"Bridge Construction And Integration" Structural Pile-soil-superstructure Seismic Response Study

At present,in the design of the railway station room,the "bridge construction and integration" structure is often adopted.To put it simply,the ?bridge-in-one? structure means that the upper station building of the station is directly supported on the pier of the lower expressway or railway beam,thus forming a comprehensive structure with efficient operation,close connection and interaction.In the "bridge construction and integration" structure system,the vibration load caused by subway operation,vehicle passing and earthquakes will affect the vibration response of the upper structure and the lower pile foundation.Especially in the event of an earthquake,it is easy to cause soft soil,sand liquefaction and large displacement,so that the bearing capacity and side friction resistance of the soil are reduced,thereby causing the pile foundation,buildings and the like to break.This paper takes the new bridge building structure system of Kunming South Railway Station as the engineering background,and focuses on the seismic response characteristics of the pile-soil-structure interaction of the ?bridge construction and integration” structure under the liquefiable field.The specific research contents,methods and results are as follows:1.Shaking table test of pile-soil-superstructure scale model for liquefiable fieldSelecting the representative pile foundation form of "Kunming South Railway Station",based on the typical characteristics of the "bridge construction and integration" structure,learn from the experience of pile-soil-structure shaking table test design of liquefiable field to determine the prototype structure and model.The structural similarity relationship,test loading conditions,measuring point arrangement and soil layer design,through the production of model structure and setting boundary conditions,successfully realized the pile-soil-structure interaction under dynamic load input.2.Simplified calculation of bridge structure and building structure qualityThe ?bridge construction and integration? structure integrates the bridge and the building into a whole structure,so as to make the model structure and the prototype structure have similar working characteristics as much as possible,and ensure that the model structure reflects the true and reliable damage situation and dynamic response law.The design experience has simplified the bridge and building structure in the prototype structure(ie,the bridge and building structure are simplified to the calculation of the weight).The results show that the different weights and the number of pile foundations are the main factors affecting the dynamic response characteristics of the structural system.3.Test analysis of pile-soil systemBased on the completed shaking table test,the pile-soil system systematically analyzes the pore water pressure,pile-soil contact pressure and acceleration time history of the liquefied sand layer under the action of different magnitudes and different types of seismic waves.The analysis shows that the closer the pore pressure is to the base of the pile,the smaller the trend along the direction of the pile body.The pore pressure at the junction of the sand layer and the clay layer becomes smaller due to the absorption of part of the water by the upper clay,and the maximum peak pore pressure is At a distance of 0.35 m from the bottom surface of the model box(ie,the bottom position of the pile),the minimum peak pore pressure appears in the transition region between the liquefied layer and the non-liquefied layer.The sand layer has a weakening effect on the input seismic wave.The sand of different depths is subjected to different degrees of liquefaction under the action of seismic load,and the liquefaction effect of sand along the lower part of the pile is more obvious.The pile-soil contact pressure increases with the increase of the magnitude,and a large shear force is likely to occur in the middle of the pile and the bottom of the pile.4.Test analysis of pile-structure systemThe acceleration peak amplification factor has an "S" type distribution,and the different weights at the top of the structural pier body have an effect of increasing the acceleration due to the inertial force.The displacement peak distributions of the four different pile structures have similar variation laws,that is,the increase of the loading magnitude will increase the displacement of the model structure,and the displacement peaks of the four model structures always maintain the size relationship of CT9>CT5>CT4>CT3.At the same time,the clay layer has a larger binding force on the pile foundation model with more piles than the pile foundation model,which is opposite to the inertial force effect generated by the mass block,which can inhibit the displacement of the upper structure from increasing to some extent..