Large Span Of Highway Tunnel Monitoring And Analysis Of The Stress State

With the rapid development of transportation demands as well as the long and large tunnels constructed both at home and abroad, bell-mouthed road tunnels with large-span appear one after another in the urban transportation. Due to the tunnels' large span, more and more engineering problems are aroused, such as supporting forms, construction methods, and stability of surrounding rocks. So far, there has been very little research on large-span tunnels, let alone the related engineering experience on bell-mouthed road tunnels with large-span. As a result, stress analysis and monitoring measures of surrounding rock on bell-mouthed section with complex stress state are more important. Combined the Fu Long tunnel of Shen Zhen, the stress and the displacement of the bell-mouth's surrounding rock and the supporting structures are studied by theories analysis, field measurement and numerical simulation , and the data of monitoring measures are analysed and feedbacked. The main research is as follows:(1) Use of elliptical holes of the elasticity theory, the two secondary stress conditions of the ellipse-shaped tunnels' surrounding rock are summarized, and the tunnel surrounding rock of Fulong road are analyzed. This is the foundation of the stability judgement and monitoring measure.(2) According to the surrounding rock stress and displacement, the section of two monitoring measure are ascertained, and the project of monitoring measure are defined, this is arch crown settlement,level convergence,the displacement of internal rock,the stress of anchors,the stress of reforced steels, which are monitored the rock displacement and the stress of surrounding rocks during the construction process.(3) Based on the anlysis of the arch crown settlement settlement as well as level convergence date, the support time of quadric liner is reasonably produced; Use multi-spot displacement meter to detect the internal displacement of surrounding rocks, the loose scope is determined; determine the stress of anchors condition by using the anchor rod tachometer; monitor the stress of reforced steels by using steel bar tachometer. All of these monitoring results work to gain information feedback and provide construction guidance as well as engineering experience of its kind.(4) Establish a 3-D model of the broadened segment of the bell-mouth, and analyze the stress and strained condition of surrounding rock, confirming together with the monitoring data.