某浅埋土质隧道的衬砌静力分析和动力响应研究

Finite Element Simulation Analysis of Static and Dynamic Response Characteristics on Shallow Soil Tunnels

浅埋砖砌土质隧道存在衬砌强度低、地下水渗透等问题,结构易遭到破坏。为合理评估隧道的稳定性及灾害影响,研究中采用midas GTS NX软件建立了详细的二维、三维数值模型,分别进行地层结构分析和线性时程分析,并结合砌体结构设计规范对衬砌的承载力进行验算。主要结论如下:稳定性分析中,砖衬砌中各部位强度满足受压和抗剪承载力要求,除侧墙和底板外的结构点均满足抗震承载力要求,拱顶的抗震承载力接近抗震承载力设计值,判定不利位置为拱顶及侧墙底。在地震作用下,隧洞周围土体塑性区向斜上45°发展,塑性区范围随时程不断增大,侧墙底及顶拱出现应力集中;隧洞竖向、水平位移最大点分别出现在拱顶和侧墙底;Mises应力和最大剪应力从隧洞中部到两端递减,顶拱应力远大于侧墙;隧洞两端加速度较大,拱顶加速度数值随时程变化大于其余部位。判定衬砌最不利位置位于拱顶45°附近及侧墙底部。

The shallow buried brick earth tunnel is easy to be damaged due to the low lining strength and groundwater penetration.In order to reasonably evaluate the stability and disaster impact,midas GTS NX software was used to establish two-dimensional and three-dimensional models,for the formation structure analysis and linear time history analysis,and combined with the design specification of masonry structure to check the bearing capacity.The conclusions are as follows:the strength of all parts of the brick lining meets the requirements of compression and shear bearing capacity,and the seismic bearing capacity of all structural points except the side wall and floor meets the requirements.The seismic bearing capacity of the arch is close to the design value of seismic bearing capacity.In the stability analysis,it is determined that the unfavorable position is the arch and the bottom of the side wall.Under the earthquake,the plastic zone develops 45°upward,and the plastic zone range increases at any time,the stress concentration appears at the bottom of the side wall and the top arch.The maximum points of vertical and horizontal displacement of the tunnel appear in the vault and the bottom of the side wall respectively.The Mises stress and maximum shear stress decreased from the middle to both ends of the tunnel,the stress was much greater than that of the side wall.The acceleration at both ends of the tunnel is larger,and the acceleration value at the arch varies more than that at other parts.It is determined that the most unfavorable position of the lining is near 45°of the vault and the bottom of the side wall.