Internal Force Analysis Of Precast And Cast-in-site Utility Tunnel Structure

Major cities in the transformation of public facilities and additional lines become common,electricity,communications,radio and television,water supply and drainage,heat,gas and other municipal projects also need to be more standardized layout.The traditional pipeline direct burial way has many drawbacks,need to be solved.The use of underground utility tunnel is becoming another way to solve the problem of urban public facilities layout.Urban underground utility tunnel to solve the road repeated excavation collapse,overhead line network intensive,land tension,urban beauty and other issues.Has long been subject to technical,financial and other reasons hinder the development of utility tunnel.The State Council in 2020 to complete the construction of a number of perfect underground utility tunnel system,2015,2016 has published 25 pilot cities,marking the full start of the underground utility tunnel pilot project.In order to complete the construction of a number of perfect underground utility tunnel system in 2020,the Ministry of Housing and Urban-Rural Development of the People’s Republic of China in 2015,2016 has published 25 pilot cities,marking the full start of the underground utility tunnel pilot project.Utility tunnel is divided into two categories,precast utility tunnel and cast-in-site utility tunnel.In this paper,the two kinds of construction methods,in a variety of conditions under the comparative analysis of the internal structure of the utility tunnel.Through the three-dimensional numerical simulation software to establish the model,the precast utility tunnel and the cast-in-site utility tunnel in a number of cases under the comparative analysis.Get the following conclusions:(1)On the homogeneous foundation,the internal force of the precast utility tunnel structure is smaller than that of the cast-in-site utility tunnel structure,and Internal force difference is small.On the longitudinal nonuniform foundation,the internal force distribution of the precast utility tunnel structure is similar to that of the cast-in-site utility tunnel structure,and the internal force of the precast utility tunnel structure is too large.It can be seen that the internal force of the precast utility tunnel structure is relatively larger.In the transverse uneven foundation,the internal force of the precast utility tunnel and the cast-in-site utility tunnel structure has a great influence,and the internal force value is similar,and the overall internal force of the cast-in-site utility tunnel is slightly larger.(2)Under the action of the vehicle,the internal force difference between cast-inplace utility tunnel and precast utility tunnel on homogeneous foundation is smaller,precast utility tunnel overall internal force slightly larger.The heterogeneity of the foundation has a greater effect on the precast utility tunnel,which has obvious influence on the axial force.The precast utility tunnel is mainly enlarged in the longitudinal direction along the length of the utility tunnel,and the apparent increase in axial force is the connection between utility tunnel,where the prestressed steel strand is subjected to axial tension.Under many working conditions,the internal force of the four edges of the utility tunnel is big,and it is easy to cause damage,so in the design and production need to strengthen the reinforcement,for reinforcement.