Numerical Simulation Of Centrifuge Model Test On Coupling Characteristics Of Bridge Approach

Subgrade, bridges, tunnels, culverts and other structures are linked together to form a whole line. When the train runs between the rigid bridge and soil embankment, it will easily cause the ride comfort problems because of stiffness and deformation properties differences between these two kinds of structures. The diseases occurred at the embankment and bridge connection are the most serious and complicated, it is the weakest link in the line. How to make the settlement between the bridge and embankment transit uniformly has been the most difficult railway construction problem. Through literature reviewing, we find that in the past bridge and approach would be considered as two different separate structures, the study focused on one aspect, and the overall performance of bridge and approach was not evaluated comprehensively. Therefore, road and bridge is discontinuous because of lacking of a unified design control parameter standards. In view of this, under the support of the transition technical measures project of the different structures in high-speed rail, the centrifuge model tests of bridge-approach were conducted. Based on the results of centrifuge model tests, numerical simulation of centrifuge model test on coupling characteristics of bridge-approach was completed. The conclusions are followed:(1)The approach settlement versus time curve can be predicted by s-shaped growth Weibull2model. The created three-dimensional simulation model to analyze the interaction of two different structures characteristic of technology route is feasible;(2)Because of low strength, great instantaneous settlement will be generated with abutment tilting toward the backfill. In soft ground for the actual project should take preloading consolidation and other means of drainage, after improving the foundation strength, the abutment and approach are constructed to reduce the instantaneous settlement of the foundation and abutments gradient.(3)The bridge-approach settlement increases gradually with the increase of the center to center spacing of the piles. Farther away from abutment, smaller the approach settlement slope is. Therefore, transition section of the pile foundation treatment should adopt the design method of changing pile spacing or pile length, focus on strengthening settlement control close to the back of abutment;(4)In the differential center to center spacing of the piles, there exists differential settlement at the abutment back, so the placement of approach slab is essential to transform the stepped settlement into continuous sloped deformation;(5) Large differential deformation of embankment will affect the reasonable structural stiffness (the late subgrade stiffness) matching problem of the line; on the other hand, the abutment angle and tilt direction, the horizontal displacement are directly related to convergence settlement value of the transition sections subgrade; The convergent settlement of embankment at the distance of20meters from abutment is proposed;(6)In order to coordinate the transition section differences in deformation of embankment and abutment, in the allowed range of abutment settlement, you can increase the bridge settlement appropriately, to reduce the slope of the bridge and subgrade surface slope, and make the design economic and reasonable.