs and inclined embedded slabs.And the influence of the horizontal displacement of ±30mm on the mechanical characteristics of the integral abutment,piles and slabs is studied.Finally,the backfill was classified according to the properties of the soil and the inclination angles of the inclined slab were set at 0,15,30,35 and 45 degrees.Then the interaction models of the Z-shaped slab-soil were established respectively to study the effects of different inclined plate angles and backfill settings on the vertical displacement of the embankment and the pavement smoothness.At the same time,the variation of the combined stiffness of slab-soil with the angles of inclined slabs is also analyzed.The main conclusions of this Thesis are as follows:1)The internal force of seamless bridge abutment and pile foundation with Z-shaped slabs is small,and the vertical displacement of slabs is also smaller than that of the other two slabs,indicating that it can better transfer the longitudinal bridge expansion and transferred from the main girder to the backfill and wiring roads.However,a large horizontal stress appears at the joint of the slabs and the integral abutment.2)The internal force of integral abutment and pile foundation increases with the increase of pile diameter,and the change of pile diameter has little effect on the horizontal stress and vertical displacement of slab.The absolute value of horizontal stress is the largest at the joint of abutment and slab.3)For the backfill of the lower part of the upper slab,the soil with large elastic modulus should be set appropriately to analyze the influence to structure stress of the change of pile length.It is concluded that the horizontal compressive stress of the slab is observed when the slabs are pushed in X direction,and the horizontal stress at the joint position of the slab and the main girder is very small,and the maximum value appears at the end of the slabs.In the case of unidirectional tension,the slabs are subjected to horizontal tensile stress,and the stress at the joint of the slabs and beams is the largest,while the stress at the end of the slabs is very small.The bending moment of the beam end is very small when the beam end is pushed in X direction,and larger when the beam end is pulled in X direction.Because of the layered soil around the pile,the influence of pile length on the stress of pile foundation is not very regular.4)The maximum stiffness of slab-soil combination is obtained when the inclination angle of inclined plate is between 35 degrees and 45 degrees.On the design of Z-shaped slabs,under the condition of meeting other design conditions,the inclination angle of inclined slabs should be as large as possible.When the backfill distribution of seamless abutment with Z-shaped slabs is carried out,it is suggested that materials with small elastic modulus should be used in the lower area of upper slabs as far as possible(such as: sand,embankment filling,etc.),and the upper area of the lower slab should try to use linear elastic materials with large elastic modulus(such as:cement-stabilized macadam,foamed concrete,etc.).