地层环境对单拱大跨装配式车站结构力学性能影响分析

Influences of Stratum Environment on the Structural Mechanical Properties of Single-arch Large-span Prefabricated Stations

随着装配式车站在滨海城市的建设,软弱土体对车站结构力学性能的影响成为备受关注的问题之一。以深圳地铁某装配式车站为工程背景,采用Midas-GTS有限元分析软件,建立地层-结构模型,分析单拱大跨装配式车站的力学特征,探索不同弹性模量、泊松比、地层条件、覆土厚度对地下车站结构变形、受力及接头内力的影响和规律,对装配式车站结构的地层适应性提出理论依据和结构设计指导。结果表明:①在泊松比不变的情况下,弹性模量对车站结构力学性能影响较大,当弹性模量从15 MPa增大到60 MPa时,弯矩减小了44.58%;并且这种影响是非线性的,弹性模量在15~30 MPa区段变化时结构变形较为敏感,当弹模达到45 MPa以上时,敏感度下降;②地层条件对结构顶板跨中和拱脚支座内力影响较大,强风化地层相对填土地层拱顶弯矩减少了约29.62%,而对侧墙内力影响较小,对BC接头影响较大;③当装配式车站所在土层为填土时,BC接头弯矩冗余量非常小,在结构设计时需要对接头进行加强,或者对地层进行适当改良;④在硬塑地层中,当覆土厚度从3 m增加到5 m时,BC接头弯矩冗余量减少了35.37%,但接头冗余量均达到29%以上,接头的安全性储备较大,接头可靠。

The influence of weak stratum on the mechanical properties of prefabricated station structures in coastal cities has become a major construction concern.Therefore,this study considers a Shenzhen station with prefabricated structures as the engineering background,establishes a strata-structure model,and uses Midas-GTS finite element analysis software to analyze the mechanical characteristics of a single-arch large-span prefabricated structure.Additionally,it explores the effects of different elastic moduli,Poisson’s ratios,stratum conditions,and buried depth of a structure on the force and joint internal force of the underground station and provides a theoretical basis and structural design guidance for the structural adaptation of the prefabricated structure to the stratum.The following results showed that.First,when the Poisson’s ratio was constant,the elastic modulus had a significant influence on the mechanical properties of the structure.When the elastic modulus increased from 15 MPa to 60 MPa,the bending moment decreased by 44.58%,and the influence was nonlinear.When the elastic modulus was 15 MPa–30 MPa,the structural deformation was more sensitive.When the elastic modulus exceeded 45 MPa,the sensitivity to structural deformation decreased.Second,the strata had a greater influence on the internal force of the middle top plate span and bearing,and significantly strongly weathered strata reduced the bending moment by approximately 29.62%compared to that of the fill layer,while it had a smaller influence on the internal force of the sidewall and a greater influence on the BC joint.Third,when an underground structure was located in the fill layer,the internal force of the BC joint decreased.When the stratum layer was a fill layer,the redundancy of the BC joint moments was extremely small,and it was necessary to strengthen the joints or improve the geological features of the area appropriately in the structural design.Finally,under hard plastic stratum conditions,when the structure burial depth increased from 3 m to 5 m,the BC joint moment redundancy decreased by 35.37%;however,the joint redundancy reached more than 29%,the safety reserve of the joints increased,and the joints were reliable.