Research On Static And Dynamic Responses Of Utility Tunnel With Different Section Forms

As a new public infrastructure formed by arranging multiple municipal pipelines in a unified underground space,the utility tunnel will play an important role in the rapid development of our economy and society.The form of the cross section of the utility tunnel directly affects the safety and cost of the use of the utility tunnel.The Ministry of Housing and Urban-Rural Development issued the "Technical Guidelines for the Construction Planning of Urban Underground Utility Tunnel" in June 2019,which stipulates from a technical point of view the section form of the utility tunnel that should be used for different construction methods,but the relevant design standards are not yet clear.The forces and deformations of utility tunnel with different section forms in actual engineering vary according to different working conditions,so the selection of the section of the utility tunnel should comprehensively consider the effects of various factors.Based on a utility tunnel project in Shijiazhuang,Hebei Province,this thesis selects common single-cabin utility tunnel structure with circular,rectangular and arched sections on the premise of the same cross-sectional area of the pipe corridor.First,the vehicle load is simplified to uniform distribution.The load is based on the vehicle load,buried depth and elastic modulus of the soil as changing parameters.Static models of interaction between single homogeneous soil and three utility tunnels are established by ABAQUS finite element software.The thesis analyzes the effects of changes in vehicle load,burial depth and soil quality on the static response of the utility tunnel,and compares the distribution laws of stress and displacement of the utility tunnel in three sections in different working conditions.Then,the thesis establishes dynamic models of interaction between single homogeneous soil and three utility tunnels under the action of El-Centro wave and artificial wave by ABAQUS,analyzes the effects of changes in ground motion characteristics and seismic peak acceleration on the dynamic response of the utility tunnel,and compares the distribution laws of stress,displacement and acceleration of the utility tunnel in three sections under different earthquakes.Through those analysis,some following main conclusions are obtained:(1)Under the effect of vehicle load,the stress and displacement of the utility tunnel increase with the increase of vehicle load,decrease with the increase of burial depth,and increase with the hardening of soil.The stress and horizontal displacement of the utility tunnel increase with the increase of the peak acceleration of the earthquake,while the acceleration amplification factor is basically unchanged.(2)When there is no vehicle load,the stress extreme value and vertical displacement extreme value of the circular pipe gallery are the smallest.Under the load of the vehicle,the stress of the superstructure of the arched utility tunnel is smaller than that of the circular utility tunnel under the same working condition,the stress of the lower structure of the rectangular utility tunnel is smaller than that of the arched utility tunnel.The stress extreme value and vertical displacement extreme value of the circular utility tunnel are the largest,the rectangular utility tunnel is the second,and the arched utility tunnel is the smallest.The circular utility tunnel has the largest horizontal displacement extreme,followed by the arched and the rectangular utility tunnel.(3)In the same working condition under the action of earthquakes with different peak acceleration levels,the arched utility tunnel has the largest stress extreme value,the rectangle is the second,and the circular utility tunnel is the smallest.The circular utility tunnel has the highest horizontal displacement extremes,the arched is the second,and the rectangular is the smallest.The acceleration amplification coefficients of the three utility tunnels are not much different.The closer to the top of the utility tunnels,the stronger the displacement response.The closer to the bottom of the utility tunnel,the stronger the acceleration response.The above conclusions are consistent with the existing research results,and can provide a reference for the selection of the section of the comprehensive pipe gallery in actual engineering.